ASN2TXT User`s Manual
Contents
1. Option Arguments Description ber Selects the use of Basic Encoding Rules for decoding per Selects the use of the Packed Encoding Rules aligned for decoding uper Selects the use of the Packed Encoding Rules unaligned for decoding ascii Scan data in untyped fields and if all bytes contain values within the ASCII character range 14 Option Arguments Description display as standard text Otherwise display as formatted hexadecimal text Note that this option only has meaning if BER DER CER data is being decoded and no schema file is specified emptyDefault Insert an element with a default value as specified in the schema at the location of a missing element in the instance emptyOptionals Insert an empty element at the location of a missing element in the schema that was declared to be optional nowhitespace Do not generate any whitespace blanks and newline characters between elements This makes the generated XML document more compact at the expense of readability 0 lt filename gt Specify the output XML lt filename gt instead of writing output to standard out Set filename to lt base gt xml to specify batch output when converting multiple files rootElement lt name gt Specify the root element lt name gt used to wrap the entire XML message at the outer level This makes it possible to create an XML document f2. 30 SEQUENCE lt UTF8STRING gt Joe lt UTF8STRING gt lt UTF8STRING gt Jones lt UTF8STRING gt SEQUENCE SEQUENCE lt UTF8STRING gt John lt UTF8STRING gt lt UTF8STRING gt P lt UTF8STRING gt lt UTF8STRING gt Smith lt UTF8STRING gt lt SEQUENCE gt With schema This example shows the results with emptyOptionals selected If it were not the first lt middle gt element would be omitted lt son gt lt Name gt lt first gt Joe lt first gt lt middle gt lt last gt Jones lt last gt lt Name gt lt Name gt lt first gt John lt first gt lt middle gt P lt middle gt lt last gt Smith lt last gt lt Name gt lt son gt CHOICE The mapping of an ASN 1 CHOICE value is the alternative element tag followed by the value translated to XML format C CHOICE a INTEGER b OCTET STRING c UTF8String Schemaless lt INTEGER gt 42 lt INTEGER gt With schema lt C gt lt a gt 42 lt a gt C Open Type The mapping of an ASN 1 open type value depends on whether the actual type used to represent the value can be determined ASN2TXT attempts to determine the actual type using the following methods in this order 1 Table constraints 2 Tag lookup in all defined schema types BER DER CER only 31 3 Universal tag lookup BER DER CER only If the type can be determined an XML element tag containing
3. q Output XML filename use lt base gt xml for batch output Print out ASCII for printable hex values Insert empty XML elements in place of missing optional elements Insert XML elements with default values in place of missing elements with default values Remove all whitespace between elements Root Element Name Field separator Set the minimum output depth Set the maximum output depth Specify the output directory Do not quote strings in output file Pad fields with data that would otherwise be empty Prefix output filenames with input filenames Turn off all output except errors The following sections summarize the command line options Common Options The following options are common to both CSV and XML transformations Option Arguments Description CSV Selects CSV output xml Selects XML output lt filename gt lt filename gt is the name of the input message to decode This element is required The use of wildcards e g and is supported schema lt filename gt This option is required when using CSV or decoding PER data When converting BER data to XML a schema is not required ASN2TXT will convert the data using tag names bitsfmt lt hex bin gt bitsfmt may be used to specify how BIT STRING items are formatted By default they are expressed as hexadecimal strings use bin to express them as binary strings instead 13 Option Arguments
4. Conversions from all ASN 1 binary encodings BER CER DER PER are supported by ASN2TXT Conversions to CSV are done by a custom transformation since no standard for converting ASN 1 encoded data to CSV exists Conversions from BER CER and DER are supported at the time of this release PER is not supported 10 Using ASN2TXT Installation ASN2TXT comes packaged as an executable installation program for Windows or a tar gz archive for UNIX systems The package is comprised of the following directory tree asn2txt v23x asnlspecs bin doc sample sample per The bin subdirectory contains the asn2txt executable The aSnlspecs directory contains specifications used by the sample programs in the sample directory This document is found in the doc directory Installing on a Windows System To install ASN2TXT on a Windows system simply double click the executable installer program Selecting the default installation options will install ASN2TXT in c Nasn2txt v23x Installing on a UNIX System To install ASN2TXT on a UNIX system simply unzip and untar the tar gz archive The program may be unpacked in any directory in which the user has permissions No installation program is available to install ASN2TXT to usr local or other common installation paths but it is not difficult to manually add links if needed 11 Command line Options Invoking asn2txt without any options will sho
