wtf/OSRandomSource.cpp

   1 /*
   2  * Copyright (C) 2011 Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY GOOGLE, INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "OSRandomSource.h"
  28
  29 #include <stdint.h>
  30 #include <stdlib.h>
  31
  32 #if OS(SYMBIAN)
  33 #include <e32math.h>
  34 #endif
  35
  36 #if OS(UNIX)
  37 #include <fcntl.h>
  38 #include <unistd.h>
  39 #endif
  40
  41 #if OS(WINDOWS)
  42 #include <windows.h>
  43 #include <wincrypt.h> // windows.h must be included before wincrypt.h.
  44 #endif
  45
  46 namespace WTF {
  47
  48 #if USE(OS_RANDOMNESS)
  49 void cryptographicallyRandomValuesFromOS(unsigned char* buffer, size_t length)
  50 {
  51 #if OS(SYMBIAN)
  52     TInt random;
  53     while (length > sizeof(random)) {
  54         random = Math::Random();
  55         memcpy(buffer, &random, sizeof(random));
  56         length -= sizeof(random);
  57         buffer += sizeof(random);
  58     }
  59     if (length > 0) {
  60         random = Math::Random();
  61         memcpy(buffer, &random, length);
  62     }
  63 #elif OS(UNIX)
  64     int fd = open("/dev/urandom", O_RDONLY, 0);
  65     if (fd < 0)
  66         CRASH(); // We need /dev/urandom for this API to work...
  67
  68     if (read(fd, buffer, length) != static_cast<ssize_t>(length))
  69         CRASH();
  70
  71     close(fd);
  72 #elif OS(WINDOWS)
  73     HCRYPTPROV hCryptProv = 0;
  74     if (!CryptAcquireContext(&hCryptProv, 0, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
  75         CRASH();
  76     if (!CryptGenRandom(hCryptProv, length, buffer))
  77         CRASH();
  78     CryptReleaseContext(hCryptProv, 0);
  79 #else
  80     #error "This configuration doesn't have a strong source of randomness."
  81     // WARNING: When adding new sources of OS randomness, the randomness must
  82     //          be of cryptographic quality!
  83 #endif
  84 }
  85 #endif
  86
  87 }