/* * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved. * (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/) * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "config.h" #include "RandomNumber.h" #include "CryptographicallyRandomNumber.h" #include "RandomNumberSeed.h" #include <limits> #include <limits.h> #include <stdint.h> #include <stdlib.h> #if USE(MERSENNE_TWISTER_19937) extern "C" { #include "mt19937ar.c" } #endif #if PLATFORM(BREWMP) #include <AEEAppGen.h> #include <AEESource.h> #include <AEEStdLib.h> #include <wtf/brew/RefPtrBrew.h> #include <wtf/brew/ShellBrew.h> #endif namespace WTF { double randomNumber() { #if USE(OS_RANDOMNESS) uint32_t bits = cryptographicallyRandomNumber(); return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0); #else // Without OS_RANDOMNESS, we fall back to other random number generators // that might not be cryptographically secure. Ideally, most ports would // define USE(OS_RANDOMNESS). #if !ENABLE(WTF_MULTIPLE_THREADS) static bool s_initialized = false; if (!s_initialized) { initializeRandomNumberGenerator(); s_initialized = true; } #endif #if USE(MERSENNE_TWISTER_19937) return genrand_res53(); #elif PLATFORM(BREWMP) uint32_t bits; // Is this a cryptographically strong source of random numbers? If so, we // should move this into OSRandomSource. // http://csrc.nist.gov/groups/STM/cmvp/documents/140-1/140sp/140sp851.pdf // is slightly unclear on this point, although it seems to imply that it is // secure. RefPtr<ISource> randomSource = createRefPtrInstance<ISource>(AEECLSID_RANDOM); ISOURCE_Read(randomSource.get(), reinterpret_cast<char*>(&bits), 4); return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0); #else uint32_t part1 = rand() & (RAND_MAX - 1); uint32_t part2 = rand() & (RAND_MAX - 1); // rand only provides 31 bits, and the low order bits of that aren't very random // so we take the high 26 bits of part 1, and the high 27 bits of part2. part1 >>= 5; // drop the low 5 bits part2 >>= 4; // drop the low 4 bits uint64_t fullRandom = part1; fullRandom <<= 27; fullRandom |= part2; // Mask off the low 53bits fullRandom &= (1LL << 53) - 1; return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53); #endif #endif } }