5. 25 ASN Tto CSV Type MappIiEscni gestes irte e DER Enkel 33 Mapping Top Level Dips anne arena rp eter 33 Mapping imple PESA A A AA 35 Mapping Complex Types scsi tbt deb be ee at Hu ins el bb ur 36 CHOICE ta iaa AI A RSS 37 Simple SbOUBNCESaud SE Isa er E 37 Mapping Nested DVpESO ne ee nes 38 SEQUENCE in SEQUENCE anna XP RI Dll ta i Veo an 38 CHOICE qmd SEQUENCE rr dario UP Re GN Rape Hit ed M re 38 SEQUENCE OF in a SE OUENGEB siii 39 Data CON s ceo nicer aive onc an ie 40 SEQUENCE OP in a SEQUENCE reaa aa a pete ntes penu aie i M CH a EHE 40 Other Nested Data PESA Tp db LR D MON MATO 41 OPTIONAL and DEFAULT Elements es an 41 Revision History e August 2012 Initial release of ASN2TXT documentation version 2 3 0 e September 2012 Updates for command line options version 2 3 0 February 2013 Document conversion in response to notes that the PDFs were corrupted on some systems version 2 3 0 Overview of ASN2TXT ASN2TXT is a command line tool that translates ASN 1 data encoded in the Basic Canonical Distinguished or Packed encoding rules into various text formats suitable for ingestion into spread sheets databases or other text processing tools At the time of initial release ASN2TXT supports converting ASN 1 data to XML and comma separated value CSV data formats Conversions to XML support both an Objective Systems custom format as well as the XML Encoding Rules standard as described in ITU T standard X 693
6. Description inputFileType binary hextext base64 gt inputFileType may be used to tell ASN2TXT how the input data are formatted By default ASN2TXT will assume that the input data are binary but it can also decode hexadecimal or base64 encoded data Whitespace in the input is ignored when hextext is specified lickey lt key gt In Linux Macintosh and Windows systems license checking is performed by the Reprise License Manager This option permits command line license activation This option is compiled out for operating systems that do not support the RLM license noopentype This option disables the conversion of open types in the output This is the default behavior when converting BER to CSV paddingbyte lt hexbyte gt lt hexbyte gt is the hexadecimal value of a padding byte that may appear in the input message Call data records CDRs are commonly continuously dumped to files by telephony equipment If no information is available the records are often padded by 0x00 or OxFF bytes The default padding byte is 0x00 lt hexbyte gt may be formatted with or without a 0x prefix pdu lt typename gt lt typename gt is the name of the PDU data type to be decoded This option is necessary when the top level data type is ambiguous It is also required when converting PER data XML Options The following options can be used when converting to XML
7. For example the default tag for a UTF8String type would be lt UTF8String gt str UTF8String testing Schemaless lt UTF8String gt TRUE lt UTF8String gt With schema lt str gt testing lt str gt Binary coded Decimal String Binary Coded Decimal BCD strings and Telephony Binary Coded Decimal TBCD strings are not part of the ASN 1 standard but their use is prevalent in many telephony related ASN 1 specifications Conversion of these types into standard numeric text strings is supported In general BCD strings pack two numeric digits into a single byte value by using a four bit nibble to hold each digit By convention the digits are reversed in TBCD strings but there are no official standards for this encoding The bcdhandling command line option can be used to force a certain type of conversion if an encoding does not follow the usual conventions The default handling is to reverse digits in strings determined to be TBCD strings and not reverse digits in BCD strings The bcd option is used to for no reversal of digits in all of these types of strings The tbcd option instructs ASN2TXT to reverse the digits for all BCD strings If no processing is desired bcdhandling none can be used to instruct ASN2TXT not to process these strings REAL An ASN 1 real value is transformed into numeric text in exponential number format If BER DER CER data is being decoded without a schema and the universal tag for thi
8. i gt ENUMERATED An ASN 1 enumerated value is transformed into the enumerated identifier text value If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed an lt ENUMERATED gt tag is added 25 colors ENUMERATED fr g b g Schemaless lt ENUMERATED gt 1 lt ENUMERATED gt XML Mode lt colors gt g lt colors gt XER Mode lt colors gt lt g gt lt colors gt BIT STRING An ASN 1 bit string value is transformed into one of three forms 1 Binary Text 0 s and 1 s 2 Hexadecimal text 3 Named bit identifiers Binary text is the default output format This is used if the bit string type contains no named bit identifiers and if specification of hexadecimal output was not specified on the asn2txt command line Hexadecimal text is displayed when the bitsfmt hex command line option is used Any unused bits in the last octet are set to zero Note that the other bits are displayed in most significant bit order as they appear in the string in the last byte i e they are not right shifted For example if the last byte contains a bit string value of 1010xxxx where x denotes an unused bit the string is displayed as A0 in the XML output not 0A Named bit identifiers are used in the case of a bit string declared with identifiers In this case the XML content is a space separated list of identifier values corresponding to the bits that are set I
9. input data omitted the default UTF8String Instead of a blank entry however the output CSV data contains test 42
10. of header data Other cases are considered in the next sections Take for example the following SEQUENCE specification S SEQUENCE i INTEGER s UTF8String b BIT STRING Each element of the SEQUENCE will be represented by an item in the output CSV file as follows 1 S D 37 Mapping Nested Types When a SEQUENCE or SET contains other complex data types it is said to be nested Types may be nested to an arbitrary depth in ASN 1 so the resulting output can be extremely verbose in complex specifications Moreover these nested types can be repeating The following sections describe how ASN2TXT handles nested types A SEQUENCE is exactly the same as a SET to ASN2TXT the two types are used interchangeably in the following sections SEQUENCE in a SEQUENCE One form of nested data occurs when a SEQUENCE type contains another as in the following example A SEQUENCE a INTEGER b SEQUENCE aa INTEGER bb BOOLEAN c BIT STRING In this case the following columns would be generated in the output CSV a aa bb c ASN2TXT removes all references to the SEQUENCE named b Instead the inner data aa and bb is collapsed into the main data type It is as though we have instead provided the following specification A SEQUENCE a INTEGER aa INTEGER bb BOOLEAN b BIT STRING While the BER encoding of the two specifications is different they are functionally equivalent to ASN2TXT CHOICE in
11. option causes ASN2TXT to operate in a quiet mode more suitable for batch processing Informational messages are limited and only error output will be reported S lt separator gt By default ASN2TXT assumes the record separator will be a comma When this conflicts with output data e g a field may consist of City State users may use the s switch to specify a different separator such as a tab or a pipe Enclosing the separator in quotation marks is necessary when using a tab or other whitespace character Using the GUI ASN2TXT for Windows is provided with a graphical user interface that can be used to invoke the command line tool from a windowed environment The GUI supports a project file format so that commonly used specifications and messages can be transformed to XML or CSV as needed The opening screen follows 16 A ASN2TXT Project Wizard il New Project amp Open Project Help lt Back u gt Cancel The initial screen contains options for users who wish to open or create a new project but this is not necessary to use the software The next screen is used to select the input specifications and message data used for decoding 17 asnzrst o Select Files and Directories ASN 1 Files Browse aA Asample employeel employee asn Remove Input message filename favdev dev sample employee message dat Browse Help lt Back secs
12. 3 objective SYSTEMS INC ASN2TXT v2 3 User s Manual Objective Systems Inc February 2013 The software described in this document is furnished under a license agreement and may be used only in accordance with the terms of this agreement Copyright Notice Copyright 61997 2013 Objective Systems Inc All rights reserved This document may be distributed in any form electronic or otherwise provided that it is distributed in its entirety and that the copyright and this notice are included Author s Contact Information Comments suggestions and inquiries regarding this product may be submitted via electronic mail to info obj sys com Table of Contents RASMUS dd MEE 6 Overview Of ASNI DOLI ee rl ae Les eves pnt Lov Rae HR emp perti dr npa 7 UsmpASNZ EXT u aate detinet n a oS A Re eoe A ee efe eic tud 8 Installations PP a aitean 8 Installing on a Window e SV Steves ance alee o aa ates 8 Installing ona UND Systeri nase RER uos Ph TR aN 8 Command line A A etn mae e ee Tree er stiri een ere 9 CGI TO PIONS asses Rene ct qu Ca Uta e det n tet iet a ONE 10 IN osea M EUR A td uM E M aM SM Ua 11 CSV ODIO Sa rat diront er avare Fede Orb eerte ite t peint 12 A Great lS 15 ASN Lto ML Type Mappnsseun ae mail leise 23 General Mapping without ASN 1 Schema Information esee 23 General Mapping with ASN 1 Schema Information near ann 24 Specific ASN 1 Type to Value Mappingscan unn energie
