asn1parse(1ssl)

1ASN1PARSE(1)                        OpenSSL                       ASN1PARSE(1)
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NAME

6       asn1parse - ASN.1 parsing tool
7

SYNOPSIS

9       openssl asn1parse [-inform PEM|DER] [-in filename] [-out filename]
10       [-noout] [-offset number] [-length number] [-i] [-oid filename]
11       [-strparse offset] [-genstr string] [-genconf file]
12

DESCRIPTION

14       The asn1parse command is a diagnostic utility that can parse ASN.1
15       structures. It can also be used to extract data from ASN.1 formatted
16       data.
17

OPTIONS

19       -inform DER|PEM
20           the input format. DER is binary format and PEM (the default) is
21           base64 encoded.
22
23       -in filename
24           the input file, default is standard input
25
26       -out filename
27           output file to place the DER encoded data into. If this option is
28           not present then no data will be output. This is most useful when
29           combined with the -strparse option.
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31       -noout
32           don't output the parsed version of the input file.
33
34       -offset number
35           starting offset to begin parsing, default is start of file.
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37       -length number
38           number of bytes to parse, default is until end of file.
39
40       -i  indents the output according to the "depth" of the structures.
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42       -oid filename
43           a file containing additional OBJECT IDENTIFIERs (OIDs). The format
44           of this file is described in the NOTES section below.
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46       -strparse offset
47           parse the contents octets of the ASN.1 object starting at offset.
48           This option can be used multiple times to "drill down" into a
49           nested structure.
50
51       -genstr string, -genconf file
52           generate encoded data based on string, file or both using
53           ASN1_generate_nconf(3) format. If file only is present then the
54           string is obtained from the default section using the name asn1.
55           The encoded data is passed through the ASN1 parser and printed out
56           as though it came from a file, the contents can thus be examined
57           and written to a file using the out option.
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59   OUTPUT
60       The output will typically contain lines like this:
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62         0:d=0  hl=4 l= 681 cons: SEQUENCE
63
64       .....
65
66         229:d=3  hl=3 l= 141 prim: BIT STRING
67         373:d=2  hl=3 l= 162 cons: cont [ 3 ]
68         376:d=3  hl=3 l= 159 cons: SEQUENCE
69         379:d=4  hl=2 l=  29 cons: SEQUENCE
70         381:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Subject Key Identifier
71         386:d=5  hl=2 l=  22 prim: OCTET STRING
72         410:d=4  hl=2 l= 112 cons: SEQUENCE
73         412:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Authority Key Identifier
74         417:d=5  hl=2 l= 105 prim: OCTET STRING
75         524:d=4  hl=2 l=  12 cons: SEQUENCE
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77       .....
78
79       This example is part of a self signed certificate. Each line starts
80       with the offset in decimal. d=XX specifies the current depth. The depth
81       is increased within the scope of any SET or SEQUENCE. hl=XX gives the
82       header length (tag and length octets) of the current type. l=XX gives
83       the length of the contents octets.
84
85       The -i option can be used to make the output more readable.
86
87       Some knowledge of the ASN.1 structure is needed to interpret the
88       output.
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90       In this example the BIT STRING at offset 229 is the certificate public
91       key.  The contents octets of this will contain the public key
92       information. This can be examined using the option -strparse 229 to
93       yield:
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95           0:d=0  hl=3 l= 137 cons: SEQUENCE
96           3:d=1  hl=3 l= 129 prim: INTEGER           :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
97         135:d=1  hl=2 l=   3 prim: INTEGER           :010001
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NOTES

100       If an OID is not part of OpenSSL's internal table it will be
101       represented in numerical form (for example 1.2.3.4). The file passed to
102       the -oid option allows additional OIDs to be included. Each line
103       consists of three columns, the first column is the OID in numerical
104       format and should be followed by white space. The second column is the
105       "short name" which is a single word followed by white space. The final
106       column is the rest of the line and is the "long name". asn1parse
107       displays the long name. Example:
108
109       "1.2.3.4  shortName A long name"
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EXAMPLES

112       Parse a file:
113
114        openssl asn1parse -in file.pem
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116       Parse a DER file:
117
118        openssl asn1parse -inform DER -in file.der
119
120       Generate a simple UTF8String:
121
122        openssl asn1parse -genstr 'UTF8:Hello World'
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124       Generate and write out a UTF8String, don't print parsed output:
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126        openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der
127
128       Generate using a config file:
129
130        openssl asn1parse -genconf asn1.cnf -noout -out asn1.der
131
132       Example config file:
133
134        asn1=SEQUENCE:seq_sect
135
136        [seq_sect]
137
138        field1=BOOL:TRUE
139        field2=EXP:0, UTF8:some random string
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BUGS

142       There should be options to change the format of output lines. The
143       output of some ASN.1 types is not well handled (if at all).
144