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libavutil: add aes-ctr support

for supporting mp4 cenc encoding/decoding

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
tags/n3.0
erankor Michael Niedermayer 9 years ago
parent
commit
23ac99dc17
4 changed files with 215 additions and 1 deletions
  1. +2
    -0
      libavutil/Makefile
  2. +129
    -0
      libavutil/aes_ctr.c
  3. +83
    -0
      libavutil/aes_ctr.h
  4. +1
    -1
      libavutil/version.h

+ 2
- 0
libavutil/Makefile View File

@@ -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 \


+ 129
- 0
libavutil/aes_ctr.c View File

@@ -0,0 +1,129 @@
/*
* 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 "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++;
}
}
}

+ 83
- 0
libavutil/aes_ctr.h View File

@@ -0,0 +1,83 @@
/*
* 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
*/

#ifndef AVUTIL_AES_CTR_H
#define AVUTIL_AES_CTR_H

#include <stdint.h>

#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 */

+ 1
- 1
libavutil/version.h View File

@@ -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, \


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