asn1parse - ASN.1 parsing tool


SYNOPSIS

       openssl asn1parse [-inform PEM|DER] [-in filename] [-out
       filename] [-noout] [-offset number] [-length number] [-i]
       [-oid filename] [-strparse offset]


DESCRIPTION

       The asn1parse command is a diagnostic utility that can
       parse ASN.1 structures. It can also be used to extract
       data from ASN.1 formatted data.


OPTIONS

       -inform DER|PEM
           the input format. DER is binary format and PEM (the
           default) is base64 encoded.

       -in filename
           the input file, default is standard input

       -out filename
           output file to place the DER encoded data into. If
           this option is not present then no data will be
           output. This is most useful when combined with the
           -strparse option.

       -noout
           don't output the parsed version of the input file.

       -offset number
           starting offset to begin parsing, default is start of
           file.

       -length number
           number of bytes to parse, default is until end of
           file.

       -i  indents the output according to the "depth" of the
           structures.

       -oid filename
           a file containing additional OBJECT IDENTIFIERs
           (OIDs). The format of this file is described in the
           NOTES section below.

       -strparse offset
           parse the contents octets of the ASN.1 object starting
           at offset. This option can be used multiple times to
           "drill down" into a nested structure.


       The output will typically contain lines like this:

         0:d=0  hl=4 l= 681 cons: SEQUENCE

       .....

         229:d=3  hl=3 l= 141 prim: BIT STRING
         373:d=2  hl=3 l= 162 cons: cont [ 3 ]
         376:d=3  hl=3 l= 159 cons: SEQUENCE
         379:d=4  hl=2 l=  29 cons: SEQUENCE
         381:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Subject Key Identifier
         386:d=5  hl=2 l=  22 prim: OCTET STRING
         410:d=4  hl=2 l= 112 cons: SEQUENCE
         412:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Authority Key Identifier
         417:d=5  hl=2 l= 105 prim: OCTET STRING
         524:d=4  hl=2 l=  12 cons: SEQUENCE

       .....

       This example is part of a self signed certificate. Each
       line starts with the offset in decimal. d=XX specifies the
       current depth. The depth is increased within the scope of
       any SET or SEQUENCE. hl=XX gives the header length (tag
       and length octets) of the current type. l=XX gives the
       length of the contents octets.

       The -i option can be used to make the output more
       readable.

       Some knowledge of the ASN.1 structure is needed to
       interpret the output.

       In this example the BIT STRING at offset 229 is the
       certificate public key.  The contents octets of this will
       contain the public key information. This can be examined
       using the option -strparse 229 to yield:

           0:d=0  hl=3 l= 137 cons: SEQUENCE
           3:d=1  hl=3 l= 129 prim: INTEGER           :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
         135:d=1  hl=2 l=   3 prim: INTEGER           :010001


NOTES

       If an OID is not part of OpenSSL's internal table it will
       be represented in numerical form (for example 1.2.3.4).
       The file passed to the -oid option allows additional OIDs
       to be included. Each line consists of three columns, the
       first column is the OID in numerical format and should be
       followed by white space. The second column is the "short
       name" which is a single word followed by white space. The
       final column is the rest of the line and is the "long
       name". asn1parse displays the long name. Example:



BUGS

       There should be options to change the format of input
       lines. The output of some ASN.1 types is not well handled
       (if at all).


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