/*
* RTMP Diffie-Hellmann utilities
* Copyright (c) 2009 Andrej Stepanchuk
* Copyright (c) 2009-2010 Howard Chu
* Copyright (c) 2012 Samuel Pitoiset
*
* 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
*/
/**
* @file
* RTMP Diffie-Hellmann utilities
*/
#include "config.h"
#include "rtmpdh.h"
#include "libavutil/random_seed.h"
#define P1024 \
"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
"29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
"EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
"E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
"EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \
"FFFFFFFFFFFFFFFF"
#define Q1024 \
"7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \
"948127044533E63A0105DF531D89CD9128A5043CC71A026E" \
"F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \
"F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \
"F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \
"FFFFFFFFFFFFFFFF"
#if CONFIG_GMP || CONFIG_GCRYPT
#if CONFIG_GMP
#define bn_new(bn) \
do { \
bn = av_malloc(sizeof(*bn)); \
if (bn) \
mpz_init2(bn, 1); \
} while (0)
#define bn_free(bn) \
do { \
mpz_clear(bn); \
av_free(bn); \
} while (0)
#define bn_set_word(bn, w) mpz_set_ui(bn, w)
#define bn_cmp(a, b) mpz_cmp(a, b)
#define bn_copy(to, from) mpz_set(to, from)
#define bn_sub_word(bn, w) mpz_sub_ui(bn, bn, w)
#define bn_cmp_1(bn) mpz_cmp_ui(bn, 1)
#define bn_num_bytes(bn) (mpz_sizeinbase(bn, 2) + 7) / 8
#define bn_bn2bin(bn, buf, len) \
do { \
memset(buf, 0, len); \
if (bn_num_bytes(bn) <= len) \
mpz_export(buf, NULL, 1, 1, 0, 0, bn); \
} while (0)
#define bn_bin2bn(bn, buf, len) \
do { \
bn_new(bn); \
if (bn) \
mpz_import(bn, len, 1, 1, 0, 0, buf); \
} while (0)
#define bn_hex2bn(bn, buf, ret) \
do { \
bn_new(bn); \
if (bn) \
ret = (mpz_set_str(bn, buf, 16) == 0); \
else \
ret = 1; \
} while (0)
#define bn_modexp(bn, y, q, p) mpz_powm(bn, y, q, p)
#define bn_random(bn, num_bits) \
do { \
int bits = num_bits; \
mpz_set_ui(bn, 0); \
for (bits = num_bits; bits > 0; bits -= 32) { \
mpz_mul_2exp(bn, bn, 32); \
mpz_add_ui(bn, bn, av_get_random_seed()); \
} \
mpz_fdiv_r_2exp(bn, bn, num_bits); \
} while (0)
#elif CONFIG_GCRYPT
#define bn_new(bn) bn = gcry_mpi_new(1)
#define bn_free(bn) gcry_mpi_release(bn)
#define bn_set_word(bn, w) gcry_mpi_set_ui(bn, w)
#define bn_cmp(a, b) gcry_mpi_cmp(a, b)
#define bn_copy(to, from) gcry_mpi_set(to, from)
#define bn_sub_word(bn, w) gcry_mpi_sub_ui(bn, bn, w)
#define bn_cmp_1(bn) gcry_mpi_cmp_ui(bn, 1)
#define bn_num_bytes(bn) (gcry_mpi_get_nbits(bn) + 7) / 8
#define bn_bn2bin(bn, buf, len) gcry_mpi_print(GCRYMPI_FMT_USG, buf, len, NULL, bn)
#define bn_bin2bn(bn, buf, len) gcry_mpi_scan(&bn, GCRYMPI_FMT_USG, buf, len, NULL)
