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Merge commit 'ab2ad8bd56882c0ea160b154e8b836eb71abc49d'

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* commit 'ab2ad8bd56882c0ea160b154e8b836eb71abc49d':
  lavf: Add functions for SRTP decryption/encryption
  lavu: Add an API for calculating HMAC (RFC 2104)

Conflicts:
	doc/APIchanges
	libavutil/version.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
pull/8/head
Michael Niedermayer 12 years ago
parent e074fe2962 ab2ad8bd56
commit e7e0186eeb
7 changed files with 584 additions and 1 deletions
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  1. 3
      doc/APIchanges
  2. 293
      libavformat/srtp.c
  3. 52
      libavformat/srtp.h
  4. 2
      libavutil/Makefile
  5. 138
      libavutil/hmac.c
  6. 95
      libavutil/hmac.h
  7. 2
      libavutil/version.h

3
doc/APIchanges
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@ -132,6 +132,9 @@ API changes, most recent first:
2012-03-26 - a67d9cf - lavfi 2.66.100
Add avfilter_fill_frame_from_{audio_,}buffer_ref() functions.
2013-01-xx - xxxxxxx - lavu 52.5.0 - hmac.h
Add AVHMAC.
2013-01-13 - xxxxxxx - lavc 54.36.0 - vdpau.h
Add AVVDPAUContext struct for VDPAU hardware-accelerated decoding.

