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QUANTUM CRYPT

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1. Total number of channel errors Total number of Dark Counts Quantum Channel s Status Finished Quantum Channel s result window Figure 9 3 Eurocontrol June 2004 116 9 2 HOW TO RUN SIMULATOR 117 Eurocontrol June 2004 Figure 9 4 Alice s Raw key ih 1010101101011 0010 111 0001 Figure 9 5 Bob s Raw key 117 118 SECTION 9 BB84 DEMONSTRATOR IN JAVA Eve s Status Constructing Error Corrected Key Figure 9 6 Eve s Raw key Kegs ess RTE Error Corrected Koy 1910101010111001110111111001011 Error Carrected Key EnTNTNNNINTTINNTTENTITTI TANIA I Bob s Status Constructing Privacy Amper Key Privacy Amplification Quantian Chan ae Alice s Status Settings Kesus Constructing Privacy Amplified Key LUE LUPLINIERC GATE TEE Tocal number of channel errors Total number of Lark Counts Settings Keysresutt Resums Error Corrected Key Re Quamum Channets Satu Finstad Focal number of tokens E DO s Hats Public Channel Status Cimsine ling Miray Aariplifierd Kany muse Figure 9 7 Result of Error Correction 118 Eurocontrol June 2004 9 2 HOW TO RUN SIMULATOR 119 Figure 9 8 Result of Privacy Amplification Eurocontrol June 2004 119 121 Acronyms APANPIRG APC APIM Air Ground Aeronautical Administrative Communications Aircraft Autonomous Inte
2. This satellite distributes an other quantum secret key K2 for AES Using the key K2 as the session key this satellite and AES establish a secure radio communication link COM2 The ATN Network and the AES negotiate a sharing secret session key by using secure communication links COM1 and COM2 As such in fact the single photon source satellite based QCKI can be considered as a satellite based QKD data relay system 84 Eurocontrol June 2004 6 2 SCENARIO OF QKD IN ATN 85 e Entangled photon source Ground based QCKI The transmitter of entangled photon pair is placed on GS Here one of the photons of the entangled pair is detected right at GS and thus the entangled photon source is used as a triggered source for single photons toward the AES see figure 6 9 Figure 6 9 Ground based QCKI with entangled photon source The satellite which acts as a quantum relay station can take part in this scenario see figure 6 10 Relay Figure 6 10 Ground based QCKI with entangled photon source This solution is not very different from the Single photon source Ground based QCKI page 82 Only the QKD technology is different Eurocontrol June 2004 85 86 SECTION 6 INTRODUCING QC IN ATN e Entangled photon source Aircraft based QCKI The transmitter of entangled photon is placed on aircrafts Here one of the photons of the entangled pair is detected right at this aircraft and thus the entangled photon source i
3. Section 4 Free Space and Satellites The development of physical techniques plays an important role in the growth of practical applications of Quantum Cryptography QC As you know one QC system contains at least one transmitter photon source one receiver detec tor and one quantum channel Fiber based links is one of two solutions for quantum channel the other is free space links Most of research so far use op tical fibers to guide the photons from Alice to Bob Although today s fiber based QC systems are very advanced such systems cannot work over the distance of 150km 30 due to the combination of fiber losses and detector noise more over fiber based links may not always be available due to some other reasons Hence there are more and more efforts in developing free space links where the photons are sent between remote telescopes The very first demonstration of free space QC system was a table top exper iment performed at the IBM Thomas J Watson Research Center in 1989 over a distance of 32cm 5 With the progress of technology the most recent result of a such system has achieved a distance of 23 4km 31 And the theoretical cal culations allow us to hope a free space communication up to 1600 km suitable for satellite based key exchange In this section we will see the state of the art of free space QC systems also the overview of satellite communications and networks for the estimation of possibility to apply QC in
4. 5 Internet Network and Transport Layers The three other ICAO Panels AMCP ADSP ASPP are also involved in the development of ATN 2 1 ATN Overview The ATN is a data communication network e It provides a common communication service for all Air Traffic Services Communication ATSC and Aeronautical Industry Service Communi cation AINSC Communications can be either Ground Ground or Air Ground e It integrates and uses existing communication networks and infrastruc ture if possible Investments in existing leased networks CIDIN and X25 networks must be preserved e It must meet security and safety requirements of ATSC and AINSC appli cations and accommodate the different levels of service required by each ATSC and AINSC application 18 Eurocontrol June 2004 2 2 CNS ATM 1 APPLICATIONS 19 e It must provide ATN users with a robust and reliable communication ser vice Its design ensures high availability because there is no single point of failure and because it permits multiple alternative routes to the same destination with dynamic switching between alternatives for both fixed and mobile communication e It must support mobile systems since an aircraft is basically mobile It must support a wide variety of mobile communication networks including AMSS VDL and Mode S It must be possible for any system to communi cate with an aircraft equipment all over the world The services provided by the ATN are implemen
5. At night Germany e 2km Ground Ground QC is equivalent to 300km Ground Space QC Theoretical results with the 2003 technology allow a 1600km distance Ground Space QC requires high standards expensive opto electronics and pointing acquisition and tracking apparatus Actual free space QC requires huge flexibility in the receiver due to active polarization control and data analysis Thus receiver is likely to stay on Earth Actual free space technology relies on photons beams which are sensible to weather conditions Further technologies may use different particles 8 Eurocontrol June 2004 Analysis and Scenarios The section 5 on page 57 studies what can be done with free space and satellite technology There are three possibilities each with its requirements and characteris tics As stressed earlier the better is to keep the receiver on earth The three possibilities are The ground station transmits a key to the satellite The satellite transmits a key to the ground station The ground station transmits a key to another ground station using the satellite as a mirror Average embedded payload is 5kg with a 10 to 30cm optics On Earth it uses a 50 to 100cm optics The size of the satellites network depends on the chosen payload and varies from 7 to 43 satellites Partial Conclusions Any improvement in AGT security must be done inside the framework of ATN and must not be too expensive Improving key
6. Tracking accuracy at the satellite is thus not as stringent gt 100 uR With such a wide field of view operation in daylight conditions may be impossible due to excess background light Reducing the detector field of view and pointing to better than 100 uR may be pre ferred When the field of view is less than 100 uR pointing ahead of the image of the ground based guidestar becomes important bo Satellite optics rotation stability The effective orientation of the satellite would be monitored by measuring guidestar polarization at the ground station and correcting at the ground Maximum distance At 1000 km range loss TL 0 00036 34dB for 10cm satellite optics and TL 0 00032 25dB for 30 cm diameter satellite optics assuming atmospheric transmission T 0 65 Setting the maximum loss tolerance at 35dB for security and error correction reason the maximum range is just 1100 km with 10cm satellite optics and gt 3000 km with 30 cm optics Expected key rates According to the formula _ RMT Lyn K 43 If there are a laser repetition rate of R 100MHz and M 0 1 photon per bit we obtain K 4500bits s at 1000 km and K 1000bits s at 2000 km for 30 cm satellite optics As for 10 cm optics this becomes K 450bits s at 1000 km Error rates and loss tolerance Background light errors could be a prob lem when transmitting from populated areas However limiting our selves to 35 dB maximum loss at maximum ra
7. of the Air Navigation Federal Aviation Administration Future Air Navigation System Facilities and Systems Implementation Document Fibre Distributed Data Interface Frequency Division Multiple Access Flight Information Centre First In First Out Flight Information Region Flight Information Services Flight Level Flight Management System Filed Flight Plan Flexible Use of Airspace Ground Ground General Aviation Ground Based Augmentation System Ground Data Link Processor GEOstationary orbit Ground Earth Station Eurocontrol June 2004 123 124 GICB GLONASS GM GNSS GPS GREPECAS GS GULS HF HMAC HMI HR IA IATA ICAO ICC ICC IDRP IEC IEEE IETF IFALPA IFATCA IFR II ILS IMC IMG INS IOC IP IPC IPR IRDP IRS IS ISDN ISO ITU JAA Kb LAAS LAN LAP LAP B LE LEOs 124 ACRONYMS Ground Initiated Comm B Global naya Navigatsionnaya Sputnikovaya Sistema Guidance Material Global Navigation Satellite System Global Positioning System Caribbean South American Regional Planning and Implementation Group Ground Station ISO Generic Upper Layer Services High Frequency 3 30 MHz Hybrid symmetric Hashed Message Authentication Code Human Machine Interface Human Resources Interconnection Agreement International Air Transport Association International Civil Aviation Organisation Inter Centre Co ordination Inter Centre Communications Inter Domain Routing Protocol
8. pute a result but they are not reversible providing the result it is impossible to recover the argument Cryptographic researchers have defined indexed families of one way function Providing a key K we name hxg the one way function indexed by K This method is similar to above mechanism but symmetric encryp tion algorithm Ex is replaced by a one way or non reversible func tion hx indexed by the previously shared key K A B rp 7 4 A gt B ra hg ra rB B 7 5 A B hg ra rB A 7 6 e Authentication by public key techniques Public key techniques may be used for authentication based identification Each participant has a public key known by every other participant and even known by the eavesdropper The public key allows to encrypt mes sages But decryption is only possible with the private key which is only known by the participant In public key technique a participant demonstrates the knowledge of its private key without disclosing it Because the participant is the only one knowing its private key this is a sure identification This can be done in one of the two following ways 1 Authentication based on public key decryption P4 and Pg denote the public key encryption algorithms of participants A and B his a one way hash function ra and rg denote random numbers produced by A and B Consider the following protocol A B h ra Pa ra A 7 7 A B h rp Pa ra rp 7 8 AB rp 7 9 A
9. ATSC ATSU AWOP BIS BNS CNS CNS ATM CNS ATM 1 CNSI COCESNA COG COTP COTS 122 ACRONYMS Africa Indian Ocean Planning and Implementation Regional Group Approach Aeronautical Radio Inc ATS Radar Tracker and Server African States Association Application Service Elements Airspace Management Abstract Syntax Notation No 1 Aeronautical Fixed Service and System Planning Panel Air Transport Action Group Air Traffic Control Air Traffic Control Assigned Airspace Air Traffic Flow Management Air Traffic Management Asynchronous Transfer Mode Aeronautical Telecommunication Network ATN Panel ATN Systems Inc Air Traffic Services Air Traffic Services Communications Air Traffic Service Unit All Weather Operations Panel Boundary Intermediate System Basic Name Server Certification Authority Civil Aviation Authority Common American European Reference ATN Facility CNS ATM Research and Development CNS ATM Systems Implementation Task Force Civil Aviation Training Centre Cost Benefit Analysis Comit Consultatif International T l graphique et T l phonique Consistent Data Store Cockpit Display of Traffic Information Commission of the European Communities Common ICAO Data Interchange Network Connectionless Network Protocol Connectionless Network Service Connectionless Transport Protocol Context Management Context Management Application Communications Management Unit Communications Navigation and Su
10. Elbert The Satellite Communication Applications Handbook Artech House Inc MA 2002 19 N Gisin G Ribordy W Tittle and H Zbinden Quantum Cryptography In Reviews of Modern Physics volume 74 pages 145 195 January 2002 20 P M Gorman P R Tapster and J G Rarity Secure Free Space Key Exchange To 1 9 km And Beyond In J Mod Opt of Physics volume 48 pages 1887 1901 2001 21 Guihua Zeng and Guangcan Guo Quantum Authentication Protocol January 2000 221 Hitoshi Inamori Norbert L tkenhaus and Dominic Mayers Uncondi tional Security of Practical Quantum Key Distribution July 2001 23 Hoi Kwong Lo Communication Complexity and Security of Quantum Key Distribution April 2004 24 Horst Hering Martin Hagmiiller and Gernot Kubin Safety and Secu rity Increase for ATM through Unnoticeable Watermark Aircraft Identifi cation Tag Transmitted with the VHF Voice Communication In Proceed ings of the 22 Digital Avionics Systems Conference DASC Indianapo lis USA october 2003 25 Horst Hering Martin Hagmiiller and Gernot Kubin Watermark Tech nology for the VHF Voice Communication In Vu Duong editor Euro control Experimental Centre 2003 Innovative Research Activity Report pages 93 103 Eurocontrol Br tigny France may 2004 26 R J Hughes J E Nordholt D Derkacs and C G Peterson Practical Free Space Quantum Key Distribution Over 10 km In Daylight
11. SECTION 7 QC COMMUNICATION PROTOCOLS 7 3 Communication protocols With the models of key exchange and authentication we can set up a secure connection There are two communication protocols proposed corresponding to quantum authentication protocol or to the classical authentication proto cols authentication by symmetric key protocol or authentication by public key techniques 1 Communication protocol with quantum authentication This protocol is also applied to authentication by symmetric key protocol In this model we use a shared key previously exchanged in a first stage This key is a quantum key k of n random bits in case of quantum authen tication or as a shared key in the case of symmetric authentication After checking the participants authentication in a second stage we pass to a third stage to establishing a secure connection with shared key exchange in first stage as shown in figure 7 2 on the next page Communication protocol with authentication by public key techniques In this method we integrate asymmetric cryptography to this model In stage of authentication we use a public and private key pair to au thenticate Because the two stages 1 and 2 are independent we use a certified message ciphered by two secret keys cert and certz one is the quantum key distributed in the first stage 1 the other is the private key of second stage 2 We cancel the operation to establish a connection and repeat
12. page 450 2002 34 Lo Hoi Kwong and Chau HF Unconditional Security of Quantum Key Distribution over Abitrarily Long Distance pages 2050 2056 1999 35 Martin Pfennigbauer Walter R Leeb Markus Aspelmeyer Thomas Jen newein and Anton Zeilinger Free Space Optical Quantum Key Distri bution Using Intersatellite Link november 2003 36 Minh Dung Dang and Hong Quang Nguyen A new Authentication Scheme for Quantum Key Distribution 2005 37 Nicolas Gisin Gregoire Ribordy Wolfgang Tittel and Hugo Zbinden Quantum Cryptography 74 March 2002 38 Nikolaos K Papanikolaou Formal Specification and Verification of Quan tum Cryptographic Protocols Technical report 2003 39 Oliver Gradon Quantum Key Travels Record Distance october 2002 40 Patrick Bellot Minh Dung Dang and Hong Quang Nguyen A New Au thentication Scheme for Quantum Key Distribution 2004 41 Peter W Shor and John Preskill Simple Proof of Security of the BB84 Quantum Key Distribution Protocol April 2004 42 A Poppe A Ferrizzi T Loriinser O Maurhardt R Ursin H R Bohm M Peev M Suda C Kurtsiefer H Weinfurter T Jennewein and A Zeilinger Practical Quantum Key Distribution with Polarization Entan gled Photons July 2004 43 J G Rarty P R Tapster P M Gorman and P Knight Ground to Satel lite Secure Key Exchange Using Quantum Cryptography 4 82 october 2002 44 Roy Oishi ARINC IA Projec
13. using photons as the only choice for long distance quantum communication The use of satellites to distribute pho tons provides a unique solution for long distance quantum communication net works This overcomes the principle limitations of Earth bound technology i e the narrow range of some 100 km provided by optical fiber and terrestrial free space links While this may not seem like much free space QC transmission between two ground based locations 2km apart is equivalent to from a ground based location to an orbiting satellite at 300km altitude Photon sources and detectors presently implemented in such classical space laser communication systems can in general not be directly employed in quantum communication systems However the available experience may serve as a starting point for the development of space qualified components needed for quantum space ex periments For the satellite free space QC transmission the main difficulty would come from beam pointing and wandering induced by turbulence because in space atmospheric interference problems go away Then minimizing the size and weight of the equipment is vital as it is ever going to be installed on a satellite The major design parameters for the transmission subsystem are laser wave length modulation format and data rate and reception technique Of equal im portance is the subsystem required for beam pointing link acquisition and au tomatic mutual terminal tracking Poin
14. 1 State of the art The idea of QC was first proposed in the 1970s by Stephen Wiesner and by H Bennett of IBM and G Brassard of The University of Montr al However this idea is so simple that any first year student since the infancy of quantum mechanics could actually have discovered it Nevertheless it is only now that the QC theory is mature enough and information security important enough that physicists are ready to consider quantum mechanics not only as a strange theory good for paradoxes but also as a tool for new engineering The first protocol for QC was proposed in 1984 by H Bennett and G Brassard hence the name BB84 After this the other more effective was born such as two state protocol six state protocol Einstein Podolsky Rosen protocol and so on But most of QC experiments so far are limited on BB84 by its simplicity and the limitation of physical devices One of the most important of QC systems is the choice of photon sources and photon counters Optical quantum cryptography is based on the use of single photon Fock states Unfortunately these states are difficult to realize exper imentally Nowadays practical implementations rely on faint laser pulses or entangled photon pairs in which both the photon and the photon pair number distribution obey Poisson statistics For large losses in the quantum channel even small fractions of these multi photons can have important consequences on the security of the key leading to int
15. International Electrotechnical Committee Institute of Electrical and Electronics Engineers Internet Engineering Task Force International Federation of Airline Pilots Associations International Federation of Air Traffic Controllers Associations Instrument Flight Rules Interrogator Identifier Instrument Landing System Instrument Meteorological Conditions Implementation Management Group Inertial Navigation System Input Output Calls Internet Protocol Inter Process Communication Intellectual Property Rights Inter Domain Routing Protocol Inertial Reference System Intermediate System Integrated Services Digital Network International Standards Organisation International Telecommunications Union Joint Aviation Authorities K bytes 1024 bytes Local Area Augmentation System Local Area Network Link Access Protocol Link Access Protocol Type B Link Establishment Low Earth Orbit Satellites Eurocontrol June 2004 ACRONYMS LLC LREF LTEP MAC MAP MASPS MEOs MET METAR MHS MIDANPIRG MLS MMR MNPS MSAS MTSAT MWO Mode S SSR NAMPG NAS NAT NAT NATIMG NATSPG NAV OACA OCD ODIAC OF OPMET ORD OSI PAC PAT PANS PAR PDC PDU PER PETAL PIRG 125 Logical Link Control Local Reference Legal and Technical Experts Panel Media Access Control Meteo Aeronautical Charts Minimum Aviation System Performance Standards Medium Earth Orbit Satellites Meteorological Meteorological Ae
16. June 2004 75 Section 6 Introducing QC in ATN 6 1 ATN Communications secured with PKI The figure 6 1 summarizes communications between the Aeronautical Telecom munication Network ATN entities AG Sub network SATCOM Co CM Application Figure 6 1 ATN communications network ATN Applications can be categorized into two main categories 27 e Air Ground A G Applications corresponding to Sub Volume 2 of SARPs e Ground Ground G G Applications corresponding to Sub Volume 3 of SARPs Eurocontrol June 2004 76 SECTION 6 INTRODUCING QC IN ATN The Context Management Application CMA is one of the A G Applications CMA provides the mechanism for an Airborne End System AES to log on the ATN Network in order to communicate and use the A G Applications and Services required and supported by the AES In general the ATN Security for G G Application employs solutions similar to those used to protect the wired world Internet As for A G Applications the use of wireless data link in A G Applications introduces a new set of threats on the operational safety of an aircraft ICAO has determined that denial of service masquerade and modification of information are the primary threats for A G Applications We can summarize the Security Requirements for ATN cf section 2 3 on page 20 e Authentication of Message Source e Message Integrity Check e Authentication of the source of routing info
17. PKI is a key management system composed of trusted entities named Certificate Authority CA CA builds and delivers authentic digital public key certificates normalized as X 509 certificates binding an identity with a pub lic key They must emit Certificates Revocation Lists CRL when certificates are revoked There is no standard concerning PKI and most of them are not interoperable Analysis 2 4 2 PKI relies on public key encryption which in turn relies on some unproven intractable mathematical problems such as factoring large num bers A few remarks e Such problems may be already solved by a mathematician whose rough interest is not to publish its result but to sell it to NSA Al Quaeda etc e Such problems may be solved by heuristics i e algorithms which may fail in some cases and succeed in some other cases e Such problems are definitively solved by the future 30 years Quantum Computers In 6 it is mentioned that there will be State Certificate Authority that is CA assigned by states e g USA assigns FAA or Europe assigns Eurocontrol and that such CA s must establish trust relationships CA authorities issue certificates to ATN entities Then there exists Operating Agency Certificate Authority OACA for instance airlines which are subordinated to the CA and issue certificates to aircraft within their domains When one wants to check a certificate one does it with the public key of the corresponding OACA The
18. QCKI and satellite based QCKI i e QAPs can be placed on the ground on the satellite or event on the aircraft The complexity of QAPs is vari able but must ensure the execution of QKD protocol with other quantum equipments such as transmitter receiver e It must use satellite based QAPs or satellite based quantum relay station in order to obtain more flexibilities In fact the QCKI is a network which is named QBONE by us in which QAPs can be disconnected The separate QAPs are essential factors of QCKI and their complexity can be different It means that one party can simply use a transmitter as the one in the first implementation of QKD 5 see fig ure 6 18 on page 92 But the other party can have the support of a complex 90 Eurocontrol June 2004 6 2 SCENARIO OF QKD IN ATN 91 GG Sub network GG Sub network Figure 6 17 QKD relays network and two G G Subnetworks quantum satellite based network Therefore we can incrementally build the QCKI as follows e Firstly we construct independently separate simple ground based QAPs at several airports These QAPs can be used immediately to assure the implementation of QKD technology at their airports e Then we can construct fiber based QKD fixed links which connect several QAPs which are gateways of the main ATN Sub networks for a frequent usage e Finally we can think about the satellites in QCKI in order to have the global QCKI With the strategy of in
19. but in which the secret key distribution will be done using QCKI instead of classical technologies such as trusted courier Diffie Hellman key exchange or every Public Key Cryptography algorithm There are two main approaches Ground based QCKI or Satellite based QCKI An aircraft on the ground can also be considered as a gateway of one ATN Sub network therefore the scenarii of Satellite based QCKI can be com pletely like those described in A G Applications see figure 6 8 on page 84 and figure 6 13 on the preceding page 88 Eurocontrol June 2004 6 2 SCENARIO OF QKD IN ATN 89 As for a Ground based QCKI beside of the same scenarii described in A G Applications review figures 6 4 and 6 5 on page 82 and figures 6 9 and 6 10 on page 85 we have one more choice because in this case we can easily use fiber based channels instead of free space channels A possible requirement of fiber based QCKI scenarii is the re use of existing optic fiber infrastructures and classic repeater stations with their characteris tic distance Figure 6 14 on the preceding page shows the simplest QCKI based secure communication between two ATN Sub networks In general there are 2 distinct communications one is a fiber based QKD direct link with the BB84 protocol and the other is classical TCP IP connection using the IPSec proto col which is one of the most current proven and trusted protocols for securing communications Based on this idea the DARPA in U
20. chooses a random r4 computes the witness x4 h r4 and the challenge e4 Pp ra A A sends 7 7 to B B decrypts e to Eurocontrol June 2004 7 1 INTRODUCTION TO COMMUNICATION PROTOCOLS 97 recover r and A computes x h r B quits if 2 A xa im plying r ra Otherwise B chooses a random rg computes zg h rg and eg Pa ra rg B sends 7 8 on the facing page to A A decrypts eg to recover r and r s computes x h r B quits if x xp Otherwise if r r4 B is well authenticated and A sends rg r to B B succeeds with entity authentication of A upon verifying the received rpg 2 Authentication based on digital signatures This way is a strong au thentication protocol specifying identification based on digital signa tures and respectively time stamps and random number challenge ra and t4 denote a random number and a times tamp gen erated by A S denotes the signature mechanism of A cert denotes the public key certificate of A Here follows mutual authentication with random number A B rp 7 10 A B certa ra B Sa ra rp B 7 11 A B certp A Sp ra rp A 7 12 B verifies that the clear text identifier is its own identifier Then using a valid signature public key for i e cert it verifies that A s signature valid over the clear text random number r4 the same number rz as sent in 7 10 and this identifier And 7 12 is pro cesse
21. further and spaces covered by satel lite is also broader There are remarks following 35 e Advantages Eurocontrol June 2004 69 70 SECTION 5 ANALYSIS AND SCENARIOS more flexible golbal distribution of key proof of concept space qualification e Disadvantages More complicated According to the preceding part there is some parameters technical shown in table 5 2 Table 5 2 Maximun range d of two types of ground station s optics diameter Optics diameter lt 2000km 2 1000 Analysis 5 3 3 The photon is sent from the satellite to the 50 cm of ground station s optics diametter One has the maximum distance d 2000 km table 5 2 and the radius couvered r 1930 km equation 5 2 on page 68 Thus the distance between tow satellites 1 3174 km equation 5 2 on page 68 and it needs 14 satellites equation 5 3 on page 68 to cover a surface of width 3174 km Analysis 5 3 4 The photon is sent from the satellite to the 100 cm of ground station s optics diameter Follows table 5 1 on the preceding page and equation 5 1 on page 67 the maximum distance d 4000 km the radius covered r 3920 km Therefore the distance between tow satellites 1 6790 km equation 5 2 on page 68 and it needs 7 satellites equation 5 3 on page 68 to cover a surface of width 6790 km In brief the distance of optical channel is really limited There is always a big problem to send photons for a long distan
22. here the law of physics mentioned in 3 2 1 on page 26 that a real one gets When the channel is active it must carry the information of a pulse num ber of photons in this pulse polarization of photon in secret from Alice Eve to Eve Bob and must produce the result to their detectors measurement The channel sometimes causes errors to the communication such as loss of pulses on transmission And like all three actors above the channel shows out its operations and accepts users modification through the GUI Detailed Implementation Now we are going into the main part of this section This is the implementa tion of a BB84 QKD protocol The protocol is applied by three main characters Alice sender Bob receiver and Eve eavesdropper All their communica tions are carried out in two separate channels quantum obeying quantum physics laws and public one using the normal laws of public communication In using Java to develop the program three actors will be represented by three separate threads and interact to each other by accessing into two channels im plemented by two public objects These two objects are created and observed by the Main thread So in total there are four threads which run simultaneously on a same computer same Java virtual machine In this communication Alice keeps the active role and Bob the passive one except his choice of the measurements polarizations and their announcement to Alice For her part Eve alwa
23. module in satellite while the receiver mod ules stay in easily accessible ground based laboratories Because of their relative stationary terminals placed on GEO satellites do not require such a highly sophisticated PAT systems as those on a LEO satel lite They would also for long duration experiments But on the other hand the link attenuation and cost are significantly larger for GEO links compared to LEO links Therefore when trading GEO based against LEO based sys tems we would rather accept the more complex PAT system and the limited connection time per orbit and suggest to use a LEO platform for the transmit ter terminal for the first experiments In the next section anyways we will analyze in more details the possible space scenarios prerequisites and perspectives of satellite aided QKD Eurocontrol June 2004 55 57 Section 5 Analysis and Scenarios 5 1 Introduction According to the analyses of preceding section one can completely send a sin gle photon in space Today June 2004 two groups have succeeded in exchang ing keys over free space ranges greater than 1 km and ongoing experiments show that ranges of 10 and 23 km 32 can easily be reached In all ex periments the first step are being taken to reduce the size mass and power consumption of the equipment primarily to allow portability in the short term and fully automated remote operation in the long term In the future one will be able to envisa
24. on the CA is broken e If the private key of an aircraft is disclosed then anyone can impersonate the aircraft communication system Analysis 1 3 2 One may worry about the 28 days key renewing delay 28 days may be sufficient to crack a public key 1 4 APIM 02 002 The ARINC IA Project Initiation Modification APIM 02 2002 named ATN Se curity results from the ICAO Air Navigation Bureau Request for Development of Specifications for Key Management and Distribution needed to implement the security provisions of ATN SARPs for avionics equipment One reason for the APIM is local implementation issues everyone has to do it the same way or it will not work 1 5 ATN Security Overview The ATN Panel ATNP has provided mechanisms which may be applied for e Authentication and Integrity of Air Ground application communications which use the ATN upper layers e Authentication and Integrity of Air Ground IDRP i e inter domain rout ing protocol communications e Authentication of Ground Ground Applications communications Ground Ground IRDP and Aeronautical Message Handling Ser vices AMHS The used technologies are rather classical e HMAC Hybrid symmetric Hashed Message Authentication Code e ECDSA Elliptic Curve Digital Signature encryption Algorithm e GULS ISO Generic Upper Layer Services 14 Eurocontrol June 2004 1 6 CONCLUSIONS 15 e CMA Context Management Application to manage mutual authentica tion durin
25. optics will be difficult to build below 5 kg Thus it is necessary to consider the size of telescope to decrease the cost 58 Eurocontrol June 2004 5 2 KEY EXCHANGE SCENARIO 59 5 2 1 The ground station transmits a key to the satellite 43 A typical system is illustrated in figure 5 2 Satellite station receiver Tracking mirror Pointing el Tracking Cook Guidance amp Guidestar Comms Timing amp Control Uplink D C7 DM lt HMNOMX Lightweaght four laser transmitter la ae Fast steering Timing amp Control Guidance amp Comms Pointing amp Tracking d ZDM HHEUNZXXD 1 Ground station transmitter Figure 5 2 a Satellite station receiver This includes a lightweight receiver module a guidestar laser for ground tracking and a CDD camera to main tain closed loop pointing An on board lightweight processor handles the point ing and tracking time synchronization and key management b The ground station incorporates the compact four laser transmitter with a high power guidestar laser and pointing tracking CDD e Ground telescope tracking pointing and turbulence Typically one would use a ground laser expanded to a near diffraction limited 30 cm beam This would imply R 1 diffraction spread To keep such a small spot pointing at the satellite requires a high speed active pointing scheme cor recting for turb
26. satellites for the global key distribution which is the ultimate goal of such systems 4 1 Free Space Free space links have been studied and already successfully implemented for several years for their application in quantum cryptography based on faint classical laser pulses 7 8 20 26 31 Free space link is one of two solutions for quantum channel Transmission over free space links has some advan tages compared to the use of fiber based links First of all the atmosphere has a high transmission window at a wavelength of around 800 nm where photons can easily be detected using commercial high efficiency photon detector Fur thermore the atmosphere is only weakly dispersive and essentially isotropic at these wavelengths It will thus not alter the polarization state of a photon However there are some drawbacks concerning free space links as well In Eurocontrol June 2004 46 SECTION 4 FREE SPACE AND SATELLITES contrast to the signal transmitted in a optical fiber guiding medium where the energy is protected and remains localized in a small space the energy trans mitted via a free space link spreads out leading to higher and varying trans mission losses In addition the background light such as ambient daylight or even moonlight at night can couple into the receiver leading to dark count er rors Finally it is clear that the performance of free space QC systems depends dramatically on atmospheric conditions 4 1
27. separated by varying distances dependent on range This can be solved by fitting a biprism element in the satellite optics as shown in figure 5 4 on the facing page The biprism angle is chosen such that the passage through either side will divert the beam by exactly half the Doppler angle A light beam entering the retro reflection system will pass through the opposite side of the biprism on its return thus suffering a deviation equalling the Doppler angle 0 We will then obtain two return beams one exactly co linear with the incoming beam and the other deviated by 20 A more detailed analysis shows that with a typical satellite this correction scheme will return the light to the ground station within its diffraction spread for most elevations above 50 The biprism will effectively halve the returned light As the output from the retro system is 0 1photons bit this requires us to have at least 10photons pulse arriving in the 10cm aperture of the satellite optics The footprint of a 1004R beam at the satellite is of order 100m im plying 10 of the laser power will enter the satellite optics For a system operating at 100M Hz repetition this implies 10 photons s This implies a ground laser emitting around 3mW of power in 100 200photons pulse at 100M Hz Power variation with range and visibility can be monitored by the satellite based single photon detector Satellite optics pointing stability In the retro reflection system w
28. takeoff of the aircraft 82 Eurocontrol June 2004 6 2 SCENARIO OF QKD IN ATN 83 e Single photon source Aircraft based QCKI Each aircraft is equipped by a single photon transmitter A straight down link using BB84 protocol to a receiver on the GS can be used to perform the negotiation of the sharing secret key see figure 6 6 Transmitter Receiver Figure 6 6 Aircraft based QCKI with single photon source We can also use a satellite as quantum relay space station see figure 6 7 Relay Figure 6 7 Aircraft based QCKI with single photon source Here too it is possible to use fiber based technology if aircraft are on the ground in European airports to distribute keys before the takeoff of the aircraft Eurocontrol June 2004 83 84 SECTION 6 INTRODUCING QC IN ATN Single photon source Satellite based QCKI The single photon transmitter is placed on the satellite This case seems more complex because it is impossible to directly negotiate a shared key between AES and GS using QKD technology It must do the following see figure 6 8 Transmitter Relay Transmitter Relay a PC a f Receiver Secured radiof z link 4 Figure 6 8 Satellite based QCKI with single photon source The scenario is A satellite distributes a quantum secret key K1 for GS Using this key K1 as the session key this satellite and the ATN Network estab lish a secure radio communication link COM1
29. the photon she must specify both its position and the capacity of her splitting mirror This strength of 0 means that Eve ignores this photon and pass it to Bob while the value of 1 shows that Eve detects all the photon in the pulse and consequently this pulse is entirely changed In the case of a success of Eve beam splitting Eve knows the Alice s polarization which is saved in the buffer Eve s method BeamSplitting on the quantum channel BeamSplitting float MirrorStrength int BufferLocation She can also use intercept resend attack independently She can do this with command IR in provide the position of pulse the polarization to measure photon and also value for resend strength And the rest of the work is for the quantum channel object It is responsible for checking the polarization chosen by Eve to update the buffer location and to return result of the measure to Eve Eve s method IR on the quantum channel IR int Polarization float ResendIntensity int BufferLocation Once Eve finishes her job she must acknowledge the value and shift the flag of Bob s permission This is accomplished by below method Eve s method tag on the quantum channel tag int BufferLocation After shifted bit of Bob s permission he can read info of this photon with the same method as Eve s IR except without parameter ResendIntensity This method will return to Bob the value of this photon or an empty message Bob s
30. the communication link named Bob A third party named Eve intercepts all qubits and regular messages sent by Alice to Bob Then Eve communicates with Bob impersonating Alice When Bob answers Eve intercepts all qubits and regular messages sent by Bob to Alice Then Eve communicates with Alice impersonating Bob Eve may retransmit the qubits or regular messages without changes In this case she is a passive eavesdropper Or she may alter the messages to provide false informations In this case she is an active eavesdropper If Eve uses an active man in the middle attack during a quantum key es tablishment session between Alice and Bob then Eve obtains two keys K4g and Kgg Kapr represents the secret quantum key established between Alice and Eve Kee represents the secret quantum key established between Eve and Bob As a result Eve can easily decrypt the ciphered texts exchanged be tween Alice and Bob If Alice sends a message to Bob she encrypts the mes sage using the key Kag Eve intercepts the message decodes it using K4g and re encrypts it using Kgg When Bob receives the message he decodes it using Kgpg Eve s interception is similar when Bob sends a message to Alice 94 Eurocontrol June 2004 7 1 INTRODUCTION TO COMMUNICATION PROTOCOLS 95 Thus it is necessary to check the received messages to ensure that they are not modified checking integrity and that they really come from the right interlocutor authenticati
31. the symmetry of this protocol greatly simplifies the security analysis and reduces optimal information gain of the eavesdropper for a given error rate QBER If the eavesdrop per measures every photon the QBER is 33 compared to 25 in the case of the BB84 protocol gt gt Figure 3 1 Three pairs of bases used in six state protocol 1Qubit quantum bit 2QBER Quantum Bit Error Rate Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 29 3 3 Detailed BB84 protocol 3 3 1 Description of protocol BB84 is the most well known quantum key distribution protocol using four different states that make a pair of basis states In the description of the protocol we use classical first name for the differ ent elements of the protocol The name Alice is used for the initiator of the protocol The name Bob is used for the responder Typically Alice is communi cating with Bob while an eavesdropper a spy is trying to listen or perturb the communication This eavesdropper is usually named Eve Secrecy of this protocol was proved by different people such as Dominic Mayers Eli Biham Michael Ben Or and so on BB84 is secure against eves dropping in the sense that Eve can t gain any information about the transfer between Alice and Bob unless she reveals her presence after data transmission We will come back to this item in the section 3 3 2 on page 31 BB84 is a non deterministic protocol That means that it distributes ran d
32. to differentiate surely two non orthogonal states So a quantum measurement must be performed to determine the received state and from that to get the classical output And this uncertainty principle provides cryptographic properties needed in quan tum cryptography For BB84 there are two measurements used to distinguish the different quantum states e measurement allowing to identify clearly between two states 0 and 1 This measurement is also called measurement in the rectilinear basis e amp measurement allowing to identify clearly between two states 0 and 1 This measurement is also called measurement in the diagonal basis In general quantum key exchange using BB84 for secret key consists of six following steps 1 Quantum Transmission This phase is the first step in a quantum key distribution In this phase a random string of n classical bits will be created by Alice and sent to Bob Each bit of this string will be encoded by a non deterministic basis A quantum encoded classical bit is called a qubit At the other side of the transmission Bob receives the qubit and he picks up by chance a rectilin ear or diagonal basis to measure it When the transmission is over Bob will get a string of classical bits called the raw key different from Alice s one in many positions about 50 even in the case of error free quantum communication or much more as apparatus error rate is included The next step of the prot
33. to first stage if cert cert2 Otherwise we set up a secure connection with quantum key as shown in figure 7 3 on the facing page In short we can apply both protocols The first protocol with the quantum authentication it is simpler it is safe and it can prevent the man in middle attack and DoS attack The second is more complex but it is also protected because two stages of key exchange and of authentication are independent 100 Eurocontrol June 2004 7 3 COMMUNICATION PROTOCOLS 101 Entity A Entity B Key Exchange i Authentication Authentication Figure 7 2 Communication with symmetric or quantum authentication Entity A Entity B Key Exchange Authentication Public Private OR Communication Communication Figure 7 3 Communication protocol with asymmetric authentication Eurocontrol June 2004 101 103 WP Ill Visual Demonstrators Eurocontrol June 2004 105 Summary and Conclusions This part summarizes the conclusions of the third step of this study These conclusions are made explicit in the following sections Summary e Chapter 8 on page 107 AIT QKD Animations in Flash is a description of the five Flash animation explaining the coupling of AIT and QKD e Chapter 9 on page 113 BB84 Demonstrator in Java is the documenta tion for using the BB84 Java demonstrator which illustrates a session of Quantum Key Distribution Eurocontrol June 20
34. www arinc com aeec projects users_forum Miami_03 6 2_ATN Security USAF pdf 6 http www arinc com aeec projects users_forum Miami_03 6 4_Key Management pdf Eurocontrol June 2004 18 SECTION 2 AERONAUTICAL TELECOMMUNICATIONS NETWORK Other ICAO Panels were involved in the ATN e The Aeronautical Mobile Communication Panel AMCP which domains of interest are Aeronautical Mobile Satellite Services AMSS High Fre quency HF Data Link and Very High Frequency VHF Data Link SARP e The Automatic Dependent Surveillance Panel ADSP which domains of interest are the Ground Ground and Air Ground CNS ATM operational requirements e The Aeronautical Fixed Service and System Planning Panel ASPP which domains of interest are the Ground Ground communications in cluding Aeronautical Fixed Telecommunications Network AFTN and Common ICAO Data Interchange Network CIDION and Aeronautical Message Handling Systems AMHS SARP Since 1994 the ATN SARP s is under the responsibility of the Aeronautical Telecommunications Network Panel ATNP It is organized in five parts 1 Introductory material 2 Air Ground applications Automatic Dependent Surveillance ADS Con troller Pilot Data Link Communications CPDLC Flight Information Services FIS and Context Management CM 3 Ground Ground applications Inter Centre Communications ICC Aero nautical Message Handling Service AMHS 4 Upper Layer Architecture UAL
35. 0 km Key rate K 1500 bits s 6500 bits s BR ed s The loss m lt 35 dB lt 35 dB at ce 5 2 8 The ground station transmits a key to another ground station using the satellite as a mirrror The system includes a pulsed laser system at ground level boresighted with the tracking telescope that acts as a receiver This laser sends a relatively broad beam up to the satellite On the satellite there is retro reflector formed by a simple telescope with a mirror set at its focal point Before the mirror is a polarization modulator which can encode the required four polarization states onto the retro reflected beam e Ground telescope tracking and pointing The system can use a rela tively high divergence ground based laser beam 100 uR This only re quires that the ground telescope points with 100 uR accuracy at the satel lite The return beam will however deviate somewhat from true retro reflection essentially due to the Doppler effect occurring because of the satellite velocity V 7km s relative to the velocity of the earth s surface The deviation angle is of order corresponding to some 474R of deviation Eurocontrol June 2004 63 64 64 SECTION 5 ANALYSIS AND SCENARIOS 47 m at the earth s surface for a satellite height of some 1000 km At first glance this system is then unworkable as this is much larger than the diffraction spreading 12uR and we would require separate track ing for the laser and telescope
36. 04 Section 8 AIT QKD Animations in Flash In this section we present animations in Flash to visualize theorys in the pre ceding sections 8 1 Installation These demonstrations are written in Flash therefore it is easy to intall First unzip the file AITQKD_anims zip You normally get a directory AITQKD_anims containing several files You can copy these files e ait html ait swf ait _qkd html ait_qkd swf atn html atn swf flightplan html flightplan swf index html intro html menu html qkd html qkd swf in a same directory wherever you want These files may be be installed on a WEB server if you want to make the demo publicly available 8 2 Opening index html To see the demo you must open the file index html in a navigator that has the Flash plugin installed Shown in figure 8 1 on page 109 you can see the principal interface There are 5 features which we will explain in the following parts Eurocontrol June 2004 108 SECTION 8 AIT QKD ANIMATIONS IN FLASH 8 3 Air Identification Tag AIT Click on 1 AIT This animation show in figure 8 2 on the facing page demonstrate the AIT show in section 2 6 on page 23 Air Identification Tag and also the risks of this communication show in section 1 1 on page 11 Why Security AIT aims at improving and facilitating identification IT inserts automat ically an unnoticeable small data link channel in the communication The in serte
37. 10MHz and K 16bits s with R 0 5MHz If a future lightweight modulator oper ating at 100M Hz is produced bit rates of K 3300bits s can be expected e Error rate using a maximum loss of 35 dB implies a maximum back ground B lt 240 counts s Summary table performance of the system ground station transmits a key to another ground station using the satellite as a mirror e Satellite optics diameter 10 cm Satellite payload a Modulator lt 5 kg R 0 5 MHz b Modulator 11 kg R 10 MHz c Future mod lt 5 kg R 100 MHz Eurocontrol June 2004 65 66 SECTION 5 ANALYSIS AND SCENARIOS e Two types of ground telescope Ground telescope Ground tracking gt 100uR gt 100uR Satellite optics 100uR 100uR pointing ability Locked to ground Locked to ground laser guidestar laser guidestar Satellite optics Corrected Corrected yaw stability from ground from ground 1500 km 3300 km Key rate K a 16 bits s a 16 bits s at 1000km b 330 bits s b 330 bits s c 3300 bits s c 3300 bits s The loss budget EG lt 35 dB lt 35 dB at 1000km In conclusion with these three scenarios we can completely send a sequence of single photons between the ground station and the satellite Therefore we can imagine entirely a system for secure key exchange from the ground to satel lite using quantum crytography Moreover nowadays using position systems GPS of United States of America Galelio of Eur
38. 62 SECTION 5 ANALYSIS AND SCENARIOS corrected at the ground e Satellite payload and power With 10 cm optics the target of 3 kg may be reached Satellite station transmitter Tracking mirror Pointing amp Tracking d Guidance amp Comms Timing amp Control Downlink gt LS DM HE2UNZXXD 1 four laser transmitter Lightweight receiver Uplink Fast steering Timing amp Control Guidance amp Comms Pointing amp Tracking d Ground station receiver Figure 5 3 a Satellite based transmitter This includes a lightweight laser system using matched lasers and electronic switching between them to select the four polarizations used in the BB84 protocol Pointing and tracking are controlled to the level by the satellite while a closed loop system incorporating CCD tracking electronics and a tip tilt mirror controls fine pointing to better than 104R b Ground station with telescope and boresighted beacon laser The four detector receiver design provides a wide field of view 1004R at the telescope output e Maximum range With 10 cm optics the diffraction spread of a 650 nm beam is of order 12 uR and the ground footprint would be 12 m from 1000 km This gives a loss in a 100cm diameter telescope at the ground station of TL 0 0046 23 5dB With a 50cm diameter telescope TL 0 0012 29 3dB With 35 dB maximum toler
39. And At Night In New Journal of Physics volume 4 pages 43 1 43 14 2002 27 ICAO Manual of Technical Provisions for the Aeronautical Telecommuni cations Network ATN Standard and Recommended Practices SARPs Mars 2001 28 Jaeook Lee and Sun Kang Satellite over Satellite sos Network A Novel Architecture for Satellite Network 29 Jim McMath Aeronautical Telecommunications Network ATN Secu rity Key Management and Distribution Security Key Management and Distribution AEEC Data Link Users Forum Miami FL USA and ESC GAD Titan Corporation Hanscom MA USA Public Release 03 0052 edition february 2003 132 Eurocontrol June 2004 30 T Kimura Y Nambu T Hatanaka A Tomita H Kosaka and K Naka mura Single Photon Interference Over 150 km Transmission Using Silica Based Integrated Optic Interferometers For Quantum Cryptogra phy Criterion In Submitted to Electronics Letters 2004 31 C Kurtsiefer P Zarda M Halder P Gorman P Tapster J Rarity and H Weinfurter Long Distance Free Space Quantum Cryptography In New Journal of Physics volume 4 pages 43 1 43 14 2002 32 C Kurtsiefer P Zarda M Halder P Gorman P Tapster J Rarity and H Weinfurter Long Distance Free Space Quantum Cryptography 2002 33 C Kurtsiefer P Zarda M Halder H Weinfurter P Gorman P Tapster and J Rarity A Step Towards Global Key Distribution In Nature volume 419
