424 lines
13 KiB
C
424 lines
13 KiB
C
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/*
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* RTMP Diffie-Hellmann utilities
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* Copyright (c) 2009 Andrej Stepanchuk
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* Copyright (c) 2009-2010 Howard Chu
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* Copyright (c) 2012 Samuel Pitoiset
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* RTMP Diffie-Hellmann utilities
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*/
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#include <stdint.h>
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#include <string.h>
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#include "config.h"
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#include "libavutil/attributes.h"
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#include "libavutil/error.h"
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#include "libavutil/mem.h"
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#include "libavutil/random_seed.h"
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#include "rtmpdh.h"
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#if CONFIG_MBEDTLS
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#include <mbedtls/ctr_drbg.h>
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#include <mbedtls/entropy.h>
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#endif
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#define P1024 \
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"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" \
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"29024E088A67CC74020BBEA63B139B22514A08798E3404DD" \
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"EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" \
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"E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
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"EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" \
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"FFFFFFFFFFFFFFFF"
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#define Q1024 \
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"7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68" \
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"948127044533E63A0105DF531D89CD9128A5043CC71A026E" \
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"F7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122" \
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"F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6" \
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"F71C35FDAD44CFD2D74F9208BE258FF324943328F67329C0" \
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"FFFFFFFFFFFFFFFF"
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#if CONFIG_GMP
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#define bn_new(bn) \
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do { \
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bn = av_malloc(sizeof(*bn)); \
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if (bn) \
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mpz_init2(bn, 1); \
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} while (0)
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#define bn_free(bn) \
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do { \
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mpz_clear(bn); \
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av_free(bn); \
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} while (0)
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#define bn_set_word(bn, w) mpz_set_ui(bn, w)
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#define bn_cmp(a, b) mpz_cmp(a, b)
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#define bn_copy(to, from) mpz_set(to, from)
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#define bn_sub_word(bn, w) mpz_sub_ui(bn, bn, w)
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#define bn_cmp_1(bn) mpz_cmp_ui(bn, 1)
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#define bn_num_bytes(bn) (mpz_sizeinbase(bn, 2) + 7) / 8
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#define bn_bn2bin(bn, buf, len) \
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do { \
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memset(buf, 0, len); \
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if (bn_num_bytes(bn) <= len) \
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mpz_export(buf, NULL, 1, 1, 0, 0, bn); \
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} while (0)
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#define bn_bin2bn(bn, buf, len) \
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do { \
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bn_new(bn); \
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if (bn) \
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mpz_import(bn, len, 1, 1, 0, 0, buf); \
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} while (0)
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#define bn_hex2bn(bn, buf, ret) \
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do { \
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bn_new(bn); \
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if (bn) \
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ret = (mpz_set_str(bn, buf, 16) == 0); \
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else \
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ret = 1; \
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} while (0)
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#define bn_random(bn, num_bits) \
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do { \
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int bits = num_bits; \
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mpz_set_ui(bn, 0); \
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for (bits = num_bits; bits > 0; bits -= 32) { \
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mpz_mul_2exp(bn, bn, 32); \
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mpz_add_ui(bn, bn, av_get_random_seed()); \
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} \
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mpz_fdiv_r_2exp(bn, bn, num_bits); \
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} while (0)
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static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p)
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{
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mpz_powm(bn, y, q, p);
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return 0;
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}
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#elif CONFIG_GCRYPT
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#define bn_new(bn) \
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do { \
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if (!gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P)) { \
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if (!gcry_check_version("1.5.4")) \
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return AVERROR(EINVAL); \
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gcry_control(GCRYCTL_DISABLE_SECMEM, 0); \