13. 8 22 25 30 Character string UNIVERSAL 23 UTCTIME UNIVERSAL 24 GENERALIZEDTIME Element content will be formatted in one of three ways hexadecimal text ASCII character text or specific typed value Hexadecimal text is the default format for untyped content ASCII text will be used if the ascii command line switch is specified and all byte values within a particular field are determined to be printable ASCII characters A specific type value encoding will be done if a known universal tag is found The mapping in this case will be as described in the Specific ASN 1 Type to XML Value Mapping section below General Mapping with ASN 1 Schema Information ASN 1 schema information is used if one or more ASN 1 schema files are specified on the command line using the schema command line switch In this case element names as specified in the schema file are used for the XML element names and the content is decoded based on the specific type It is possible to use the pdu command line switch to force the association of a type within the specification to the message This is only necessary if the ASN 1 files contain multiple types with the same start tag as the message type Otherwise the program will be able to determine on its own which type to use by matching tags This is true for BER DER CER messages only for PER it is necessary to specify the PDU type along with the schema 24 Specific ASN 1 Type to Value Mapping
14. Cancel The next button in the file selection window will not activate until both the input message and input specification have been provided After this is done the following common options can be set 18 amp ASN2TXT Kl Common Options r Output file type Encoding Rules Input File Type em BER C Base64 C PER C Hex O d C UPER Binary r Handling of OCTET STRINGs declared to be BCD Strings Default C TBCD C BCD C None r BIT STRING content output Format C Binary Hexadecimal r ASN 1 Options Message PDU type name 7 Change padding byte value Skip n bytes between messages skip n bytes at the start of the message Disable automatic open type decoding Hep lt Back secs Cancel The options are described in detail in the User s Guide When selecting CSV output the GUI will automatically disable the PER input options and open type decoding Conversions to CSV do not support either PER or open type decoding at this time If XML is the selected output format the following screen will appear 19 ax XML Generation Options r Output Options Root Element name i Output XML in XER Format Insert empty XML elements in place of missing optional elements r Insert XML elements with default values in place of missing elements with defaults values Print out ASCII for printable hex values FT R
15. G and OCTET STRING values 29 If the value being translated is a constructed type or if it may contain whitespace the value is wrapped in a tag which is either the name of the encapsulating type defined or built in or the SEQUENCE OF element name if this form of the type was used If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed a lt SEQUENCE gt or lt SET gt tag is added That is because the tag value hex 30 or 31 is the same for SEQUENCE OF or SET OF as it is for SEQUENCE or SET soi SEQUENCE OF INTEGER 1 2 3 Schemaless SEQUENCE lt INTEGER gt 1 lt INTEGER gt lt INTEGER gt 2 lt INTEGER gt lt INTEGER gt 3 lt INTEGER gt lt SEQUENCE gt With schema lt soi gt lt INTEGER gt 1 lt INTEGER gt lt INTEGER gt 2 lt INTEGER gt lt INTEGER gt 3 lt INTEGER gt lt soi gt sos SEQUENCE OF UTF8String test 1 test 2 Schemaless lt SEQUENCE gt lt UTF8STRING gt test 1 lt UTF8STRING gt lt UTF8STRING gt test 2 lt UTF8STRING gt SEQUENCE With schema lt SOS gt lt UTF8String gt test 1 lt UTF8String gt lt UTF8String gt test 2 lt UTF8String gt lt SOS gt Name SEQUENCE son SEQUENCE OF Name first UTF8String first Joe middle UTF8String OPTIONAL last Jones last UTF8String first John middle P last Smith Schemaless lt SEQUENCE gt
16. V BER CER and DER data are encoded in a hierarchical format that lends itself to translation to other hierarchical formats such as XML CSV on the other hand is flat data format there are no structured types or children and all data in a CSV file are displayed on single lines This complicates the translation of ASN 1 to CSV since structured data types like SEQUENCESs can be nested to an arbitrary depth or repeated an arbitrary number of times While these limitations make conversion a difficult problem CSV offers some advantages over XML CSV files are usually considerably smaller than XML since no markup is necessary to distinguish elements Many databases import CSV data directly into tables so no intermediate transformations are required CSV files can be easier to manipulate procedurally no external XML parsers are required to read the files and many scripting languages have built in facilities for working with comma delimited data We may divide conversion into roughly two steps collecting the column headers and then outputting the column data Header information comes from parsing the input specification while the column data are found in the actual encoded content This documentation is primarily concerned with how the column headers are collected Mapping Top Level Types PDU data types are stored in their own CSV file usually in the form of ModuleName ProductionName csv There are three main top level data types of interes
