1=pod 2 3=head1 NAME 4 5asn1parse - ASN.1 parsing tool 6 7=head1 SYNOPSIS 8 9B<openssl> B<asn1parse> 10[B<-inform PEM|DER>] 11[B<-in filename>] 12[B<-out filename>] 13[B<-noout>] 14[B<-offset number>] 15[B<-length number>] 16[B<-i>] 17[B<-oid filename>] 18[B<-dump>] 19[B<-dlimit num>] 20[B<-strparse offset>] 21[B<-genstr string>] 22[B<-genconf file>] 23 24=head1 DESCRIPTION 25 26The B<asn1parse> command is a diagnostic utility that can parse ASN.1 27structures. It can also be used to extract data from ASN.1 formatted data. 28 29=head1 OPTIONS 30 31=over 4 32 33=item B<-inform> B<DER|PEM> 34 35the input format. B<DER> is binary format and B<PEM> (the default) is base64 36encoded. 37 38=item B<-in filename> 39 40the input file, default is standard input 41 42=item B<-out filename> 43 44output file to place the DER encoded data into. If this 45option is not present then no data will be output. This is most useful when 46combined with the B<-strparse> option. 47 48=item B<-noout> 49 50don't output the parsed version of the input file. 51 52=item B<-offset number> 53 54starting offset to begin parsing, default is start of file. 55 56=item B<-length number> 57 58number of bytes to parse, default is until end of file. 59 60=item B<-i> 61 62indents the output according to the "depth" of the structures. 63 64=item B<-oid filename> 65 66a file containing additional OBJECT IDENTIFIERs (OIDs). The format of this 67file is described in the NOTES section below. 68 69=item B<-dump> 70 71dump unknown data in hex format. 72 73=item B<-dlimit num> 74 75like B<-dump>, but only the first B<num> bytes are output. 76 77=item B<-strparse offset> 78 79parse the contents octets of the ASN.1 object starting at B<offset>. This 80option can be used multiple times to "drill down" into a nested structure. 81 82=item B<-genstr string>, B<-genconf file> 83 84generate encoded data based on B<string>, B<file> or both using 85L<ASN1_generate_nconf(3)|ASN1_generate_nconf(3)> format. If B<file> only is 86present then the string is obtained from the default section using the name 87B<asn1>. The encoded data is passed through the ASN1 parser and printed out as 88though it came from a file, the contents can thus be examined and written to a 89file using the B<out> option. 90 91=back 92 93=head2 OUTPUT 94 95The output will typically contain lines like this: 96 97 0:d=0 hl=4 l= 681 cons: SEQUENCE 98 99..... 100 101 229:d=3 hl=3 l= 141 prim: BIT STRING 102 373:d=2 hl=3 l= 162 cons: cont [ 3 ] 103 376:d=3 hl=3 l= 159 cons: SEQUENCE 104 379:d=4 hl=2 l= 29 cons: SEQUENCE 105 381:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Subject Key Identifier 106 386:d=5 hl=2 l= 22 prim: OCTET STRING 107 410:d=4 hl=2 l= 112 cons: SEQUENCE 108 412:d=5 hl=2 l= 3 prim: OBJECT :X509v3 Authority Key Identifier 109 417:d=5 hl=2 l= 105 prim: OCTET STRING 110 524:d=4 hl=2 l= 12 cons: SEQUENCE 111 112..... 113 114This example is part of a self signed certificate. Each line starts with the 115offset in decimal. B<d=XX> specifies the current depth. The depth is increased 116within the scope of any SET or SEQUENCE. B<hl=XX> gives the header length 117(tag and length octets) of the current type. B<l=XX> gives the length of 118the contents octets. 119 120The B<-i> option can be used to make the output more readable. 121 122Some knowledge of the ASN.1 structure is needed to interpret the output. 123 124In this example the BIT STRING at offset 229 is the certificate public key. 125The contents octets of this will contain the public key information. This can 126be examined using the option B<-strparse 229> to yield: 127 128 0:d=0 hl=3 l= 137 cons: SEQUENCE 129 3:d=1 hl=3 l= 129 prim: INTEGER :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897 130 135:d=1 hl=2 l= 3 prim: INTEGER :010001 131 132=head1 NOTES 133 134If an OID is not part of OpenSSL's internal table it will be represented in 135numerical form (for example 1.2.3.4). The file passed to the B<-oid> option 136allows additional OIDs to be included. Each line consists of three columns, 137the first column is the OID in numerical format and should be followed by white 138space. The second column is the "short name" which is a single word followed 139by white space. The final column is the rest of the line and is the 140"long name". B<asn1parse> displays the long name. Example: 141 142C<1.2.3.4 shortName A long name> 143 144=head1 EXAMPLES 145 146Parse a file: 147 148 openssl asn1parse -in file.pem 149 150Parse a DER file: 151 152 openssl asn1parse -inform DER -in file.der 153 154Generate a simple UTF8String: 155 156 openssl asn1parse -genstr 'UTF8:Hello World' 157 158Generate and write out a UTF8String, don't print parsed output: 159 160 openssl asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der 161 162Generate using a config file: 163 164 openssl asn1parse -genconf asn1.cnf -noout -out asn1.der 165 166Example config file: 167 168 asn1=SEQUENCE:seq_sect 169 170 [seq_sect] 171 172 field1=BOOL:TRUE 173 field2=EXP:0, UTF8:some random string 174 175 176=head1 BUGS 177 178There should be options to change the format of output lines. The output of some 179ASN.1 types is not well handled (if at all). 180 181=head1 SEE ALSO 182 183L<ASN1_generate_nconf(3)|ASN1_generate_nconf(3)> 184 185=cut 186