zcashd/src/random.cpp

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or https://www.opensource.org/licenses/mit-license.php .

#include "random.h"

#include "support/cleanse.h"
#ifdef WIN32
#include "compat.h" // for Windows API
#endif
#include "serialize.h"        // for begin_ptr(vec)
#include "util.h"             // for LogPrint()
#include "utilstrencodings.h" // for GetTime()

#include <limits>

#ifndef WIN32
#include <sys/time.h>
#endif

#include <librustzcash.h>

static inline int64_t GetPerformanceCounter()
{
    int64_t nCounter = 0;
#ifdef WIN32
    QueryPerformanceCounter((LARGE_INTEGER*)&nCounter);
#else
    timeval t;
    gettimeofday(&t, NULL);
    nCounter = (int64_t)(t.tv_sec * 1000000 + t.tv_usec);
#endif
    return nCounter;
}

void GetRandBytes(unsigned char* buf, size_t num)
{
    librustzcash_getrandom(buf, num);
}

uint64_t GetRand(uint64_t nMax)
{
    if (nMax == 0)
        return 0;

    // The range of the random source must be a multiple of the modulus
    // to give every possible output value an equal possibility
    uint64_t nRange = (std::numeric_limits<uint64_t>::max() / nMax) * nMax;
    uint64_t nRand = 0;
    do {
        GetRandBytes((unsigned char*)&nRand, sizeof(nRand));
    } while (nRand >= nRange);
    return (nRand % nMax);
}

int GetRandInt(int nMax)
{
    return GetRand(nMax);
}

uint256 GetRandHash()
{
    uint256 hash;
    GetRandBytes((unsigned char*)&hash, sizeof(hash));
    return hash;
}

FastRandomContext::FastRandomContext(bool fDeterministic)
{
    // The seed values have some unlikely fixed points which we avoid.
    if (fDeterministic) {
        Rz = Rw = 11;
    } else {
        uint32_t tmp;
        do {
            GetRandBytes((unsigned char*)&tmp, 4);
        } while (tmp == 0 || tmp == 0x9068ffffU);
        Rz = tmp;
        do {
            GetRandBytes((unsigned char*)&tmp, 4);
        } while (tmp == 0 || tmp == 0x464fffffU);
        Rw = tmp;
    }
}

int GenIdentity(int n)
{
    return n-1;
}