293
libavformat/srtp.c
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@ -0,0 +1,293 @@
/*
* SRTP encryption/decryption
* Copyright (c) 2012 Martin Storsjo
*
* 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 "libavutil/base64.h"
#include "libavutil/aes.h"
#include "libavutil/hmac.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "rtp.h"
#include "srtp.h"
void ff_srtp_free(struct SRTPContext *s)
{
if (!s)
return;
av_freep(&s->aes);
if (s->hmac)
av_hmac_free(s->hmac);
s->hmac = NULL;
}
static void encrypt_counter(struct AVAES *aes, uint8_t *iv, uint8_t *outbuf,
int outlen)
{
int i, j, outpos;
for (i = 0, outpos = 0; outpos < outlen; i++) {
uint8_t keystream[16];
AV_WB16(&iv[14], i);
av_aes_crypt(aes, keystream, iv, 1, NULL, 0);
for (j = 0; j < 16 && outpos < outlen; j++, outpos++)
outbuf[outpos] ^= keystream[j];
}
}
static void derive_key(struct AVAES *aes, const uint8_t *salt, int label,
uint8_t *out, int outlen)
{
uint8_t input[16] = { 0 };
memcpy(input, salt, 14);
// Key derivation rate assumed to be zero
input[14 - 7] ^= label;
memset(out, 0, outlen);
encrypt_counter(aes, input, out, outlen);
}
int ff_srtp_set_crypto(struct SRTPContext *s, const char *suite,
const char *params)
{
uint8_t buf[30];
ff_srtp_free(s);
// RFC 4568
if (!strcmp(suite, "AES_CM_128_HMAC_SHA1_80")) {
s->hmac_size = 10;
} else if (!strcmp(suite, "AES_CM_128_HMAC_SHA1_32")) {
s->hmac_size = 4;
} else {
av_log(NULL, AV_LOG_WARNING, "SRTP Crypto suite %s not supported\n",
suite);
return AVERROR(EINVAL);
}
if (av_base64_decode(buf, params, sizeof(buf)) != sizeof(buf)) {
av_log(NULL, AV_LOG_WARNING, "Incorrect amount of SRTP params\n");
return AVERROR(EINVAL);
}
// MKI and lifetime not handled yet
s->aes = av_aes_alloc();
s->hmac = av_hmac_alloc(AV_HMAC_SHA1);
if (!s->aes || !s->hmac)
return AVERROR(ENOMEM);
memcpy(s->master_key, buf, 16);
memcpy(s->master_salt, buf + 16, 14);
// RFC 3711
av_aes_init(s->aes, s->master_key, 128, 0);
derive_key(s->aes, s->master_salt, 0x00, s->rtp_key, sizeof(s->rtp_key));
derive_key(s->aes, s->master_salt, 0x02, s->rtp_salt, sizeof(s->rtp_salt));
derive_key(s->aes, s->master_salt, 0x01, s->rtp_auth, sizeof(s->rtp_auth));
derive_key(s->aes, s->master_salt, 0x03, s->rtcp_key, sizeof(s->rtcp_key));
derive_key(s->aes, s->master_salt, 0x05, s->rtcp_salt, sizeof(s->rtcp_salt));
derive_key(s->aes, s->master_salt, 0x04, s->rtcp_auth, sizeof(s->rtcp_auth));
return 0;
}
static void create_iv(uint8_t *iv, const uint8_t *salt, uint64_t index,
uint32_t ssrc)
{
uint8_t indexbuf[8];
int i;
memset(iv, 0, 16);
AV_WB32(&iv[4], ssrc);
AV_WB64(indexbuf, index);
for (i = 0; i < 8; i++) // index << 16
iv[6 + i] ^= indexbuf[i];
for (i = 0; i < 14; i++)
iv[i] ^= salt[i];
}
int ff_srtp_decrypt(struct SRTPContext *s, uint8_t *buf, int *lenptr)
{
uint8_t iv[16] = { 0 }, hmac[20];
int len = *lenptr;
int ext, seq_largest;
uint32_t ssrc, roc;
uint64_t index;
int rtcp;
// TODO: Missing replay protection
if (len < s->hmac_size)
return AVERROR_INVALIDDATA;
rtcp = RTP_PT_IS_RTCP(buf[1]);
// Authentication HMAC
av_hmac_init(s->hmac, rtcp ? s->rtcp_auth : s->rtp_auth, sizeof(s->rtp_auth));
// If MKI is used, this should exclude the MKI as well
av_hmac_update(s->hmac, buf, len - s->hmac_size);
if (!rtcp) {
int seq = AV_RB16(buf + 2);
uint32_t v;
uint8_t rocbuf[4];
// RFC 3711 section 3.3.1, appendix A
seq_largest = s->seq_initialized ? s->seq_largest : seq;
v = roc = s->roc;
if (seq_largest < 32768) {
if (seq - seq_largest > 32768)
v = roc - 1;
} else {
if (seq_largest - 32768 > seq)
v = roc + 1;
}
if (v == roc) {
seq_largest = FFMAX(seq_largest, seq);
} else if (v == roc + 1) {
seq_largest = seq;
roc = v;
}
index = seq + (((uint64_t)v) << 16);
AV_WB32(rocbuf, roc);
av_hmac_update(s->hmac, rocbuf, 4);
}
av_hmac_final(s->hmac, hmac, sizeof(hmac));
if (memcmp(hmac, buf + len - s->hmac_size, s->hmac_size)) {
av_log(NULL, AV_LOG_WARNING, "HMAC mismatch\n");
return AVERROR_INVALIDDATA;
}
len -= s->hmac_size;
*lenptr = len;
if (len < 12)
return AVERROR_INVALIDDATA;
if (rtcp) {
uint32_t srtcp_index = AV_RB32(buf + len - 4);
len -= 4;
*lenptr = len;
ssrc = AV_RB32(buf + 4);
index = srtcp_index & 0x7fffffff;
buf += 8;
len -= 8;
if (!(srtcp_index & 0x80000000))
return 0;
} else {
s->seq_initialized = 1;
s->seq_largest = seq_largest;
s->roc = roc;
ext = buf[0] & 0x10;
ssrc = AV_RB32(buf + 8);
buf += 12;
len -= 12;
if (ext) {
if (len < 4)
return AVERROR_INVALIDDATA;
ext = (AV_RB16(buf + 2) + 1) * 4;
if (len < ext)
return AVERROR_INVALIDDATA;
len -= ext;
buf += ext;
}
}
create_iv(iv, rtcp ? s->rtcp_salt : s->rtp_salt, index, ssrc);
av_aes_init(s->aes, rtcp ? s->rtcp_key : s->rtp_key, 128, 0);
encrypt_counter(s->aes, iv, buf, len);
return 0;
}
int ff_srtp_encrypt(struct SRTPContext *s, const uint8_t *in, int len,
uint8_t *out, int outlen)
{
uint8_t iv[16] = { 0 }, hmac[20];
uint64_t index;
uint32_t ssrc;
int rtcp;
uint8_t *buf;
if (len + 14 > outlen)
return 0;
if (len < 12)
return 0;
memcpy(out, in, len);
buf = out;
rtcp = RTP_PT_IS_RTCP(buf[1]);
if (rtcp) {
ssrc = AV_RB32(buf + 4);
index = s->rtcp_index++;
buf += 8;
len -= 8;
} else {
int ext;
int seq = AV_RB16(buf + 2);
ssrc = AV_RB32(buf + 8);
if (seq < s->seq_largest)
s->roc++;
s->seq_largest = seq;
index = seq + (((uint64_t)s->roc) << 16);
ext = buf[0] & 0x10;
buf += 12;
len -= 12;
if (ext) {
if (len < 4)
return AVERROR_INVALIDDATA;
ext = (AV_RB16(buf + 2) + 1) * 4;
if (len < ext)
return AVERROR_INVALIDDATA;
len -= ext;
buf += ext;
}
}
create_iv(iv, rtcp ? s->rtcp_salt : s->rtp_salt, index, ssrc);
av_aes_init(s->aes, rtcp ? s->rtcp_key : s->rtp_key, 128, 0);
encrypt_counter(s->aes, iv, buf, len);
if (rtcp) {
AV_WB32(buf + len, 0x80000000 | index);
len += 4;
}
av_hmac_init(s->hmac, rtcp ? s->rtcp_auth : s->rtp_auth, sizeof(s->rtp_auth));
av_hmac_update(s->hmac, out, buf + len - out);
if (!rtcp) {
uint8_t rocbuf[4];
AV_WB32(rocbuf, s->roc);
av_hmac_update(s->hmac, rocbuf, 4);
}
av_hmac_final(s->hmac, hmac, sizeof(hmac));
memcpy(buf + len, hmac, s->hmac_size);
len += s->hmac_size;
return buf + len - out;
}

