2 * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
4 * This file is part of Libav.
6 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 #if HAVE_CRYPTGENRANDOM
34 #include "intreadwrite.h"
37 #include "random_seed.h"
40 static int read_random(uint32_t *dst, const char *file)
43 int fd = avpriv_open(file, O_RDONLY);
48 err = read(fd, dst, sizeof(*dst));
57 static uint32_t get_generic_seed(void)
59 struct AVSHA *sha = av_sha_alloc();
61 static uint64_t i = 0;
62 static uint32_t buffer[512] = { 0 };
63 unsigned char digest[20];
72 buffer[++i & 511] += (t - last_t) % 3294638521U;
73 if (last_i && i - last_i > 4 || i - last_i > 64)
82 // Unable to allocate an sha context, just xor the buffer together
83 // to create something hopefully unique.
84 for (j = 0; j < 512; j++)
88 av_sha_init(sha, 160);
89 av_sha_update(sha, (const uint8_t *) buffer, sizeof(buffer));
90 av_sha_final(sha, digest);
92 return AV_RB32(digest) + AV_RB32(digest + 16);
95 uint32_t av_get_random_seed(void)
99 #if HAVE_CRYPTGENRANDOM
101 if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
102 CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
103 BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
104 CryptReleaseContext(provider, 0);
110 if (read_random(&seed, "/dev/urandom") == sizeof(seed))
112 if (read_random(&seed, "/dev/random") == sizeof(seed))
114 return get_generic_seed();