40. DS Key AES Private Key Agreement KA Key Step 1 creates CM CPDLC Logon Request CM Logon using AES ID CPDLCA ID time Request signs on CM Logon Request using AES DS Pri Key sends CM Logon Request to CMA Step 2 CM Logon Response computes CMA Session Key using CMA Pub KA Key AES Pri KA Key authenticates CM Logon Response by CMA s MAC CMA Identity CPDLC Identity CMA Private KA Key CPDLC Private KA Key invokes PKI services for retrieve AES certificates CPDLCA certificates authenticates AES s CM Logon Request using AES s DS generates the CMA Session key using AES Pub KA Key CMA Pri KA Key generates CM Logon Response using CMA s Pub KA Key CPDLC s Pub KA Key CMA Session Key CMA s MAC sends CM Logon Response back to AES Step 3 computes CPDLC Session Key using computes CPDLC Session Key Create CPDLC AES Pri KA Key CPDLC Pub KA Key using AES Pub KA Key Session Key CPDLC Pri KA Key Step 4 protects exchanged messages using Exchange CPDLC Session Key protected messages protects exchanged messages using CPDLC Session Key Figure 6 2 Based PKI secured A G communications Tid HLIM OHHNIAS SNOILVOINNWANOD NIV T9 LL 78 SECTION 6 INTRODUCING QC IN ATN In the above scenario AES holds two secret Session Keys CMA Session Key and CPDLC Session Key The first one is used for the protected communication with CM Application and the oth
41. ITY 109 Figure 8 1 Demonstration in Flash Figure 8 2 Air Identification Tag Eurocontrol June 2004 109 110 SECTION 8 AIT QKD ANIMATIONS IN FLASH Quantum Ke Distribution Figure 8 3 Quantum Key Distribution Figure 8 4 Flight Plan 110 Eurocontrol June 2004 8 6 AUTHENTICATION AND INTEGRITY 111 ATN Key Dispatching Figure 8 6 Authentication and Integrity Eurocontrol June 2004 111 113 Section 9 BB84 Demonstrator in Java User Manual Following chapter 3 on page 25 the QKD simulator is composed of six pack ages including 23 source files 6 executable jar files and a Makefile This pro gram is compatible with Unix Linux MacOS and Windows 9 1 Program installation Choose and follow the suitable guide with your operating system Verify that jdk1 4 0 or later or the equivalent jre is installed on yourmachine Unpack the file BB84_demo zip to obtain the directory BB84_Protocol 9 1 1 For users on Unix Linux or MacOS To unpack BB84_demo zip type on the command line unzip BB84_demo zip On MacOS systems you can double click on the file BB84_demo zip After execution of this command you have a directory named BB84_Protocol And there you can find sources executalbe files and the simulation api specification Recompiling the files is not necessary but if you want to recompile all the programs you need the jdk e To remove all already compiled classes use comman
42. MGCS SNDCF SO SPG SSR STDMA 126 ACRONYMS PETAL Integration Team Public Key Infrastructure Primary Surveillance Radar Quantum Access Point Quantum Bit Error Bit Quantum Bone Quantum Cryptography Quantum Confidentiality Key Infrastructure Quantum Key Distribution Quality of Service QUantum BIT Resolution Advisory Rules of the Air and Air Traffic Services Reference ATN Facility Regional Area Forecast Centre Receiver Autonomous Integrity Monitoring Required Communications Performance Routing Domain Research Development and Test Radio Frequency Request for Comments Radio Frequency Interference Review of the General Concept of Separation Panel Radar Message Conversion and Distribution Equipment Area Navigation Required Navigation Capability Required Navigation Performance Required Navigation Performance Capability Router Reference Implementation Required System Performance Radio Technical Commission for Aeronautics Required Total System Performance Reduced Vertical Separation Minima Single Attached Concentrator Standards and Recommended Practices Standards and Recommended Practices Single Attached Station Space Based Augmentation System System Control and Monitoring SSR Improvements and Collision Avoidance Systems Significant Meteorological Effects Significant Weather Serveur d Informations Radar Secondary Surveillance Radar Improvements and Collision Avoidance Systems Standard Length Me
43. SA is trying to build a such quantum network the BBN network Basically the BBN network is a classical Virtual Private Network VPN in which the key distribution and key renewing is done using QKD devices instead of classical technologies such as Diffie Hellman key exchange The main benefit of an IPSec VPN is that the corporation has complete control over the robust security policy such that someone attaching to a LAN has all the privileges of a local LAN user and all applications work transparently Therefore by using QKD technology for the problem of key distribution and key renewing the BBN network becomes a totally secured network The simplest QKD based secured communications as above are limited by constraints of distance and sight of line communication in the case of Free Space QKD technology In order to overcome these drawbacks one may use quantum relay or QKD data relay stations There are some solutions 11 17 such as the using of ground based QKD data relays see figure 6 15 or space based QKD data relays see figure 6 16 on the next page Internet Link GG Sub network Figure 6 15 QKD relays between two G G Subnetworks As useful as a QKD relays link may be it still suffers from another striking drawback because an isolated point to point link is subject to simple denial of service attacks such as active eavesdropping or cutting the QKD link This drawback can be mitigated by organizing a number of QKD li
44. SEY ICO GPS For a little knowledge about satellite networks we will see the GPS that is one of the most known satellite networks The Global Positioning System GPS is a constellation of 24 well spaced satellites that orbit the Earth and make possible for people with ground re ceivers to pinpoint their geographic location The location accuracy is any where from 100 to 10 meters for most equipment Accuracy can be pinpointed to within one meter with special military approved equipment GPS equip ment is widely used in science and has now become sufficiently low cost so that almost anyone can own a GPS receiver Orbit Planes Argument 80 of Latitude 0 Equator s Spare 320 a Active 280 Orbit Position 240 ID 317 77 137 197 257 Right Ascension of the Ascending Node Figure 4 6 Simplified Representation of Nominal GPS Constellation The GPS is owned and operated by the U S Department of Defense but is available for general use around the world Briefly here is how it works e 21 GPS satellites and three spare satellites are in orbit at 10 600 miles 20 200 km in 6 orbital planes above the Earth The satellites are spaced so that from any point on Earth four satellites will be above the horizon figure 4 6 Each satellite contains a computer an atomic clock and a radio With an understanding of its own orbit and the clock it continually broadcasts its changing position and time Once a day ea
45. TN QKD optic fiber technology can be used to secure G G communications Otherwise QKD freespace technology may be used for A G communications The most interesting way of truly se curing the ATN would require a satellite network If ATN has to be secured and it will be secured all communications end points have to receive encryption keys Distributing a key to an aircraft coming from outside Europe or from an untrustable country would re quire radio communications that could be eavesdropped The same occurs for aircraft standing on the tarmac at airports and which are not wired to the terminal In these case Freespace QKD could provide a solution that could not be eavesdropped Eurocontrol June 2004 74 We can consider a QKD system for ATN Network as the Quantum Confi dentiality Key Infrastructure QCKT which provides confidential sharing of encryption keys between two endpoints replacing PKI in a progressive manner For instance a subnetwork such as an airport could be QCKI equipped meanwhile the other parts of the ATN may continue to use classical PKI For instance airport control tower may be equipped to distribute keys to all airplanes standing at the airport for signature of A G com munications or Air Identification Tag AIT For instance QCKI could be used tu unconditionnaly secure links between some ATN subnetworks and this may be incrementally ap plied to all links There are many ways to local
46. UN ASE Bow ee ey Sone RD aS 45 4 1 1 State oftheart n sanea ghee ae a See die nt date aoe hb a be 46 4 1 2 The most recent success 47 4 2 Satellites Communication 50 4 2 1 Overview of satellites communication 50 4 2 2 Satellites Free space Communication 54 5 Analysis and Scenarios 57 Del Introduction Bose Bid axe wile a eld ie ene Bh ee ee eis eg 57 5 2 Key exchange scenario 2 58 5 2 1 The ground station transmits a key to the satellite 59 5 2 2 The satellite transmits a key to the ground station 61 5 2 8 The ground station transmits a key to another ground station using the satel liteasamirrror e e e e aoa e a E A E a a a a a a a E E ai 63 5 8 Satellite network 66 5 3 1 Ground Based Transmitter Terminal 68 5 8 2 Space Based Transmitter Terminal 69 II ATN and QKD Scenarios 71 Summary and Conclusions 73 6 Introducing QC in ATN 6 1 ATN Communications secured with PKI 6 2 Scenario of QKD in ATN 6 2 1 QCKI for A G Applications 6 2 2 QCKI for G G Applications 6 2 3 A proposal QKCI for ATN Network 7 QC Communication Protocols 7 1 Introduction to Communication Protocols 7 1 1 Classical Authentication 7 12 Qua
47. able loss the max imum ranges are gt 4000 km for a 100cm telescope and gt 2000km for the 50cm telescope At these higher ranges we have had to take into account the extra loss from atmospheric transmission at low elevation angles in the atmosphere Expected key rate at 1000 km range The key rate will be limited by the maximum repetition rate of the lasers and the loss With R 100MHz 62 Eurocontrol June 2004 5 2 KEY EXCHANGE SCENARIO 63 and TL 0 0045 we expect a ground key rate at 0 1 photon per bit of K 6600bits s For a smaller 50cm ground telescope K 1600bits s Error rate At a night sky the error rates due to background light will be low Again using a maximum loss of 35 dB implies a maximum back ground B lt 240 counts s With suitable filters this may allow operation at night when the satellite is still in sunlight However daylight operation is not possible due to the wide viewing angle 100 uR proposed for ease of tracking in the receiver Better tracking might allow a smaller field of view and thus limit daylight background Summary table performance of the system e Satellite optics diameter 10 cm and weight of telescope 3 kg e Two types of ground telescope Ground tracking gt 100uR gt eee eM md patag OOOO O 7 Satellite optics 12uR 12uR pointing ability Locked to ground Locked to ground laser guidestar laser guidestar Satellite optics Corrected Corrected gt 2000 km gt 400
48. actors these interfaces are implemented in separate frames within three corresponding classes AliceInt class EveInt class and BobInt class Each interface contains a tab for setting another for result or both In the tab for setting text fields correspond with their parameters are included to allow users to enter desired values to experiment The one of Alice has a little more difference in having additional button Start used to initiate the protocol Two other ones are for quantum channel and public one Both of these are included in QuantumChannel class and PublicChannel class And below is the description of principal parameters to be configured before the start of simulation in each interface of actors and also the two channels further details referred to 3 3 2 e Alice s setting Transmission Size is an integer larger than 0 and less than 1000000 because the buffer location is limited by 1000000 This is the size of qubit string transmitted on the quantum channel Beam Intensity is a floating point number in the interval 0 1 This number decides Eve or Bob s successful rate when detecting a pho ton And it is also the proportion of bits assumed to be successfully detected by Eve in use of beam splitting Confirmation Sample Size is the number of bits chosen randomly in phase Confirmation It is an integer greater than 0 Security Factor is an integer added to Eve s assumed key size before privacy ampli
49. and cite as dcyate Eve s parameters Eve s attack capacity is dependent on these param eters For beam splitting attack there are two parameters to be config ured One is the proportion of total pulses to attempt to split BS and the other is the proportion of beam number of photons in a pulse desired to split Mirror Strength In applying Intercept Resend the first factor to be considered is proportion of beams to intercept IR and the second is about the intensity of resent beam Resendintensity Formulas used in this protocol referred to 10 These formulas are divided into two portions One concerns Eve s info the others about the info in quantum channel Estimation of Eve s info In Privacy Amplification function h x from the class of hash func tions 0 1 0 1 of which n is PlainKeyien lis EEsampie and s is arbitrary security parameter is selected It is estimated that Eve knows at most l deterministic bits before this phase And then Eve s amount of info is recalculated as below hee In2 The number of bits leaked to Eve is estimated by simply calculating the sum of number of bits received by Eve by both beam splitting and intercept resend The equation 3 2 gives the rate of bits leaked to Eve by intercept resend with p error rate in the channel referred AS TTrate in Alice s parameters 3 1 TRyate 3 2 4 V2 And in attack by beam splitting it is assumed that every pulses a
50. assed phase s result Relation of all objects implemented in this simulation is described in below graph 3 3 3 QCrypt class f f Alice class Eve class Bob class a a a ra Alic Alice Eve Eve Bob Bob eInt Proc Int Proc Proc Int class class class class class class Qubit 2 7 2 nA __ m QuantumChannel class PublicChannel class class Figure 3 3 Diagram of relation among principal objects in simulation of BB84 protocol There are in total five principal classes two channel objects and three actors in this communication All three actor objects have the same struc ture They all implement the Runnable interface which allows to be launched as three separate threads by Qcrypt class Each of the actors has two other classes an Interface class and a Protocol class The Interface classes are described as in the part just above The GUI And Protocol ones are instantiated by the major classes Alice class Eve class and Bob class when button start in Alice s interface is clicked They begin by setting up all parameters with the values got from the Frame object and activate their RunProtocol method This method helps actors to go through all phases of BB84 protocol and displays the correlated result with each phase to the correspondent interface 44 Eurocontrol June 2004 45
51. ate at 1000 km The key rate will be limited by the max imum rate of modulation of the retro reflecting polarization modulator Eurocontrol June 2004 5 2 KEY EXCHANGE SCENARIO 65 Satellite station Pointing amp a Tracking fi Guidance amp sisesta P Comms I Ti Timing amp f E Control J s Modulated Prism Retroreflector Downlink Y SPD Fast steering mirror Timing amp Control Guidance amp _ Comms Eco Pointing amp sl Tracking F CW laser a Ground station Pen Figure 5 4 a Satellite station using a polarization modulating retro reflector Doppler shifts due to the relative motion between satellite and ground is com pensated by a biprism design The CCD is used to point the satellite at the ground station with an accuracy set by the field of view of the retro reflector gt 1004R A guidestar laser is used to lock the ground station pointing b Ground station for the retro reflection system A bright pulsed laser is roughly collimated to point at the satellite The guidestar satellite image in the CCD camera is used for closed loop tracking to within the field of view of the receiver module 100 4R Using present technologies this is about R 10M Hz in a 10kg electro optic system R 0 5MHz in a 0 2kg liquid crystal modulator From the above 0 5TL 0 0023 and K 330bits s with R
52. ate mechanisms implemented by the ATN Internet As a result of this work it is believed that application messages need to be protected by digital signatures providing both authentication of the sender and a high quality data integrity check Furthermore the source of routing information needs also to be similarly authenticated We can summarize the Security Requirements for ATN e Authentication of Message Source protect against misreporting protect against masquerade of controllers e Message Integrity Check protect against message substitution protect against message replay e Authenticate source of routing information protect against false route 2 4 Key Management 6 mentions ICAO ATN Panel sent a letter inviting AEEC to develop specifi cations for Key Management in ATN Reference ICAO ATN SARPS 9705 Ed 3 The elements of the ICAO request are e ATNP needs a suitable mechanism for secure installation and update of the aircraft private keys in the context of data link information security e ATN security mechanisms require support of a Public Key Infrastruc ture PKI Eurocontrol June 2004 21 22 SECTION 2 AERONAUTICAL TELECOMMUNICATIONS NETWORK e There is a need for secure installation and update of aircraft private keys as well as public keys of other avionics Analysis 2 4 1 One of the main security problems of ATN is the delivery of encryption keys as in any secured system A
53. atial filter using a conical mirror and relay lens Each laser is rotated to produce one of the four polarizations 0 90 45 or 135 and illuminates a spatial filter consisting of two pinholes with a diameter of 100 um spaced at a distance of 9 mm Since the overlap of the emission modes of the four laser diodes with the filter mode is rather poor the initially very bright laser pulses are attenuated to about the required one photon per pulse level This system uses pulses with 0 05 0 5 photons per pulse The actual attenuation can be fine tuned by manipulating the diode current and precisely calibrated by optionally shining the light transmitting the spatial filter onto a single photon detector The filter erases all spatial information about which laser diode fired Spectral informa tion is also not attainable by an eavesdropper as the spectra of the four laser 48 Eurocontrol June 2004 4 1 FREE SPACE 49 diodes well overlap with a width of about 3 nm in pulsed mode A bright con tinuous wave CW laser beam can be injected with an auxiliary mirror AM for alignment purposes into the same spatial filter as the faint pulses while a calibration of the number of photons per bit can be made by inserting mirror FM and measuring a reference photo count The output of the spatial filter is then transformed to a collimated beam with 2 mm full width at half maximum FWHM and further expanded in a x20 telescope L1 and L2 to produc
54. ation There are remarks following 35 e Advantages easily accessible source e Disadvantages high attenuation due to atmospheric effects distance limited 68 Eurocontrol June 2004 5 3 SATELLITE NETWORK 69 Figure 5 9 Satellites network According to the part 5 2 there is some parameters technical shown in table 5 1 Table 5 1 Maximun range d of two types of satellite s optics diametter Optics diameter 1000km 3000km Analysis 5 3 1 The photon is sent from the ground station to the 10 cm of satellite s optics diametter Follows table 5 1 and equation 5 1 on page 67 the maximum distance d 1000 km the radius couvered r 600 km Thus the distance between two satellites 1 1040 km equation 5 2 on the preceding page and it needs 43 satellites equation 5 3 on the facing page to cover a surface of width 1040 km Analysis 5 3 2 The photon is sent from the ground station to the 30 cm of satellite s optics diametter Follows table 5 1 and equation 5 1 on page 67 the maximum distance d 3000 km the radius couvered r 2890 km Therefore the distance between tow satellites 1 5010 km equation 5 2 on the preceding page and it needs 9 satellites equation 5 3 on the facing page to cover a surface of width 5010 km 5 3 2 Space Based Transmitter Terminal Distributing key from satellite Because the optics of ground station is larger than the optics of satellites the distance is
55. bility theory Peter W Shor and John Preskill s one 41 Shor and Preskill have brought us a simple proof of security of the BB84 pro tocol They used Entanglement Distillation Protocols EDP to prove security of BB84 Firstly a key distribution protocol based on entanglement purifi cation is constructed and can be proven secure using methods from Lo and Chau s proof of security for a similar protocol And then the security of this protocol is shown to imply the security of BB84 The EDP uses Calderbank Shor Steane CSS codes and properties of these codes are used to remove the use of quantum computation from the Lo and Chau protocol Daniel Gottesman and Hoi Kwong Lo s proof 14 To prove the security of BB84 against the most general attack like Shor Preskill Gottesman and Lo use the entanglement purification except in two ways They prove clearly the advantage of classical post processing with two way classical communications over classical post processing with only one way classical communication in QKD This is done by the explicit construction of a new protocol for the error correction detection and privacy amplification of BB84 that can tolerate a bit error rate of up to 18 9 which is higher than any BB84 scheme with only one way classical communications can possibly tolerate normally 11 23 So their protocol leads to a higher key generation rate and remains secure over longer distances than previous ones And more o
56. bn Ol ah aes 12 KA SAPIME02 002 9 des fig ee ale ee ete Ph at atk awe Coste Ost og RU es 14 1 5 ATN Security Overview 14 156 Conclusions sive sige ech MS D dan ee ad does oe ta de ee he eae 15 2 Aeronautical Telecommunications Network 17 2 1 ATN Overview oir dak Verea de doute de 8 eee ee pe bye ba GO ee 18 2 2 CNS ATM 1 Applications 19 DS ATEN SECUTI ES ne ea te ct MON Tiny BG aie Sp pases Qian wt ROIS DS 20 2 4 Key Management 21 2 5 ATN andIPv6 vse rue re ne eh Raise wR ew cal eS Aas PRR Ge re ee 22 26 Air Identification Tag 44 wed ee ds ates ie ear ee es a a ad te Sea ae S 23 3 Quantum Key Distribution 25 8 1 Why is Quantum chosen for Cryptography 25 8 1 1 Weakness of classical cryptography 25 8 1 2 Appearance of Quantum Cryptography QC 26 8 2 Quantum Key Distribution QKD 26 8 2 1 Principles of QKD 26 8 2 2 Some protocols for QC 27 8 8 Detailed BB84 protocol 29 8 3 1 Description of protocol 29 8 3 2 Security of BB84 31 8 3 3 Specification for a simple implementation of BB84 37 4 Free Space and Satellites 45 4 Tr Bree Spaces rien le demie RD S
57. but two or more than one And thanks to these photons in excess Eve uses the form of half silver mirror to split the beam of photons Then she keeps one or two photons to measure and lets the others travel onto Bob In this case it is difficult to detect Eve s presence Because splitting some photons from a beam of multi photon will not affect the polarization of this beam Nevertheless Alice and Bob can pre compromise the time delay of photon to discover Eve s appearance Man in the middle An evident shortcoming of BB84 is lack of authentication Additionally with high level technology Eve may think of an attack called man in the middle or middleman attack in which Eve becomes an fake She will intercept the secure channel quantum one and acts as Bob with Alice and inversely By doing so she can achieve all exchanged information between Alice and Bob without they can notice anything Thus in order to break down this kind of attack authentication is the most great concern for BB84 protocol Protections against attacks We will give the most simple way to protect BB84 from the first two strategies Intercept Resend Beam splitting and for the third one Man in the middle a new proposal for BB84 s authentication will be produced The initial idea proposed by Bennett and Brassard is that if any errors were found in the raw quantum key the key would be negotiated and also could be left off However this work has led to the procedur
58. capacity for activities such as navigation and intelligence Now they are an essential part of our daily lives Communication satellites al low radio television and telephone transmissions to be sent live anywhere in the world Before satellites transmissions were difficult or impossible at long distances The signals which travel in straight lines could not bend around the round Earth to reach a destination far away Because satellites are in or bit the signals can be sent instantaneously into space and then redirected to another satellite or directly to their destination 50 Eurocontrol June 2004 4 2 SATELLITES COMMUNICATION 51 A communication satellite functions has an overhead wireless repeater sta tion that provides a communication link between two geographically remote sites Due to its high altitude satellite transmissions can cover a wide area over the surface of the earth Each satellite normally is equipped with various transponders consisting of a transceiver and an antenna tuned to a certain part of the allocated spectrum The incoming signal is amplified and then re broadcast on a different frequency Most satellites simply broadcast whatever they receive and are often referred to as bent pipes These were traditionally used to support applications such as TV broadcasts and voice telephony In recent times the use of satellites in packet data transmission has been on the rise They are typically used in WAN netw
