| /* |
| * Copyright (c) 1996, David Mazieres <dm@uun.org> |
| * Copyright (c) 2008, Damien Miller <djm@openbsd.org> |
| * |
| * Permission to use, copy, modify, and distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
| * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
| * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| */ |
| |
| /* |
| * Arc4 random number generator for OpenBSD. |
| * |
| * This code is derived from section 17.1 of Applied Cryptography, |
| * second edition, which describes a stream cipher allegedly |
| * compatible with RSA Labs "RC4" cipher (the actual description of |
| * which is a trade secret). The same algorithm is used as a stream |
| * cipher called "arcfour" in Tatu Ylonen's ssh package. |
| * |
| * RC4 is a registered trademark of RSA Laboratories. |
| */ |
| |
| #include "config.h" |
| #include "CryptographicallyRandomNumber.h" |
| |
| #include "OSRandomSource.h" |
| #include "StdLibExtras.h" |
| #include "ThreadingPrimitives.h" |
| |
| namespace WTF { |
| |
| #if USE(OS_RANDOMNESS) |
| |
| namespace { |
| |
| class ARC4Stream { |
| public: |
| ARC4Stream(); |
| |
| uint8_t i; |
| uint8_t j; |
| uint8_t s[256]; |
| }; |
| |
| class ARC4RandomNumberGenerator { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| ARC4RandomNumberGenerator(); |
| |
| uint32_t randomNumber(); |
| void randomValues(void* buffer, size_t length); |
| |
| private: |
| inline void addRandomData(unsigned char *data, int length); |
| void stir(); |
| void stirIfNeeded(); |
| inline uint8_t getByte(); |
| inline uint32_t getWord(); |
| |
| ARC4Stream m_stream; |
| int m_count; |
| Mutex m_mutex; |
| }; |
| |
| ARC4Stream::ARC4Stream() |
| { |
| for (int n = 0; n < 256; n++) |
| s[n] = n; |
| i = 0; |
| j = 0; |
| } |
| |
| ARC4RandomNumberGenerator::ARC4RandomNumberGenerator() |
| : m_count(0) |
| { |
| } |
| |
| void ARC4RandomNumberGenerator::addRandomData(unsigned char* data, int length) |
| { |
| m_stream.i--; |
| for (int n = 0; n < 256; n++) { |
| m_stream.i++; |
| uint8_t si = m_stream.s[m_stream.i]; |
| m_stream.j += si + data[n % length]; |
| m_stream.s[m_stream.i] = m_stream.s[m_stream.j]; |
| m_stream.s[m_stream.j] = si; |
| } |
| m_stream.j = m_stream.i; |
| } |
| |
| void ARC4RandomNumberGenerator::stir() |
| { |
| unsigned char randomness[128]; |
| size_t length = sizeof(randomness); |
| cryptographicallyRandomValuesFromOS(randomness, length); |
| addRandomData(randomness, length); |
| |
| // Discard early keystream, as per recommendations in: |
| // http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps |
| for (int i = 0; i < 256; i++) |
| getByte(); |
| m_count = 1600000; |
| } |
| |
| void ARC4RandomNumberGenerator::stirIfNeeded() |
| { |
| if (m_count <= 0) |
| stir(); |
| } |
| |
| uint8_t ARC4RandomNumberGenerator::getByte() |
| { |
| m_stream.i++; |
| uint8_t si = m_stream.s[m_stream.i]; |
| m_stream.j += si; |
| uint8_t sj = m_stream.s[m_stream.j]; |
| m_stream.s[m_stream.i] = sj; |
| m_stream.s[m_stream.j] = si; |
| return (m_stream.s[(si + sj) & 0xff]); |
| } |
| |
| uint32_t ARC4RandomNumberGenerator::getWord() |
| { |
| uint32_t val; |
| val = getByte() << 24; |
| val |= getByte() << 16; |
| val |= getByte() << 8; |
| val |= getByte(); |
| return val; |
| } |
| |
| uint32_t ARC4RandomNumberGenerator::randomNumber() |
| { |
| MutexLocker locker(m_mutex); |
| |
| m_count -= 4; |
| stirIfNeeded(); |
| return getWord(); |
| } |
| |
| void ARC4RandomNumberGenerator::randomValues(void* buffer, size_t length) |
| { |
| MutexLocker locker(m_mutex); |
| |
| unsigned char* result = reinterpret_cast<unsigned char*>(buffer); |
| stirIfNeeded(); |
| while (length--) { |
| m_count--; |
| stirIfNeeded(); |
| result[length] = getByte(); |
| } |
| } |
| |
| ARC4RandomNumberGenerator& sharedRandomNumberGenerator() |
| { |
| DEFINE_STATIC_LOCAL(ARC4RandomNumberGenerator, randomNumberGenerator, ()); |
| return randomNumberGenerator; |
| } |
| |
| } |
| |
| uint32_t cryptographicallyRandomNumber() |
| { |
| return sharedRandomNumberGenerator().randomNumber(); |
| } |
| |
| void cryptographicallyRandomValues(void* buffer, size_t length) |
| { |
| sharedRandomNumberGenerator().randomValues(buffer, length); |
| } |
| |
| #endif |
| |
| } |