2 * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
29 #if HAVE_CRYPTGENRANDOM
39 #include "intreadwrite.h"
41 #include "random_seed.h"
48 static int read_random(uint32_t *dst, const char *file)
51 int fd = avpriv_open(file, O_RDONLY);
56 err = read(fd, dst, sizeof(*dst));
65 static uint32_t get_generic_seed(void)
68 struct AVSHA *sha = (void*)tmp;
71 static uint64_t i = 0;
72 static uint32_t buffer[512] = { 0 };
73 unsigned char digest[20];
76 av_assert0(sizeof(tmp) >= av_sha_size);
79 memset(buffer, 0, sizeof(buffer));
83 buffer[13] ^= AV_READ_TIME();
84 buffer[41] ^= AV_READ_TIME()>>32;
90 if (last_t + 2*last_td + 1 >= t) {
92 buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U);
95 buffer[++i & 511] += last_td % 3294638521U;
96 if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8)
103 buffer[0] = buffer[1] = 0;
106 buffer[111] += AV_READ_TIME();
110 av_sha_init(sha, 160);
111 av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer));
112 av_sha_final(sha, digest);
113 return AV_RB32(digest) + AV_RB32(digest + 16);
116 uint32_t av_get_random_seed(void)
120 #if HAVE_CRYPTGENRANDOM
122 if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
123 CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
124 BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
125 CryptReleaseContext(provider, 0);
135 if (read_random(&seed, "/dev/urandom") == sizeof(seed))
137 if (read_random(&seed, "/dev/random") == sizeof(seed))
139 return get_generic_seed();