1 /* 2 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved. 3 * (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "config.h" 28 #include "RandomNumber.h" 29 30 #include "CryptographicallyRandomNumber.h" 31 #include "RandomNumberSeed.h" 32 33 #include <limits> 34 #include <limits.h> 35 #include <stdint.h> 36 #include <stdlib.h> 37 38 #if USE(MERSENNE_TWISTER_19937) 39 extern "C" { 40 #include "mt19937ar.c" 41 } 42 #endif 43 44 #if PLATFORM(BREWMP) 45 #include <AEEAppGen.h> 46 #include <AEESource.h> 47 #include <AEEStdLib.h> 48 #include <wtf/brew/RefPtrBrew.h> 49 #include <wtf/brew/ShellBrew.h> 50 #endif 51 52 namespace WTF { 53 54 double randomNumber() 55 { 56 #if USE(OS_RANDOMNESS) 57 uint32_t bits = cryptographicallyRandomNumber(); 58 return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0); 59 #else 60 // Without OS_RANDOMNESS, we fall back to other random number generators 61 // that might not be cryptographically secure. Ideally, most ports would 62 // define USE(OS_RANDOMNESS). 63 64 #if !ENABLE(JSC_MULTIPLE_THREADS) 65 static bool s_initialized = false; 66 if (!s_initialized) { 67 initializeRandomNumberGenerator(); 68 s_initialized = true; 69 } 70 #endif 71 72 #if USE(MERSENNE_TWISTER_19937) 73 return genrand_res53(); 74 #elif PLATFORM(BREWMP) 75 uint32_t bits; 76 // Is this a cryptographically strong source of random numbers? If so, we 77 // should move this into OSRandomSource. 78 // http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp851.pdf 79 // is slightly unclear on this point, although it seems to imply that it is 80 // secure. 81 RefPtr<ISource> randomSource = createRefPtrInstance<ISource>(AEECLSID_RANDOM); 82 ISOURCE_Read(randomSource.get(), reinterpret_cast<char*>(&bits), 4); 83 84 return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0); 85 #else 86 uint32_t part1 = rand() & (RAND_MAX - 1); 87 uint32_t part2 = rand() & (RAND_MAX - 1); 88 // rand only provides 31 bits, and the low order bits of that aren't very random 89 // so we take the high 26 bits of part 1, and the high 27 bits of part2. 90 part1 >>= 5; // drop the low 5 bits 91 part2 >>= 4; // drop the low 4 bits 92 uint64_t fullRandom = part1; 93 fullRandom <<= 27; 94 fullRandom |= part2; 95 96 // Mask off the low 53bits 97 fullRandom &= (1LL << 53) - 1; 98 return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53); 99 #endif 100 #endif 101 } 102 103 } 104