17. a SEQUENCE When a CHOICE appears in a SEQUENCE each of the elements in the CHOICE is represented in the output CSV file even though only one will be selected in any given message For example take the following specification 38 A SEQUENCE a INTEGER b CHOICE aa INTEGER bb BOOLEAN c BIT STRING The resulting columns will appear as though the CHOICE were actually aSEQUENCE a aa bb c SEQUENCE OF in aSEQUENCE The last data type to consider is the SEQUENCE OF This is handled very much like a SEQUENCE the SEQUENCE OF is ignored and its contents are represented for the column headers as in the following example A SEQUENCE a INTEGER b SEQUENCE OF INTEGER c BIT STRING In this case the columns will be straightforwardly translated a b c It is possible that the repeated data type is not primitive but rather complex For example A SEQUENCE a INTEGER b SEQUENCE OF SEQUENCE aa INTEGER bb BOOLEAN c BIT STRING In this case the innermost data are represented in the output CSV files but the actual SEQUENCE OF will be ignored as before a aa bb c The exact same columns would be represented if a CHOICE were used instead of a SEQUENCE ASN2TXT will always do its best to collapse nested data types drilling down to the innermost data to collect the column headers 39 Data Conversion Having collected column headers for the output CSV the second and final step is
18. ction A single row may be used to output a message without repeating types The CHOICE data type bears some explanation The following specification is the same used in the previous section A SEQUENCE a INTEGER b CHOICE aa INTEGER bb BOOLEAN c BIT STRING Some example output data follows a aa bb c 1 FALSE 101010 2 137 100001 The output lines will contain data in either the aa or bb columns but not both Only the selected data should be represented in the output line OPTIONAL and DEFAULT Elements Optional primitive elements that are missing in an input message will result in a blank entry in the output CSV file Take for example the following specification A SEQUENCE a INTEGER b UTF8String OPTIONAL c BIT STRING This might result in the following output a b c l test string 100100 2 100101 3 another test 100100 In this example the second message does not contain the optional UTF8String so it is omitted from the output 41 Elements marked DEFAULT are handled differently in the output If an element is missing in the input specification the default value is copied into the output CSV file The following specification is used to demonstrate A SEQUENCE a INTEGER b UTF8String DEFAULT test c BIT STRING In this case we might have the following output a b c l test string 100100 2 test 100101 3 another test 100100 Like the previous example the
19. e outputted on separate lines One of the implications of this kind of translation is that the message structure cannot be reconstructed from the output data files A top level data type of a CHOICE SEQUENCE or SEQUENCE OF may result in exactly the same output files even though the bytes of the message may differ Such ambiguity should not cause any problems since a specification is required for decoding the ASN 1 data Mapping Simple Types Simple types in ASN 1 consist of the following BOOLEAN INTEGER BIT STRING e OCTET STRING NULL OBJECT IDENTIFIER REAL ENUMERATED 35 e Character strings RELATIVE OID e UTCTime GeneralizedTime e GraphicString e VisibleString e CGeneralString Each simple type is mapped to a corresponding string representation of the input data This is a relatively straightforward conversion Of special note we use the BOOLEAN values TRUE for any hex octet not equal to 0x00 and FALSE for any hex octet equal to 0x00 NULL values are outputted simply as NULL Simple type mappings require no extra logic for output Their textual representations are generally quite straightforward Mapping complex types however is more difficult Mapping Complex Types Complex types of interest include the following SEQUENCE SEQUENCE OF SET SET OF CHOICE Complex types by their nature are more difficult to transform than simple types They can be self refere
20. emove all whitespace between elements Output XML Filename Browse Help lt Back u gt Cancel Users have two options for how to direct their XML output it can be dumped to the GUI directly or else to a file When the XML output filename is not provided users will see the decoded XML output in the compilation window If output to CSV is requested the following screen will appear instead 20 ax CSV Generation Options r Output Options Field Separator Minimum Output Level Maximum Output Level 7 Do not quote fields in the output files Pad fields that otherwise would be empty Help lt Back u gt Cancel Unlike XML output CSV output is always directed to a file or more likely several files The output in the compilation window is therefore a little different than what is seen when XML output is selected without an output filename This behavior is normal When the appropriate options for either type have been selected the following screen is presented for compilation 21 amp ASN2TXT Compile Compilation Results 22 ASN 1 to XML Type Mappings This chapter defines the mapping between ASN 1 encoded data values and XML for each of the ASN 1 types defined in the X 680 standard General Mapping without ASN 1 Schema Information A BER DER or CER encoded data stream may be translated to XML format without provid