#define bn_hex2bn(bn, buf, ret) ret = (gcry_mpi_scan(&bn, GCRYMPI_FMT_HEX, buf, 0, 0) == 0)
#define bn_modexp(bn, y, q, p) gcry_mpi_powm(bn, y, q, p)
#define bn_random(bn, num_bits) gcry_mpi_randomize(bn, num_bits, GCRY_WEAK_RANDOM)
#endif
#define MAX_BYTES 18000
#define dh_new() av_malloc(sizeof(FF_DH))
static FFBigNum dh_generate_key(FF_DH *dh)
{
int num_bytes;
num_bytes = bn_num_bytes(dh->p) - 1;
if (num_bytes <= 0 || num_bytes > MAX_BYTES)
return NULL;
bn_new(dh->priv_key);
if (!dh->priv_key)
return NULL;
bn_random(dh->priv_key, 8 * num_bytes);
bn_new(dh->pub_key);
if (!dh->pub_key) {
bn_free(dh->priv_key);
return NULL;
}
bn_modexp(dh->pub_key, dh->g, dh->priv_key, dh->p);
return dh->pub_key;
}
static int dh_compute_key(FF_DH *dh, FFBigNum pub_key_bn,
uint32_t secret_key_len, uint8_t *secret_key)
{
FFBigNum k;
bn_new(k);
if (!k)
return -1;
bn_modexp(k, pub_key_bn, dh->priv_key, dh->p);
bn_bn2bin(k, secret_key, secret_key_len);
bn_free(k);
/* return the length of the shared secret key like DH_compute_key */
return secret_key_len;
}
void ff_dh_free(FF_DH *dh)
{
if (!dh)
return;
bn_free(dh->p);
bn_free(dh->g);
bn_free(dh->pub_key);
bn_free(dh->priv_key);
av_free(dh);
}
#elif CONFIG_OPENSSL
#define bn_new(bn) bn = BN_new()
#define bn_free(bn) BN_free(bn)
#define bn_set_word(bn, w) BN_set_word(bn, w)
#define bn_cmp(a, b) BN_cmp(a, b)
#define bn_copy(to, from) BN_copy(to, from)
#define bn_sub_word(bn, w) BN_sub_word(bn, w)
#define bn_cmp_1(bn) BN_cmp(bn, BN_value_one())
#define bn_num_bytes(bn) BN_num_bytes(bn)
#define bn_bn2bin(bn, buf, len) BN_bn2bin(bn, buf)
#define bn_bin2bn(bn, buf, len) bn = BN_bin2bn(buf, len, 0)
#define bn_hex2bn(bn, buf, ret) ret = BN_hex2bn(&bn, buf)
#define bn_modexp(bn, y, q, p) \
do { \
BN_CTX *ctx = BN_CTX_new(); \
if (!ctx) \
return AVERROR(ENOMEM); \
if (!BN_mod_exp(bn, y, q, p, ctx)) { \
BN_CTX_free(ctx); \
return AVERROR(EINVAL); \
} \
BN_CTX_free(ctx); \
} while (0)
#define dh_new() DH_new()
#define dh_generate_key(dh) DH_generate_key(dh)
static int dh_compute_key(FF_DH *dh, FFBigNum pub_key_bn,
uint32_t secret_key_len, uint8_t *secret_key)
{
if (secret_key_len < DH_size(dh))
return AVERROR(EINVAL);
return DH_compute_key(secret_key, pub_key_bn, dh);
}
void ff_dh_free(FF_DH *dh)
{
if (!dh)
return;
DH_free(dh);
}
#endif
static int dh_is_valid_public_key(FFBigNum y, FFBigNum p, FFBigNum q)
{
FFBigNum bn = NULL;
int ret = AVERROR(EINVAL);
bn_new(bn);
if (!bn)
return AVERROR(ENOMEM);
/* y must lie in [2, p - 1] */
bn_set_word(bn, 1);
if (!bn_cmp(y, bn))
goto fail;
/* bn = p - 2 */
bn_copy(bn, p);
bn_sub_word(bn, 1);
if (!bn_cmp(y, bn))
goto fail;
/* Verify with Sophie-Germain prime
*
* This is a nice test to make sure the public key position is calculated
* correctly. This test will fail in about 50% of the cases if applied to
* random data.