59. ce free space Thus the scenario of distribution key from the satellite to the ground station is the best choice because it is easy to install a large telescope at the ground station with less low budget 70 Eurocontrol June 2004 71 WP II ATN and QKD Scenarios Eurocontrol June 2004 73 Summary and Conclusions This part summarizes the conclusions of the second step of this study These conclusions are made explicit in the following sections Summary Chapter 6 on page 75 ATN Communications secured with PKI de scribes several scenarii for the integration of Quantum Key Distribu tion QKD in the Aeronautical Telecommunication Network ATN for Air Ground A G telecommunications for Ground Ground G G telecommunications This chapter emphasizes on the requirement of incrementality of the pro posed solutions and of course on the minimization of the costs Chapter 7 on page 93 QC Communication Protocols describes methods for resolving one of the main problems of telecommunications that is the authentication of the other party Partial Conclusions One must be aware that WP2 has been conducted with the assumption that all QKD equipments were already available Even if quantum tech nology is fastly evolving the current available QKD equipments do not allow all the scenarii to be implemented If all the QKD equipments were available then numerous scenarii are available to secure the A
60. ch satellite checks its own sense of time and position with a ground station and makes any minor correction e On the ground any GPS receiver contains a computer that triangulates its own position by getting bearings from three of the four satellites The Eurocontrol June 2004 53 54 SECTION 4 FREE SPACE AND SATELLITES result is provided in the form of a geographic position longitude and latitude to for most receivers within 100 meters e If the receiver is also equipped with a display screen that shows a map the position can be shown on the map If a fourth satellite can be received the receiver computer can figure out the altitude as well as the geographic position e If you are moving your receiver may also be able to calculate your speed and direction of travel and give you estimated times of arrival to specified destinations The GPS is being used in science to provide data that has never been avail able before in the quantity and degree of accuracy that the GPS makes possible Scientists are using the GPS to measure the movement of the arctic ice sheets the Earth s tectonic plates and volcanic activity 4 2 2 Satellites Free space Communication At present the only suitable systems for long distance quantum communica tion are photonic Other systems such as atoms or ions are studied thoroughly however their applicability for quantum communication schemes is presently not feasible within the near future
61. cremental construction we can hope that QCKI will take part soon in ATN Network Eurocontrol June 2004 91 92 SECTION 6 INTRODUCING QC IN ATN Ground QAP Fixed fiber based link Figure 6 18 The QKCI of ATN Network 92 Eurocontrol June 2004 93 Section 7 QC Communication Protocols 7 1 Introduction to Communication Protocols According to the preceding sections we have scenarii for the distribution of a quantum key between an aircraft and a ground station and between other elements of the Aeronautical Telecommunication Network ATN In this part we develop a secure communication protocol between them A protocol is the description of all steps from the beginning of the procedure to establish a secured and authenticated communication link between the two parties First of all we can imagine a general protocol which contains three follow ing stages shown in figure 7 1 Key Exchange Communication Figure 7 1 Three stages of a general communication protocol Eurocontrol June 2004 94 SECTION 7 QC COMMUNICATION PROTOCOLS 1 Secure key exchange using quantum cryptography This question is al ready well described in the preceding sections cf section 3 on page 25 for a deep description of the quantum key distribution process We choose to use protocol BB84 to exchange a secure key between the aircraft and the ground station using for instance a satellite network We choose it beca
62. d make clean e To compile source files to obtain classes run command make Eurocontrol June 2004 114 SECTION 9 BB84 DEMONSTRATOR IN JAVA 9 1 2 For users on Windows Using a compression utility to unpack the file BB84_demo zip such as WinZip WinRar or Total commander If your Windows is well configured it may be sufficient to double click on BB84_demo zip Recompiling the files is not necessary but once obtaining directory BB84_Protocol you can do the same as users of MacOS Linux or Unix to recompile the program using command line In the case of being unfamiliar with command you can use an editor sup porting java language to recompile sources or run Makefile 9 2 How to run simulator To run the program enter BB84_Protocol directory 9 2 1 For users on Unix Linux or MacOS To launch the simulator typing command on a command line make run or click directly on jar files alice jar bob jar eve jar qc jar pc jar in current directory in the file manager window 9 2 2 For users on Windows You can do the same as users of MacOS Linux or Unix to run the program on command line Or if you are familiar with Windows Explorer launch the simulator by click on five executable files in the current directory alice jar bob jar eve jar qc jar pc jar 9 2 3 The application is running Five windows will be displayed on your screen Once the simulator is launched you will see five windows laid ou
63. d analogously to 7 11 Analysis 7 1 1 In these classical methods there are two ways to verify identi fiers of participants authentication by symmetric key techniques and authenti cation by asymmetric key techniques public key techniques With first method we can use quantum key as a shared key in symmetric encryption algorithm And in second we can integrate PKI into QKD to solve problem of authenti cation 7 1 2 Quantum Authentication Quantum authentication is a process to verify identifiers of legitimate users in key exchange using protocols similar to QKD protocol This method uses as well a secret key authentication key to authenticate but be safe against the man in middle attack and the Denial of Service DoS attack The DoS Denial of Service attack is a type of attack on a network that is designed to bring the network to its knees by flooding it with useless traffic In the case of authentication a typical DoS attack consists for a false participant to repeatedly trying to authenticate himself At each try the true participant uses a new pre positioned key If it does not use a new key each time the false participant may gain a few information on the key at each try If a new key is used at each try the set of pre positioned key can be exhausted 2Public Key Infrastructure 3Quantum Key Distribution Eurocontrol June 2004 97 98 SECTION 7 QC COMMUNICATION PROTOCOLS The Quantum Authentication protocol d
64. d data can be a digital signature associated with the emitter and may be used to achieve reinforcement of audible stimulus with a visual stimulus But this communication method is opposite the attacks monitoring spoofing mod ifying Therefore one needs the ways coded with the quantum key show in following section 8 4 Quantum Key Distribution Click on 2 QKD To securely communicate the plane and the control stations must have the same key coding For that before taking off the plane is distributed a key by the tower control show in figure 8 3 on page 110 show also in section 3 8 on page 29 Quantum Key Distribution and in section 6 2 on page 78 Scenario of QKD in ATN 8 5 Flight plan and ATN Click on 3 Flight plan and then on 4 ATN After the distribution the key to the aircraft this key is dispatched to all station where the plane will pass show in figure 8 4 on page 110 There are two ways distributing the key between the stations distribution by a satellite network show in section 5 on page 57 or direct distribution that depends the distance between them In this demonstration we visualize a direct scenario show in figure 8 5 on page 111 8 6 Authentication and Integrity Click on AIT QKD On board the plane can communicate with the stations on its plan with the authentication by using the distributed key show in figure 8 6 on page 111 108 Eurocontrol June 2004 8 6 AUTHENTICATION AND INTEGR
65. dest and the most typ ical protocol in QKD Secondly it provides a rather entirely detailed specifi cation to be easily implemented by anyone who is interested in QKD and has intention to possess his own simulation of a quantum key distribution system Thirdly and also lastly this implementation would experiment the proposed Eurocontrol June 2004 37 38 SECTION 3 QUANTUM KEY DISTRIBUTION authentication scheme in 3 3 2 on the preceding page The simulation will simulate the key exchange process between two major actors Alice Bob and an unexpected one the eavesdropper called Eve The exchange is realized over two channels a quantum and a classical channel which are considered as two others actors of system System requirements For the simplicity of experimentation the simulation will run on only one machine The software is developed under Solaris version 8 The program will be implemented in Java a familiar programming language with great support of graphical interfaces implementation As Java is used the software will be executable on almost all systems and computers Functions descriptions The primary target of the simulation as mentioned above in part Objec tives is to illustrate the operation of quantum cryptography in reality In ad dition it will simulate the actions of Alice Bob Eve and the channel between them Alice Alice is the sender of the encrypted message She must communicate with Bob to produce a
66. diameter It too has closed loop tracking but with lower resolution than the transmitter Ground telescope tracking and pointing To make it easy to track the satellite a field of view gt 1004R could be engineered This would re quire an effective f 5 100 cm telescope with 0 5 mm detectors Using high numerical aperture relay lenses before the detectors we could reach an effective f 2 telescope 250 uR field of view In this form daylight back ground levels will be high and night operation will be preferred With a large field of view point ahead tracking corrections may not be necessary Satellite optics pointing stability With the laser on the satellite we will have to point with an accuracy of 12 uR This will require the use of an upward pointing beacon laser co aligned with the ground telescope The bandwidth of this system should not be high involving probably drift time scales of the order of seconds Thus we could use a slow tip tilt mir ror at an intermediate stage Placing a tip tilt mirror at a position where beam diameter is 25mm the 0 5 stability of the satellite is magni fied by a factor of 4 The tip tilt system thus requires a full scale tilt of order 34 mR 2 and the closed loop needs to operate with an accuracy lt 40uR Satellite optics rotation stability The effective orientation of the satellite would be monitored by measuring polarization at the ground station and Eurocontrol June 2004 61
67. distribution inside ATN may be considered as admissible Coupling QC with AIT may also be considered as admissible For in stance AIT may be coupled with QC Authentication algorithm to provide a secure identification Using PKI for key distribution is not proven to be secure One may find a way or may already have found a way to break it If Quantum Com puters are built PKI is considered as broken since algorithms for these computers allow to break it Quantum Key Distribution is the only key distribution scheme which is proven to be secure using the quantum physics laws QKD authentication is not subject to key exhaustion by Denial of Service attacks Free Space Quantum Technology for Ground Plane Ground Satellite and Plane Satellite key distribution is not ready Theoretical results allow such a technology which may be ready in 10 years according to current progress records Current technology allows admissible payload either in aircraft or satellites The most foreseeable plan would be to use satellites based key distribu tion The required number of satellites varies from 7 to 43 depending on the evolution of technology It is a costly solution which may be used only if PKI is broken by Quantum Computers or mathematical progress Eurocontrol June 2004 9 10 10 WP2 Future Works e To provide a visual demonstrator of BB84 protocol e To develop several satellite based scenarios with the following constraints and qu
68. e s ones Bob s ones and Eve s ones e Quantum s parameters These ones are related to the quantum chan nel In fact a real quantum channel causes noises itself because of the imperfection of channel s material So to have a successful simulation of a quantum channel the factor of quantum channel efficiency should be added called for short as Q And this one will be later on included into the capacity of detecting photons at Eve s and Bob s detector Besides the intensity of photons transmitted in quantum channel is considerable Be cause in fact it has not been possible yet to transmit a single photon each time so in the realized experiment they had to replace single photon by faint pulses which contain few photons That is why the intensity of the beam A is included as a parameter of quantum channel e Alice s parameters Almost considered factors will be found in Alice s configuration The first one is mentioned here is the raw transmission size RawKey the length of Alice s initial string of qubits to send After Base Announcement the plain key sized PlainKey is achieved A proportion of this key EE sampic Will be randomly taken as a sample for Error Estimation And then error rate err qic will be estimated as following EE sample Plaink eYjen ETT rate In the next phase Reconciliation Cascade an interactive and parity based error correction scheme are repeated several times Befor
69. e with ATN and it must be incremental We can consider a QKD system for ATN Network as the Quantum Confi dentiality Key Infrastructure QCKI which provides confidential sharing of encryption keys between two endpoints As we have seen the main drawbacks of QKD technology are constraints of distance in the case of optic fiber 130km or freespace 23km and constraints of sight of line communication in case of freespace QKD technology Therefore if we want to construct an effective QCKI we must consider two important concepts quantum relay and QKD data relay We need to distin guish QKD data relay from quantum relay A quantum relay would redirect and or manipulate qubit states without ac tually measuring reading them By contrast a QKD data relay system is a network apparatus able to establish a secure communication using QKD tech nology with the previous element of the chain and another secure communi cation with the following element of the chain It is a QKD data relay system with the following characteristics 2Kb K bytes 1024 bytes 78 Eurocontrol June 2004 6 2 SCENARIO OF QKD IN ATN 79 e Relay k establishes an encrypted radio communication link with relay k 1 based on a shared QKD key e Relay k receives encrypted data from relay k 1 e Data are decrypted and stored in the memory of relay k e Relay k establishes an encrypted radio communication link with relay k 1 based on a shared QKD key e Data i
70. e a near diffraction limited 40mm FWHM beam A precision translator with lens L1 allows the fine focus adjustment Mirrors AM FM M1 and M2 are gold coated for high reflectivity in the infra red Together with the alignment laser and the single photon detector the whole system is mounted on a 25x50 cm breadboard attached to a micro radian sensitive pointing stage on a sturdy tripod The computer uses a pre stored random number to choose the polarization for the present set of experiments Alternatively nearly real time generation was possible where a sequence of bits produced by a quantum random number generator running at 20 MHz was produced in the second right before the transmission telescope 25 cm Schmidt Cassegrain from FM K receiver module itter IF transmitter j i BS A 2 PBS gt E P N yg Sg j discriminator i 4 amp pulse i mixing Ss Tenet CCD EE C Camera reference alignement laser clock we computer with timing card Li Figure 4 2 The receiver Bob Schmidt Cassegrainian telescope and attached miniature detector module The receiver system figure 4 2 consists of a 25 cm diameter commercial telescope Meade LX200 with computer controlled pointing capability realized by using a flip mirror and a CCD camera to view the incoming light Unfortu nately the resolution of the mechanics of this system was the limiting factor for the alignment of th
71. e called Privacy Amplification that we consider as one of the main phases in BB84 In this phase it is assumed that Alice and Bob share a secret key of length k and a set of these bits sized s were leaked to Eve s lt k Alice and Bob estimate what amount of the key Eve possessing from intercept resend or beam splitting attack Then they apply privacy amplification to make Eve s data useless This phase is based on a hashing function in form 0 1 0 1 where p gt 0 is some security parameter to shorten the shared key in order to comb out 36 Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 37 or minimize Eve s information Finally Eve can know nothing or a negligible amount of the final key between Alice and Bob Proposal for BB84 s authentication The original BB84 paper 9 mentioned the authentication problem and in troduced a solution to it by Wegman and Carter based on some classes of hash functions This solution requires a pre shared secret small key which is used to choose a hash function from the class to produce an authentication hash of the public correspondence between them By the nature of universal hash ing without knowing the key the probability to deceive the correspondence is extremely low even with unlimited computational power And now we will introduce here a new authentication scheme for QKD pro posed by Dang Minh Dung which will be added into the next section 3 3 3 For other as
72. e re quire only that the ground station remains within the field of view of the retro reflector This will usually be limited by the polarization switch which will have a limited acceptance angle Present low voltage 200V electro optic switches have a 10mR field of view in a 1mm beam translat ing to 1004R in an output beam of 10cm diameter However a larger area liquid crystal device will offer a much wider field of view up to 20mR at the telescope entrance which may only require pointing of the satellite to an accuracy of a degree Tracking the ground station is achieved by locking the image of the ground station laser to the centre of a sensitive CCD camera Satellite optics rotation stability The effective orientation of the biprism would have to be maintained normal to the satellite motion This requires an accuracy of a few degrees This effect could not be corrected from the ground Maximun range The retro reflected beam will be diffraction limited when the mirror is at the exact optical focus For 10cm optics this would mean a diffraction spread of 124R and a 12m spot on the ground An extra 50 loss is also inherent in the biprism system This gives a loss of 0 5TL 0 0023 26 5dB in a 100cm diameter telescope and 0 5TL 0 0006 32dB with a 50cm diameter telescope at the ground station With 35dB maximum loss the maximum ranges are gt 3000km for a 100cm telescope and gt 1800km for the 50cm telescope Expected key r
73. e receiver and was also difficult to handle at the harsh outdoor conditions compact four detector photon counting module 12 was coupled to the back of the telescope after an RG780 long pass filter to block out short wavelength background The module consists of a non polarizing beam splitter BS passing two beams to polarizing beam splitters PBS that are fol lowed by four photon counting avalanche diodes One polarizing beam splitter in the D1 D3 arm is preceded by a 45 polarization rotator half wave plate Photons detected in this channel are thus measured in the 45 basis while the other polarizer allows measurement in the 0 90 basis Since the splitting of incoming photons to the two analyzers by the beam splitter is truly random no random number sequence nor any space consuming optics are required on the receiver side however The module incorporated high voltage supplies and discriminatory circuitry to produce standard NIM pulses at the output The Eurocontrol June 2004 49 50 SECTION 4 FREE SPACE AND SATELLITES detector outputs D3 D4 are combined with the D1 D2 outputs with a delay of 5 ns and input into the two channel time digitization card Guide Technol ogy GT654 in the PC Thus the four detectors outputs are combined into the two channels with a delay of 5 ns The delay is then used to discriminate be tween the two measurement bases The overall optical detection efficiency of the receiver is about 16 ti
74. e run ning this protocol the initial block size blk for parity testing must be chosen together with the number of rounds The initial block size blko is chosen to be blko T ETT rate E Terrrate The block size blk 1 is defined as blk 2 blk The last normal round occurs when the block size exceeds fth of all bits Two extra passes are used with block size about Note that block size never exceed tth of all bits In this phase named Error Correction in 10 there is another choice of these parameters As in that implementation the block size is chosen experimentally in turn to be 5 7 10 14 And the size for Confirmation sample is 15 as mentioned in 10 Due to the security analysis in 1 the value for the extra shrinking parameter Eurocontrol June 2004 33 34 34 SECTION 3 QUANTUM KEY DISTRIBUTION another name as security parameter in privacy amplification is selected as below s P Apara Plain Ketien E Esanpic Bob s parameters Bob s parameters are in relation with his detector In fact a detector as the quantum channel itself has its own efficiency which represents its capacity to detect successfully a photon This is called for short as Deff Another problem affecting Bob s received bits rate is dark count When the detector takes a detection event detector s click without any photon dark count is generated So dark count rate is also included in the detector capacity
75. eaper and smaller ground stations Moreover some satellites can dynamically redirect their beams and thus change their coverage area Satellites can be positioned in orbits with different heights and shapes cir cular or elliptical Based on the orbital radius all satellites fall into one of the following three categories e Low Earth Orbit LEO e Medium Earth Orbit MEO e Geostationary Orbit GEO Some features of 3 satellite types are showed in the figure 4 5 on the follow ing page Eurocontrol June 2004 51 52 SECTION 4 FREE SPACE AND SATELLITES Height 100 300 miles 6000 12000 miles 22 282 miles Time in LOS Merits Lower launch costs Covers 42 2 of very short round Moderate launch the earth s surface delays small path cost small round trip constant view loss delays no problems due to dropper Demerits Very short life Larger delays Very large round 1 3 month trip delays encounters Greater path loss Expensive ES radiation belts due to weak signal Figure 4 5 Salient features of different satellite constellations Satellites are also classified in terms of their payload Satellites that weigh in the range of 800 1000 kg fall in the Small class whereas the heavier class is named as Big satellites GEO satellites are typically Big satellites whereas LEO satellites can fall in either class 18 Some protocols for the satellites communication e ALOHA It is one of the basic protocol in the pac
76. ection 3 on page 25 describing the BB84 protocol 1 A generates a random bit string 2 For presenting each bit and uses a quantum eigen state in a random basis chosen in 9 8 3 sends these quantum states to B 4 B uses a random basis chosen in to measure each received quan tum state 5 The bases used by A for quantum encoding are collected into a bit string ba 0 for 1 for Q 6 A encrypts the string ba with the pre positioning key k and sends the string b k to B using the classical public channel 98 Eurocontrol June 2004 7 2 QUANTUM AUTHENTICATION PROTOCOL 99 7 The bases used by B for quantum measurements are collected into a bit 10 11 string b 0 for 1 for B encrypts the string b with the pre positioning key k f and sends the string b k to A using the classical public channel A and B decrypt the bases received and could then find out ba amp by They discard the results at all positions i where bali b fi 1 i e po sitions where b i and b i are different They interpret the rest and get the two strings x for A and x for B A and B can compare some distilled bits from x and x to detect the presence of Eve the eavesdropper impersonating the parties 12 If Eve is not detected then they validate the authentication Security Analysis We only give informal deduction Full quantum based et information theory based proof are curren
77. ee TELECOM PARIS fools matienale upremo tes Hina QUANTUM CRYPT ENHANCEMENT OF AGT COMMUNICATIONS SECURITY USING QUANTUM CRYPTOGRAPHY Work Package I page 5 Work Package II page 71 Work Package III page 103 ENST EEC QC 12 01 WP3 A Michel RIGUIDEL Ecole nationale sup rieure des t l communications Network and Computer Science department 46 rue Barrault 75013 Paris France Phone 33 0 1 45 81 78 70 Fax 33 0 1 45 81 71 58 Email riguidel enst fr January 5 2005 B EUROCONTROL European Organisation for the Safety of Air Navigation EUROCONTROL June 2004 This document is published by EUROCONTROL in the interests of the exchange of information It may be copied in whole or in part providing that this copyright notice and disclaimer are included The information contained in this document may not be modified without prior written permission from EUROCONTROL EUROCONTROL makes no warranty either im plied or express for the information contained in this document neither does it assume any legal liability or responsibility for the accuracy completeness or usefulness of this information Contents I ATN and QKD Technologies 5 WP1 Summary and Conclusions 7 1 AGT Security Overview 11 LP Why Security 7 d ik bt tke ek de ed aaa Seite a de tee rte ES 11 12 AEEC Ad Hoc Meeting on DLK Security 12 1 3 ATN SARPS o aeg Mu a uen he Se ee OPA Pee Baek BU de
