1OPENSSL-ASN1PARSE(1ossl) OpenSSL OPENSSL-ASN1PARSE(1ossl)
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6 openssl-asn1parse - ASN.1 parsing command
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9 openssl asn1parse [-help] [-inform DER|PEM] [-in filename] [-out
10 filename] [-noout] [-offset number] [-length number] [-i] [-oid
11 filename] [-dump] [-dlimit num] [-strparse offset] [-genstr string]
12 [-genconf file] [-strictpem] [-item name]
13
15 This command is a diagnostic utility that can parse ASN.1 structures.
16 It can also be used to extract data from ASN.1 formatted data.
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19 -help
20 Print out a usage message.
21 -inform DER|PEM
23 The input format; the default is PEM. See
24 openssl-format-options(1) for details.
25 -in filename
27 The input file, default is standard input.
28 -out filename
30 Output file to place the DER encoded data into. If this option is
31 not present then no data will be output. This is most useful when
32 combined with the -strparse option.
33 -noout
35 Don't output the parsed version of the input file.
36 -offset number
38 Starting offset to begin parsing, default is start of file.
39 -length number
41 Number of bytes to parse, default is until end of file.
42 -i Indents the output according to the "depth" of the structures.
44 -oid filename
46 A file containing additional OBJECT IDENTIFIERs (OIDs). The format
47 of this file is described in the NOTES section below.
48 -dump
50 Dump unknown data in hex format.
51 -dlimit num
53 Like -dump, but only the first num bytes are output.
54 -strparse offset
56 Parse the contents octets of the ASN.1 object starting at offset.
57 This option can be used multiple times to "drill down" into a
58 nested structure.
59 -genstr string, -genconf file
61 Generate encoded data based on string, file or both using
62 ASN1_generate_nconf(3) format. If file only is present then the
63 string is obtained from the default section using the name asn1.
64 The encoded data is passed through the ASN1 parser and printed out
65 as though it came from a file, the contents can thus be examined
66 and written to a file using the -out option.
67 -strictpem
69 If this option is used then -inform will be ignored. Without this
70 option any data in a PEM format input file will be treated as being
71 base64 encoded and processed whether it has the normal PEM BEGIN
72 and END markers or not. This option will ignore any data prior to
73 the start of the BEGIN marker, or after an END marker in a PEM
74 file.
75 -item name
77 Attempt to decode and print the data as an ASN1_ITEM name. This can
78 be used to print out the fields of any supported ASN.1 structure if
79 the type is known.
80 Output
82 The output will typically contain lines like this:
83 0:d=0 hl=4 l= 681 cons: SEQUENCE
85 .....
87 229:d=3 hl=3 l= 141 prim: BIT STRING
89 373:d=2 hl=3 l= 162 cons: cont [ 3 ]
90 376:d=3 hl=3 l= 159 cons: SEQUENCE
91 379:d=4 hl=2 l= 29 cons: SEQUENCE
92 381:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Subject Key Identifier
93 386:d=5 hl=2 l= 22 prim: OCTET STRING
94 410:d=4 hl=2 l= 112 cons: SEQUENCE
95 412:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Authority Key Identifier
96 417:d=5 hl=2 l= 105 prim: OCTET STRING
97 524:d=4 hl=2 l= 12 cons: SEQUENCE
98 .....
100 This example is part of a self-signed certificate. Each line starts
102 with the offset in decimal. "d=XX" specifies the current depth. The
103 depth is increased within the scope of any SET or SEQUENCE. "hl=XX"
104 gives the header length (tag and length octets) of the current type.
105 "l=XX" gives the length of the contents octets.
106 The -i option can be used to make the output more readable.
108 Some knowledge of the ASN.1 structure is needed to interpret the
110 output.
111 In this example the BIT STRING at offset 229 is the certificate public
113 key. The contents octets of this will contain the public key
114 information. This can be examined using the option "-strparse 229" to
115 yield:
116 0:d=0 hl=3 l= 137 cons: SEQUENCE
118 3:d=1 hl=3 l= 129 prim: INTEGER :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
119 135:d=1 hl=2 l= 3 prim: INTEGER :010001
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122 If an OID is not part of OpenSSL's internal table it will be
123 represented in numerical form (for example 1.2.3.4). The file passed to
124 the -oid option allows additional OIDs to be included. Each line
125 consists of three columns, the first column is the OID in numerical
126 format and should be followed by white space. The second column is the
127 "short name" which is a single word followed by whitespace. The final
128 column is the rest of the line and is the "long name". Example:
129 "1.2.3.4 shortName A long name"
131 For any OID with an associated short and long name, this command will
133 display the long name.
134
136 Parse a file:
137 openssl asn1parse -in file.pem
139 Parse a DER file:
141 openssl asn1parse -inform DER -in file.der
143 Generate a simple UTF8String:
145 openssl asn1parse -genstr 'UTF8:Hello World'
147 Generate and write out a UTF8String, don't print parsed output:
149 openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der
151 Generate using a config file:
153 openssl asn1parse -genconf asn1.cnf -noout -out asn1.der
155 Example config file:
157 asn1=SEQUENCE:seq_sect
159 [seq_sect]
161 field1=BOOL:TRUE
163 field2=EXP:0, UTF8:some random string
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166 There should be options to change the format of output lines. The
167 output of some ASN.1 types is not well handled (if at all).
168
170 openssl(1), ASN1_generate_nconf(3)
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173 Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
174 Licensed under the Apache License 2.0 (the "License"). You may not use
176 this file except in compliance with the License. You can obtain a copy
177 in the file LICENSE in the source distribution or at
178 <https://www.openssl.org/source/license.html>.
1793.0.9 2023-07-27 OPENSSL-ASN1PARSE(1ossl)