From acd554c103459ae7a5d89caa611e91bbc9bf695f Mon Sep 17 00:00:00 2001 From: Samuel Pitoiset Date: Thu, 19 Jul 2012 14:13:58 +0200 Subject: RTMPE protocol support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This adds two protocols, but one of them is an internal implementation detail just used as an abstraction layer/generalization in the code. The RTMPE protocol implementation uses ffrtmpcrypt:// as an alternative to the tcp:// protocol. This allows moving most of the lower level logic out from the higher level generic rtmp code. Signed-off-by: Martin Storsjö --- libavformat/rtmpdh.c | 329 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 329 insertions(+) create mode 100644 libavformat/rtmpdh.c (limited to 'libavformat/rtmpdh.c') diff --git a/libavformat/rtmpdh.c b/libavformat/rtmpdh.c new file mode 100644 index 0000000000..8ddc5fcee8 --- /dev/null +++ b/libavformat/rtmpdh.c @@ -0,0 +1,329 @@ +/* + * RTMP Diffie-Hellmann utilities + * Copyright (c) 2012 Samuel Pitoiset + * + * This file is part of Libav. + * + * Libav 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. + * + * Libav 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 Libav; 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" + +#define P1024 \ + "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \ + "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \ + "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \ + "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \ + "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \ + "FFFFFFFFFFFFFFFF" + +#define Q1024 \ + "7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \ + "948127044533E63A0105DF531D89CD9128A5043CC71A026E" \ + "F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \ + "F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \ + "F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \ + "FFFFFFFFFFFFFFFF" + +#if CONFIG_NETTLE || CONFIG_GCRYPT +#if CONFIG_NETTLE +#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) nettle_mpz_get_str_256(len, buf, bn) +#define bn_bin2bn(bn, buf, len) \ + do { \ + bn_new(bn); \ + if (bn) \ + nettle_mpz_set_str_256_u(bn, len, buf); \ + } while (0) +#define bn_hex2bn(bn, buf, ret) \ + do { \ + bn_new(bn); \ + if (bn) \ + ret = (mpz_set_str(bn, buf, 16) == 0); \ + } while (0) +#define bn_modexp(bn, y, q, p) mpz_powm(bn, y, q, p) +#define bn_random(bn, num_bytes) mpz_random(bn, num_bytes); +#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_bytes) gcry_mpi_randomize(bn, num_bytes, 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, 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 pub_key_len, uint8_t *secret_key) +{ + FFBigNum k; + int num_bytes; + + num_bytes = bn_num_bytes(dh->p); + if (num_bytes <= 0 || num_bytes > MAX_BYTES) + return -1; + + bn_new(k); + if (!k) + return -1; + + bn_modexp(k, pub_key_bn, dh->priv_key, dh->p); + bn_bn2bin(k, secret_key, pub_key_len); + bn_free(k); + + /* return the length of the shared secret key like DH_compute_key */ + return pub_key_len; +} + +void ff_dh_free(FF_DH *dh) +{ + 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) +#define dh_compute_key(dh, pub, len, secret) DH_compute_key(secret, pub, dh) + +void ff_dh_free(FF_DH *dh) +{ + 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) +{ + 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, pub_key_len, + secret_key)) < 0) { + ret = AVERROR(EINVAL); + goto fail; + } + +fail: + bn_free(pub_key_bn); + bn_free(q1); + + return ret; +} + -- cgit v1.2.3