78. elays which do not exist the model of these scenarii does not seem to require strong modifications But there would be many changes in the technical equipment and and in the protocols Analysis 6 2 2 With our current knowledge of the ATN network we can rec ognize that the use of QKD technology do not imply any significant changes in the framework of ATN A G Applications It is just the another way to securely distribute encryption keys without the using of a heavy PKI system 6 2 2 QCKI for G G Applications Here we describe a basic scenario for protected communications enhanced by QKD technology between two ATN Sub networks The scenario can be de scribed as follows e Step 1 QCKI distributes a Quantum Session Key for two gateways end points of two ATN Sub networks e Step 2 These two ATN Sub networks use this Quantum Session Key for protecting messages traffic that will transit through the Internet within IPSec tunnels GG Sub network GIG Sub nstrork Figure 6 14 Fiber based QKD between two G G Subnetworks In ATN G G Applications the QCKI will provide confidential sharing of encryp tion keys between two gateways of ATN Sub networks on the GS These gate ways are in charge of establishing a secure communication using this quantum secret key As such we will take advantages of QKD technology into G G com munications by employing solutions similar to those used to protect the wired world Internet
79. ement differentiates his operation from hers This is the broadcast of all randomly chosen bases used by his photon detector to measure Alice s pulses Another difference be tween Alice and Bob is the decision of polarization of photon On Alice side this is decided by her apparatus but on Bob s side it is done by him But the common point here is that both choices are random Finally Bob must output his result in the same way as Alice s except fewer parameters to configure such as efficiency of his detector Eve Eve stands in the middle of Alice and Bob She acts both their roles at the same time Thus she shares with them many common functions in order to exploit 38 Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 39 BB84 Her major motivation is to collect as much as possible the information about the shared key between Alice and Bob without being discovered Her ad vantage is to be able to both receive and send pulses over the quantum channel in use intercept resend strategy and to realize beam splitting attacks But this is limited by the configuration of channel Lastly her same responsibility as Alice and Bob is to lay out her actions and results as well She must also allow users to change her configuration like percentage of intercepted message Channel The objective of the simulation is to make the object Channel mostly like the quantum channel in reality It means that this one must have all the proper ties
80. ent cryptosystems generate keys for ci pher or decipher messages using e arandom choice from a set of possible values as in DES and its variants e or one way functions which are considered difficult to reverse as in Diffie Hellman and RSA 13 Time needed for reversing such functions is expo nential in the input size For the former we can think that it is safe when the key is randomly generated but it is not really possible to achieve random key generation in principle by using present deterministic finite state computers However the situation is not better with one way functions because unfortunately up to now nobody builds any proof that one way functions are believably mathematically difficult to inverse Moreover Peter Shor discovered in 1994 that time to factor a large integer or calculate the discrete logarithm is polynomial if applying quantum computers So the main cause which menaces today s cryptosystem is the really rapid development in quantum computer technology But no problem has no solution duty is just to find out it And a proposition for current cryptography is Quantum Cryptography Eurocontrol June 2004 26 SECTION 3 QUANTUM KEY DISTRIBUTION 3 1 2 Appearance of Quantum Cryptography QC In 1970 QC was firstly proposed by Wiesner in his paper which had not been published until 1983 appeared in SIGACT News 15 no 1 And QC helped the scientists to open the door for the application of quantu
81. eparated by Besides these above commands there are two others commands New and End used by Alice to signal Bob the start and the end of a session of QKD The simulation will be triggered by Alice s New command sent through public chan nel accompanied with the length of qubit string to be sent Then Alice begins to send sequentially her message one bit by one bit This is done by using the method Write of quantum channel object in producing her intended polar ization the value of this qubit number of photons in the pulse and the order of the qubit And this info will be written into Quantum buffer and signaled to Eve by Quantum Channel Alice s method Write on the quantum channel Write int Polarization int value float Intensity int BufferLocation 40 Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 41 Eve receives the signal from Quantum Channel of the bits written in Quantum buffer and must at least acknowledge them before Bob is allowed to view them This is to resolve the problem of synchronism in reality Once Alice has transmitted all of the bits in her message she waits for Bob s response When receiving a qubit Eve chooses which attacks to be taken to read its info or let it proceed to Bob She has different choices beam splitting inter cept resend both attacks or nothing Eve can apply some attacks separately on the same location in quantum channel buffer If she attempts to split
82. er is used for the protected communication with a CPDLC Application In the current situation of ATN this scenario above is executed by the supporting of ATN s PKI which have to provide the following Cryptographic Schemes e Encryption Scheme Asymmetric or Symmetric Encryption e Digital Signature Scheme Asymmetric Encryption and Hash Function e Key Agreement Scheme Asymmetric Encryption e Message Authentication Code Scheme Hash Function Analysis 6 1 2 The introduction of PKI in A G exchanged messages will sig nificantly increase the overhead on the band limited communication channels for example a classical X 509 certificate is about 20Kb We must have some so lutions such as compression in order to minimize the size of secured messages Analysis 6 1 3 Typically the Certificates Revocation Lists CRL are very large therefore CRLs should not be transmitted to the AES over band limited A Glinks In order to overcome this problem of CRLs the Private Keys for AES and GS Applications should be short lived and the lifetime of these keys should be for the duration of a flight Hence as the AES will normally be located within physically secure boundaries controlled by ATN one option can be to manually upload the keys in the AES before flight 6 2 Scenario of QKD in ATN It is very important that any solution any improvement of the security must be done in the framework of the ATN construction It must be fully compatibl
83. erest in photon guns As for the pho ton counter in principle this can be achieved using a variety of techniques for instance photon multipliers avalanche photo diodes multi channel plates and super conducting Josephson junctions 19 Today the best choice of wavelength for free space QC systems is of 800 nm for which efficient avalanche photo diodes APD counters are commercially available In addition the receiver uses a combination of spectral filtering spa tial filtering and timing discrimination using coincidence window of typically a few nanoseconds to decrease the dark count errors Free space transmission is restricted to line of sight links Thus the beam pointing is still difficult for moving targets Despite the progress of the QC theory the free space QC systems are not popular In the early 1990s the first experiment performed by Bennett and co workers at the IBM laboratory over a distance of 30cm 5 After this there are some others significant free space experiments e 1996 J Franson Baltimore 150 m daylight e 1998 R Hughes Los Alamos 1 km night 7 e 2000 R Hughes Los Alamos 1 6 km daylight 8 46 Eurocontrol June 2004 4 1 FREE SPACE 47 e 2001 J Rarity QinetiQ 1 9 km night 20 e 2002 R Hughes Los Alamos over 10 km 26 e 2003 P Morris 23 4 km night 31 The results achieved of P Morris form a significant step towards a key ex change system Such a system using
84. estions Is it possible to incrementally inject QC inside the ATN PKI Is it possible to use QC for specific links only such as VHF AIT links Is there some environmental impact Is there some public health concern e To provide visual demonstrators for the preceding scenarios Eurocontrol June 2004 Section 1 11 AGT Security Overview Informations from this section are mainly provided from 29 It is a short description of the state of the art in Air Ground Telecommunications AGT Se curity and a short description of the institutional concerns 1 1 Why Security AGT Data Link DLK provides numerical communications between ground stations and aircraft These communications are used for Graphical Position Reports Contact Reports etc One may classify different threats on Data Link communications sd ee Main sources Monitoring A third party may listen to the Data Link communications and gain informa tions on the traffic Current Data Link commu nications do not guarantee privacy Spoofing A third party may listen to the Data Link communications and gain authentication informations in order to impersonate one of the parties Modifying A third party may impersonate the second party with respect to the first party meanwhile he may also impersonate the first party with respect to the second party man in the middle attack Integrity of the data is not preserved Data may be c
85. eting were e Security of Data Link communications is a serious concern e There exists a problem with the open distribution of threat and vulnera bility informations e A ACARS solution compatible with ATN security has to be found e Minimizing costs of a solution is a concern 1 3 ATN SARPs ATN Standards and Recommended Practices is documented by ICAO Docu ment 9705 third edition Sub Volume 8 October 2002 ATN SARPs is based on the following elements e Eurocontrol has performed a risk analysis and has identified the follow ing threats and vulnerability Modification and replay of AGT Denial of services by flooding routing databases e Airlines require confidentiality of operational data 12 Eurocontrol June 2004 1 3 ATN SARPS 13 ATN SARPs provides the following security services e Authentication and integrity of Air Ground Telecommunications e Authentication and integrity of IRDP Inter Domain Routing Protocol communications e Supporting Public Key Infrastructure PKI Note that the ATN Panel ATNP WG B Sub Group 3 is enhancing the ATN SARPs with confidentiality services The SARPs document is organized as follows e 8 1 Introductory Materials 8 1 1 ATN Security Services Support operational requirements of secure exchange Support mobile and fixed network users 8 1 2 ATN Security Services Providers x Message assurance from originator x Authenticatio
86. eveloped by our team at Enst is described in the following section It is safe against man in the middle attack and against the Denial of Service DoS attack 7 2 Quantum Authentication Protocol In this party we present a quantum authentication protocol 21 40 This au thentication scheme is based on the same technique as the BB84 protocol Here we assume A and B are two participants who want to authenticate themselves Let m be a message and let k be a key m and k are supposed to have the same bit length The Vernam encryption of m using key k is writ ten m k It is an XOR or equivalently an addition modulo 2 of the corresponding bits of m and k i e if m is the i th bit of m if k is the i th bit of k then the i th bit of m k is m XOR b Given the encrypted message m amp k et the key k the message can be recovered by computing m k k Using the theory of Information of Shannon it can be proved that Ver nam cipher is uncontionnally secure provided that the keys are used only once A and B use a shared authentication key as precedently described Let us name k this key of bit length n e k T and k respectively denote the string k k 1 k n and its inverse k n amp 1 e Let m a message of length p n mk denotes the Vernam encryp tion of message m by a key obtained by concatenating p copies of the key k The protocol executes the following steps The terminology can be found in s
87. fication It allows to increase the security of the system by an additional factor e Eve s setting Beam Split is a floating point number between 0 and 1 This is the percentage which Eve takes for beam splitting Mirror Strength is floating point number 0 to 1 inclusive This is used to decide how much of a pulse is used for beam splitting Intercept Resend This is similar to Beam Split but used for Inter cept Eurocontrol June 2004 43 44 SECTION 3 QUANTUM KEY DISTRIBUTION Resend Strength After intercept a pulse from Alice Eve does not know the intensity So she must create her own pulse with a new intensity e Bob s setting In Bob s interface there is only one result box which display the key bits and its length through each phase e Quantum channel s setting Mirror Efficiency its value is in the interval 0 1 When Eve takes action of splitting a pulse it absorbs partially this photon So lower mirror efficiency means much more photons absorbed from the pulse Channel Efficiency is to measure channel s interference to the pulse upon it Higher this rate is less interference on pulses Detector Efficiency measures the capability of Bob s detector Its value is in 0 1 Dark Counts represents the sudden occurrence of a dark count at Bob s detector e Public channel s setting This interface has only one tab the result to display the current transmission upon it and each p
88. g initial contact The message costs are the following e CMA initial contact Logon request 400 bits Logon response and certificate 1500 bits e Subsequent secured message 32 bits Message Authentication Code Note that efforts have been made to minimize the costs For instance a X 509 certificate is about 20 KB The Certificate Delivery Services delivers certificates and Certificate revo cation Lists CRL to ATN entities X 500 directory is likely to help on the ground e Ground scenarios Applications and routers have directory access CMA has directory access and provides certificates and CRL Certificates are pre stored at initial deployment e Air scenarios Short lived certificates sent to aircraft CMA certificates pre stored at initial deployment Analysis 1 5 1 An eavesdropper accessing the pre stored certificates may en danger the security system 1 6 Conclusions Analysis 1 6 1 Any solution any addition or improvement to the security must be done in the frame of the ATN construction It must be fully compatible with ATN Analysis 1 6 2 ATN Security relies on very classical technologies which have been mapped to the particular structure of ATN Such technologies are not fully proved to be sure Eurocontrol June 2004 15 17 Section 2 Aeronautical Telecommunications Network In 1983 the International Civil Aviation Organization ICAO created the Spe cial C
89. ge modern equipment which will allow to exchange photons over 1000 km 39 One can thus imagine a scenario of distribution of key be tween the station on the ground and the plane But how is it done One can easily know that there are many disadvantages if the station and the plane are communicated directly 35 e The distance of communication is limited Therefore it is necessary to install ground stations of each thousand km to contact the planes It is not possible because the budget to maintain these stations is too high Especially the installation of the ground stations is facing much natural obstacles e High attenuation due to atmospheric effects is shown in figure 5 1 on the next page It is easy to see that the way passed by satellite BP and AG is shorter than by the direct communication PG in the zone of atmospheric effects The light gray zone is full of noise Thus the direct communica tion causes several bad information by lost photons To solve these disadvantages we suggest a scenario of communication using satellite With this model there are following advantages 35 e Easy to cover a space with a network of satellites Thus one can well solve the problem of distance e Ground station may easily be removable or re installable in short time e Point to multipoint a satellite can contact several of ground stations or planes Eurocontrol June 2004 58 SECTION 5 ANALYSIS AND SCENARIOS Figure 5 1 Influe
90. grity Monitoring Airborne Based Augmentation System Aircraft Communications Addressing and Reporting System Airborne Collision Avoidance System Area Control Centre Association Control Service Element Aircraft Data Link Processor Automatic Dependent Surveillance Automatic Dependent Surveillance Broadcast Automatic Dependent Surveillance Panel Airlines Electronic Engineering Committee Airborne End System Auto Forward Area Forecast Centre African Civil Aviation Conference Aeronautical Fixed Service Aeronautical Fixed Telecommunications Network Air Ground Telecommunication ATS Interfacility Data Communication Aeronautical Industry Service Communication Aeronautical Information Publication Aeronautical Information Region Aeronautical Information Service Aeronautical Industry Service Communication Air Identification Tag All Planning and Implementation Regional Groups Mobile DTE Sub Address Aeronautical Mobile Communication Panel Aeronautical Message Handling System Aeronautical Mobile Satellite Service Air Navigation Commission Air Navigation Plan Air Navigation Services Aeronautical Operational Control Application Process Asia Pacific Air Navigation Planning and Implementation Regional Group Aeronautical Passenger Communications ARINC IA Project Initiation Modification Eurocontrol June 2004 122 APIRG APP ARINC ARTAS ASECNA ASEs ASM ASN 1 ASPP ATAG ATC ATCAA ATFM ATM ATM ATN ATNP ATNSI ATS
91. he insecure channel classical one And for the quantum channel Eve applies some following typical attack strategies to dig as maximum information as possible Eurocontrol June 2004 35 36 SECTION 3 QUANTUM KEY DISTRIBUTION Intercept Resend Intercept resend is the most used strategy which Eve applies to attack BB84 This simple and even practical attack consists for Eve to measure each qubit in one of the two bases precisely as Bob does Then she prepares a qubit in a state corresponding to her measurement result She sends this qubit to Bob Eve has a probability of 50 to correctly measure the qubit sent by Al ice In this case she can resend successfully the original qubit to Bob without Alice and Bob s awareness For the other 50 Eve causes the uncorrelation between Alice and Bob s results That will help Alice and Bob to discover Eves presence In brief the intercept resend brings to Eve 50 information while it increases the error rate in Alice and Bob s sifted key up to about 25 even after discarding bits measured in incompatible states Eve normally does not apply this attack to 100 communication just only to a fraction say 20 then the error rate will be only 5 while Eve s achieved info up to 10 Beam splitting 4 The second frequently used attack is beam splitting Eve takes advantage of the imperfection of the system to extract the information This is due to pulses generating not only one photon
92. ircraft in Flight VHF Omni directional Radio Range Very Small Aperture Terminal Wide Area Augmentation System US World Area Forecast Centre World Area Forecast System Wide Area Network World Geodetic Standard Eurocontrol June 2004 127 129 Index A A G 75 ACARS 12 ADS 18 ADSP 18 AES 76 AFTN 18 AGT Data Link 11 AGT Security 11 AGT Threats 11 Air Identification Tag 23 AIT 23 Alice 29 AMCP 18 AMHS 14 18 AMSS 18 ANC 17 APD 46 ARINC 14 ASPP 18 ATM 17 ATN 17 75 93 ATN Security 14 ATN security services 13 ATN threats 12 ATN vulnerability 12 ATNP 18 authentication 94 classical 95 digital signature 97 public key 96 symmetric key 95 B Bob 29 BS 50 C CA 22 Cascade 31 CDMA 52 Certificate authority 22 Certificates Revocation List 22 CIDIN 18 CM 18 CMA 76 CNS 17 CPDLC 18 CRL 22 78 CW 49 Data Link 11 Data Link monitoring 12 Denial of Service 97 DLK 11 DLK monitoring 12 DoS 97 DSP 12 E ESA 55 Eurocontrol 12 Eve 29 F FANS 17 FDMA 52 FIS 18 FWHM 49 G G G 75 GEO 51 GM 17 GPS 53 GS 76 H hash function 96 HF Data Link 18 I ICAO 14 17 ICC 18 IETF 22 Internet Protocol 22 IPSec 23 IPv4 22 IPv6 22 IRDP 13 14 ISO 17 L LEO 51 M MEO 51 N NAT 23 O OACA 22 OGS 55 one way function 96 OSI 17 Eurocont
93. ircrafts Context Management Application to contact a dif ferent flight region Eurocontrol June 2004 19 20 SECTION 2 AERONAUTICAL TELECOMMUNICATIONS NETWORK Automatic Dependent Surveillance ADS is designed to give automatic reports from an aircraft to a ground system This information is provided on demand and in an emergency Aircraft position and trajectory and meteorological data are typical uses of this service Controller Pilot Data Link Communications CPDLC provides a mean for two way message oriented communications including a set of clearance information request messages corresponding to current voice phraseology employed by ATC procedures Flight Information Services FIS can support a variety of information services providing information about the ground to an aircraft This can include information about an airport such as runways in use and weather conditions ATS Interfacility Data Communication AIDC provides a mean for the exchange of ATC information between Air Traffic Services Units in sup port of ATC functions including notifications of flights approaching a Flight Information Region boundary co ordination of boundary crossing conditions and transfer of control The Aeronautical Message Handling System AHMS provides a mean for the exchange and distribution of message oriented traffic between Air Traffic Services Units It is an AFTN replacement that may be used addi tionally to provide new messagi
94. ive QCKI we must know scenarii in which the QCKI can co operate with A G Applications According to the architecture of the QCKI i e the ways of arrangement of the transmitter and the receiver also the type of photon sources i e single photon source or entangled photon source we can imagine the following possible scenarii of using the QCKI in the ATN Network e Single photon source Ground based QCKI see page 82 e Single photon source Aircraft based QCKI see page 83 e Single photon source Satellite based QCKI see page 84 e Entangled photon source Ground based QCKI see page 85 e Entangled photon source Aircraft based QCKI see page 86 e Entangled photon source Satellite based QCKI see page 87 Eurocontrol June 2004 81 82 SECTION 6 INTRODUCING QC IN ATN e Single photon source Ground based QCKI The single photon transmitter is placed at the GS A straight laser up link using BB84 protocol to one receiver on the AES can be used to per form the negotiation of the sharing secret key see figure 6 4 Reeetver ansmitter Figure 6 4 Ground based QCKI with single photon source We can also use a satellite which acts as a quantum relay space station see figure 6 5 Relay Receiver Transmitter Figure 6 5 Ground based QCKI with single photon source Moreover it is also possible to use fiber based technology if aircraft are on the ground in European airports In this case the key is distributed before the
95. ization valued 0 or 1 too a tag field to check the interception of Eve and another for the number of photons in that pulse This simulated quantum channel operates as a real one in physical aspect It provides different methods for Alice Eve and Bob that they can interact together They can send or read information from the channel or launch an attack upon it for Eve Below we have specific rules to follow e Alice She can transmit as many qubits as she likes in her time slot without worrying about Eve or Bob s receipt yet e Eve She cannot directly extract information from a photon such as its polarization She may change the polarization of a photon due to her wrong measurement After Eve intercepts a pulse the tag field will be changed to permit Bob s access to it e Bob He cannot access directly to the photon to get the information of a qubit neither read the qubit before Eve before switch of tag field Below is the description of qubit object value int polarization int tag float photons Public channel All phases of the qubit string treatment from which to distill the final key take place on public channel Each phase is negotiated between Alice and Bob with transmitted necessary parameters And these exchanges are repeated and have the same structure of the name phase and its parameters So all these phases information are fixed in the following format NamePhase parameters the parameters s
96. ket radio communica tions The ALOHA system has a simple structure and easy control How ever it is difficult to receive a packet correctly if packet collision occurs Frequency Division Multiple Access FDMA It is the oldest and still one of the most common method for channel allocation In this scheme the available satellite channel bandwidth is broken into frequency bands for different stations e Time Division Multiple Access TDMA In this method channels are time multiplexed in a sequential fashion Each earth station gets to transmit in several fixed time slot only e Code Division Multiple Access CDMA This scheme uses a hybrid of time frequency multiplexing and is a form of spread spectrum modula tion It is a relatively new scheme but is expected to be more common in future satellites e Packet Reservation Multiple Access PRMA It is an improved form of TDMA that combines TDMA with the techniques of Slotted ALOHA Up to now there are various uses of satellite communication e Traditional Telecommunications e Cellular e Television Signals e Marine Communications lhttp www cis ohio state edu jain cis788 97 satellite_nets index html 52 Eurocontrol June 2004 4 2 SATELLITES COMMUNICATION 53 e Spacebourne Land Mobile e Satellite Messaging for Commercial Jets e Global Positioning Services There are some modern satellite networks for instance IRRIDIUM IN MARSAT M GLOBALSTAR TELEDESIC ODYS
97. l we probably believe that the share key is now the same maybe with error but at an acceptable rate if z is large enough 6 Privacy Amplification Finally Alice and Bob may have an identical key but what about Eve After all the previous phases maybe she has gained some information so it does not secure the identical shared key So what has to be done to resolve this problem And Privacy Amplification is exactly the answer The aim of this phase is to minimize as far as possible Eve s informa tion about the key and to generate a shorter but more confident key At that moment Eve collects only a negligible amount of information about this string and Alice and Bob can safely use it directly for unconditionally secure encryption For privacy amplification a publicly known univer sal hash functions is always chosen that will map n bit strings to r bit strings This choice can be determined over the public channel And this proposition was made by Charles Benett Gilles Brassard Claude Cre peau and Ueli Maurer 3 3 2 Security of BB84 As we know normally a protocol is said to be secure when it is proved to be se cure against all attack strategies of eavesdropping This is called unconditional security i e without assumptions And up to now this is still really difficult duty even for an idealized system such as BB84 protocol with single photon source Proof of BB84 security The security of BB84 however has been theoreticall
98. ly insert QCKI inside the ATN The last but very expensive step would be to use satellites We mention several possibilities of key distribution Single photon source Ground based QCKI see page 82 Single photon source Aircraft based QCKI see page 83 Single photon source Satellite based QCKI see page 84 Entangled photon source Ground based QCKI see page 85 Entangled photon source Aircraft based QCKI see page 86 Entangled photon source Satellite based QCKI see page 87 Environmental impact We did not see any environmental impact since the QKD quantum equipments do not produce anything Health concerns QKD technology uses lasers However it is faint pulse lasers which are not supposed to hurt people WP3 Future Works To provide visual animations to illustrate one or two scenarii that we have explored To provide a animated implementation of BB84 To build a follow up proposition to be submitted to the CARE manager Its main characteristics are It must provide an effective realization within two years We will have a Quantum Physics laboratory specialized in lasers as a partner for the equipment items of the project It must be a step towards the integration of QKD inside the ATN It could be a way for the authentication of Air identification Tag AIT which has been developed at Eurocontrol with the cooperation of the Graz University of Technology in Austria Eurocontrol
99. m information theory which itself is founded on the fundamental axioms of quantum physics More detailed QC provides a secure protocol to exchange cryptographic keys This protocol is called quantum key distribution or quantum exchange 3 2 Quantum Key Distribution QKD 8 2 1 Principles of QKD The quantum key exchange is based on two physical theorems which help to generate a secure key between Alice and Bob They are the no cloning theorem and uncertainty principle 37 e uncertainty principle this is one of the fundamental principles in quan tum mechanics which says that if the measurement used is incompatible with the unknown state prepared so it will interfere the original one of the system e no cloning theorem based on the uncertainty principle there is no way to know a state for sure And cloning an unknown state is impossible we cannot have a perfect copy of a random quantum state In comparison with traditional cryptography key distribution QKD can solve some shortcomings Besides strong points QKD also has some some weak points mentioned below Advantages of QKD As mentioned in the precedent part QKD is based on quantum mechanics The main strong point of QKD is that it ensures the confidentiality of keys guaranteed by the quantum physical laws This is the major reason why QKD is favored QKD techniques can provide automatic distribution of keys that offers a greatest security than classical ones The Quantum p
100. ming jitter was smaller 1 ns Beside of quantum devices the timing and the synchronization are very im portant The two separate computers were linked via modems operating over a standard mobile telephone link 9 6 Kbaud bit rate Local oven stabilized 10 MHz clocks were synchronized to better than ns using a software phase locked loop driven by the received photo detections The photo detections thus can be gated in two 1 4 ns wide time windows separated by 5 ns Pulses outside these timing gates are ignored The error rate due to dark and background counts is thus suppressed by a factor of 1 35 The random polarization pulses are sent in 700 ms blocks preceded by a series of predetermined pseudo random data sets lasting 110 ms to uniquely determine the start time of each block Following the transmission of the block a settling time of 300 ms allows the computers to check for a successful transmission Gross block length is thus just over 1 1 s Sifting and error correction of the 700 ms data blocks were then performed over the telephone link using software developed in the 1 9 km experiment 20 Figure 4 3 shows some results achieved Night Number of Quantum Final photons per bit bit 10 626 367 Figure 4 3 Summary of selected experiments 4 2 Satellites Communication 4 2 1 Overview of satellites communication Not so long ago satellites were exotic top secret devices They were used pri marily in a military
101. n J E Nord holt and C G Peterson Daylight Quantum Key Distribution Over 1 6 km In Phys Rev Lett volume 84 pages 5652 5655 June 2000 9 Charles Bennett and Gilles Brassard Quantum Cryptography Public Key Distribution and Coin Tossing In Proceedings of IEEE International Conference on Computers Systems and Signal Processing pages 175 179 Bangalore India December 1984 10 Charles H Bennett Francois Bessettee Gilles Brassard Louis Salvail and John Smolin Experimental Quantum Cryptography September 1991 11 Chip Elliott Building The Quantum Networks BBN Technolgies USA June 2002 121 Chip Elliott Dr David Pearson and Dr Gregory Troxel Quantum Cryp tography in Practice May 2003 13 Christoph Guenther The Relevance of Quantum Cryptography in Mod ern Cryptographic Systems December 2003 14 Daniel Gottesman and Hoi Kwong Lo Proof of Security of Quantum Key Distribution with Two Way Classical Communications September 2002 Eurocontrol June 2004 132 BIBLIOGRAPHY 15 Data Link Ad Hoc Committee Ad Hoc Meeting on Security Executive Summary for AEEC General Session 2002 Membership ESC GAD Titan Corporation Hanscom MA USA may 2002 16 Dominic Mayers Unconditional Security in Quantum Cryptography 48 351 406 July 2002 17 Dung Dang Minh and Michel Riguidel Usage of Secure Networks built using Quantum Technology 2004 18 B R
102. n by receiving entity e 8 2 General ATN Security Concept and Services e 8 3 ATN Security Framework Standards Provision of Security Services ATN Physical Security Framework e 8 4 ATN Public Key Infrastructure PKI Certificate Policy Certificate Format Certificate Revocation List CRL Format Certificate and CRL Validation process e 8 5 ATN Cryptographic Infrastructure Key Agreement Digital Signature Message Authentication e 8 6 ATN System Security Object e 8 7 ASN 1 Module for ATN Security 29 quotes the following sentences from the ICAO SARPs section 8 1 2 notes Security services in general support but do not guarantee protection from se curity violations Cryptanalytic advances may affect the overall level of pro tection Eurocontrol June 2004 13 14 SECTION 1 AGT SECURITY OVERVIEW Analysis 1 3 1 The SARPs mentions that PKI based security is not guaran teed and that it depends on advances in cryptanalysis But it does not mention the possible birth of Quantum Computers That is exactly the problems that Quantum Cryptography claims to solve For instance SARPs mentions that Key Pairs public and private keys must be changed every 28 days and that private keys must be protected The fact that private keys must be protected is an evidence e If the private key of a Certificate Authority CA is disclosed then the whole security system depending
103. n memory are encoded and sent to relay k 1 As we have already mentioned the ATN Network have two main categories of applications Air Ground A G Applications and Ground Ground G G Ap plications Now we will suppose that all current necessary physical equip ments of QKD technology are perfect And let us see the scenarii for the inte gration of QCKI in each type of ATN applications 6 2 1 QCKI for A G Applications As we know one of main drawbacks of the ATN s PKI is the band limitation of A G links In the case of AES located in European airports we can use PKI to distribute keys to AES on the ground before takeoff But with PKI it seems to have no solution in the case of AES entering the European sky QCKI may be a better candidate for this case because his flexibility The Quantum Confidentiality Key Infrastructure QCKI is responsible of providing confidential sharing of encryption keys between two endpoints In ATN A G Applications one endpoint is always an aircraft AES and the other can be any Ground Station GS which is connected with the ATN Net work Normally the selected quantum channel must be a free space quantum channel because aircrafts can be in the sky In the case of aircraft on the ground one can use fiber based channels instead of free space channels if the aircraft is wired to the airport infrastructure Otherwise if the aircraft is on the tarmac with no physical link to the airport infrastructure frees
104. n one can check OACA certificates with the public key of its CA Analysis 2 4 3 Moreover the secrecy and the validity of the certificates rely on the security of the whole PKI infrastructure If one CA or OACA private key is stolen the PKI system is broken 2 5 ATN and IPv6 The ATN is an Internet network with fixed and mobile elements Such a net work is managed using protocols Most of today s Internet is managed using IPv4 Internet Protocol Version 4 However the Internet Engineering Task Force IETF has designed Internet Protocol Version 6 IP v6 the next genera tion Internet Protocol IPv6 fixes a number of problems existing for IPv4 such as the absence of Quality of Service QoS IPv4 only supports Best Effort or the shortage of available IP addresses For instance IPv4 addresses are limited to 32 bits It was sufficient 25 years ago However addresses are allocated by classes and much of the big classes 22 Eurocontrol June 2004 2 6 AIR IDENTIFICATION TAG 23 are allocated to US providers IPv6 has a 128 bits address space allowing 3 4 x 10 possible IP addresses Every square centimeter on earth can be in dividually addressed using IPv6 Internet programs such as Network Address Translator NAT allowing to hide a sub network behind one IP address with some drawbacks are not needed any more IPv6 has built in security services The support of IPSec is mandatory IPv6 has support services for mobility with
105. nce of atmosphere on the QKD With all these disadvantages and advantages one can say that the model of satellite communication is ideal In the following parts let us propose the key exchange to satellite scenario and also a network of architecture using satellites 5 2 Key exchange scenario With first stage we consider the exchange of key between a ground station and a low earth orbit satellite 800 km According to 43 there are three options to analyze e The ground station transmits a key to the satellite e The satellite transmits a key to the ground station e The ground station transmits a key to another ground station using the satellite as a mirror For all the three models it needs a classical channel which must be able to exchange digital data at high bit rates to allow interactive alignment time synchronization key sifting and error correction to be carried out in real time Ethernet bandwidths 10 MHz are needed for real time operation Lower clas sical bandwidth would require some time after optical key exchange for the protocol to be completed thus limiting the number of key bits that could be ex changed on a typical pass For the optical channel we suggest telescopes like the following e A big telescope on the ground station with a diameter up to 30 100 cm which must be able to track the satellite e Asmall telescope on the satellite 10 or 30 cm With 10cm optics the tar get of 3 kg may be reached but 30 cm
106. neighboring discovery mechanisms IPv6 also has support for Quality of Service QoS One element of these services is the presence of packet flow identification which does not exist in IPv4 Most of the operating systems commercial and not commercial now support IPv6 which can coexist with IPv4 Some studies for instance Eurocontrol iPAX claim that ATN could use IPv6 because the expected number of aircraft using ATN in the next 25 years is over 100 000 Each aircraft is expected to have many equipments on board subject to be linked to the ATN With its indecent number of available address each equipment could have its own IP address Moreover IPv6 is claimed to be scalable to very large networks and it has supports for security and QoS IPv6 is viewed as a possible enhancement of the ATN and an option for ACARS IETF is working on new mechanisms for mobility NEMO IPv6 would need mobility mechanism that meets the ATH requirements in particular concurrent use of multiple data links When OSI has been chosen for the ATN it was the only network proto col that could meet most of the ATN requirements However OSI has not fulfilled the expectation that it would replace TCP IP IPv6 is still in its in fancy Since IPv6 and IPv4 can coexist there may be a gradual shift from IPv4 to IPv6 Internet and telecommunications companies are interested and work ing to improve IP protocols and many investments are made into IPv6 Aero nautical companie
107. ng services including Electronic Mail and Electronic Data Interchange It is based on ITU recommendation X 400 See http www helios is com atn atnover S59577 htm for more de tails 2 3 ATN Security As a result of study done by Eurocontrol it is suggested that the following are threats against the ATN including ATN management and application services which pose a significant threat to which the ATN is vulnerable and hence require specific counter measures 1 To Air Traffic Control Messages both Air Ground and Ground Ground there are threats resulting from e Modification e Replay e Masquerade e Jamming 2 To X 400 Message Handling System MHS there are threats resulting from e Modification e Masquerade 1Cf http www helios is com atn atnover 59616 htm 20 Eurocontrol June 2004 2 4 KEY MANAGEMENT 21 3 To OSI Systems Management e Modification e Replay e Masquerade e Unauthorized modification of management information base 4 For all applications vulnerabilities exist to Denial of Service attacks on the ATN which impact Air Traffic Control Messages including e Jamming air ground links e Flooding the ATN with data packets e Causing switches and data links to fail e Unauthorized modification of routing information These are to be addressed by network design and topology and physical access security which should be considered by regional planning bodies and by appropri
108. nge implies a maximum background B lt 240 counts s which is easily achieved at night with nanometer bandwidth filters In short with this scenario there are following significant technical figures Diameter of ground optics 30 cm 2T atmospheric transmission Lg geometric loss 3 K expected key exchange rate M number of photons per pulse n detection system lumped efficiency 60 4B background count rate per second Eurocontrol June 2004 5 2 KEY EXCHANGE SCENARIO 61 Technical numbers concerning the satellite optics diameter 10 cm 30 cm Ground tracking 4uR 4uR and pointing diffraction diffraction Satellite optics 100uR 100uR pointing ability Locked to ground Locked to ground laser guidestar laser guidestar weight of telescope Satellite optics Corrected Corrected yaw stability from ground from ground Key rate K 450 bits s at 1000 km 4500 bits s at 1000 km 1000 bit at 2000 km The loss budget RES lt 35 dB lt 35 dB at 1000km 5 2 2 The satellite transmits a key to the ground station The satellite optics transmitter is shown in figure 5 3 on the next page The four laser source can be made extremely compact and lightweight A beam splitter picks off a view of the ground for a CCD camera so that closed loop pointing control can be performed The beam is then expanded to 10 cm to send to the ground The receiver is in the ground station with a fixed telescope with up to a 100 cm
109. nject copies However this strategy has to fail because half the time the eavesdropper will Eurocontrol June 2004 47 48 SECTION 4 FREE SPACE AND SATELLITES have chosen the wrong measurement basis and the re injected pulses will in duce an error rate of 25 Of course a certain level of error could be caused by imperfections in the equipment used but in order to guarantee absolute se curity any error should be attributed to partial interception Below a certain threshold the error can be corrected and potential knowledge of the key by any eavesdropper can be erased by privacy amplification protocols It is similar to all of QC systems the QC system of P Morris consists of 3 main components e transmitter e detector e quantum channel free space L2 base plate sitting on precision tip tilt aligner alignement laser source module spatial filter Figure 4 1 The Alice compact 20x50 cm breadboard transmitter The transmitter figure 4 1 is designed round a 80 mm diameter transmit telescope The digital I O card delivers a random 2 bit signal at 10 MHz syn chronized to the reference clock This signal is used in the pulse driver for randomly firing one of four 500 ps picosecond duration lasers 850 nm wave length in the miniature source module This miniature source uses polariza tion approximating coded faint pulses in the place of single photons The four lasers are combined in a sp
110. nks into QCKI The figure 6 17 on page 91 shows a QCKI in highly schematic form Eurocontrol June 2004 89 90 SECTION 6 INTRODUCING QC IN ATN Sub network Sub network Figure 6 16 Satellite based QKD between two G G Subnetworks 6 2 3 A proposal QKCI for ATN Network As we know the use of satellites is the most significant but also expensive investment Although costly to deploy and to maintain it still seems a unique solution for a stable long distance QCKI A satellite based QCKI can overcome the principle limitation of Earth bound technology i e the range of the order of 150km afforded by both optical fiber and by terrestrial free space links because of reduced influence of atmospheric turbulence Therefore the satellite based QCKI allows us thinking about the preferred configuration for global QCKI Currently QKD equipments are not standardized But if the quantum equipments are perfect and standardized the use of QKD technology will be come easy In fact we can imagine a ATN s QKCI as following see figure on page e Each European airport must support a Quantum Access Point QAP which is securely attached to the ATN Network and acts as the QKD gateway in order to access into the ATN Network e There are no needs to have QKD fixed links between QAPs Each QAP is independent from each other but is strictly bounded with ATN Network e ATN s QKCI is the integration of ground based QKCI aircraft based
111. ntum Authentication 7 2 Quantum Authentication Protocol 7 3 Communication protocols III Visual Demonstrators Summary and Conclusions 8 AIT QKD Animations in Flash 8 1 Installation 8 2 Opening index html 8 3 Air Identification Tag AIT 8 4 Quantum Key Distribution 8 5 Flight plan and ATN 8 6 Authentication and Integrity 9 BB84 Demonstrator in Java 9 1 Program installation 9 1 1 For users on Unix Linux or MacOS 9 1 2 For users on Windows 9 2 How to run simulator 9 2 1 For users on Unix Linux or MacOS 9 2 2 For users on Windows 9 2 8 The application is running Acronyms Index Bibliography 103 105 107 107 107 108 108 108 108 113 113 113 114 114 114 114 114 121 129 131 WP I ATN and QKD Technologies Summary and Conclusions The security of aeronautical telecommunication has become a crucial matter Aeronautical telecommunication may be secured using classical cryptography Classical cryptography provides so called cryptographic security That means that the security relies on the assumed difficulty of some mathematical prob lems On the other side Quantum Cryptology QC provides unconditional secu rity relying on the quantum physics law Such a security is called information theoretic security because it is proved using the theory of information In this work we stud
112. o account Existing infrastructure must be re used Eurocontrol June 2004 Quantum Key Distribution QKD The section 3 on page 25 describes the Quantum Cryptology principle as de scribed in its initial design called BB84 e Quantum Cryptography QC uses classical encryption algorithms such as DES or AES e The main strength of QC is the Quantum Key Distribution QKD mech anism which allows to distribute the encryption keys Confidentiality of QKD is ensured by the quantum physics laws not by the assumed but unproved intractability of some mathematical prob lems e Authentication in QC is realized using special algorithms protected against key exhaustion by Denial of Service Dos attacks However a shared authentication key is still necessary Free space and Satellites It must be pointed out that the current state of the art of Free Space Quantum Cryptology is extremely volatile because the technology and the theory are evolving quickly This is mainly due to the funded research projects in Europe and USA QKD uses a quantum channel which may be an optic fiber or a free space laser beam The section 4 on page 45 studies the use of free space QC and satellites for the distribution of encryption keys Free space QC technology is rapidly evolving Laboratory IBM T J Watson USA Day light Baltimore USA At night Los Alamos USA Day light Baltimore USA At night QinetiQ UK Day light Los Alamos USA
113. ocol will help to replace the uncorrelated uncorre sponding bits between Alice s and Bob s string which are possible errors caused by either Eve or noisy quantum transmission 2 Bases Announcement As mentioned in the previous part in this phase all the positions where the same bits are shared will be kept and the rest will be discarded Firstly using classical channel Bob sends all the bases he used to mea sure Alice s qubit string to Alice Alice then compares this sequence of bases with hers and discloses every uncorrelated positions to Bob over classical channel After that both Alice and Bob replace all the bits at positions informed by Alice And the distilled part of raw key called plain key is totally the same between Alice and Bob regardless apparatus error but still or even quite different from each other in fact 3 Error Estimation To reduce the difference between Alice s and Bob s plain key due to ap paratus imperfection it is necessary to correct errors It is the phase in which the plain key error is estimated It will be performed as follows Alice will extract a small sequence of the plain key and send it to Bob Alice will inform Bob a subset of positions of size K and the bit values at those positions in the raw key got in the last step Both transmitter and receiver have to compute the observed error rate e and keep this trans mission if error rate is less than a desired threshold And finally they take a
114. oes not have the additional equipment it will not interpret the watermark but the communication will not be perturbed If the other party has the decoder then it interprets the signature and displays the aircraft identification AIT could be used to avoid oral misunderstanding of aircraft identification But it can also be used for security purposes because it proposes a digital iden tification of the aircraft Communication hack becomes much more difficult Analysis 2 6 1 Aircraft digital signature for AIT could be distributed using Quantum Key Distribution 24 Eurocontrol June 2004 25 Section 3 Quantum Key Distribution 3 1 Why is Quantum chosen for Cryptography Information exchange is always an essential need in the human life particu larly in the nowadays modern society The amount of information exchanged is increasing every minute even second or smaller time unit And it is unavoid able to take into account the importance of its secrecy It concerns the confi dentiality and integrity of data transferred This was thought to be secured by classical cryptography techniques for instance symmetric asymmetric key or both of them in today s best systems However in the age of powerful computers with developed technology of chip processors at high speed billion calculations per seconds classical cryptography gradually reveals its weakness 3 1 1 Weakness of classical cryptography As we have known almost all curr
115. om sequence of bits BB84 cannot be used for the transmission of a deter mined message Alice and Bob s communication being successful merely bases on the randomness at every stage of the protocol Now let s go to see how BB84 works The BB84 quantum coding scheme was the first proposed quantum encod ing of classical information in such a way that the receiver legitimate or ille gitimate cannot recover with 100 reliability It constitutes a base that most others quantum protocols fund on With this scheme classical bits are encoded by quantum states Each quan tum state can represent both classical bit 1 or 0 and inversely each 0 or 1 cor relates corresponds to a mixture of two equally likely non orthogonal quan tum states One of many representations is in figure 3 2 where we represent by 0 1 0 1 the four states illustrated i o CAPA 45 deg p 0 Figure 3 2 Non orthogonal four states used in protocol BB84 Information transmitted in the quantum channel is usually under the form of polarized photons Encoding the classical bits is done using the direction of the polarization In BB84 coding scheme the classical bit 0 is represented by a photon polarized both 0 and 45 of horizontal axe and the two corresponding orthogonal directions 90 and 135 are used for bit 1 Eurocontrol June 2004 29 30 SECTION 3 QUANTUM KEY DISTRIBUTION According to quantum mechanics there is no way
116. ommittee for Future Air Navigation Systems FANS for studying new concepts and new technologies and making recommendations for the future of air transportation FANS emphasized the need for interchange of digital data over several data links It recommended the Open Systems Interconnection architecture OSI from the International Organization for Standardization ISO FANS s work ended in 1988 with the proposition of the Communication Navigation and Surveillance CNS concept to help the development and evo lution of Air Traffic Management ATM In 1989 the Air Navigation Commission ANC included the development of ICAO material for the interoperability between all Air Traffic Services ATS Data Link to the Secondary Surveillance Radar Improvements and Collision Avoidance Systems Panel SISCASP which were already responsible of the Surveillance and Traffic Alert Collision Avoidance System TCAS The SISCAS Panel proposed the concept of Aeronautical Telecommuni cations Network ATN which were first published as an ICAO manual in 1991 and then completed in 1993 The Standards and Recommended Prac tices SARP and Guidance Material GM were published in 1997 ATN was described as an Internet network based on classical OSI protocols supporting global communications and all ICAO Air Ground Data Links Main sources 15 http www arinc com aeec projects users_forum Miami_03 6 3_Ad Hoc Security Report Exec Summary pdf 29 http
