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
|
/* ctr.c
Cipher counter mode.
Copyright (C) 2005 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* 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.
or both in parallel, as here.
GNU Nettle 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 copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "ctr.h"
#include "ctr-internal.h"
#include "macros.h"
#include "memxor.h"
#include "nettle-internal.h"
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
static size_t
ctr_fill (size_t block_size, uint8_t *ctr, size_t length, uint8_t *buffer)
{
size_t i;
for (i = 0; i + block_size <= length; i += block_size)
{
memcpy (buffer + i, ctr, block_size);
INCREMENT(block_size, ctr);
}
return i;
}
#if WORDS_BIGENDIAN
# define USE_CTR_CRYPT16 1
static nettle_fill16_func ctr_fill16;
static void
ctr_fill16(uint8_t *ctr, size_t blocks, union nettle_block16 *buffer)
{
uint64_t hi, lo;
size_t i;
hi = READ_UINT64(ctr);
lo = READ_UINT64(ctr + 8);
for (i = 0; i < blocks; i++)
{
buffer[i].u64[0] = hi;
buffer[i].u64[1] = lo;
hi += !(++lo);
}
WRITE_UINT64(ctr, hi);
WRITE_UINT64(ctr + 8, lo);
}
#else /* !WORDS_BIGENDIAN */
# if HAVE_BUILTIN_BSWAP64
# define USE_CTR_CRYPT16 1
static nettle_fill16_func ctr_fill16;
static void
ctr_fill16(uint8_t *ctr, size_t blocks, union nettle_block16 *buffer)
{
uint64_t hi, lo;
size_t i;
/* Read hi in native endianness */
hi = LE_READ_UINT64(ctr);
lo = READ_UINT64(ctr + 8);
for (i = 0; i < blocks; i++)
{
buffer[i].u64[0] = hi;
buffer[i].u64[1] = __builtin_bswap64(lo);
if (!++lo)
hi = __builtin_bswap64(__builtin_bswap64(hi) + 1);
}
LE_WRITE_UINT64(ctr, hi);
WRITE_UINT64(ctr + 8, lo);
}
# else /* ! HAVE_BUILTIN_BSWAP64 */
# define USE_CTR_CRYPT16 0
# endif
#endif /* !WORDS_BIGENDIAN */
void
ctr_crypt(const void *ctx, nettle_cipher_func *f,
size_t block_size, uint8_t *ctr,
size_t length, uint8_t *dst,
const uint8_t *src)
{
#if USE_CTR_CRYPT16
if (block_size == 16)
{
_nettle_ctr_crypt16(ctx, f, ctr_fill16, ctr, length, dst, src);
return;
}
#endif
if(src != dst)
{
size_t filled = ctr_fill (block_size, ctr, length, dst);
f(ctx, filled, dst, dst);
memxor(dst, src, filled);
if (filled < length)
{
TMP_DECL(block, uint8_t, NETTLE_MAX_CIPHER_BLOCK_SIZE);
TMP_ALLOC(block, block_size);
f(ctx, block_size, block, ctr);
INCREMENT(block_size, ctr);
memxor3(dst + filled, src + filled, block, length - filled);
}
}
else
{
/* For in-place CTR, construct a buffer of consecutive counter
values, of size at most CTR_BUFFER_LIMIT. */
TMP_DECL(buffer, uint8_t, CTR_BUFFER_LIMIT);
size_t buffer_size;
if (length < block_size)
buffer_size = block_size;
else if (length <= CTR_BUFFER_LIMIT)
buffer_size = length;
else
buffer_size = CTR_BUFFER_LIMIT;
TMP_ALLOC(buffer, buffer_size);
while (length >= block_size)
{
size_t filled
= ctr_fill (block_size, ctr, MIN(buffer_size, length), buffer);
assert (filled > 0);
f(ctx, filled, buffer, buffer);
memxor(dst, buffer, filled);
length -= filled;
dst += filled;
}
/* Final, possibly partial, block. */
if (length > 0)
{
f(ctx, block_size, buffer, ctr);
INCREMENT(block_size, ctr);
memxor(dst, buffer, length);
}
}
}
|
