6 asn1parse - ASN.1 parsing tool
10 B<openssl> B<asn1parse>
30 The B<asn1parse> command is a diagnostic utility that can parse ASN.1
31 structures. 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|PEM>
43 The input format. B<DER> is binary format and B<PEM> (the default) is base64
48 The input file, default is standard input.
50 =item B<-out 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 number>
62 Starting offset to begin parsing, default is start of file.
64 =item B<-length 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 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.
83 Like B<-dump>, but only the first B<num> bytes are output.
85 =item B<-strparse 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 string>, B<-genconf file>
92 Generate encoded data based on B<string>, B<file> or both using
93 L<ASN1_generate_nconf(3)> format. If B<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.
109 Attempt to decode and print the data as B<ASN1_ITEM name>. This can be used to
110 print out the fields of any supported ASN.1 structure if the type is known.
116 The output will typically contain lines like this:
118 0:d=0 hl=4 l= 681 cons: SEQUENCE
122 229:d=3 hl=3 l= 141 prim: BIT STRING
123 373:d=2 hl=3 l= 162 cons: cont [ 3 ]
124 376:d=3 hl=3 l= 159 cons: SEQUENCE
125 379:d=4 hl=2 l= 29 cons: SEQUENCE
126 381:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Subject Key Identifier
127 386:d=5 hl=2 l= 22 prim: OCTET STRING
128 410:d=4 hl=2 l= 112 cons: SEQUENCE
129 412:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Authority Key Identifier
130 417:d=5 hl=2 l= 105 prim: OCTET STRING
131 524:d=4 hl=2 l= 12 cons: SEQUENCE
135 This example is part of a self-signed certificate. Each line starts with the
136 offset in decimal. B<d=XX> specifies the current depth. The depth is increased
137 within the scope of any SET or SEQUENCE. B<hl=XX> gives the header length
138 (tag and length octets) of the current type. B<l=XX> gives the length of
141 The B<-i> option can be used to make the output more readable.
143 Some knowledge of the ASN.1 structure is needed to interpret the output.
145 In this example the BIT STRING at offset 229 is the certificate public key.
146 The contents octets of this will contain the public key information. This can
147 be examined using the option B<-strparse 229> to yield:
149 0:d=0 hl=3 l= 137 cons: SEQUENCE
150 3:d=1 hl=3 l= 129 prim: INTEGER :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
151 135:d=1 hl=2 l= 3 prim: INTEGER :010001
155 If an OID is not part of OpenSSL's internal table it will be represented in
156 numerical form (for example 1.2.3.4). The file passed to the B<-oid> option
157 allows additional OIDs to be included. Each line consists of three columns,
158 the first column is the OID in numerical format and should be followed by white
159 space. The second column is the "short name" which is a single word followed
160 by white space. The final column is the rest of the line and is the
161 "long name". B<asn1parse> displays the long name. Example:
163 C<1.2.3.4 shortName A long name>
169 openssl asn1parse -in file.pem
173 openssl asn1parse -inform DER -in file.der
175 Generate a simple UTF8String:
177 openssl asn1parse -genstr 'UTF8:Hello World'
179 Generate and write out a UTF8String, don't print parsed output:
181 openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der
183 Generate using a config file:
185 openssl asn1parse -genconf asn1.cnf -noout -out asn1.der
189 asn1=SEQUENCE:seq_sect
194 field2=EXP:0, UTF8:some random string
199 There should be options to change the format of output lines. The output of some
200 ASN.1 types is not well handled (if at all).
204 L<ASN1_generate_nconf(3)>
208 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
210 Licensed under the OpenSSL license (the "License"). You may not use
211 this file except in compliance with the License. You can obtain a copy
212 in the file LICENSE in the source distribution or at
213 L<https://www.openssl.org/source/license.html>.