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gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0); \
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} \
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bn = gcry_mpi_new(1); \
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} while (0)
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#define bn_free(bn) gcry_mpi_release(bn)
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#define bn_set_word(bn, w) gcry_mpi_set_ui(bn, w)
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#define bn_cmp(a, b) gcry_mpi_cmp(a, b)
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#define bn_copy(to, from) gcry_mpi_set(to, from)
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#define bn_sub_word(bn, w) gcry_mpi_sub_ui(bn, bn, w)
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#define bn_cmp_1(bn) gcry_mpi_cmp_ui(bn, 1)
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#define bn_num_bytes(bn) (gcry_mpi_get_nbits(bn) + 7) / 8
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#define bn_bn2bin(bn, buf, len) gcry_mpi_print(GCRYMPI_FMT_USG, buf, len, NULL, bn)
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#define bn_bin2bn(bn, buf, len) gcry_mpi_scan(&bn, GCRYMPI_FMT_USG, buf, len, NULL)
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#define bn_hex2bn(bn, buf, ret) ret = (gcry_mpi_scan(&bn, GCRYMPI_FMT_HEX, buf, 0, 0) == 0)
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#define bn_random(bn, num_bits) gcry_mpi_randomize(bn, num_bits, GCRY_WEAK_RANDOM)
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static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p)
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{
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gcry_mpi_powm(bn, y, q, p);
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return 0;
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}
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#elif CONFIG_OPENSSL
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#define bn_new(bn) bn = BN_new()
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#define bn_free(bn) BN_free(bn)
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#define bn_set_word(bn, w) BN_set_word(bn, w)
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#define bn_cmp(a, b) BN_cmp(a, b)
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#define bn_copy(to, from) BN_copy(to, from)
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#define bn_sub_word(bn, w) BN_sub_word(bn, w)
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#define bn_cmp_1(bn) BN_cmp(bn, BN_value_one())
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#define bn_num_bytes(bn) BN_num_bytes(bn)
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#define bn_bn2bin(bn, buf, len) BN_bn2bin(bn, buf)
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#define bn_bin2bn(bn, buf, len) bn = BN_bin2bn(buf, len, 0)
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#define bn_hex2bn(bn, buf, ret) ret = BN_hex2bn(&bn, buf)
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#define bn_random(bn, num_bits) BN_rand(bn, num_bits, 0, 0)
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static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p)
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{
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BN_CTX *ctx = BN_CTX_new();
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if (!ctx)
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return AVERROR(ENOMEM);
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if (!BN_mod_exp(bn, y, q, p, ctx)) {
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BN_CTX_free(ctx);
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return AVERROR(EINVAL);
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}
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BN_CTX_free(ctx);
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return 0;
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}
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#elif CONFIG_MBEDTLS
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#define bn_new(bn) \
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do { \
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bn = av_malloc(sizeof(*bn)); \
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if (bn) \
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mbedtls_mpi_init(bn); \
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} while (0)
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#define bn_free(bn) \
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do { \
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mbedtls_mpi_free(bn); \
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av_free(bn); \
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} while (0)
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#define bn_set_word(bn, w) mbedtls_mpi_lset(bn, w)
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#define bn_cmp(a, b) mbedtls_mpi_cmp_mpi(a, b)
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#define bn_copy(to, from) mbedtls_mpi_copy(to, from)
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#define bn_sub_word(bn, w) mbedtls_mpi_sub_int(bn, bn, w)
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#define bn_cmp_1(bn) mbedtls_mpi_cmp_int(bn, 1)
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#define bn_num_bytes(bn) (mbedtls_mpi_bitlen(bn) + 7) / 8
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#define bn_bn2bin(bn, buf, len) mbedtls_mpi_write_binary(bn, buf, len)
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#define bn_bin2bn(bn, buf, len) \
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do { \
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bn_new(bn); \
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if (bn) \
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mbedtls_mpi_read_binary(bn, buf, len); \
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} while (0)
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#define bn_hex2bn(bn, buf, ret) \
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do { \
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bn_new(bn); \
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if (bn) \
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ret = (mbedtls_mpi_read_string(bn, 16, buf) == 0); \
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else \
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ret = 1; \
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} while (0)
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#define bn_random(bn, num_bits) \
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do { \
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mbedtls_entropy_context entropy_ctx; \
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mbedtls_ctr_drbg_context ctr_drbg_ctx; \
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\
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mbedtls_entropy_init(&entropy_ctx); \
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mbedtls_ctr_drbg_init(&ctr_drbg_ctx); \
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mbedtls_ctr_drbg_seed(&ctr_drbg_ctx, \
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mbedtls_entropy_func, \
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&entropy_ctx, \
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NULL, 0); \
