rng.h
/*
* Copyright (C) 2014-2017 Savoir-faire Linux Inc.
* Author : Adrien Béraud <adrien.beraud@savoirfairelinux.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#pragma once
#include <random>
#include <algorithm>
#include <functional>
namespace dht {
namespace crypto {
#ifndef _MSC_VER
#ifdef _WIN32
class random_device {
public:
using result_type = std::random_device::result_type;
using pseudo_engine = std::mt19937_64;
static_assert(
sizeof(result_type) == 2 ||
sizeof(result_type) == 4 ||
sizeof(result_type) == 8,
"result_type must be 16, 32 or 64 bits");
random_device();
result_type operator()();
static constexpr result_type min() {
return std::numeric_limits<result_type>::lowest();
}
static constexpr result_type max() {
return std::numeric_limits<result_type>::max();
}
double entropy() const {
if (hasRdrand() or hasRdseed())
return 1.;
return 0.;
}
static bool hasRdrand() {
static const bool hasrdrand = _hasRdrand();
return hasrdrand;
}
static bool hasRdseed() {
static const bool hasrdseed = _hasRdseed();
return hasrdseed;
}
private:
random_device& operator=(random_device&) = delete;
pseudo_engine gen;
std::uniform_int_distribution<result_type> dis {};
static bool hasIntelCpu();
static bool _hasRdrand();
static bool _hasRdseed();
struct CPUIDinfo {
unsigned int EAX;
unsigned int EBX;
unsigned int ECX;
unsigned int EDX;
CPUIDinfo(const unsigned int func, const unsigned int subfunc);
};
bool rdrandStep(result_type* r);
bool rdrand(result_type* r);
bool rdseedStep(result_type* r);
bool rdseed(result_type* r);
};
#else
using random_device = std::random_device;
#endif
#else
using random_device = std::random_device;
#endif
template<class T = std::mt19937, std::size_t N = T::state_size>
auto getSeededRandomEngine () -> typename std::enable_if<!!N, T>::type {
typename T::result_type random_data[N];
random_device source;
std::generate(std::begin(random_data), std::end(random_data), std::ref(source));
std::seed_seq seeds(std::begin(random_data), std::end(random_data));
T seededEngine (seeds);
return seededEngine;
}
}} // dht::crypto
dht
Definition: callbacks.h:34