52
libavformat/srtp.h
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@ -0,0 +1,52 @@
/*
* SRTP encryption/decryption
* Copyright (c) 2012 Martin Storsjo
*
* 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 AVFORMAT_SRTP_H
#define AVFORMAT_SRTP_H
#include <stdint.h>
struct AVAES;
struct AVHMAC;
struct SRTPContext {
struct AVAES *aes;
struct AVHMAC *hmac;
int hmac_size;
uint8_t master_key[16];
uint8_t master_salt[14];
uint8_t rtp_key[16], rtcp_key[16];
uint8_t rtp_salt[14], rtcp_salt[14];
uint8_t rtp_auth[20], rtcp_auth[20];
int seq_largest, seq_initialized;
uint32_t roc;
uint32_t rtcp_index;
};
int ff_srtp_set_crypto(struct SRTPContext *s, const char *suite,
const char *params);
void ff_srtp_free(struct SRTPContext *s);
int ff_srtp_decrypt(struct SRTPContext *s, uint8_t *buf, int *lenptr);
int ff_srtp_encrypt(struct SRTPContext *s, const uint8_t *in, int len,
uint8_t *out, int outlen);
#endif /* AVFORMAT_SRTP_H */

2
libavutil/Makefile
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@ -22,6 +22,7 @@ HEADERS = adler32.h \
eval.h \
fifo.h \
file.h \
hmac.h \
imgutils.h \
intfloat.h \
intfloat_readwrite.h \
@ -72,6 +73,7 @@ OBJS = adler32.o \
fifo.o \
file.o \
float_dsp.o \
hmac.o \
imgutils.o \
intfloat_readwrite.o \
intmath.o \

