| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * AES-CTR cipher | ||
| 3 | * Copyright (c) 2015 Eran Kornblau <erankor at gmail dot com> | ||
| 4 | * | ||
| 5 | * This file is part of FFmpeg. | ||
| 6 | * | ||
| 7 | * FFmpeg is free software; you can redistribute it and/or | ||
| 8 | * modify it under the terms of the GNU Lesser General Public | ||
| 9 | * License as published by the Free Software Foundation; either | ||
| 10 | * version 2.1 of the License, or (at your option) any later version. | ||
| 11 | * | ||
| 12 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 15 | * Lesser General Public License for more details. | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU Lesser General Public | ||
| 18 | * License along with FFmpeg; if not, write to the Free Software | ||
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| 20 | */ | ||
| 21 | |||
| 22 | #include <string.h> | ||
| 23 | |||
| 24 | #include "aes_ctr.h" | ||
| 25 | #include "aes.h" | ||
| 26 | #include "aes_internal.h" | ||
| 27 | #include "macros.h" | ||
| 28 | #include "mem.h" | ||
| 29 | #include "random_seed.h" | ||
| 30 | |||
| 31 | #define AES_BLOCK_SIZE (16) | ||
| 32 | |||
| 33 | typedef struct AVAESCTR { | ||
| 34 | uint8_t counter[AES_BLOCK_SIZE]; | ||
| 35 | uint8_t encrypted_counter[AES_BLOCK_SIZE]; | ||
| 36 | int block_offset; | ||
| 37 | AVAES aes; | ||
| 38 | } AVAESCTR; | ||
| 39 | |||
| 40 | 5 | struct AVAESCTR *av_aes_ctr_alloc(void) | |
| 41 | { | ||
| 42 | 5 | return av_mallocz(sizeof(struct AVAESCTR)); | |
| 43 | } | ||
| 44 | |||
| 45 | 1 | void av_aes_ctr_set_iv(struct AVAESCTR *a, const uint8_t* iv) | |
| 46 | { | ||
| 47 | 1 | memcpy(a->counter, iv, AES_CTR_IV_SIZE); | |
| 48 | 1 | memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) - AES_CTR_IV_SIZE); | |
| 49 | 1 | a->block_offset = 0; | |
| 50 | 1 | } | |
| 51 | |||
| 52 | 147 | void av_aes_ctr_set_full_iv(struct AVAESCTR *a, const uint8_t* iv) | |
| 53 | { | ||
| 54 | 147 | memcpy(a->counter, iv, sizeof(a->counter)); | |
| 55 | 147 | a->block_offset = 0; | |
| 56 | 147 | } | |
| 57 | |||
| 58 | 1 | const uint8_t* av_aes_ctr_get_iv(struct AVAESCTR *a) | |
| 59 | { | ||
| 60 | 1 | return a->counter; | |
| 61 | } | ||
| 62 | |||
| 63 | 1 | void av_aes_ctr_set_random_iv(struct AVAESCTR *a) | |
| 64 | { | ||
| 65 | uint32_t iv[2]; | ||
| 66 | |||
| 67 | 1 | iv[0] = av_get_random_seed(); | |
| 68 | 1 | iv[1] = av_get_random_seed(); | |
| 69 | |||
| 70 | 1 | av_aes_ctr_set_iv(a, (uint8_t*)iv); | |
| 71 | 1 | } | |
| 72 | |||
| 73 | 5 | int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key) | |
| 74 | { | ||
| 75 | 5 | av_aes_init(&a->aes, key, 128, 0); | |
| 76 | |||
| 77 | 5 | memset(a->counter, 0, sizeof(a->counter)); | |
| 78 | 5 | a->block_offset = 0; | |
| 79 | |||
| 80 | 5 | return 0; | |
| 81 | } | ||
| 82 | |||
| 83 | 868 | void av_aes_ctr_free(struct AVAESCTR *a) | |
| 84 | { | ||
| 85 | 868 | av_free(a); | |
| 86 | 868 | } | |
| 87 | |||
| 88 | 5183 | static void av_aes_ctr_increment_be64(uint8_t* counter) | |
| 89 | { | ||
| 90 | uint8_t* cur_pos; | ||
| 91 | |||
| 92 |
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5183 | for (cur_pos = counter + 7; cur_pos >= counter; cur_pos--) { |
| 93 | 5183 | (*cur_pos)++; | |
| 94 |
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5183 | if (*cur_pos != 0) { |
| 95 | 5183 | break; | |
| 96 | } | ||
| 97 | } | ||
| 98 | 5183 | } | |
| 99 | |||
| 100 | ✗ | void av_aes_ctr_increment_iv(struct AVAESCTR *a) | |
| 101 | { | ||
| 102 | ✗ | av_aes_ctr_increment_be64(a->counter); | |
| 103 | ✗ | memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) - AES_CTR_IV_SIZE); | |
| 104 | ✗ | a->block_offset = 0; | |
| 105 | ✗ | } | |
| 106 | |||
| 107 | 148 | void av_aes_ctr_crypt(struct AVAESCTR *a, uint8_t *dst, const uint8_t *src, int count) | |
| 108 | { | ||
| 109 | 148 | const uint8_t* src_end = src + count; | |
| 110 | const uint8_t* cur_end_pos; | ||
| 111 | uint8_t* encrypted_counter_pos; | ||
| 112 | |||
| 113 |
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5331 | while (src < src_end) { |
| 114 |
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5183 | if (a->block_offset == 0) { |
| 115 | 5183 | av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL, 0); | |
| 116 | |||
| 117 | 5183 | av_aes_ctr_increment_be64(a->counter + 8); | |
| 118 | } | ||
| 119 | |||
| 120 | 5183 | encrypted_counter_pos = a->encrypted_counter + a->block_offset; | |
| 121 | 5183 | cur_end_pos = src + AES_BLOCK_SIZE - a->block_offset; | |
| 122 | 5183 | cur_end_pos = FFMIN(cur_end_pos, src_end); | |
| 123 | |||
| 124 | 5183 | a->block_offset += cur_end_pos - src; | |
| 125 | 5183 | a->block_offset &= (AES_BLOCK_SIZE - 1); | |
| 126 | |||
| 127 |
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87210 | while (src < cur_end_pos) { |
| 128 | 82027 | *dst++ = *src++ ^ *encrypted_counter_pos++; | |
| 129 | } | ||
| 130 | } | ||
| 131 | 148 | } | |
| 132 |