1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
|
=pod
=head1 NAME
ASN1_generate_nconf, ASN1_generate_v3 - ASN1 generation functions
=head1 SYNOPSIS
#include <openssl/asn1.h>
ASN1_TYPE *ASN1_generate_nconf(char *str, CONF *nconf);
ASN1_TYPE *ASN1_generate_v3(char *str, X509V3_CTX *cnf);
=head1 DESCRIPTION
These functions generate the ASN1 encoding of a string
in an B<ASN1_TYPE> structure.
B<str> contains the string to encode B<nconf> or B<cnf> contains
the optional configuration information where additional strings
will be read from. B<nconf> will typically come from a config
file wherease B<cnf> is obtained from an B<X509V3_CTX> structure
which will typically be used by X509 v3 certificate extension
functions. B<cnf> or B<nconf> can be set to B<NULL> if no additional
configuration will be used.
=head1 GENERATION STRING FORMAT
The actual data encoded is determined by the string B<str> and
the configuration information. The general format of the string
is:
=over 2
=item B<[modifier,]type[:value]>
=back
That is zero or more comma separated modifiers followed by a type
followed by an optional colon and a value. The formats of B<type>,
B<value> and B<modifier> are explained below.
=head2 SUPPORTED TYPES
The supported types are listed below. Unless otherwise specified
only the B<ASCII> format is permissible.
=over 2
=item B<BOOLEAN>, B<BOOL>
This encodes a boolean type. The B<value> string is mandatory and
should be B<TRUE> or B<FALSE>. Additionally B<TRUE>, B<true>, B<Y>,
B<y>, B<YES>, B<yes>, B<FALSE>, B<false>, B<N>, B<n>, B<NO> and B<no>
are acceptable.
=item B<NULL>
Encode the B<NULL> type, the B<value> string must not be present.
=item B<INTEGER>, B<INT>
Encodes an ASN1 B<INTEGER> type. The B<value> string represents
the value of the integer, it can be preceeded by a minus sign and
is normally interpreted as a decimal value unless the prefix B<0x>
is included.
=item B<ENUMERATED>, B<ENUM>
Encodes the ASN1 B<ENUMERATED> type, it is otherwise identical to
B<INTEGER>.
=item B<OBJECT>, B<OID>
Encodes an ASN1 B<OBJECT IDENTIFIER>, the B<value> string can be
a short name, a long name or numerical format.
=item B<UTCTIME>, B<UTC>
Encodes an ASN1 B<UTCTime> structure, the value should be in
the format B<YYMMDDHHMMSSZ>.
=item B<GENERALIZEDTIME>, B<GENTIME>
Encodes an ASN1 B<GeneralizedTime> structure, the value should be in
the format B<YYYYMMDDHHMMSSZ>.
=item B<OCTETSTRING>, B<OCT>
Encodes an ASN1 B<OCTET STRING>. B<value> represents the contents
of this structure, the format strings B<ASCII> and B<HEX> can be
used to specify the format of B<value>.
=item B<BITSTRING>, B<BITSTR>
Encodes an ASN1 B<BIT STRING>. B<value> represents the contents
of this structure, the format strings B<ASCII>, B<HEX> and B<BITLIST>
can be used to specify the format of B<value>.
If the format is anything other than B<BITLIST> the number of unused
bits is set to zero.
=item B<UNIVERSALSTRING>, B<UNIV>, B<IA5>, B<IA5STRING>, B<UTF8>,
B<UTF8String>, B<BMP>, B<BMPSTRING>, B<VISIBLESTRING>,
B<VISIBLE>, B<PRINTABLESTRING>, B<PRINTABLE>, B<T61>,
B<T61STRING>, B<TELETEXSTRING>, B<GeneralString>, B<NUMERICSTRING>,
B<NUMERIC>
These encode the corresponding string types. B<value> represents the
contents of this structure. The format can be B<ASCII> or B<UTF8>.
=item B<SEQUENCE>, B<SEQ>, B<SET>
Formats the result as an ASN1 B<SEQUENCE> or B<SET> type. B<value>
should be a section name which will contain the contents. The
field names in the section are ignored and the values are in the
generated string format. If B<value> is absent then an empty SEQUENCE
will be encoded.
=back
=head2 MODIFIERS
Modifiers affect the following structure, they can be used to
add EXPLICIT or IMPLICIT tagging, add wrappers or to change
the string format of the final type and value. The supported
formats are documented below.
=over 2
=item B<EXPLICIT>, B<EXP>
Add an explicit tag to the following structure. This string
should be followed by a colon and the tag value to use as a
decimal value.