*/
/* y must fulfill y^q mod p = 1 */
bn_modexp(bn, y, q, p);
if (bn_cmp_1(bn))
goto fail;
ret = 0;
fail:
bn_free(bn);
return ret;
}
av_cold FF_DH *ff_dh_init(int key_len)
{
FF_DH *dh;
int ret;
if (!(dh = dh_new()))
return NULL;
bn_new(dh->g);
if (!dh->g)
goto fail;
bn_hex2bn(dh->p, P1024, ret);
if (!ret)
goto fail;
bn_set_word(dh->g, 2);
dh->length = key_len;
return dh;
fail:
ff_dh_free(dh);
return NULL;
}
int ff_dh_generate_public_key(FF_DH *dh)
{
int ret = 0;
while (!ret) {
FFBigNum q1 = NULL;
if (!dh_generate_key(dh))
return AVERROR(EINVAL);
bn_hex2bn(q1, Q1024, ret);
if (!ret)
return AVERROR(ENOMEM);
ret = dh_is_valid_public_key(dh->pub_key, dh->p, q1);
bn_free(q1);
if (!ret) {
/* the public key is valid */
break;
}
}
return ret;
}
int ff_dh_write_public_key(FF_DH *dh, uint8_t *pub_key, int pub_key_len)
{
int len;
/* compute the length of the public key */
len = bn_num_bytes(dh->pub_key);
if (len <= 0 || len > pub_key_len)
return AVERROR(EINVAL);
/* convert the public key value into big-endian form */
memset(pub_key, 0, pub_key_len);
bn_bn2bin(dh->pub_key, pub_key + pub_key_len - len, len);
return 0;
}
int ff_dh_compute_shared_secret_key(FF_DH *dh, const uint8_t *pub_key,
int pub_key_len, uint8_t *secret_key,
int secret_key_len)
{
FFBigNum q1 = NULL, pub_key_bn = NULL;
int ret;
/* convert the big-endian form of the public key into a bignum */
bn_bin2bn(pub_key_bn, pub_key, pub_key_len);
if (!pub_key_bn)
return AVERROR(ENOMEM);
/* convert the string containing a hexadecimal number into a bignum */
bn_hex2bn(q1, Q1024, ret);
if (!ret) {
ret = AVERROR(ENOMEM);
goto fail;
}
/* when the public key is valid we have to compute the shared secret key */
if ((ret = dh_is_valid_public_key(pub_key_bn, dh->p, q1)) < 0) {
goto fail;
} else if ((ret = dh_compute_key(dh, pub_key_bn, secret_key_len,
secret_key)) < 0) {
ret = AVERROR(EINVAL);
goto fail;
}
fail:
bn_free(pub_key_bn);
bn_free(q1);
return ret;
}
#ifdef TEST
static int test_random_shared_secret(void)
{
FF_DH *peer1 = NULL, *peer2 = NULL;
int ret;
uint8_t pubkey1[128], pubkey2[128];
uint8_t sharedkey1[128], sharedkey2[128];
peer1 = ff_dh_init(1024);
peer2 = ff_dh_init(1024);
if (!peer1 || !peer2) {
ret = AVERROR(ENOMEM);
goto fail;
}
if ((ret = ff_dh_generate_public_key(peer1)) < 0)
goto fail;
if ((ret = ff_dh_generate_public_key(peer2)) < 0)
goto fail;
