2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-asn1parse - ASN.1 parsing command
10 B<openssl> B<asn1parse>
12 [B<-inform> B<DER>|B<PEM>|B<B64>]
16 [B<-offset> I<number>]
17 [B<-length> I<number>]
22 [B<-strparse> I<offset>]
23 [B<-genstr> I<string>]
30 This command is a diagnostic utility that can parse ASN.1 structures.
31 It can also be used to extract data from ASN.1 formatted data.
39 Print out a usage message.
41 =item B<-inform> B<DER>|B<PEM>|B<B64>
43 The input format; the default is B<PEM>.
44 See L<openssl-format-options(1)> for details.
46 =item B<-in> I<filename>
48 The input file, default is standard input.
50 =item B<-out> I<filename>
52 Output file to place the DER encoded data into. If this
53 option is not present then no data will be output. This is most useful when
54 combined with the B<-strparse> option.
58 Don't output the parsed version of the input file.
60 =item B<-offset> I<number>
62 Starting offset to begin parsing, default is start of file.
64 =item B<-length> I<number>
66 Number of bytes to parse, default is until end of file.
70 Indents the output according to the "depth" of the structures.
72 =item B<-oid> I<filename>
74 A file containing additional OBJECT IDENTIFIERs (OIDs). The format of this
75 file is described in the NOTES section below.
79 Dump unknown data in hex format.
81 =item B<-dlimit> I<num>
83 Like B<-dump>, but only the first B<num> bytes are output.
85 =item B<-strparse> I<offset>
87 Parse the contents octets of the ASN.1 object starting at B<offset>. This
88 option can be used multiple times to "drill down" into a nested structure.
90 =item B<-genstr> I<string>, B<-genconf> I<file>
92 Generate encoded data based on I<string>, I<file> or both using
93 L<ASN1_generate_nconf(3)> format. If I<file> only is
94 present then the string is obtained from the default section using the name
95 B<asn1>. The encoded data is passed through the ASN1 parser and printed out as
96 though it came from a file, the contents can thus be examined and written to a
97 file using the B<-out> option.
101 If this option is used then B<-inform> will be ignored. Without this option any
102 data in a PEM format input file will be treated as being base64 encoded and
103 processed whether it has the normal PEM BEGIN and END markers or not. This
104 option will ignore any data prior to the start of the BEGIN marker, or after an
105 END marker in a PEM file.
107 =item B<-item> I<name>
109 Attempt to decode and print the data as an B<ASN1_ITEM> I<name>. This can be
110 used to print out the fields of any supported ASN.1 structure if the type is
117 The output will typically contain lines like this:
119 0:d=0 hl=4 l= 681 cons: SEQUENCE
123 229:d=3 hl=3 l= 141 prim: BIT STRING
124 373:d=2 hl=3 l= 162 cons: cont [ 3 ]
125 376:d=3 hl=3 l= 159 cons: SEQUENCE
126 379:d=4 hl=2 l= 29 cons: SEQUENCE
127 381:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Subject Key Identifier
128 386:d=5 hl=2 l= 22 prim: OCTET STRING
129 410:d=4 hl=2 l= 112 cons: SEQUENCE
130 412:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Authority Key Identifier
131 417:d=5 hl=2 l= 105 prim: OCTET STRING
132 524:d=4 hl=2 l= 12 cons: SEQUENCE
136 This example is part of a self-signed certificate. Each line starts with the
137 offset in decimal. C<d=XX> specifies the current depth. The depth is increased
138 within the scope of any SET or SEQUENCE. C<hl=XX> gives the header length
139 (tag and length octets) of the current type. C<l=XX> gives the length of
142 The B<-i> option can be used to make the output more readable.
144 Some knowledge of the ASN.1 structure is needed to interpret the output.
146 In this example the BIT STRING at offset 229 is the certificate public key.
147 The contents octets of this will contain the public key information. This can
148 be examined using the option C<-strparse 229> to yield:
150 0:d=0 hl=3 l= 137 cons: SEQUENCE
151 3:d=1 hl=3 l= 129 prim: INTEGER :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
152 135:d=1 hl=2 l= 3 prim: INTEGER :010001
156 If an OID is not part of OpenSSL's internal table it will be represented in
157 numerical form (for example 1.2.3.4). The file passed to the B<-oid> option
158 allows additional OIDs to be included. Each line consists of three columns,
159 the first column is the OID in numerical format and should be followed by white
160 space. The second column is the "short name" which is a single word followed
161 by whitespace. The final column is the rest of the line and is the
162 "long name". Example:
164 C<1.2.3.4 shortName A long name>
166 For any OID with an associated short and long name, this command will display
173 openssl asn1parse -in file.pem
177 openssl asn1parse -inform DER -in file.der
179 Generate a simple UTF8String:
181 openssl asn1parse -genstr 'UTF8:Hello World'
183 Generate and write out a UTF8String, don't print parsed output:
185 openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der
187 Generate using a config file:
189 openssl asn1parse -genconf asn1.cnf -noout -out asn1.der
193 asn1=SEQUENCE:seq_sect
198 field2=EXP:0, UTF8:some random string
203 There should be options to change the format of output lines. The output of some
204 ASN.1 types is not well handled (if at all).
209 L<ASN1_generate_nconf(3)>
213 Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.
215 Licensed under the Apache License 2.0 (the "License"). You may not use
216 this file except in compliance with the License. You can obtain a copy
217 in the file LICENSE in the source distribution or at
218 L<https://www.openssl.org/source/license.html>.