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] [-dump]
11       [-dlimit num] [-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.
30
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.
36
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.
41
42       -oid filename
43           a file containing additional OBJECT IDENTIFIERs (OIDs). The format
44           of this file is described in the NOTES section below.
45
46       -dump
47           dump unknown data in hex format.
48
49       -dlimit num
50           like -dump, but only the first num bytes are output.
51
52       -strparse offset
53           parse the contents octets of the ASN.1 object starting at offset.
54           This option can be used multiple times to "drill down" into a
55           nested structure.
56
57       -genstr string, -genconf file
58           generate encoded data based on string, file or both using
59           ASN1_generate_nconf(3) format. If file only is present then the
60           string is obtained from the default section using the name asn1.
61           The encoded data is passed through the ASN1 parser and printed out
62           as though it came from a file, the contents can thus be examined
63           and written to a file using the out option.
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65   OUTPUT
66       The output will typically contain lines like this:
67
68         0:d=0  hl=4 l= 681 cons: SEQUENCE
69
70       .....
71
72         229:d=3  hl=3 l= 141 prim: BIT STRING
73         373:d=2  hl=3 l= 162 cons: cont [ 3 ]
74         376:d=3  hl=3 l= 159 cons: SEQUENCE
75         379:d=4  hl=2 l=  29 cons: SEQUENCE
76         381:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Subject Key Identifier
77         386:d=5  hl=2 l=  22 prim: OCTET STRING
78         410:d=4  hl=2 l= 112 cons: SEQUENCE
79         412:d=5  hl=2 l=   3 prim: OBJECT            :X509v3 Authority Key Identifier
80         417:d=5  hl=2 l= 105 prim: OCTET STRING
81         524:d=4  hl=2 l=  12 cons: SEQUENCE
82
83       .....
84
85       This example is part of a self signed certificate. Each line starts
86       with the offset in decimal. d=XX specifies the current depth. The depth
87       is increased within the scope of any SET or SEQUENCE. hl=XX gives the
88       header length (tag and length octets) of the current type. l=XX gives
89       the length of the contents octets.
90
91       The -i option can be used to make the output more readable.
92
93       Some knowledge of the ASN.1 structure is needed to interpret the
94       output.
95
96       In this example the BIT STRING at offset 229 is the certificate public
97       key.  The contents octets of this will contain the public key
98       information. This can be examined using the option -strparse 229 to
99       yield:
100
101           0:d=0  hl=3 l= 137 cons: SEQUENCE
102           3:d=1  hl=3 l= 129 prim: INTEGER           :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
103         135:d=1  hl=2 l=   3 prim: INTEGER           :010001
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NOTES

106       If an OID is not part of OpenSSL's internal table it will be
107       represented in numerical form (for example 1.2.3.4). The file passed to
108       the -oid option allows additional OIDs to be included. Each line
109       consists of three columns, the first column is the OID in numerical
110       format and should be followed by white space. The second column is the
111       "short name" which is a single word followed by white space. The final
112       column is the rest of the line and is the "long name". asn1parse
113       displays the long name. Example:
114
115       "1.2.3.4  shortName A long name"
116

EXAMPLES

118       Parse a file:
119
120        openssl asn1parse -in file.pem
121
122       Parse a DER file:
123
124        openssl asn1parse -inform DER -in file.der
125
126       Generate a simple UTF8String:
127
128        openssl asn1parse -genstr 'UTF8:Hello World'
129
130       Generate and write out a UTF8String, don't print parsed output:
131
132        openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der
133
134       Generate using a config file:
135
136        openssl asn1parse -genconf asn1.cnf -noout -out asn1.der
137
138       Example config file:
139
140        asn1=SEQUENCE:seq_sect
141
142        [seq_sect]
143
144        field1=BOOL:TRUE
145        field2=EXP:0, UTF8:some random string
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BUGS

148       There should be options to change the format of output lines. The
149       output of some ASN.1 types is not well handled (if at all).
150