if ((ret = ff_dh_write_public_key(peer1, pubkey1, sizeof(pubkey1))) < 0)
goto fail;
if ((ret = ff_dh_write_public_key(peer2, pubkey2, sizeof(pubkey2))) < 0)
goto fail;
if ((ret = ff_dh_compute_shared_secret_key(peer1, pubkey2, sizeof(pubkey2),
sharedkey1, sizeof(sharedkey1))) < 0)
goto fail;
if ((ret = ff_dh_compute_shared_secret_key(peer2, pubkey1, sizeof(pubkey1),
sharedkey2, sizeof(sharedkey2))) < 0)
goto fail;
if (memcmp(sharedkey1, sharedkey2, sizeof(sharedkey1))) {
printf("Mismatched generated shared key\n");
ret = AVERROR_INVALIDDATA;
} else {
printf("Generated shared key ok\n");
}
fail:
ff_dh_free(peer1);
ff_dh_free(peer2);
return ret;
}
static const char *private_key =
"976C18FCADC255B456564F74F3EEDA59D28AF6B744D743F2357BFD2404797EF896EF1A"
"7C1CBEAAA3AB60AF3192D189CFF3F991C9CBBFD78119FCA2181384B94011943B6D6F28"
"9E1B708E2D1A0C7771169293F03DA27E561F15F16F0AC9BC858C77A80FA98FD088A232"
"19D08BE6F165DE0B02034B18705829FAD0ACB26A5B75EF";
static const char *public_key =
"F272ECF8362257C5D2C3CC2229CF9C0A03225BC109B1DBC76A68C394F256ACA3EF5F64"
"FC270C26382BF315C19E97A76104A716FC998A651E8610A3AE6CF65D8FAE5D3F32EEA0"
"0B32CB9609B494116A825D7142D17B88E3D20EDD98743DE29CF37A23A9F6A58B960591"
"3157D5965FCB46DDA73A1F08DD897BAE88DFE6FC937CBA";
static const uint8_t public_key_bin[] = {
0xf2, 0x72, 0xec, 0xf8, 0x36, 0x22, 0x57, 0xc5, 0xd2, 0xc3, 0xcc, 0x22,
0x29, 0xcf, 0x9c, 0x0a, 0x03, 0x22, 0x5b, 0xc1, 0x09, 0xb1, 0xdb, 0xc7,
0x6a, 0x68, 0xc3, 0x94, 0xf2, 0x56, 0xac, 0xa3, 0xef, 0x5f, 0x64, 0xfc,
0x27, 0x0c, 0x26, 0x38, 0x2b, 0xf3, 0x15, 0xc1, 0x9e, 0x97, 0xa7, 0x61,
0x04, 0xa7, 0x16, 0xfc, 0x99, 0x8a, 0x65, 0x1e, 0x86, 0x10, 0xa3, 0xae,
0x6c, 0xf6, 0x5d, 0x8f, 0xae, 0x5d, 0x3f, 0x32, 0xee, 0xa0, 0x0b, 0x32,
0xcb, 0x96, 0x09, 0xb4, 0x94, 0x11, 0x6a, 0x82, 0x5d, 0x71, 0x42, 0xd1,
0x7b, 0x88, 0xe3, 0xd2, 0x0e, 0xdd, 0x98, 0x74, 0x3d, 0xe2, 0x9c, 0xf3,
0x7a, 0x23, 0xa9, 0xf6, 0xa5, 0x8b, 0x96, 0x05, 0x91, 0x31, 0x57, 0xd5,
0x96, 0x5f, 0xcb, 0x46, 0xdd, 0xa7, 0x3a, 0x1f, 0x08, 0xdd, 0x89, 0x7b,
0xae, 0x88, 0xdf, 0xe6, 0xfc, 0x93, 0x7c, 0xba
};
static const uint8_t peer_public_key[] = {
0x58, 0x66, 0x05, 0x49, 0x94, 0x23, 0x2b, 0x66, 0x52, 0x13, 0xff, 0x46,
0xf2, 0xb3, 0x79, 0xa9, 0xee, 0xae, 0x1a, 0x13, 0xf0, 0x71, 0x52, 0xfb,
0x93, 0x4e, 0xee, 0x97, 0x05, 0x73, 0x50, 0x7d, 0xaf, 0x02, 0x07, 0x72,
0xac, 0xdc, 0xa3, 0x95, 0x78, 0xee, 0x9a, 0x19, 0x71, 0x7e, 0x99, 0x9f,
