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
|
/*
* ASN.1 buffer writing functionality
*
* Copyright (C) 2006-2012, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "polarssl/config.h"
#if defined(POLARSSL_ASN1_WRITE_C)
#include "polarssl/asn1write.h"
int asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
{
if( len < 0x80 )
{
if( *p - start < 1 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = len;
return( 1 );
}
if( len <= 0xFF )
{
if( *p - start < 2 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = len;
*--(*p) = 0x81;
return( 2 );
}
if( *p - start < 3 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
// We assume we never have lengths larger than 65535 bytes
//
*--(*p) = len % 256;
*--(*p) = ( len / 256 ) % 256;
*--(*p) = 0x82;
return( 3 );
}
int asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
{
if( *p - start < 1 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = tag;
return( 1 );
}
int asn1_write_mpi( unsigned char **p, unsigned char *start, mpi *X )
{
int ret;
size_t len = 0;
// Write the MPI
//
len = mpi_size( X );
if( *p - start < (int) len )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
(*p) -= len;
mpi_write_binary( X, *p, len );
// DER format assumes 2s complement for numbers, so the leftmost bit
// should be 0 for positive numbers and 1 for negative numbers.
//
if ( X->s ==1 && **p & 0x80 )
{
if( *p - start < 1 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = 0x00;
len += 1;
}
ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_INTEGER ) );
return( len );
}
int asn1_write_null( unsigned char **p, unsigned char *start )
{
int ret;
size_t len = 0;
// Write NULL
//
ASN1_CHK_ADD( len, asn1_write_len( p, start, 0) );
ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_NULL ) );
return( len );
}
int asn1_write_oid( unsigned char **p, unsigned char *start, char *oid )
{
int ret;
size_t len = 0;
// Write OID
//
len = strlen( oid );
if( *p - start < (int) len )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
(*p) -= len;
memcpy( *p, oid, len );
ASN1_CHK_ADD( len , asn1_write_len( p, start, len ) );
ASN1_CHK_ADD( len , asn1_write_tag( p, start, ASN1_OID ) );
return( len );
}
int asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
char *algorithm_oid )
{
int ret;
size_t null_len = 0;
size_t oid_len = 0;
size_t len = 0;
// Write NULL
//
ASN1_CHK_ADD( null_len, asn1_write_null( p, start ) );
// Write OID
//
ASN1_CHK_ADD( oid_len, asn1_write_oid( p, start, algorithm_oid ) );
len = oid_len + null_len;
ASN1_CHK_ADD( len, asn1_write_len( p, start, oid_len + null_len ) );
ASN1_CHK_ADD( len, asn1_write_tag( p, start,
ASN1_CONSTRUCTED | ASN1_SEQUENCE ) );
return( len );
}
int asn1_write_int( unsigned char **p, unsigned char *start, int val )
{
int ret;
size_t len = 0;
// TODO negative values and values larger than 128
// DER format assumes 2s complement for numbers, so the leftmost bit
// should be 0 for positive numbers and 1 for negative numbers.
//
if( *p - start < 1 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
len += 1;
*--(*p) = val;
if ( val > 0 && **p & 0x80 )
{
if( *p - start < 1 )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = 0x00;
len += 1;
}
ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_INTEGER ) );
return( len );
}
int asn1_write_printable_string( unsigned char **p, unsigned char *start,
char *text )
{
int ret;
size_t len = 0;
// Write string
//
len = strlen( text );
if( *p - start < (int) len )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
(*p) -= len;
memcpy( *p, text, len );
ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_PRINTABLE_STRING ) );
return( len );
}
int asn1_write_ia5_string( unsigned char **p, unsigned char *start,
char *text )
{
int ret;
size_t len = 0;
// Write string
//
len = strlen( text );
if( *p - start < (int) len )
return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
(*p) -= len;
memcpy( *p, text, len );
ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_IA5_STRING ) );
return( len );
}
#endif
|
