65e3a1e762
We're using GetRandomBytes in several contexts where it's either unwieldy to return an error, or an error would mean a fatal exception anyhow. @gmaxwell checked OpenSSL a while ago and discovered that it never actually fails, but it can't hurt to be a bit paranoid here.
138 lines
3.9 KiB
C++
138 lines
3.9 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2014 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "random.h"
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#ifdef WIN32
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#include "compat.h" // for Windows API
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#endif
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#include "serialize.h" // for begin_ptr(vec)
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#include "util.h" // for LogPrint()
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#include "utilstrencodings.h" // for GetTime()
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#include <limits>
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#ifndef WIN32
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#include <sys/time.h>
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#endif
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#include <openssl/crypto.h>
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#include <openssl/err.h>
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#include <openssl/rand.h>
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static inline int64_t GetPerformanceCounter()
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{
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int64_t nCounter = 0;
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#ifdef WIN32
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QueryPerformanceCounter((LARGE_INTEGER*)&nCounter);
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#else
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timeval t;
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gettimeofday(&t, NULL);
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nCounter = (int64_t)(t.tv_sec * 1000000 + t.tv_usec);
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#endif
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return nCounter;
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}
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void RandAddSeed()
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{
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// Seed with CPU performance counter
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int64_t nCounter = GetPerformanceCounter();
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RAND_add(&nCounter, sizeof(nCounter), 1.5);
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OPENSSL_cleanse((void*)&nCounter, sizeof(nCounter));
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}
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void RandAddSeedPerfmon()
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{
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RandAddSeed();
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// This can take up to 2 seconds, so only do it every 10 minutes
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static int64_t nLastPerfmon;
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if (GetTime() < nLastPerfmon + 10 * 60)
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return;
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nLastPerfmon = GetTime();
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#ifdef WIN32
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// Don't need this on Linux, OpenSSL automatically uses /dev/urandom
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// Seed with the entire set of perfmon data
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std::vector<unsigned char> vData(250000, 0);
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long ret = 0;
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unsigned long nSize = 0;
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const size_t nMaxSize = 10000000; // Bail out at more than 10MB of performance data
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while (true) {
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nSize = vData.size();
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ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", NULL, NULL, begin_ptr(vData), &nSize);
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if (ret != ERROR_MORE_DATA || vData.size() >= nMaxSize)
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break;
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vData.resize(std::max((vData.size() * 3) / 2, nMaxSize)); // Grow size of buffer exponentially
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}
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RegCloseKey(HKEY_PERFORMANCE_DATA);
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if (ret == ERROR_SUCCESS) {
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RAND_add(begin_ptr(vData), nSize, nSize / 100.0);
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OPENSSL_cleanse(begin_ptr(vData), nSize);
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LogPrint("rand", "%s: %lu bytes\n", __func__, nSize);
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} else {
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static bool warned = false; // Warn only once
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if (!warned) {
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LogPrintf("%s: Warning: RegQueryValueExA(HKEY_PERFORMANCE_DATA) failed with code %i\n", __func__, ret);
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warned = true;
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}
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}
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#endif
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}
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void GetRandBytes(unsigned char* buf, int num)
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{
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if (RAND_bytes(buf, num) != 1) {
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LogPrintf("%s: OpenSSL RAND_bytes() failed with error: %s\n", __func__, ERR_error_string(ERR_get_error(), NULL));
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assert(false);
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}
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}
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uint64_t GetRand(uint64_t nMax)
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{
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if (nMax == 0)
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return 0;
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// The range of the random source must be a multiple of the modulus
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// to give every possible output value an equal possibility
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uint64_t nRange = (std::numeric_limits<uint64_t>::max() / nMax) * nMax;
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uint64_t nRand = 0;
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do {
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GetRandBytes((unsigned char*)&nRand, sizeof(nRand));
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} while (nRand >= nRange);
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return (nRand % nMax);
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}
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int GetRandInt(int nMax)
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{
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return GetRand(nMax);
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}
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uint256 GetRandHash()
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{
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uint256 hash;
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GetRandBytes((unsigned char*)&hash, sizeof(hash));
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return hash;
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}
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uint32_t insecure_rand_Rz = 11;
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uint32_t insecure_rand_Rw = 11;
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void seed_insecure_rand(bool fDeterministic)
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{
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// The seed values have some unlikely fixed points which we avoid.
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if (fDeterministic) {
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insecure_rand_Rz = insecure_rand_Rw = 11;
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} else {
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uint32_t tmp;
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do {
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GetRandBytes((unsigned char*)&tmp, 4);
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} while (tmp == 0 || tmp == 0x9068ffffU);
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insecure_rand_Rz = tmp;
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do {
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GetRandBytes((unsigned char*)&tmp, 4);
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} while (tmp == 0 || tmp == 0x464fffffU);
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insecure_rand_Rw = tmp;
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}
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}
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