21. ing associated ASN 1 schema information In this case XML element names are derived from built in ASN 1 tag information contained within the message and values are encoded as either hexadecimal text ASCII text or as specific data typed values if universal tag information is present XML element names derived from ASN 1 tag names for all tags except known universal tags is in the following general form TagClass TagValue where TagClass is the tag class name APPLICATION CONTEXT or PRIVATE and TagValue is the numeric tag value For example an APPLICATION 1 tag would be printed as APPLICATION 1 and a 0 tag context specific zero would be printed as CONTEXT 0 In the case of known universal tags the tag value is derived using the name of the known type In general this is the type name defined in the ASN 1 standard with an underscore character used in place of embedded whitespace if it exists The following table shows the XML tag names for the known types Tag XML Element Name UNIVERSAL 1 BOOLEAN UNIVERSAL 2 INTEGER UNIVERSAL 3 BIT STRING UNIVERSAL 4 OCTET STRING UNIVERSAL 5 NULL UNIVERSAL 6 OBJECT IDENTIFIER UNIVERSAL 7 OBJECT DESCRIPTOR UNIVERSAL 8 EXTERNAL UNIVERSAL 9 REAL UNIVERSAL 10 ENUMERATED 23 Tag XML Element Name UNIVERSAL 12 EMBEDDED PDV UNIVERSAL 13 RELATIVE OID UNIVERSAL 16 SEQUENCE UNIVERSAL 17 SET UNIVERSAL 1
22. ntial and nested which complicates transformation CSV is a flat file format that cannot properly represent nested types in a fixed number of columns so care must be taken in transforming the data to ensure that it is properly represented This process is very similar to a first order database normalization 36 CHOICE As explained in the previous section the CHOICE at the top level is effectively ignored the elements of the CHOICE are used to generate the output of a file instead In the routine case where the CHOICE is contained in another data type or stands alone the mapping is slightly different Take for example the following CHOICE C CHOICE i INTEGER b BOOLEAN s UTF8String The elements contained in the CHOICE will be used as the column names The name of the CHOICE itself will be ignored The resulting column names from this example would look like this i b s Simple SEQUENCEs and SETs This section describes the transformation of SEQUENCE data types The SET data type is analogous to the SEQUENCE and so bears no extra discussion As described in previous sections the SEQUENCE OF and SET OF types are likewise equivalent The only significant difference between SEQUENCE and SET is that elements may be encoded in any order in a SET ASN2TXT will order SET elements in the order they appear in the specification The SEQUENCEs considered in this section contain only simple types to simplify the collection
23. or an ASN 1 file containing multiple individually encoded binary messages a common feature of many Call Detail Record ASN 1 formats CSV Options The following options can be used when converting to CSV Option Arguments Description maxLevel lt level gt By default all entries in the input file will be dumped to the output file Deeply nested types may result in excessive output however The maxLevel switch causes ASN2TXT to skip outputting data after lt level gt levels have been processed minLevel lt level gt Similar to the maxLevel option the minLevel option will cause ASN2TXT to skip outputting top level data types lt level gt levels deep noquotes By default ASN2TXT will quote all of the fields to ensure that they are processed as text by 15 Option Arguments Description spreadsheet programs to avoid converting numeric fields into scientific notation Using this option suppresses that behavior padfields ASN2TXT will omit fields that would normally be duplicated in output files Using this option will output these fields It produces larger files but is more explicit and may simplify ingesting the data prefix ASN2TXT will normally output all records to a predetermined filename based on the module name and PDU When the prefix option is selected the output filenames will be prefixed with the input message filename q This
