| /* |
| * 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 <stdint.h> |
| #include <string.h> |
| |
| #include "config.h" |
| |
| #include "libavutil/attributes.h" |
| #include "libavutil/error.h" |
| #include "libavutil/mem.h" |
| #include "libavutil/random_seed.h" |
| |
| #include "rtmpdh.h" |
| |
| #if CONFIG_MBEDTLS |
| #include <mbedtls/ctr_drbg.h> |
| #include <mbedtls/entropy.h> |
| #endif |
| |
| #define P1024 \ |
| "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \ |
| "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \ |
| "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \ |
| "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \ |
| "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \ |
| "FFFFFFFFFFFFFFFF" |
| |
| #define Q1024 \ |
| "7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \ |
| "948127044533E63A0105DF531D89CD9128A5043CC71A026E" \ |
| "F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \ |
| "F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \ |
| "F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \ |
| "FFFFFFFFFFFFFFFF" |
| |
| #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_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) |
| static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p) |
| { |
| mpz_powm(bn, y, q, p); |
| return 0; |
| } |
| #elif CONFIG_GCRYPT |
| #define bn_new(bn) \ |
| do { \ |
| if (!gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P)) { \ |
| if (!gcry_check_version("1.5.4")) \ |
| return AVERROR(EINVAL); \ |
| gcry_control(GCRYCTL_DISABLE_SECMEM, 0); \ |
| gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0); \ |
| } \ |
| bn = gcry_mpi_new(1); \ |
| } while (0) |
| #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_random(bn, num_bits) gcry_mpi_randomize(bn, num_bits, GCRY_WEAK_RANDOM) |
| static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p) |
| { |
| gcry_mpi_powm(bn, y, q, p); |
| return 0; |
| } |
| #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_random(bn, num_bits) BN_rand(bn, num_bits, 0, 0) |
| static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p) |
| { |
| 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); |
| return 0; |
| } |
| #elif CONFIG_MBEDTLS |
| #define bn_new(bn) \ |
| do { \ |
| bn = av_malloc(sizeof(*bn)); \ |
| if (bn) \ |
| mbedtls_mpi_init(bn); \ |
| } while (0) |
| #define bn_free(bn) \ |
| do { \ |
| mbedtls_mpi_free(bn); \ |
| av_free(bn); \ |
| } while (0) |
| #define bn_set_word(bn, w) mbedtls_mpi_lset(bn, w) |
| #define bn_cmp(a, b) mbedtls_mpi_cmp_mpi(a, b) |
| #define bn_copy(to, from) mbedtls_mpi_copy(to, from) |
| #define bn_sub_word(bn, w) mbedtls_mpi_sub_int(bn, bn, w) |
| #define bn_cmp_1(bn) mbedtls_mpi_cmp_int(bn, 1) |
| #define bn_num_bytes(bn) (mbedtls_mpi_bitlen(bn) + 7) / 8 |
| #define bn_bn2bin(bn, buf, len) mbedtls_mpi_write_binary(bn, buf, len) |
| #define bn_bin2bn(bn, buf, len) \ |
| do { \ |
| bn_new(bn); \ |
| if (bn) \ |
| mbedtls_mpi_read_binary(bn, buf, len); \ |
| } while (0) |
| #define bn_hex2bn(bn, buf, ret) \ |
| do { \ |
| bn_new(bn); \ |
| if (bn) \ |
| ret = (mbedtls_mpi_read_string(bn, 16, buf) == 0); \ |
| else \ |
| ret = 1; \ |
| } while (0) |
| #define bn_random(bn, num_bits) \ |
| do { \ |
| mbedtls_entropy_context entropy_ctx; \ |
| mbedtls_ctr_drbg_context ctr_drbg_ctx; \ |
| \ |
| mbedtls_entropy_init(&entropy_ctx); \ |
| mbedtls_ctr_drbg_init(&ctr_drbg_ctx); \ |
| mbedtls_ctr_drbg_seed(&ctr_drbg_ctx, \ |
| mbedtls_entropy_func, \ |
| &entropy_ctx, \ |
| NULL, 0); \ |
| mbedtls_mpi_fill_random(bn, (num_bits + 7) / 8, mbedtls_ctr_drbg_random, &ctr_drbg_ctx); \ |
| mbedtls_ctr_drbg_free(&ctr_drbg_ctx); \ |
| mbedtls_entropy_free(&entropy_ctx); \ |
| } while (0) |
| #define bn_modexp(bn, y, q, p) mbedtls_mpi_exp_mod(bn, y, q, p, 0) |
| |
| #endif |
| |
| #define MAX_BYTES 18000 |
| |
| #define dh_new() av_mallocz(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; |
| } |
| |
| if (bn_modexp(dh->pub_key, dh->g, dh->priv_key, dh->p) < 0) |
| return NULL; |
| |
| 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; |
| int ret; |
| |
| bn_new(k); |
| if (!k) |
| return -1; |
| |
| if ((ret = bn_modexp(k, pub_key_bn, dh->priv_key, dh->p)) < 0) { |
| bn_free(k); |
| return ret; |
| } |
| 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); |
| } |
| |
| 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 */ |
| if ((ret = bn_modexp(bn, y, q, p)) < 0) |
| goto fail; |
| |
| ret = AVERROR(EINVAL); |
| 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; |
| } |
