5 asn1parse - ASN.1 parsing tool
9 B<openssl> B<asn1parse>
28 The B<asn1parse> command is a diagnostic utility that can parse ASN.1
29 structures. It can also be used to extract data from ASN.1 formatted data.
37 Print out a usage message.
39 =item B<-inform> B<DER|PEM>
41 the input format. B<DER> is binary format and B<PEM> (the default) is base64
46 the input file, default is standard input
48 =item B<-out filename>
50 output file to place the DER encoded data into. If this
51 option is not present then no data will be output. This is most useful when
52 combined with the B<-strparse> option.
56 don't output the parsed version of the input file.
58 =item B<-offset number>
60 starting offset to begin parsing, default is start of file.
62 =item B<-length number>
64 number of bytes to parse, default is until end of file.
68 indents the output according to the "depth" of the structures.
70 =item B<-oid filename>
72 a file containing additional OBJECT IDENTIFIERs (OIDs). The format of this
73 file is described in the NOTES section below.
77 dump unknown data in hex format.
81 like B<-dump>, but only the first B<num> bytes are output.
83 =item B<-strparse offset>
85 parse the contents octets of the ASN.1 object starting at B<offset>. This
86 option can be used multiple times to "drill down" into a nested structure.
88 =item B<-genstr string>, B<-genconf file>
90 generate encoded data based on B<string>, B<file> or both using
91 L<ASN1_generate_nconf(3)> format. If B<file> only is
92 present then the string is obtained from the default section using the name
93 B<asn1>. The encoded data is passed through the ASN1 parser and printed out as
94 though it came from a file, the contents can thus be examined and written to a
95 file using the B<out> option.
99 If this option is used then B<-inform> will be ignored. Without this option any
100 data in a PEM format input file will be treated as being base64 encoded and
101 processed whether it has the normal PEM BEGIN and END markers or not. This
102 option will ignore any data prior to the start of the BEGIN marker, or after an
103 END marker in a PEM file.
109 The output will typically contain lines like this:
111 0:d=0 hl=4 l= 681 cons: SEQUENCE
115 229:d=3 hl=3 l= 141 prim: BIT STRING
116 373:d=2 hl=3 l= 162 cons: cont [ 3 ]
117 376:d=3 hl=3 l= 159 cons: SEQUENCE
118 379:d=4 hl=2 l= 29 cons: SEQUENCE
119 381:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Subject Key Identifier
120 386:d=5 hl=2 l= 22 prim: OCTET STRING
121 410:d=4 hl=2 l= 112 cons: SEQUENCE
122 412:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Authority Key Identifier
123 417:d=5 hl=2 l= 105 prim: OCTET STRING
124 524:d=4 hl=2 l= 12 cons: SEQUENCE
128 This example is part of a self-signed certificate. Each line starts with the
129 offset in decimal. B<d=XX> specifies the current depth. The depth is increased
130 within the scope of any SET or SEQUENCE. B<hl=XX> gives the header length
131 (tag and length octets) of the current type. B<l=XX> gives the length of
134 The B<-i> option can be used to make the output more readable.
136 Some knowledge of the ASN.1 structure is needed to interpret the output.
138 In this example the BIT STRING at offset 229 is the certificate public key.
139 The contents octets of this will contain the public key information. This can
140 be examined using the option B<-strparse 229> to yield:
142 0:d=0 hl=3 l= 137 cons: SEQUENCE
143 3:d=1 hl=3 l= 129 prim: INTEGER :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
144 135:d=1 hl=2 l= 3 prim: INTEGER :010001
148 If an OID is not part of OpenSSL's internal table it will be represented in
149 numerical form (for example 1.2.3.4). The file passed to the B<-oid> option
150 allows additional OIDs to be included. Each line consists of three columns,
151 the first column is the OID in numerical format and should be followed by white
152 space. The second column is the "short name" which is a single word followed
153 by white space. The final column is the rest of the line and is the
154 "long name". B<asn1parse> displays the long name. Example:
156 C<1.2.3.4 shortName A long name>
162 openssl asn1parse -in file.pem
166 openssl asn1parse -inform DER -in file.der
168 Generate a simple UTF8String:
170 openssl asn1parse -genstr 'UTF8:Hello World'
172 Generate and write out a UTF8String, don't print parsed output:
174 openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der
176 Generate using a config file:
178 openssl asn1parse -genconf asn1.cnf -noout -out asn1.der
182 asn1=SEQUENCE:seq_sect
187 field2=EXP:0, UTF8:some random string
192 There should be options to change the format of output lines. The output of some
193 ASN.1 types is not well handled (if at all).
197 L<ASN1_generate_nconf(3)>
201 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
203 Licensed under the OpenSSL license (the "License"). You may not use
204 this file except in compliance with the License. You can obtain a copy
205 in the file LICENSE in the source distribution or at
206 L<https://www.openssl.org/source/license.html>.