0x2a, 0xd4, 0xb3, 0xe2, 0x0c, 0x1d, 0x1a, 0x78, 0x4c, 0xde, 0xf1, 0xad,
0xb4, 0x60, 0xa8, 0x51, 0xac, 0x71, 0xec, 0x86, 0x70, 0xa2, 0x63, 0x36,
0x92, 0x7c, 0xe3, 0x87, 0xee, 0xe4, 0xf1, 0x62, 0x24, 0x74, 0xb4, 0x04,
0xfa, 0x5c, 0xdf, 0xba, 0xfa, 0xa3, 0xc2, 0xbb, 0x62, 0x27, 0xd0, 0xf4,
0xe4, 0x43, 0xda, 0x8a, 0x88, 0x69, 0x60, 0xe2, 0xdb, 0x75, 0x2a, 0x98,
0x9d, 0xb5, 0x50, 0xe3, 0x99, 0xda, 0xe0, 0xa6, 0x14, 0xc9, 0x80, 0x12,
0xf9, 0x3c, 0xac, 0x06, 0x02, 0x7a, 0xde, 0x74
};
static const uint8_t shared_secret[] = {
0xb2, 0xeb, 0xcb, 0x71, 0xf3, 0x61, 0xfb, 0x5b, 0x4e, 0x5c, 0x4c, 0xcf,
0x5c, 0x08, 0x5f, 0x96, 0x26, 0x77, 0x1d, 0x31, 0xf1, 0xe1, 0xf7, 0x4b,
0x92, 0xac, 0x82, 0x2a, 0x88, 0xc7, 0x83, 0xe1, 0xc7, 0xf3, 0xd3, 0x1a,
0x7d, 0xc8, 0x31, 0xe3, 0x97, 0xe4, 0xec, 0x31, 0x0e, 0x8f, 0x73, 0x1a,
0xe4, 0xf6, 0xd8, 0xc8, 0x94, 0xff, 0xa0, 0x03, 0x84, 0x03, 0x0f, 0xa5,
0x30, 0x5d, 0x67, 0xe0, 0x7a, 0x3b, 0x5f, 0xed, 0x4c, 0xf5, 0xbc, 0x18,
0xea, 0xd4, 0x77, 0xa9, 0x07, 0xb3, 0x54, 0x0b, 0x02, 0xd9, 0xc6, 0xb8,
0x66, 0x5e, 0xec, 0xa4, 0xcd, 0x47, 0xed, 0xc9, 0x38, 0xc6, 0x91, 0x08,
0xf3, 0x85, 0x9b, 0x69, 0x16, 0x78, 0x0d, 0xb7, 0x74, 0x51, 0xaa, 0x5b,
0x4d, 0x74, 0xe4, 0x29, 0x2e, 0x9e, 0x8e, 0xf7, 0xe5, 0x42, 0x83, 0xb0,
0x65, 0xb0, 0xce, 0xc6, 0xb2, 0x8f, 0x5b, 0xb0
};
static int test_ref_data(void)
{
FF_DH *dh;
int ret = AVERROR(ENOMEM);
uint8_t pubkey_test[128];
uint8_t sharedkey_test[128];
dh = ff_dh_init(1024);
if (!dh)
goto fail;
bn_hex2bn(dh->priv_key, private_key, ret);
if (!ret)
goto fail;
bn_hex2bn(dh->pub_key, public_key, ret);
if (!ret)
goto fail;
if ((ret = ff_dh_write_public_key(dh, pubkey_test, sizeof(pubkey_test))) < 0)
goto fail;
if (memcmp(pubkey_test, public_key_bin, sizeof(pubkey_test))) {
printf("Mismatched generated public key\n");
ret = AVERROR_INVALIDDATA;
goto fail;
} else {
printf("Generated public key ok\n");
}
if ((ret = ff_dh_compute_shared_secret_key(dh, peer_public_key, sizeof(peer_public_key),
sharedkey_test, sizeof(sharedkey_test))) < 0)
goto fail;
if (memcmp(shared_secret, sharedkey_test, sizeof(sharedkey_test))) {
printf("Mismatched generated shared key\n");
ret = AVERROR_INVALIDDATA;
} else {
printf("Generated shared key ok\n");
}
fail:
ff_dh_free(dh);
return ret;
}
int main(void)
{
if (test_random_shared_secret() < 0)
return 1;
if (test_ref_data() < 0)
return 1;
return 0;
}
#endif