24. s This section defines the type to value mapping for each of the specific ASN 1 types By default these mappings are not in the form defined in the ASN 1 XML Encoding Rules XER standard ITU T X 693 When a schema is provided using the schema option the output may be adjusted to conform to XER if desired by using the Xer option XER is more verbose and less validation friendly than our native XML export It is provided for those occasions when strict conformance is required Differences between the two formats are provided along with the schemaless mappings below BOOLEAN An ASN 1 boolean value is transformed into the keyword true or false If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed a lt BOOLEAN gt tag is added b BOOLEAN TRUE Schemaless lt BOOLEAN gt TRUE lt BOOLEAN gt XML Mode lt b gt true lt b gt XER Mode lt b gt lt TRUE gt lt b gt INTEGER An ASN 1 integer value is transformed into numeric text The one exception to this rule is if named number identifiers are specified for the integer type In this case if the number matches one ofthe declared identifiers the identifier text is used If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed an lt INTEGER gt tag is added i INTEGER 35 Schemaless lt INTEGER gt 35 lt INTEGER gt With schema lt i gt 35 lt
25. s type is parsed a lt REAL gt tag is added r REAL 2 99 28 Schemaless lt REAL gt 2 99 lt REAL gt With schema lt r gt 2 99 lt r gt SEQUENCE and SET An ASN 1 sequence value is transformed into an XML value containing an element wrapper with each of the XML element encoded values inside name SEQUENCE name Name first UTF8String first Joe middle UTF8String OPTIONAL last Jones last UTF8String Schemaless lt SEQUENCE gt lt CONTEXT_0 gt lt UTF8String gt Joe lt UTF8String gt CONTEXT 0 CONTEXT 2 lt UTF8String gt Jones lt UTF8String gt CONTEXT 2 SEQUENCE With schema name lt first gt Joe lt first gt lt last gt Jones lt last gt lt name gt With emptyOptionals lt name gt lt first gt Joe lt first gt lt middle gt lt last gt Jones lt last gt lt name gt When a SET is used instead the outer SEQUENCE tag is replaced with SET The mappings are otherwise identical SEQUENCE OF SET OF The representation of a repeating value in XML varies depending on the type of the element value If the value being translated is a sequence of an atomic primitive type the XML content is a space separated list of values The definition of atomic primitive type is any primitive type whose value may not contain embedded whitespace This includes BOOLEAN INTEGER ENUMERATED REAL BIT STRIN
26. t 1 SEQUENCE SEQUENCE OF 2 SET SET OF 3 CHOICE The list types SEQUENCE and SET OF are the same as the unit types The content is repeated when needed on multiple rows of the CSV file 33 Simple types may be used as top level data types but in practice this is rare Translation in this case proceeds as described in the following sections As an example the following SEQUENCE would be dumped to MyModule Typel csv MyModule DEFINITIONS BEGIN Typel SEQUENCE END If the input file type had two such SEQUENCEs the resulting files would be MyModule Typel csvandMyModule Type2 csv When a CHOICE is used as the top level data type the typename for the CHOICE is ignored and the files are generated using the typenames in the CHOICE For example the following specification would generate the same output as the one with two top level SEQUENCEs named Typel and Type2 MyModule DEFINITIONS AUTOMATIC TAGS BEGIN Typel SEQUENCE Type2 SEQUENCE PDU CHOICE tl Typel t2 Type2 34 When a SEQUENCE or SET OF type is used as the top level the underlying unit type is referenced instead For example the following ASN 1 specification would create the file MyModule Typel csv MyModule DEFINITIONS BEGIN Typel SEQUENCE cn PDU SEQUENCE OF Typel END In this case the PDU type carries no extra information for outputting the data the contents of Typel ar
27. t lt n gt OBJECT IDENTIFIER and RELATIVE OID An ASN 1 object identifier value is mapped into space separated list of identifiers in numeric and or named number format The identifiers are enclosed in curly braces Numeric identifiers are simply numbers The named number format is a textual identifier followed by the corresponding numeric identifier in parentheses It is used in cases where the identifier can be determined from the schema or is a well known identifier as specified in the ASN 1 standard If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed an OBJECT IDENTIFIER tag is added oid OBJECT IDENTFIER 1 2 840 113549 112 Schemaless lt OBJECTIDENTIFIER gt 1 2 840 113549 1 1 2 lt OBJECTIDENTIFIER gt With schema lt oid gt 1 2 840 113549 1 1 2 lt oid gt 27 The mapping for RELATIVE OID is the same as that for OBJECT IDENTIFIER Character String An ASN 1 value of any of the known character string types is transformed into the character string text in whatever the default encoding for that type is For example an IA5String would contain an ASCII text value whereas a BMPString would contain a Unicode value If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed a tag is added which is the name of the character string type as defined in the ASN 1 standard in angle brackets