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mbedtls_mpi_fill_random(bn, (num_bits + 7) / 8, mbedtls_ctr_drbg_random, &ctr_drbg_ctx); \
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mbedtls_ctr_drbg_free(&ctr_drbg_ctx); \
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mbedtls_entropy_free(&entropy_ctx); \
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} while (0)
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#define bn_modexp(bn, y, q, p) mbedtls_mpi_exp_mod(bn, y, q, p, 0)
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#endif
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#define MAX_BYTES 18000
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#define dh_new() av_mallocz(sizeof(FF_DH))
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static FFBigNum dh_generate_key(FF_DH *dh)
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{
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int num_bytes;
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num_bytes = bn_num_bytes(dh->p) - 1;
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if (num_bytes <= 0 || num_bytes > MAX_BYTES)
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return NULL;
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bn_new(dh->priv_key);
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if (!dh->priv_key)
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return NULL;
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bn_random(dh->priv_key, 8 * num_bytes);
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bn_new(dh->pub_key);
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if (!dh->pub_key) {
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bn_free(dh->priv_key);
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return NULL;
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}
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if (bn_modexp(dh->pub_key, dh->g, dh->priv_key, dh->p) < 0)
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return NULL;
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return dh->pub_key;
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}
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static int dh_compute_key(FF_DH *dh, FFBigNum pub_key_bn,
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uint32_t secret_key_len, uint8_t *secret_key)
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{
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FFBigNum k;
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int ret;
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bn_new(k);
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if (!k)
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return -1;
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if ((ret = bn_modexp(k, pub_key_bn, dh->priv_key, dh->p)) < 0) {
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bn_free(k);
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return ret;
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}
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bn_bn2bin(k, secret_key, secret_key_len);
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bn_free(k);
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/* return the length of the shared secret key like DH_compute_key */
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return secret_key_len;
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}
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void ff_dh_free(FF_DH *dh)
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{
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if (!dh)
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return;
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bn_free(dh->p);
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bn_free(dh->g);
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bn_free(dh->pub_key);
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bn_free(dh->priv_key);
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av_free(dh);
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}
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static int dh_is_valid_public_key(FFBigNum y, FFBigNum p, FFBigNum q)
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{
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FFBigNum bn = NULL;
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int ret = AVERROR(EINVAL);
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bn_new(bn);
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if (!bn)
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return AVERROR(ENOMEM);
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/* y must lie in [2, p - 1] */
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bn_set_word(bn, 1);
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if (!bn_cmp(y, bn))
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goto fail;
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/* bn = p - 2 */
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bn_copy(bn, p);
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bn_sub_word(bn, 1);
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if (!bn_cmp(y, bn))
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goto fail;
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/* Verify with Sophie-Germain prime
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*
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* This is a nice test to make sure the public key position is calculated
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* correctly. This test will fail in about 50% of the cases if applied to
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* random data.
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*/
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/* y must fulfill y^q mod p = 1 */
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if ((ret = bn_modexp(bn, y, q, p)) < 0)
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goto fail;
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ret = AVERROR(EINVAL);
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if (bn_cmp_1(bn))
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goto fail;
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ret = 0;
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fail:
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bn_free(bn);
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return ret;
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}
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av_cold FF_DH *ff_dh_init(int key_len)
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{
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FF_DH *dh;
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int ret;
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if (!(dh = dh_new()))
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return NULL;
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bn_new(dh->g);
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if (!dh->g)
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goto fail;
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bn_hex2bn(dh->p, P1024, ret);
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if (!ret)
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goto fail;
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|
|
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;
|
||
|
|
}
|