138
libavutil/hmac.c
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@ -0,0 +1,138 @@
/*
* Copyright (C) 2012 Martin Storsjo
*
* 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 "hmac.h"
#include "md5.h"
#include "sha.h"
#include "mem.h"
#define MAX_HASHLEN 20
#define MAX_BLOCKLEN 64
struct AVHMAC {
void *hash;
int blocklen, hashlen;
void (*final)(void*, uint8_t*);
void (*update)(void*, const uint8_t*, int len);
void (*init)(void*);
uint8_t key[MAX_BLOCKLEN];
int keylen;
};
static void sha1_init(void *ctx)
{
av_sha_init(ctx, 160);
}
AVHMAC *av_hmac_alloc(enum AVHMACType type)
{
AVHMAC *c = av_mallocz(sizeof(*c));
if (!c)
return NULL;
switch (type) {
case AV_HMAC_MD5:
c->blocklen = 64;
c->hashlen = 16;
c->init = av_md5_init;
c->update = av_md5_update;
c->final = av_md5_final;
c->hash = av_md5_alloc();
break;
case AV_HMAC_SHA1:
c->blocklen = 64;
c->hashlen = 20;
c->init = sha1_init;
c->update = av_sha_update;
c->final = av_sha_final;
c->hash = av_sha_alloc();
break;
default:
av_free(c);
return NULL;
}
if (!c->hash) {
av_free(c);
return NULL;
}
return c;
}
void av_hmac_free(AVHMAC *c)
{
if (!c)
return;
av_free(c->hash);
av_free(c);
}
void av_hmac_init(AVHMAC *c, const uint8_t *key, unsigned int keylen)
{
int i;
uint8_t block[MAX_BLOCKLEN];
if (keylen > c->blocklen) {
c->init(c->hash);
c->update(c->hash, key, keylen);
c->final(c->hash, c->key);
c->keylen = c->hashlen;
} else {
memcpy(c->key, key, keylen);
c->keylen = keylen;
}
c->init(c->hash);
for (i = 0; i < c->keylen; i++)
block[i] = c->key[i] ^ 0x36;
for (i = c->keylen; i < c->blocklen; i++)
block[i] = 0x36;
c->update(c->hash, block, c->blocklen);
}
void av_hmac_update(AVHMAC *c, const uint8_t *data, unsigned int len)
{
c->update(c->hash, data, len);
}
int av_hmac_final(AVHMAC *c, uint8_t *out, unsigned int outlen)
{
uint8_t block[MAX_BLOCKLEN];
int i;
if (outlen < c->hashlen)
return AVERROR(EINVAL);
c->final(c->hash, out);
c->init(c->hash);
for (i = 0; i < c->keylen; i++)
block[i] = c->key[i] ^ 0x5C;
for (i = c->keylen; i < c->blocklen; i++)
block[i] = 0x5C;
c->update(c->hash, block, c->blocklen);
c->update(c->hash, out, c->hashlen);
c->final(c->hash, out);
return c->hashlen;
}
int av_hmac_calc(AVHMAC *c, const uint8_t *data, unsigned int len,
const uint8_t *key, unsigned int keylen,
uint8_t *out, unsigned int outlen)
{
av_hmac_init(c, key, keylen);
av_hmac_update(c, data, len);
return av_hmac_final(c, out, outlen);
}

95
libavutil/hmac.h
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@ -0,0 +1,95 @@
/*
* Copyright (C) 2012 Martin Storsjo
*
* 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_HMAC_H
#define AVUTIL_HMAC_H
#include <stdint.h>
/**
* @defgroup lavu_hmac HMAC
* @ingroup lavu_crypto
* @{
*/
enum AVHMACType {
AV_HMAC_MD5,
AV_HMAC_SHA1,
};
typedef struct AVHMAC AVHMAC;
/**
* Allocate an AVHMAC context.
* @param type The hash function used for the HMAC.
*/
AVHMAC *av_hmac_alloc(enum AVHMACType type);
/**
* Free an AVHMAC context.
* @param ctx The context to free, may be NULL
*/
void av_hmac_free(AVHMAC *ctx);
/**
* Initialize an AVHMAC context with an authentication key.
* @param ctx The HMAC context
* @param key The authentication key
* @param keylen The length of the key, in bytes
*/
void av_hmac_init(AVHMAC *ctx, const uint8_t *key, unsigned int keylen);
/**
* Hash data with the HMAC.
* @param ctx The HMAC context
* @param data The data to hash
* @param len The length of the data, in bytes
*/
void av_hmac_update(AVHMAC *ctx, const uint8_t *data, unsigned int len);
/**
* Finish hashing and output the HMAC digest.
* @param ctx The HMAC context
* @param out The output buffer to write the digest into
* @param outlen The length of the out buffer, in bytes
* @return The number of bytes written to out, or a negative error code.
*/
int av_hmac_final(AVHMAC *ctx, uint8_t *out, unsigned int outlen);
/**
* Hash an array of data with a key.
* @param ctx The HMAC context
* @param data The data to hash
* @param len The length of the data, in bytes
* @param key The authentication key
* @param keylen The length of the key, in bytes
* @param out The output buffer to write the digest into
* @param outlen The length of the out buffer, in bytes
* @return The number of bytes written to out, or a negative error code.
*/
int av_hmac_calc(AVHMAC *ctx, const uint8_t *data, unsigned int len,
const uint8_t *key, unsigned int keylen,
uint8_t *out, unsigned int outlen);
/**
* @}
*/
#endif /* AVUTIL_HMAC_H */

2
libavutil/version.h
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@ -75,7 +75,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 52
#define LIBAVUTIL_VERSION_MINOR 14
#define LIBAVUTIL_VERSION_MINOR 15
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

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