117. on The main point is authentication If the quantum key exchange is supported with authentication then the exchanged key is only shared by Alice and Bob and Eve cannot intercept messages We can classify authentication algorithms in two groups classical authenti cation and quantum authentication Quantum authentication is currently de veloped at Enst 40 meanwhile classical authentication technologies are well described in the literature 3 7 1 1 Classical Authentication Classical cryptography describes several techniques to implement authentica tion i e there are several means of realizing authentication 3 e Authentication by symmetric key techniques Authentication based on symmetric key techniques requires the two participants to previously share a key For a closed system with a restricted number of users each pair of users may easily share a key But in larger systems employing symmetric key techniques identification protocols often involve the use of a trusted on line server with which each party shares a key The on line server effectively acts like the hub of a spoked wheel providing a common session key to two parties each time one party requests authentication with another party But in the ATN we can use quantum keys distributed by the protocol BB84 as symmetric authentication keys Thus we can solve the problem of shared key using QKD With this technique we can apply the methods described below ra den
118. ope in the future we can easily locate an object in space with errors of a few centimetres 2 So it does not need the guidestar laser for tracking and CCD camera to maintain closed loop pointing That s why the weight of satellite is lighter Thus the satellite network project for secure key exchange in space is more feasible Afterwards we will consider some suggested architectures to create a satellite network in the following section 5 3 Satellite network According to three scenarios for secure key exchange in free space it is not difficult to exchange the key between two points in free space The problem suggested here is the cover of an enormous space European space Thus we have need a satellite network to cover it shown in figure 5 5 on the next page and in figure 5 6 on the facing page To install this network there are several questions to answer e It needs how much satellite to form this network e How the satellites and the station are communicated In this part we propose some models to create a satellite network There are two choices 35 e Ground Based transmitter terminal key is transmitted from the ground to the satellite 66 Eurocontrol June 2004 5 3 SATELLITE NETWORK 67 transit satellite source satellite 22 AN P a satellite a ij IW oF up down up down link link a af amp D lt destination station source station Figure 5 5 Satellite network e Space Based tran
119. orks where they provide backbone links to geographically dispersed LAN s and MAN s 18 Normally satellite links can operate in different frequency bands and use separate carrier frequencies for the up link and down link The figure 4 4 shows the most common frequency bands The use of C bands was most com mon in 1st generation Satellite systems However this band is already crowded as terrestrial microwave links also use these frequencies The current trend is towards the higher frequencies of Ku and Ka bands Attenuation due to rain is a major problem in both of these bands Also due to the higher frequencies microwave equipment is still very expensive especially in the Ka band UP LINK GHz DOWN LINK GHz ISSUES C 4 3 7 4 2 6 5 925 6 425 Interference with ground links Ku 11 11 7 12 2 14 14 0 14 5 Attenuation due to rain 20 17 7 21 7 30 27 5 30 5 High Equipment cost e 1 6 1 610 1 625 2 4 2 483 2 500 Interference with ISM band Figure 4 4 Frequency spectrum allocation for some common bands The area of the earth s surface covered by a satellite s transmission beam is referred to as the footprint of the satellite transponders The up link is a highly directional point to point link using a high gain dish antenna at the ground station The down link can have a large footprint providing coverage for a substantial area or a spot beam can be used to focus high power on a small region thus requiring ch
120. orrupted 15 http www arinc com aeec projects users_forum Miami_03 6 3_Ad Hoc Security Report Exec Summary pdf 29 http www arinc com aeec projects users_forum Miami_03 6 2_ATN Security USAF pdf 44 http www arinc com aeec projects users_forum Miami_03 6 6_APIM ATN Security pdf 6 http www arinc com aeec projects users_forum Miami_03 6 4_Key Management pdf Eurocontrol June 2004 12 SECTION 1 AGT SECURITY OVERVIEW It is very easy to monitor Aircraft Communications Addressing and Report ing System ACARS Data Link Messages One needs e A personal computer e A sound card e A Radio Frequency RF scanner e Few software available on the WEB 1 2 AEEC Ad Hoc Meeting on DLK Security The meeting was held in Columbia Maryland USA from 7 to 9 may 2002 and was hosted by Honeywell There were many presentations by the interested agencies which are look ing at security concerns All meeting attendees agreed that it is time to look at standards of development for AGT security They emphasized that opportuni ties exist for Data Link Service Provider DSP ATN security remains the baseline ACARS security must be compatible with Aeronautical Telecommunications Network ATN cf section 2 on page 17 security requirements One must not build an ACARS only solution Analysis 1 2 1 This is a very important point a security solution must be compatible with the future ATN The main conclusions of the me
121. otes a random number generated by the partici pant party A using appropriate techniques Ex denotes a symmetric encryption algorithm such as AES with a key K shared by the two parties A B M means that that the participant A sends the message M to the participant B A B M means that that the participant B sends the message M to the participant A Optional message fields are denoted by an asterisk i e while a comma i e within the scope of Ex de notes concatenation of messages For sake of concision Alice may be called A and Bob may be called B a Advanced Encryption Standard 1Aeronautical Telecommunication Network Eurocontrol June 2004 95 96 96 1 SECTION 7 QC COMMUNICATION PROTOCOLS Authentication based on symmetric key encryption In this case the two parties the participants A and B may carry out unilateral en tity authentication in two passes using random numbers This au thentication algorithm is described as follows AB rp 7 1 A B Ex ra rp B 7 2 A B Ex ra re 7 3 where K is the shared key Upon reception of message 7 2 B car ries out checks as above and in addition recovers the decrypted r4 for inclusion in 7 3 Upon decrypting 7 3 A checks that both ran dom numbers match those used earlier Authentication based on one way function One way functions are similar to hash functions Providing arguments they can fastly com
122. ouncement with new Authentication scheme Error Correcting Error Estimation As mentioned in part 3 3 1 on page 29 this phase is to improve the result of the next one Reconciliation Alice sends to Bob command ErrorEstimation with the size K of subset extracted from plain key and a se quence of pairs position value And Bob returns his bits received at those positions with same command ErrorEstimation K posl valuel posk valuek ErrorEstimation valuel valuek Then both of them compute the observed error rate by ireorrelatedbits They reject quantum transmission in case of error rate less than the initially set one otherwise K bits being removed from the plain key and step to the next Reconciliation This phase is for error correction Up to now Alice and Bob share a sequence of bits and Eve may know a part of it without use of authentication scheme In this common string there may be errors caused by attacks of Eve by noise of the quantum channel or dark counts inefficiency of Bob s detector and etc Reconciliation helps Bob and Alice to check and correct these errors Alice first calculates the size of block to be used based on the error rate like in 3 3 2 Then Alice divides her string into blocks of length k And she sends all positions in each block one block at a time to Bob with command ErrorCheck And it is Bob who calculates the parity of each block and replies to Alice this parit
123. pace QKD technology can be used With the support of QCKI an aircraft will be able to easily establish a pro tected communication with A G Applications supported by the ATN Network as the following basic scenario see figure 6 3 on the next page Eurocontrol June 2004 79 08 PpO0S unr Jor UOI0IN QCKI Airborne End System AES CM Application CMA CPDLC Application CPDLCA Step 0 Initialization Step 1 CM Logon Request Step 2 CM Logon Response Step 3 Distribute CPDLC Session Key Step 4 Exchange protected messages distributes a quantum secret key for AES and CMA distributes a quantum secret key for AES and CPDLCA receives the Quantum CM Key receives the Quantum CM Session Key from QCKI Session Key from QCKI encrypts CM Logon Request using QCM Session Key sends to CMA checks CM Logon Request using QCM Session Key encrypts CM Logon Response using QCM Session Key sends to EAS checks CM Logon Response using QCM Session Key receives the QCPDLC receives the QCPDLC Session Key from QCKI Session Key from QCKI uses QCPDLC Session Key uses QCPDLC Session Key in order to protect exchanged in order to protect exchanged messages messages Figure 6 3 Secured A G communications using QCKI 08 NIV NI 9 DNIONGOULNI 9 NOLLOHS 6 2 SCENARIO OF QKD IN ATN 81 QKD technology have specific characteristics Hence if we want to con struct an effect
124. pects such as proof of security you may refer to this article 36 This authentication is based on BB84 protocol According the author the scheme could be applied to some other protocols equivalent to BB84 Bennett s 2 states Bell s inequality based protocol of Ekert and so on Authentication scheme for QKD 1 Alice generates a random bit string and for presenting each bit uses a quantum eigen state in a random basis 6 Alice sends these quan tum states to Bob Bob uses a random basis to measure each received quantum states Bob uses a bit string b to present his bases 0 for 4 1 for amp encrypts this string with the prepositioned key ky and sends it to Alice b ky using the classical channel Alice uses a bit string b to present her bases and sends her used bases encrypted with the key ka to Bob i e b k on the classical channel Alice and Bob decrypt the bases used by each other and could then find out b 6b They discard the results at all positions i with bali amp i 1 and interpret the rest of results to two string x and zy Alice and Bob can compare some distilled bits from x and x to detect the presence of Eve or to validate the authentication 3 3 3 Specification for a simple implementation of BB84 In this section a detail specification will be introduced for a simulation of QKD using BB84 protocol Objectives This simulation is firstly aiming at illustrating the ol
125. r but rather make them use the methods which decide if Eve s and Bob s measurements are correct or not and update data in buffer before returning a result Another aspect concerns the simulation of transmitted pulses of light rather than single photons in the channel In this simulation this is resolved by using Poisson distribution about intensity of photons u to decide whether at least one photon exists in that pulse or not It operates simply like this after Alice sends a pulse to Bob in such a way as to produce an average of u photons this pulse reaches to Eve s or Bob s detector quantum channel invokes the PhotonExist method of Poisson class and the result returned is either true or false And below one can find the formula 3 6 used to calculate the probability of x occurrences in Poisson distribution about a mean of y mos 3 6 x The following equation 3 7 returns the probability of at least one occurrence in the same distribution u e P x gt 1 1 p 0 1 I l e 3 7 This formula is used in the method PhotonExist being called each time Eve or Bob detect a photon In BeamSplitting bigger portion of a pulse will be splitted by Eve with higher probability that Eve detects a photon Some types of Attacks of Eve against BB84 During the communication between Alice and Bob Eve can be trying to lis ten both quantum and classical channel She can we assume easily pick up everything that travels over t
126. random key This will be done by following sequentially all steps in the part 3 3 1 on page 29 In other words Alice will interact with Bob through the quantum channel in order to exchange the key She has to prepare this key under the form of a string of random qubits She must inform Bob about the start and end of both the message and each pulse She is also capable of listen ing the channel to know when Bob finishes his detection of a pulse Once all of the qubits have been sent and received Alice will communicate to Bob in which bases she used to measure pulses error correction and privacy amplification Her communication with Bob is on both quantum and public channel So she will interact directly with the channel object simulating her transmission of pulses in a random polarization The final task of Alice is to display all the results of her consecutive actions for the aim of the demonstration And she must also provide to the users an interface to modify parameters affecting the protocol such as the number of photons in a pulse or the size desired for error estimation etc Bob Bob is Alice s partner in this protocol He is the destination of her message Some of his functions are the same with hers like listening to channel read ing writing the information in to the channel He also interacts with Eve to make as real as possible a quantum key exchange To reply to Alice s pulse he must acknowledge the receipt The phase Bases Announc
127. read includes the effects of noise in channel Bob s detector efficiency and dark counts as well All these are only applied to Bob whose technology is realistic while Eve is assumed to have a perfect technology to detect pulses When all bits received Bob steps in phase Bases Announcement sends Re ceivingBase command to Alice with his sequence of pairs containing position of qubit and its guessed polarization Bob can send to Alice a message like this ChosenBases posl polarl pos2 polar2 Then the diagonal and rectilinear polarizations are represented by digits 1s or Os When this message reaches Alice she prepares a BaseConfirm message to reply to Bob in the same form of his ChosenBases except her parameters Eurocontrol June 2004 41 42 SECTION 3 QUANTUM KEY DISTRIBUTION being subset of his Her pair contains positions where Bob measured correctly and its original polarization BaseConfirm posi ori polari posj polarj Eve may extract useful info for her from both above messages And she will insert a blank in her key string where she did not detect successfully or guessed correctly a photon In case of applying the Authentication scheme these two messages are en crypted with two reconciled key between Alice and Bob These messages be come incomprehensible for Eve As an expected result the exchanged informa tion is confidential and safe from Eve Hence Eve acquires no useful informa tion from the phase BaseAnn
128. rmations Analysis 6 1 1 As such the security requirements developed by ICAO only ad dress data integrity and peer entity authentication However the basic ICAO security framework can be used to protect user information The ATN secu rity architecture based on Public Key Infrastructure PKI is described in Sub Volume 8 Security Services of SARPs In the secure ATN framework when an AES wants to communicate with a A G Application at Ground Station GS for instance the CPDLC Application normally the AES and GS will cooperate to execute a basic scenario like the following e Step 0 Initialization of ATN s PKI services for ATN entities who want to take part in secure communications such as Airborne End System AES Context Management Application CMA CPDLC Application e Step 1 AES creates a CM Logon CPDLC Request and sends it to CMA Step 2 CMA sends a CM Logon CPDLC Response back to AES Step 3 AES and CPDLC Application compute a common secret Session Key e Step 4 AES and CPDLC Application protect their exchanged messages by using this secret Session Key The table 6 2 on the facing page shows this scenario in more detail 1CPLDC Controller Pilot Data Link Communications 76 Eurocontrol June 2004 po0s Sun Jor UOI0IM LL Airborne End System AES Context Management Application CMA CPDLC Application CPDLCA Step 0 AES Identity Initialization of AES Private Digital Signature
129. rodrome Report Message Handling System Middle East Air Navigation Planning And Implementation Regional Group Microwave Landing System Multi Mode Receiver Minimum Navigation Performance Specification Multi Purpose Satellite Based Augmentation System Multi Purpose Transport Satellite Meteorological Watch Offices Mode S Secondary Surveillance Radar North American Planning Group National Airspace System North Atlantic Network Adress Translator Internet North Atlantic Implementation Management Group North Atlantic Systems Planning Group Navigation Non Directional Beacon Nautical Mile Notice to Airmen Network Protocol Data Unit Node and Process Management Net Present Value Network Service Access Point Operating Agency Certificate Authority Operational Concept Document Operational Development of Initial Air Ground Data Link Communications Option Flag Operational Meteorological Traffic Operational Requirements Document Open Systems Interconnection Pacific Pointing Acquisition and Tracking Procedures for Air Navigation Services Precision Approach Radar Private Data Channel Protocol Data Unit Packed Encoding Rules Preliminary Eurocontrol Test of Air ground data Link Planning and Implementation Regional Group Eurocontrol June 2004 125 126 PIT PSR RGCSP RMCDE RNAV RNC RNP RNPC RRI RSP RTCA RTSP RVSM SAC SARPS SARPs SAS SBAS SCM SICAS SIGMET SIGWX SIR SISCASP SLM S
130. rol June 2004 130 P PAT 55 PBS 50 PKI 13 22 76 PRMA 52 protocol 93 Public Key Infrastructure 22 QAP 90 QBER 28 QC 45 QCKI 78 QKD data relay 78 QKD relay 78 QKD plain key 30 QKD raw key 30 QoS 23 qubit 28 30 R Radio Frequency 12 RF 12 S SARP 17 security services 13 SILEX 55 SISCAS 17 T TDMA 52 U UAL 18 V Very High Frequency 23 VHE 23 VHF Data Link 18 VPN 89 130 INDEX Eurocontrol June 2004 131 Bibliography 1 QuCrypt Center for KvanteInformatik University of Aarhus 2 Le GPS au Service de la S curit Routi re 2004 3 Alfred J Menezes Paul C van Oorschot and Scott A Vanstone Identifi cation and Entity Authentication chapter 10 pages 385 420 CRC Press edition October 1996 4 Andrew G D Rowley The BB84 Protocol June 2001 5 H Bennett F Bessette G Brassard L Salvail and J Smolin Exper iment Quantum Cryptography In J Cryptology volume 5 pages 3 28 May 1992 6 Bob Witulski Key Management In Presentation at DLK Users Forum Brussels Belgium june 2003 7 W T Buttler R J Hughes P G Kwiat S K Lamoreaux G G Lutherand G L Morgan J E Nordholt C G Peterson and C M Sim mons Practical Free Space Quantum Key Distribution Over 1km In Phys Rev Lett volume 81 pages 3283 3286 1998 8 W T Buttler R J Hughes S K Lamoreaux G L Morga
131. roperties used in QKD are e Entanglement quantum correlation A quantum system may be corre lated with one or more quantum systems Each sub system generates randomly its states and none of them has a fixed state e Causality and superposition Causality is not an ingredient of non relativistic quantum mechanics Nevertheless it is used for the aim of combination with superposition used for secret key exchange 26 Eurocontrol June 2004 3 2 QUANTUM KEY DISTRIBUTION QKD 27 Shortcomings of QKD Authentication When exchanging the secret data one must pay atten tion a lot to address the right destination It is a pity that authentication is not primitively included in QKD This problem is being studied to im prove QKD and has opened some approaches such as including the secret key in the distant devices or hybrid QKD public key schemes Sufficiently rapid delivery of keys A rapid speed is taken into account when distributing keys The reached order of today s QKD is about 1000 bit s throughput for keying material but in fact often runs much more times slowly 12 Robustness It is really a weak point of QKD since it uses a single point to point connection So it can be easily weakened by an eavesdropper or by a possible accident like fiber cutting However it is unprobable if using multi path for transmission of data Distance and Location Dependence We can clearly realize that QKD is notably short of this attrib
132. rors so the protocol will be restarted by clicking Start again on Alice panel When the text Finished is displayed on all status bars it is the moment the protocol is completed The final key may be produced or not in the case there had not been enough bits in phase of error correction Eurocontrol June 2004 115 SECTION 9 BB84 DEMONSTRATOR IN JAVA 116 Pi 3 4 3 a x a rs S Settings Sequence of photons transmitted through QC Polarisation of photon value LALLIIZ LIL TL TL ILILLLLLIALLLL PHOPEFASED SOT UHE 111 2 L2iL12Lii2 OFF S48 oO gt PHOPEERHS TOROS OE Se OHeTeOSET CORE CELL LLLILLLLLILZA Tretesotresesee CTILIILLILELIE TT LA Lil Li LISLLILIILLIELL CLLLLELLALLEZL 2 LIZ2ZILIALLIEL esse Steeereee TH CReP TER DEE TS 309 90 seesy CLETLELLA LLTALLLLLIZ2 LALI2112122 LALSLLILLISITIELITIIEI17 218221118121 Stes Ce see Frans ttes PTTIIETIL1172112 LIILLILI2L Sept LALLIILLZILITLALLLLIALILLLLLLLL2LL LLILILLI 211844 PERSeOTe 227227 LLELLLLLILLLLEL viser LLILLILIL LIL TEETE CLLLLIALLL a LLILIALIIELISLLIIIEL DIATITTIREL RIT TIEL PITLIAdLI SL I IE TE 122 parodo thsrencesese Error Correction Privacy Amplification Alice s Status Waiting for Bob to Send His List of Bases ission Process of photons transm Figure 9 2 Quantum Channel Ht Results Total number of photons Settings
133. rveillance CNS Air Traffic Management CNS ATM Package 1 CNS Implementation Carribbean and Central American States Association Co ordination Group Connection Oriented Transport Protocol Connection Oriented Transport Service Eurocontrol June 2004 ACRONYMS CPDLC CRL CSMA CTS CWP D8PSK DAC DAS DES DOS DLK DME DSP DTE EANPG EATCHIP EATMS ECDSA ECAC ECU EDP EGNOS ELM EOLIA ERD ES ESCAN EUR EUROCONTROL FAA FANS FASID FDDI FDMA FIC FIFO FIR FIS FL FMS FPL FUA G G GA GBAS GDLP GEO GES 123 Controller Pilot Data Link Communications Certificates Revocation List Carrier Sense Multiple Access Conformance Test Suite Controller Working Position Differentially encoded 8 Phase Shift Keying Dual Attached Concentrator Dual Attached Station Data Encryption Standard Denial Of Service Data LinK Distance Measuring Equipment Data link Service Provider Data Terminal Equipment European Air Navigation Planning Group European ATC Harmonisation and Integration Programme European Air Traffic Management System Elliptic Curve Digital Signature encryption Algorithm European Civil Aviation Conference European Currency Unit Entanglement Distillation Protocols European Geostationary Navigation Overlay System Extended Length Message European preOperational dataLInk Applications End Routing Domains End System Electronically Scanned Europe European Organisation for the Safety
134. s could benefit of these investments 2 6 Air Identification Tag Air identification Tag AIT has been developed by the University of Graz Aus tria and Eurocontrol It is described in Eurocontrol Experimental Cen ter EEC Innovative Research activity report for year 2003 Controller pilot Very High Frequency VHF voice communications in Air Traffic Control ATC relies on amplitude modulation by a carrier frequency Pilots have to identify themselves with their call signs Human imperfections in speaking and hearing added to the poor quality of this communication chan nel may cause identification problems AIT aims at improving and facilitating identification IT inserts automat ically an unnoticeable small data link channel in the communication The in serted data can be a digital signature associated with the emitter and may be used to achieve reinforcement of audible stimulus with a visual stimulus To embed the data into the pilot s communication AIT uses watermarking the signal is digitalized then the digital watermark is added and the result ing signal is converted to an analogical signal again One can obtain about 200 bits sec of embedded communications without modifying current airplane Eurocontrol June 2004 23 24 SECTION 2 AERONAUTICAL TELECOMMUNICATIONS NETWORK AC equipment The use of the pilot s Push To Talk PTT switch automatically inserts a digital signature in the communication If the other party d
135. s used as a triggered source for single photons toward GS see figure 6 11 Transmitter Receiver eceiver Figure 6 11 Aircraft based QCKI with entangled photon source The satellite which acts as a relay station can take part in this scenario see figure 6 12 Relay Figure 6 12 Aircraft based QCKI with entangled photon source This solution is not very different from the Single photon source Aircraft based QCKT page 83 Only the QKD technology is different 86 Eurocontrol June 2004 6 2 SCENARIO OF QKD IN ATN 87 e Entangled photon source Satellite based QCKI The transmitter of entangled photon pairs is placed on satellites This is the most interesting use of entangled photon technology In the most simplest scenario the sharing secret key between a AES and a GS can be established by pointing each of the photons of an entangled pair ei ther toward the AES and the GS see figure 6 13 item a Another set of satellite based relays can be used to further distribute the entangled photons to AES and GS see figure 6 13 item b c and d In these scenarii AESs can be on the ground or in the sky neelav Trans mutter nn l Relay aT f A acaiver P wo Figure 6 13 Satellite based QCKI with entangled photon source Eurocontrol June 2004 87 88 SECTION 6 INTRODUCING QC IN ATN Analysis 6 2 1 In all the scenarii above if we use QKD data relays instead of quantum r
