From 23ac99dc17b0c4ff43bb56c1f8cbe7feb34bada5 Mon Sep 17 00:00:00 2001 From: erankor Date: Mon, 7 Dec 2015 11:58:41 +0200 Subject: [PATCH] libavutil: add aes-ctr support for supporting mp4 cenc encoding/decoding Signed-off-by: Michael Niedermayer --- libavutil/Makefile | 2 + libavutil/aes_ctr.c | 129 ++++++++++++++++++++++++++++++++++++++++++++ libavutil/aes_ctr.h | 83 ++++++++++++++++++++++++++++ libavutil/version.h | 2 +- 4 files changed, 215 insertions(+), 1 deletion(-) create mode 100644 libavutil/aes_ctr.c create mode 100644 libavutil/aes_ctr.h diff --git a/libavutil/Makefile b/libavutil/Makefile index b43cede0c2..bf8c713e9f 100644 --- a/libavutil/Makefile +++ b/libavutil/Makefile @@ -4,6 +4,7 @@ NAME = avutil HEADERS = adler32.h \ aes.h \ + aes_ctr.h \ attributes.h \ audio_fifo.h \ avassert.h \ @@ -80,6 +81,7 @@ BUILT_HEADERS = avconfig.h \ OBJS = adler32.o \ aes.o \ + aes_ctr.o \ audio_fifo.o \ avstring.o \ base64.o \ diff --git a/libavutil/aes_ctr.c b/libavutil/aes_ctr.c new file mode 100644 index 0000000000..234354374f --- /dev/null +++ b/libavutil/aes_ctr.c @@ -0,0 +1,129 @@ +/* + * AES-CTR cipher + * Copyright (c) 2015 Eran Kornblau + * + * 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 "common.h" +#include "aes_ctr.h" +#include "aes.h" +#include "random_seed.h" + +#define AES_BLOCK_SIZE (16) + +typedef struct AVAESCTR { + struct AVAES* aes; + uint8_t counter[AES_BLOCK_SIZE]; + uint8_t encrypted_counter[AES_BLOCK_SIZE]; + int block_offset; +} 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; +} + +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) +{ + a->aes = av_aes_alloc(); + if (!a->aes) { + return AVERROR(ENOMEM); + } + + 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) +{ + if (a) { + av_freep(&a->aes); + av_freep(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++; + } + } +} diff --git a/libavutil/aes_ctr.h b/libavutil/aes_ctr.h new file mode 100644 index 0000000000..f596fa6a46 --- /dev/null +++ b/libavutil/aes_ctr.h @@ -0,0 +1,83 @@ +/* + * AES-CTR cipher + * Copyright (c) 2015 Eran Kornblau + * + * 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 + */ + +#ifndef AVUTIL_AES_CTR_H +#define AVUTIL_AES_CTR_H + +#include + +#include "attributes.h" +#include "version.h" + +#define AES_CTR_KEY_SIZE (16) +#define AES_CTR_IV_SIZE (8) + +struct AVAESCTR; + +/** + * Allocate an AVAESCTR context. + */ +struct AVAESCTR *av_aes_ctr_alloc(void); + +/** + * Initialize an AVAESCTR context. + * @param key encryption key, must have a length of AES_CTR_KEY_SIZE + */ +int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key); + +/** + * Release an AVAESCTR context. + */ +void av_aes_ctr_free(struct AVAESCTR *a); + +/** + * Process a buffer using a previously initialized context. + * @param dst destination array, can be equal to src + * @param src source array, can be equal to dst + * @param size the size of src and dst + */ +void av_aes_ctr_crypt(struct AVAESCTR *a, uint8_t *dst, const uint8_t *src, int size); + +/** + * Get the current iv + */ +const uint8_t* av_aes_ctr_get_iv(struct AVAESCTR *a); + +/** + * Generate a random iv + */ +void av_aes_ctr_set_random_iv(struct AVAESCTR *a); + +/** + * Forcefully change the iv + */ +void av_aes_ctr_set_iv(struct AVAESCTR *a, const uint8_t* iv); + +/** + * Increment the top 64 bit of the iv (performed after each frame) + */ +void av_aes_ctr_increment_iv(struct AVAESCTR *a); + +/** + * @} + */ + +#endif /* AVUTIL_AES_CTR_H */ diff --git a/libavutil/version.h b/libavutil/version.h index e7f04888de..22cd66b554 100644 --- a/libavutil/version.h +++ b/libavutil/version.h @@ -64,7 +64,7 @@ */ #define LIBAVUTIL_VERSION_MAJOR 55 -#define LIBAVUTIL_VERSION_MINOR 10 +#define LIBAVUTIL_VERSION_MINOR 11 #define LIBAVUTIL_VERSION_MICRO 100 #define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \