mirror of
https://github.com/FFmpeg/FFmpeg.git
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121 lines
3.3 KiB
C
121 lines
3.3 KiB
C
/*
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* AES-CTR cipher
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* Copyright (c) 2015 Eran Kornblau <erankor at gmail dot com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <string.h>
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#include "aes_ctr.h"
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#include "aes.h"
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#include "aes_internal.h"
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#include "intreadwrite.h"
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#include "macros.h"
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#include "mem.h"
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#include "random_seed.h"
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#define AES_BLOCK_SIZE (16)
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typedef struct AVAESCTR {
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DECLARE_ALIGNED(8, uint8_t, counter)[AES_BLOCK_SIZE];
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DECLARE_ALIGNED(8, uint8_t, encrypted_counter)[AES_BLOCK_SIZE];
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AVAES aes;
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} AVAESCTR;
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struct AVAESCTR *av_aes_ctr_alloc(void)
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{
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return av_mallocz(sizeof(struct AVAESCTR));
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}
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void av_aes_ctr_set_iv(struct AVAESCTR *a, const uint8_t* iv)
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{
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memcpy(a->counter, iv, AES_CTR_IV_SIZE);
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memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) - AES_CTR_IV_SIZE);
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}
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void av_aes_ctr_set_full_iv(struct AVAESCTR *a, const uint8_t* iv)
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{
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memcpy(a->counter, iv, sizeof(a->counter));
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}
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const uint8_t* av_aes_ctr_get_iv(struct AVAESCTR *a)
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{
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return a->counter;
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}
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void av_aes_ctr_set_random_iv(struct AVAESCTR *a)
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{
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uint32_t iv[2];
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iv[0] = av_get_random_seed();
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iv[1] = av_get_random_seed();
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av_aes_ctr_set_iv(a, (uint8_t*)iv);
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}
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int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key)
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{
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av_aes_init(&a->aes, key, 128, 0);
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memset(a->counter, 0, sizeof(a->counter));
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return 0;
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}
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void av_aes_ctr_free(struct AVAESCTR *a)
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{
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av_free(a);
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}
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static inline void av_aes_ctr_increment_be64(uint8_t* counter)
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{
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uint64_t c = AV_RB64A(counter) + 1;
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AV_WB64A(counter, c);
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}
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void av_aes_ctr_increment_iv(struct AVAESCTR *a)
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{
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av_aes_ctr_increment_be64(a->counter);
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memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) - AES_CTR_IV_SIZE);
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}
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void av_aes_ctr_crypt(struct AVAESCTR *a, uint8_t *dst, const uint8_t *src, int count)
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{
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while (count >= AES_BLOCK_SIZE) {
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av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL, 0);
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av_aes_ctr_increment_be64(a->counter + 8);
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#if HAVE_FAST_64BIT
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for (int len = 0; len < AES_BLOCK_SIZE; len += 8)
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AV_WN64(&dst[len], AV_RN64(&src[len]) ^ AV_RN64A(&a->encrypted_counter[len]));
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#else
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for (int len = 0; len < AES_BLOCK_SIZE; len += 4)
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AV_WN32(&dst[len], AV_RN32(&src[len]) ^ AV_RN32A(&a->encrypted_counter[len]));
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#endif
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dst += AES_BLOCK_SIZE;
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src += AES_BLOCK_SIZE;
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count -= AES_BLOCK_SIZE;
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}
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if (count > 0) {
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av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL, 0);
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av_aes_ctr_increment_be64(a->counter + 8);
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for (int len = 0; len < count; len++)
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dst[len] = src[len] ^ a->encrypted_counter[len];
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}
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}
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