28. t is assumed that bits in the string all have corresponding identifier values If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed a lt BIT_STRING gt tag is added bs BIT STRING z 0 a 1 b 2 c 3 100100 B Schemaless BIT STRING gt 100100 lt BIT STRING gt With Schema lt bs gt 100100 lt bs gt OCTET STRING An ASN 1 octet string value is transformed into one of two forms 1 Hexadecimal text 2 ASCII character text 26 Hexadecimal text is the default display type ASCII text will be used for the content when the ascii command line option is used and the field contains are printable ASCII characters A special case of OCTET STRING handling is for declared binary coded decimal BCD data types This is discussed in a later section If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed a lt OCTET_STRING gt tag is added os OCTET STRING 3031 H Schemaless OCTET STRING gt 3031 lt OCTET STRING With schema lt 0S gt 3031 lt os gt With ascii lt os gt 01 lt os gt NULL An ASN 1 null value is displayed as an empty XML element If BER DER CER data is being decoded without a schema and the universal tag for this type is parsed a lt NULL gt tag is added n NULL NULL Schemaless NULL XML Mode lt n gt XER Mode lt n gt lt NULL g
29. the type name is first added followed by the translated content of the value If the type cannot be determined the open type content is translated into hexadecimal text from of the encoded value This will also be done if the noopentype command line switch is used As an example consider the Algorithmldentifier type used in the AuthenticationFramework and other related security specifications AlgorithmIdentifier SEQUENCE algorithm ALGORITHM amp id SupportedAlgorithms parameters ALGORITHM amp Type SupportedAlgorithms algorithm OPTIONAL In this case the parameters element references an open type that is tied to a type value based on the value of the algorithm key Without getting into the details of the use of the accompanying information object sets it is known that for an algorithm value of object identifier 1 2 840 113549 1 1 2 the type of the parameters field is NULL i e there are no associated parameters The XML translation in this case will be the following lt algorithm gt 1 2 840 113549 1 1 2 lt algorithm gt lt parameters gt lt NULL gt lt parameters gt 32 ASN 1 to CSV Type Mappings Converting ASN 1 types to CSV output is not always very straightforward It is akin to normalizing a database except that there is only one table For complex types it is necessary to duplicate information across several rows There exists no standard for converting ASN 1 data to CS
30. to output the actual data from the decoded BER message Fortunately this is considerably more straightforward than collapsing the data structures in the specification The main case to consider is that in which data types are repeated when a SEQUENCE OF is nested inside of a SEQUENCE Some brief comments follow for other nested data types SEQUENCE OF in a SEQUENCE Take for example the simple case previously seen A SEQUENCE a INTEGER b SEQUENCE OF INTEGER c BIT STRING Let us assume for sake of argument that there are two integers in the inner SEQUENCE OF In this case the resulting CSV file will have two rows in addition to the header row The common data columns a and C will be represented once in the output file unless padFields is specified while the repeated element b will change For example a b c 1 97823789324 010010 18927481 If you have chosen to pad the fields the output will look like this a b c 1 97823789324 010010 1 18927481 010010 While this example is very simple it is possible to nest data types to an arbitrary depth and the representation of columns and their data can be quite large In pathological instances the CSV output may be larger than the output generated by other tools like ASN2XML 40 Other Nested Data Types The other nested data types SEQUENCE and CHOICE are relatively trivial to convert once the columns have been assembled as described in the previous se
31. w a usage message that contains the command line options ASN2TXT version 2 3 x ASN 1 to text formatter Copyright c 2012 Objective Systems Inc All Rights Reserved Usage asn2txt lt input files gt options lt input files gt ASN 1 message file name wildcards are okay options xml Output to XML CSV Output to CSV Common options schema lt filename gt ASN 1 definition file name s I lt directory gt Import ASN 1 files from lt directory gt ber Use basic encoding rules BER pdu lt typename gt Message PDU type name bcdhandling default none bcd tbcd Define handling of OCTET STRINGs declared to be binary coded decimal BCD strings noopentype Disable automatic open type decoding paddingbyte lt hexbyte gt Additional padding byte bitsfmt hex bin BIT STRING content output format inputFileType lt binary hextext base64 gt Format of data in input file skip lt num gt Skip lt num gt bytes between messages headerOffset num Skip the first num bytes in a data file lickey key License key to activate XML options per Use aligned packed encoding rules PER uper Use unaligned packed encoding rules U PER xer Output XML in ASN 1 XER format 12 o filename ascii emptyoptionals emptydefault nowhitespace rootElement element CSV options S separator minLevel num maxLevel num outdir directory noquotes padFields prefix
Download Pdf Manuals
Related Search