136. slightly bigger telescopes optimized fil ters and anti reflection coasting combined with sophisticated automatic point ing and tracking hardware could be stable up to 34dB of loss the limitation of loss acceptable for QC system and capable of maximum ranges exceeding 1600km We could engineer the possibility of the exchanged keys with low earth orbit satellites such as a secure relay station this has the potential for secure key exchange between any two arbitrary locations on the globe For a better understanding we will study the most recent success of free space QC system of P Morris 4 1 2 The most recent success From September 2001 to January 2002 P Morris have tested a semi portable free space QC system between two mountain tops Karwendelspitze 2244m and Zugspitze 2960m in Southern Germany for the exchange of keys 81 The distance between the two locations is 23 4km The elevated beam path dramatically reduced the air turbulence effects experienced in previous low altitude tests but also caused unprecedented requirements on stability against temperature changes reliability under extreme weather conditions and ease of alignment The transmitter named Alice encodes a random binary number in weak pulses of light using one linear polarization to encode 1 s and orthogonally polarized pulses to encode zeros To prevent eavesdropping the number of pho tons per pulse is limited to much less than unity the actual a
137. smitter terminal key is transmitted from the nal op tique satellite to the ground or to another satellite 800 km Figure 5 6 Space covered by satellite network Normally with a satellite of the altitude a 800 km and its maximum range d one can calculate the surface covered on the ground with a diameter 2r shown in figure 5 7 on the next page 28 r y d2 a 5 1 Really when one forms a satellite network to cover an enormous surface one cannot install the satellites with the distance 2r because there is a small unknown area space black shown in figure a 5 8 on the following page Each satellite covers only one surface of a hexagon registers in the circle shown in figure b 5 8 on the next page Eurocontrol June 2004 67 68 SECTION 5 ANALYSIS AND SCENARIOS Figure 5 7 Space covered by a satellite CD 1 a b c Figure 5 8 Distance between two satellites of network Therefore the distance between two satellites is 1 shown in figure c 5 8 l rvV3 5 2 Theoretically the radius of the Earth is of 6378km and the altitude of satel lite is of 800 km Therefore the radius of satellite orbit is of 7178km and it needs n satellites to cover a surface of width l km shown in figure 5 9 on the next page 2771 451 a 78 2100 5 3 In two following parts it is the same calculation for each scenario 5 3 1 Ground Based Transmitter Terminal Distribution key from ground st
138. ssage Surface Movement Guidance and Control System Subnetwork Dependent Convergence Function Specialist Objective Spectrum Protection Group Secondary Surveillance Radar Self Organising Time Division Multiple Access Eurocontrol June 2004 ACRONYMS STP SUA SVC TAF TAR TC TC TCAS TCB TCDC TCM TCP TDMA TDWR TFM TIS TIS TLS TMA TPDU TRD TS TSDU UAL UBSS UDP ULA UNDP USA UTC 127 Standardized Training Package Special Use Airspace Switched Virtual Circuit Terminal Area Forecast Trials ATN Router Temporary Channel counter Transport Connection Traffic Alert Collision Avoidance System Technical Co operation Bureau Technical Co operation amongst Developing Countries Time and Clock Management Transmission Control Protocol Time Division Multiple Access Terminal Doppler Weather Radar Traffic Flow Management Terminal Information Services Traffic Information Service Target Level of Safety Terminal Manoeuvring Area Transport Protocol Data Unit Transit Routing Domains Transport Service Transport Service Data Unit pper Layer Architecture nix Basic System Software ser Datagram Protocol pper Layer Architecture nited Nations Development Programme Jnited States of America Jniversal Co ordinated Time T T T T GG Ele CEE VHF Digital Link Visual Flight Rules Very High Frequency 30 300 MHz Visual Meteorological Conditions Meteorological Information for A
139. t Initiation Modification APIM february 2008 45 Roy Oishi ARINC IA Project Initiation Modification APIM february 2008 46 Tom McParland BCI and Egg Harbor Township Public Key Infrastruc ture for Air Traffic Management Systems 2001 133
140. t intensity of u will be beam splitted with successful rate of 100 for safety So that Eve can learn a portion of u bits through beam splitting The total rate of bits leaked to Eve by two types of attacks is estimated by equation 3 3 4 BS rate LE vepitrate p W 3 3 ed In order to take into account all sampling errors we have encoun tered in the estimations above it should be added on the Eve s ex pected key size a number of standard deviations And this additional Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 35 part can be computed as in 3 4 where N is the length of confirmed key N u u 1 4 2V2 p 3 4 Now we can get the estimated length of Eve s key by simply multi plying the number of bits in the confirmed key by Eve s bit rate with additional part of standard deviation And finally Eve s assumed key size is the result of 3 5 EvVepeysize Np 5 V N u u 1 F 4 2V2 p 3 5 Quantum Channel Simulation To successfully simulate the quantum key exchange it is necessary to pay an adequate attention to quantum channel The crucial aspect of a quantum channel is in which a photon is sub ject to Heisenberg s Uncertainty Principle As mentioned in 3 2 1 on page 26 uncertainty principle simply states that it is incapable to observe something without affecting it And to simulate this Quan tum Channel object just does not allow Bob and Eve to access di rectly to buffe
141. t on the screen with the appropriate title Alice Bob Eve Quantum Channel and Pub lic Channel And now you get a screen as below All the control buttons are on windows Alice and Bob After the configura tion of all parameters on window Alice Eve and Quantum Channel you can start the transmission of photons on the quantum channel from Alice to Bob 114 Eurocontrol June 2004 9 2 HOW TO RUN SIMULATOR 115 Public Channel Figure 9 1 Alice s setting window by click on button Start on Alice window This process is observed on Photon Transmission tab After transmission finished total number of photons detected by Bob will be displayed on the Result tab of Quantum Channel Besides you can know the number of errors made in this channel due to configured experimental error rate on the Settings tab and also the number dark counts detected Now pass to phase Base Confirm on press the button Base Confirm of the same name on Bob window and the result Raw Key is produced On the panel you may see some green bits on both Alice and Bob panels at these positions bases used are not correlated And below are the bits in Raw Key which Eve eavesdropped Now you realise sequentially phases Error Correction and Privacy Am plification by pressint the relative buttons in Alice window Note the status of each panel to choose the correspond button Sometimes in phase error cor rection there may be not enough bits to check er
142. ting Acquisition and Tracking QC Quan tum PAT Because of the very narrow widths of the communication beams involved PAT asks for highly sophisticated concepts and for electro mechanic and electro optic hardware meeting exceptional technological standards Ma jor parameters entering the link capacity are telescope size optical transmit power link distance and receiver sensitivity Other aspects are mass volume and power consumption of the terminal Examples for existing space laser com munication links include European Space Agency ESA s inter satellite link Semiconductor Laser Inter satellite Link Experiment SILEX and a satel lite ground link which was only recently realized between the GEO satellite 54 Eurocontrol June 2004 4 2 SATELLITES COMMUNICATION 55 ARTEMIS end ESA s optical ground station Optical Ground Station OGS at Tenerife Although space to space links have the attractive advantage of not being in fluenced by Earth s atmosphere of the position correlation between satellites in the network see the figure 4 6 on page 53 it is too much difficult at present due to the expected disproportionate technological and financial effort as com pared to alternative schemes with at least one of the communication terminals on ground Most envisioned quantum experiments require higher flexibility at the receiver due to active polarization control or data analysis thus it is more reasonable to place the transmitter
143. ting the OSI Transport Ser vice referred as ISO 8072 In order to build ATN applications ATN proposes common functional components in an architecture known as the Upper Layer Architecture ULA based on the layered OSI Reference Model There exist seven layers Two types of entities are identified e End systems such as computers using the 7 layers e Intermediate systems such as routers using the 3 lower layers The seven OSI layers are listed below from the upper to the lower e The Application Layer Semantics of end to end exchanged information e The Presentation Layer Syntax of end to end exchanged information e The Session Layer Format of end to end exchanged information e The Transport Layer End to end flow control and information exchange e The Network Layer Establish maintain and terminate switched connec tions e The Data Link Layer Synchronization and error control over the physical link e The Physical Layer Management of the physical link The three upper layers provide common functions that are used for the estab lishment and release of connection and for the encoding of information 2 2 CNS ATM 1 Applications The Communications Navigation and Surveillance Air Traffic Management Applications that has been specified for the first phase of ATN e Context Management CM provides a mean to find out communications services within a given flight region and for a ground system or controller to direct an a
144. tly built e Against passive attacks This scheme would more secure than BB84 where b is transfered in plain text e Against active attacks Against the man in middle attack For the case Eve impersonates B to communicate with A She would use a random key ke and sends be ke to A A considers be ke as sent by B A calculates bh be Ok Gk f and announces ba k to Eve A would maintain the result at positions i where bali befi 0 Therefore the positions are not announced to Eve and she cannot calculate i from ba k ke and be She would deduce x from the measurement result at some random position 7 Thus x and x are of different lengths and independent And if A and Eve compare some distilled bits from x and ze there would be an average error rate of 50 that would be detected Against the DoS attack For the case Eve impersonates B to communicate with A As Eve does not know if the bit code for the i th quantum state cor responding to b i is maintained or not she does not know either which bits are in za We could estimate that the uncertainty about measurement of new key bit is bound by H k k T where H is the entropy function of Shannon Thus he could not use A s announcement of some distilled bits from x to discover the corresponding bases used by A and he could not gain information about the authentication key k or k f Eurocontrol June 2004 99 100
145. ttenuation is linked to the overall transmission and is usually chosen as 0 1 photons per pulse Furthermore the encoding basis is randomly changed by introducing a 45 polarization rotation on half the sent pulses In the receiver named Bob single photon counting detectors detect the pulses converting the light to macroscopic electronic pulses The two polarizations are separated in a po larizing beam splitter and a zero or one is recorded depending on the detected polarization A random switch selects whether to measure in a 0 or 45 po larization basis Due to the initial attenuation and the attenuation along the transmission line only very few of the sent pulses result in detected events at the receiver A record of when the pulses are detected is kept and at the end of the transmission the receiver uses a classical channel for instance the telephone line to tell the sender which pulses arrived and what basis they were measured in All lost pulses and all detected pulses measured in a dif ferent basis to the encoding basis are erased from the sender s record Thus identical random keys are retained by sender and receiver Any remaining dif ferences errors signal the interception of an eavesdropper If an eavesdropper measures the polarization of one pulse that pulse being a single photon is de stroyed and does not reach Bob and thus is not incorporated in the key The eavesdropper could choose a basis measure the pulses then re i
146. ulence wander at the ground station On the satellite the pointing and tracking requirement would be less stringent 100 uR but both the ground station and the satellite would need to be fitted with laser beacons guidestars A suitable point ahead scheme will be needed as the satellite velocity will take a considerable distance tens of meters or 20 50 uR in the time it takes a beacon to reach the ground and a signal to return This also means that the guidestar beam will not pass through the same column of atmosphere as the up going signal beam As most turbulence occurs in the 1 km boundary layer where beam deviation will be at most 50 mm in a 30 cm wide beam we expect this will not strongly 1R pulse repetition rate of the system Eurocontrol June 2004 59 60 SECTION 5 ANALYSIS AND SCENARIOS affect the closed loop pointing The best space based optical communi cation experiments are just achieving 2 uR tracking without turbulence and we suspect that from the ground one might achieve 3 5 uR tracking accuracy This will degrade our effective beam spread to around 6 4R Satellite optics pointing stability We require only that the ground station remains within the field of view of the detectors The angular field of view 6 at the output optic is given by as of where D is the detector diameter typically 500 um and f is the tele scope focal length For a 10 cm 30 cm optic L telescope the field of view is 0 5 mR 0 17 mR
147. use it is a simple well known et mathematically proved procedure Moreover we already suggested some physical architectures to distribute the key inside or outside the airport We also presented models for secure exchange of the quantum key before or after of the aircraft take off 2 Authentication Authentication is a procedure to verify that a received message really comes from a certain entity and has not been altered Au thentication is not required in all situation More precisely we will see that authentication may be done by position in the case of aircrafts in stead of using an authentication procedure 3 Connection establishment When one party has obtained the key and has well checked authenticated its interlocutor this party can establish a secure connection for communication using common symmetric encryp tion mechanism After a communication period T to be determined the party go back to the first stage to renew the quantum key In the next parts we will present some authentication protocols Today many Quantum Key Distribution QKD protocols have been proposed and some have been verified with practical experiments However in practice all the presented QKD protocols are sometimes insecure against the man in middle attack because they do not authenticate the parties The man in middle attack occurs when a legitimate endpoint of the communication link named Alice communicates with the other le gitimate endpoint of
148. ute Two entities of a QKD system must have a dedicated connection and the distance between them is limited by the material used for transmit photons Resistance to traffic analysis Someone may enjoy to carry out traffic analysis on a key distribution particularly on dedicated system which promises interesting things behind It probably causes some risks To ease the life it should be preventing such analysis Unfortunately QKD cannot do that thing but attracts a lot the curious eyes by its dedicated setups 3 2 2 Some protocols for QC Up to now there are several protocols being proposed since the birth of the first one BB84 We will summarize some of them in this section BB84 protocol It is the first protocol for Quantum Cryptography introduced by Bennet and Brassard in 1984 thus it was named BB84 In 1994 this proto col was proved to be secure against eavesdropping by Dominic Mayers Eli Biham Michael Ben Or BB84 is a non deterministic protocol which means that it is useful for distribution of a random sequence only We will come back to this in detail in section 3 3 on page 29 Two state protocol In 1992 according to Bennett s notice four states are too much for QC only two non orthogonal ones are sufficient In truth the security of QC bases on the inability of an evildoer to distinguish surely and without per turbation the different states that Alice sends to Bob hence two states are enough Bennett 1992 if the
149. ver their investigation suggests that two way entanglement purification is a useful tool in the study of advantage distillation error correction and privacy amplification protocols Despite all of above proofs BB84 still remains unsecured due to lack of authentication Once Eve acts as inter mediator which means that Eve acts as Alice with Bob and inversely as Bob in communication with Alice and that leads the loss of BB84 s security It is the man in the middle attack A solu tion will be proposed in the sub section 3 3 2 on page 37 Moreover another challenge for the assurance of security of BB84 is the source of photon When each pulse contains more than one photon Eve can use indirect copy to at tack BB84 She could extract only one in the transmitted beam of photons Nevertheless this issue has been being researched by physicists to create an apparatus generating one photon each pulse 32 Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 33 Considerable parameters In the implementation of BB84 many parameters have to be taken into ac count In this part some of the most major ones will be examined And all the information was referred and extracted from the article 10 the report of the first implementation of BB84 and a software developed for driving the quantum cryptography experiment 1 These parameters will be divided by the concerning actors Thus they fall into four portions general quantum parameters Alic
150. way the K checked bits and observe the rest In the case where the estimated error rate is more than the threshold the key will be aborted 30 Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 31 4 Reconciliation After this phase a reconciled key will be achieved after applying a recon ciliation protocol to the plain key Reconciliation is an interactive process taking place over the public channel The purpose of this phase is to cor rect the errors equivalently to reduce the difference between sender s and receiver s plain keys But it is important to take note that as few bits as possible are sent over the public channel since Eve may exploit this information A protocol called Cascade is applied here Cascade per forms error correction by sending very little information over the public channel and was proposed by Gilles Brassard and Louis Salvail Cascade operates in a number of rounds We will go in detail in the next part Im plementation The next phase is the confirmation of the equality of Alice and Bob s reconciled keys And if Cascade ends successfully then the next phase will confirm the result 5 Confirmation In order to make sure that no error will be found Alice and Bob will ex change and compare the parity of random subsets of positions In general if a z parity bits comparison is done and there is no differences then the current shared key is identical to the rate of 277 And if this phase is suc cessfu
151. y are incompatible i e not mutually orthogonal But in practice this protocol is not really effective Indeed Eurocontrol June 2004 27 28 SECTION 3 QUANTUM KEY DISTRIBUTION although two nonorthogonal states cannot be distinguished unambigu ously without perturbation one can unambiguously distinguish between them at the cost of some losses Ivanovic 1987 Peres 1988 This possi bility has been demonstrated in practice Huttner Gautier et al 1996 Clarke et al 2000 37 Three state protocol This protocol is to improve BB84 The BB84 protocol is symmetric in its use of polarization After the generation of the key it is necessary to exchange more other information for secrecy of the key Is it possible not only to distribute the key but also to provide additional information about the integrity Three state protocol proposed to use three states in place of four in BB84 and three detectors instead of two for BB84 to break the symmetry of BB84 This reduces eavesdropping s probability to get right states and also minimizes the amount of useful information received by Alice Moreover we can also discover her presence on the line Six state protocol While two states are enough and four states are standard a six state protocol better respects the symmetry of the qubit state space see 3 2 2 The six states constitute three bases hence the probability that Alice and Bob choose the same basis is only 1 3 but
152. y if Quantum Cryptology can be applied in the frame of the Aero nautical Telecommunication Network This part summarizes the partial conclusions of this first step study These conclusions are partially made explicit and explained in the following sections AGT amp ATN The section 1 on page 11 is an overview of AGT Security and the section 2 on page 17 briefly describes the Aeronautical Telecommunications Network e All aeronautical communications are or will be handled by Aeronautical Communications Network ATN The ATN is an Internet network and may switch to IPv6 in the future Security and confidentiality of communications are primary concerns This is true for the ATN and for all aeronautical communications in gen eral Security and confidentiality in the ATN will be handled using public key cryptography But public key cryptography is not proven to be uncondi tionally sure Public key cryptography necessitates a Public Key Infrastructure PKI PKI are heavy administrative tools Any failure compromises the sys tem PKI is likely to be applied in a well trusted operators area such as European countries Air Identification Tag AIT proposed by Eurocontrol EEC enforces se curity by allowing automatic digitalized identification without modifying current communication installations e Any solution for improving security must be done inside the framework of the ATN It must consider costs and existing infrastructure int
153. y proved by different scien tists In this section some proofs will be given to readers but only as overview For more details refer to listed documents Eurocontrol June 2004 31 32 SECTION 3 QUANTUM KEY DISTRIBUTION Mayers proof 16 The first one should be mentioned here is the Dominic Mayers proof in 1996 more than a decade since the original proposal of BB84 which is general but rather complex one D Mayers followed some other previous proofs by Eli Bi ham or collaborators and Michael Ben Or To prove the BB84 s security posi tive operator valued measure POVM was applied In his proof he used basic techniques the proof of security of a practical quantum key distribution proto col against all attacks allowed by quantum mechanics Lo and Chau s proof 34 Quantum key distribution is widely thought to offer unconditional security in communication between two users Unfortunately a widely accepted proof of its security in the presence of source device and channel noises has been miss ing This long standing problem is solved in this proof showing that given fault tolerant quantum computers quantum key distribution over an arbitrar ily long distance of a realistic noisy channel can be made unconditionally se cure The proof is reduced from a noisy quantum scheme to a noiseless quan tum scheme and then from a noiseless quantum scheme to a noiseless classical scheme which can then be tackled by classical proba
154. y with command ParityConfirm ParityConfirm parityBlocki Then Alice and Bob both delete the last bit of block to avoid info leakage to Eve Alice compares her parity with the one sent from Bob If they match then this block is considered correct Otherwise Alice uses bisective searches to find and remove errors They repeat this work through all blocks sized k and also with 2 k until block size over passes of plainkey s length Confirmation To eliminate maximum errors from shared key Alice contin ues her work with subset of randomly picked positions rather than a continu 42 Eurocontrol June 2004 3 3 DETAILED BB84 PROTOCOL 43 ous block Privacy Amplification Now Alice and Bob may be sure that their shared key has no errors or a negligible quantity but it is partially secured only So they have to carry out the Privacy Amplification This phase is performed by a simple round of random subset hashing To this extent Alice declares sets of bits with PrivacyAmplification command Then Alice and Bob both calculate the parity bit of the random subset But they do not reveal their result And this result makes out the final key Finally Alice sends End command to Bob through public channel to inform him about the termination of the QKD The GUI For graphical part the package Swing of javax will be exploited Each object in this simulation has its own graphical interface These GUI are extended from JFrame For three
155. ys tries her best to extract useful informations about the key from Alice and Bob s info exchange by applying different attack methods And for simulation of synchronicity in three person s communication all written data into channel will be hold in a buffer The quantum buffer can be accessed and written into by anyone But for the public one it is only available for everyone to read from it But only Alice and Bob can write into it not Eve The moment one can access to channel for information will be decided by two objects channel If it is the unavailable moment the actor will receive a null value and will fall again into the wait state In this simulation the digit 1 will represent diagonal polarization and the digit 0 rectilinear one Outline class structure As mentioned above all transactions between three main actors Alice Bob and Eve are processed on both channels firstly on quantum one then on public one So we will divide the following analysis of implementation into two major parts quantum channel and public one and a supplement one GUI Quantum channel The quantum channel is simulated as an object in the main thread It is intrinsically a controller of the string of pulses transmitted from Alice via Eurocontrol June 2004 39 40 SECTION 3 QUANTUM KEY DISTRIBUTION Eve to Bob Here these pulses are implemented as qubit objects A qubit object contains the value of correlated binary bit 0 or 1 its polar

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