By following the number with B<U>, B<A>, B<P> or B<C> UNIVERSAL,
APPLICATION, PRIVATE or CONTEXT SPECIFIC tagging can be used,
the default is CONTEXT SPECIFIC.
=item B<IMPLICIT>, B<IMP>
This is the same as B<EXPLICIT> except IMPLICIT tagging is used
instead.
=item B<OCTWRAP>, B<SEQWRAP>, B<SETWRAP>, B<BITWRAP>
The following structure is surrounded by an OCTET STRING, a SEQUENCE,
a SET or a BIT STRING respectively. For a BIT STRING the number of unused
bits is set to zero.
=item B<FORMAT>
This specifies the format of the ultimate value. It should be followed
by a colon and one of the strings B<ASCII>, B<UTF8>, B<HEX> or B<BITLIST>.
If no format specifier is included then B<ASCII> is used. If B<UTF8> is
specified then the value string must be a valid B<UTF8> string. For B<HEX> the
output must be a set of hex digits. B<BITLIST> (which is only valid for a BIT
STRING) is a comma separated list of the indices of the set bits, all other
bits are zero.
=back
=head1 EXAMPLES
A simple IA5String:
IA5STRING:Hello World
An IA5String explicitly tagged:
EXPLICIT:0,IA5STRING:Hello World
An IA5String explicitly tagged using APPLICATION tagging:
EXPLICIT:0A,IA5STRING:Hello World
A BITSTRING with bits 1 and 5 set and all others zero:
FORMAT:BITLIST,BITSTRING:1,5
A more complex example using a config file to produce a
SEQUENCE consiting of a BOOL an OID and a UTF8String:
asn1 = SEQUENCE:seq_section
[seq_section]
field1 = BOOLEAN:TRUE
field2 = OID:commonName
field3 = UTF8:Third field
This example produces an RSAPrivateKey structure, this is the
key contained in the file client.pem in all OpenSSL distributions
(note: the field names such as 'coeff' are ignored and are present just
for clarity):
asn1=SEQUENCE:private_key
[private_key]
version=INTEGER:0
n=INTEGER:0xBB6FE79432CC6EA2D8F970675A5A87BFBE1AFF0BE63E879F2AFFB93644\
D4D2C6D000430DEC66ABF47829E74B8C5108623A1C0EE8BE217B3AD8D36D5EB4FCA1D9
e=INTEGER:0x010001
d=INTEGER:0x6F05EAD2F27FFAEC84BEC360C4B928FD5F3A9865D0FCAAD291E2A52F4A\
F810DC6373278C006A0ABBA27DC8C63BF97F7E666E27C5284D7D3B1FFFE16B7A87B51D
p=INTEGER:0xF3929B9435608F8A22C208D86795271D54EBDFB09DDEF539AB083DA912\
D4BD57
q=INTEGER:0xC50016F89DFF2561347ED1186A46E150E28BF2D0F539A1594BBD7FE467\
46EC4F
exp1=INTEGER:0x9E7D4326C924AFC1DEA40B45650134966D6F9DFA3A7F9D698CD4ABEA\
9C0A39B9
exp2=INTEGER:0xBA84003BB95355AFB7C50DF140C60513D0BA51D637272E355E397779\
E7B2458F
coeff=INTEGER:0x30B9E4F2AFA5AC679F920FC83F1F2DF1BAF1779CF989447FABC2F5\
628657053A
This example is the corresponding public key in a SubjectPublicKeyInfo
structure:
# Start with a SEQUENCE
asn1=SEQUENCE:pubkeyinfo
# pubkeyinfo contains an algorithm identifier and the public key wrapped
# in a BIT STRING
[pubkeyinfo]
algorithm=SEQUENCE:rsa_alg
pubkey=BITWRAP,SEQUENCE:rsapubkey
# algorithm ID for RSA is just an OID and a NULL
[rsa_alg]
algorithm=OID:rsaEncryption
parameter=NULL
# Actual public key: modulus and exponent
[rsapubkey]
n=INTEGER:0xBB6FE79432CC6EA2D8F970675A5A87BFBE1AFF0BE63E879F2AFFB93644\
D4D2C6D000430DEC66ABF47829E74B8C5108623A1C0EE8BE217B3AD8D36D5EB4FCA1D9
e=INTEGER:0x010001
=head1 RETURN VALUES
ASN1_generate_nconf() and ASN1_generate_v3() return the encoded
data as an B<ASN1_TYPE> structure or B<NULL> if an error occurred.
The error codes that can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
=head1 SEE ALSO
L<ERR_get_error(3)|ERR_get_error(3)>
=head1 HISTORY
ASN1_generate_nconf() and ASN1_generate_v3() were added to OpenSSL 0.9.8
=cut
|
