1 /* 2 * RTMP Diffie-Hellmann utilities 3 * Copyright (c) 2012 Samuel Pitoiset 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22 #ifndef AVFORMAT_RTMPDH_H 23 #define AVFORMAT_RTMPDH_H 24 25 #include <stdint.h> 26 27 #include "config.h" 28 29 #if CONFIG_GMP 30 #include <gmp.h> 31 32 typedef mpz_ptr FFBigNum; 33 #elif CONFIG_GCRYPT 34 #include <gcrypt.h> 35 36 typedef gcry_mpi_t FFBigNum; 37 38 #elif CONFIG_OPENSSL 39 #include <openssl/bn.h> 40 #include <openssl/dh.h> 41 42 typedef BIGNUM *FFBigNum; 43 #elif CONFIG_MBEDTLS 44 #include <mbedtls/bignum.h> 45 46 typedef mbedtls_mpi *FFBigNum; 47 48 #endif 49 50 typedef struct FF_DH { 51 FFBigNum p; 52 FFBigNum g; 53 FFBigNum pub_key; 54 FFBigNum priv_key; 55 long length; 56 } FF_DH; 57 58 59 /** 60 * Initialize a Diffie-Hellmann context. 61 * 62 * @param key_len length of the key 63 * @return a new Diffie-Hellmann context on success, NULL otherwise 64 */ 65 FF_DH *ff_dh_init(int key_len); 66 67 /** 68 * Free a Diffie-Hellmann context. 69 * 70 * @param dh a Diffie-Hellmann context to free 71 */ 72 void ff_dh_free(FF_DH *dh); 73 74 /** 75 * Generate a public key. 76 * 77 * @param dh a Diffie-Hellmann context 78 * @return zero on success, negative value otherwise 79 */ 80 int ff_dh_generate_public_key(FF_DH *dh); 81 82 /** 83 * Write the public key into the given buffer. 84 * 85 * @param dh a Diffie-Hellmann context, containing the public key to write 86 * @param pub_key the buffer where the public key is written 87 * @param pub_key_len the length of the buffer 88 * @return zero on success, negative value otherwise 89 */ 90 int ff_dh_write_public_key(FF_DH *dh, uint8_t *pub_key, int pub_key_len); 91 92 /** 93 * Compute the shared secret key from the private FF_DH value and the 94 * other party's public value. 95 * 96 * @param dh a Diffie-Hellmann context, containing the private key 97 * @param pub_key the buffer containing the public key 98 * @param pub_key_len the length of the public key buffer 99 * @param secret_key the buffer where the secret key is written 100 * @param secret_key_len the length of the secret key buffer 101 * @return length of the shared secret key on success, negative value otherwise 102 */ 103 int ff_dh_compute_shared_secret_key(FF_DH *dh, const uint8_t *pub_key, 104 int pub_key_len, uint8_t *secret_key, 105 int secret_key_len); 106 107 #endif /* AVFORMAT_RTMPDH_H */ 108