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
|
/* cipher-aeswrap.c - Generic AESWRAP mode implementation
* Copyright (C) 2009, 2011 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser general Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "g10lib.h"
#include "cipher.h"
#include "bufhelp.h"
#include "./cipher-internal.h"
/* Perform the AES-Wrap algorithm as specified by RFC3394. We
implement this as a mode usable with any cipher algorithm of
blocksize 128. */
gcry_err_code_t
_gcry_cipher_aeswrap_encrypt (gcry_cipher_hd_t c,
byte *outbuf, size_t outbuflen,
const byte *inbuf, size_t inbuflen )
{
int j, x;
size_t n, i;
unsigned char *r, *a, *b;
unsigned char t[8];
unsigned int burn, nburn;
#if MAX_BLOCKSIZE < 8
#error Invalid block size
#endif
/* We require a cipher with a 128 bit block length. */
if (c->spec->blocksize != 16)
return GPG_ERR_INV_LENGTH;
/* The output buffer must be able to hold the input data plus one
additional block. */
if (outbuflen < inbuflen + 8)
return GPG_ERR_BUFFER_TOO_SHORT;
/* Input data must be multiple of 64 bits. */
if (inbuflen % 8)
return GPG_ERR_INV_ARG;
n = inbuflen / 8;
/* We need at least two 64 bit blocks. */
if (n < 2)
return GPG_ERR_INV_ARG;
burn = 0;
r = outbuf;
a = outbuf; /* We store A directly in OUTBUF. */
b = c->u_ctr.ctr; /* B is also used to concatenate stuff. */
/* If an IV has been set we use that IV as the Alternative Initial
Value; if it has not been set we use the standard value. */
if (c->marks.iv)
memcpy (a, c->u_iv.iv, 8);
else
memset (a, 0xa6, 8);
/* Copy the inbuf to the outbuf. */
memmove (r+8, inbuf, inbuflen);
memset (t, 0, sizeof t); /* t := 0. */
for (j = 0; j <= 5; j++)
{
for (i = 1; i <= n; i++)
{
/* B := AES_k( A | R[i] ) */
memcpy (b, a, 8);
memcpy (b+8, r+i*8, 8);
nburn = c->spec->encrypt (&c->context.c, b, b);
burn = nburn > burn ? nburn : burn;
/* t := t + 1 */
for (x = 7; x >= 0; x--)
{
t[x]++;
if (t[x])
break;
}
/* A := MSB_64(B) ^ t */
buf_xor(a, b, t, 8);
/* R[i] := LSB_64(B) */
memcpy (r+i*8, b+8, 8);
}
}
if (burn > 0)
_gcry_burn_stack (burn + 4 * sizeof(void *));
return 0;
}
/* Perform the AES-Unwrap algorithm as specified by RFC3394. We
implement this as a mode usable with any cipher algorithm of
blocksize 128. */
gcry_err_code_t
_gcry_cipher_aeswrap_decrypt (gcry_cipher_hd_t c,
byte *outbuf, size_t outbuflen,
const byte *inbuf, size_t inbuflen)
{
int j, x;
size_t n, i;
unsigned char *r, *a, *b;
unsigned char t[8];
unsigned int burn, nburn;
#if MAX_BLOCKSIZE < 8
#error Invalid block size
#endif
/* We require a cipher with a 128 bit block length. */
if (c->spec->blocksize != 16)
return GPG_ERR_INV_LENGTH;
/* The output buffer must be able to hold the input data minus one
additional block. Fixme: The caller has more restrictive checks
- we may want to fix them for this mode. */
if (outbuflen + 8 < inbuflen)
return GPG_ERR_BUFFER_TOO_SHORT;
/* Input data must be multiple of 64 bits. */
if (inbuflen % 8)
return GPG_ERR_INV_ARG;
n = inbuflen / 8;
/* We need at least three 64 bit blocks. */
if (n < 3)
return GPG_ERR_INV_ARG;
burn = 0;
r = outbuf;
a = c->lastiv; /* We use c->LASTIV as buffer for A. */
b = c->u_ctr.ctr; /* B is also used to concatenate stuff. */
/* Copy the inbuf to the outbuf and save A. */
memcpy (a, inbuf, 8);
memmove (r, inbuf+8, inbuflen-8);
n--; /* Reduce to actual number of data blocks. */
/* t := 6 * n */
i = n * 6; /* The range is valid because: n = inbuflen / 8 - 1. */
for (x=0; x < 8 && x < sizeof (i); x++)
t[7-x] = i >> (8*x);
for (; x < 8; x++)
t[7-x] = 0;
for (j = 5; j >= 0; j--)
{
for (i = n; i >= 1; i--)
{
/* B := AES_k^1( (A ^ t)| R[i] ) */
buf_xor(b, a, t, 8);
memcpy (b+8, r+(i-1)*8, 8);
nburn = c->spec->decrypt (&c->context.c, b, b);
burn = nburn > burn ? nburn : burn;
/* t := t - 1 */
for (x = 7; x >= 0; x--)
{
t[x]--;
if (t[x] != 0xff)
break;
}
/* A := MSB_64(B) */
memcpy (a, b, 8);
/* R[i] := LSB_64(B) */
memcpy (r+(i-1)*8, b+8, 8);
}
}
/* If an IV has been set we compare against this Alternative Initial
Value; if it has not been set we compare against the standard IV. */
if (c->marks.iv)
j = memcmp (a, c->u_iv.iv, 8);
else
{
for (j=0, x=0; x < 8; x++)
if (a[x] != 0xa6)
{
j=1;
break;
}
}
if (burn > 0)
_gcry_burn_stack (burn + 4 * sizeof(void *));
return j? GPG_ERR_CHECKSUM : 0;
}
|
