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
|
/*
* AES-CTR cipher
* Copyright (c) 2015 Eran Kornblau <erankor at gmail dot com>
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <string.h>
#include "aes_ctr.h"
#include "aes.h"
#include "aes_internal.h"
#include "macros.h"
#include "mem.h"
#include "random_seed.h"
#define AES_BLOCK_SIZE (16)
typedef struct AVAESCTR {
uint8_t counter[AES_BLOCK_SIZE];
uint8_t encrypted_counter[AES_BLOCK_SIZE];
int block_offset;
AVAES aes;
} AVAESCTR;
struct AVAESCTR *av_aes_ctr_alloc(void)
{
return av_mallocz(sizeof(struct AVAESCTR));
}
void av_aes_ctr_set_iv(struct AVAESCTR *a, const uint8_t* iv)
{
memcpy(a->counter, iv, AES_CTR_IV_SIZE);
memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) - AES_CTR_IV_SIZE);
a->block_offset = 0;
}
void av_aes_ctr_set_full_iv(struct AVAESCTR *a, const uint8_t* iv)
{
memcpy(a->counter, iv, sizeof(a->counter));
a->block_offset = 0;
}
const uint8_t* av_aes_ctr_get_iv(struct AVAESCTR *a)
{
return a->counter;
}
void av_aes_ctr_set_random_iv(struct AVAESCTR *a)
{
uint32_t iv[2];
iv[0] = av_get_random_seed();
iv[1] = av_get_random_seed();
av_aes_ctr_set_iv(a, (uint8_t*)iv);
}
int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key)
{
av_aes_init(&a->aes, key, 128, 0);
memset(a->counter, 0, sizeof(a->counter));
a->block_offset = 0;
return 0;
}
void av_aes_ctr_free(struct AVAESCTR *a)
{
av_free(a);
}
static void av_aes_ctr_increment_be64(uint8_t* counter)
{
uint8_t* cur_pos;
for (cur_pos = counter + 7; cur_pos >= counter; cur_pos--) {
(*cur_pos)++;
if (*cur_pos != 0) {
break;
}
}
}
void av_aes_ctr_increment_iv(struct AVAESCTR *a)
{
av_aes_ctr_increment_be64(a->counter);
memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) - AES_CTR_IV_SIZE);
a->block_offset = 0;
}
void av_aes_ctr_crypt(struct AVAESCTR *a, uint8_t *dst, const uint8_t *src, int count)
{
const uint8_t* src_end = src + count;
const uint8_t* cur_end_pos;
uint8_t* encrypted_counter_pos;
while (src < src_end) {
if (a->block_offset == 0) {
av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL, 0);
av_aes_ctr_increment_be64(a->counter + 8);
}
encrypted_counter_pos = a->encrypted_counter + a->block_offset;
cur_end_pos = src + AES_BLOCK_SIZE - a->block_offset;
cur_end_pos = FFMIN(cur_end_pos, src_end);
a->block_offset += cur_end_pos - src;
a->block_offset &= (AES_BLOCK_SIZE - 1);
while (src < cur_end_pos) {
*dst++ = *src++ ^ *encrypted_counter_pos++;
}
}
}
|
