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C++

// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2017 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
// Non-cryptographic random number generator
#ifndef OPENVPN_RANDOM_MTRANDAPI_H
#define OPENVPN_RANDOM_MTRANDAPI_H
#include <random>
#include <openvpn/common/size.hpp>
#include <openvpn/random/randapi.hpp>
#include <openvpn/random/randbytestore.hpp>
namespace openvpn {
class MTRand : public RandomAPI
{
public:
OPENVPN_EXCEPTION(mtrand_error);
typedef RCPtr<MTRand> Ptr;
typedef std::mt19937_64 rand_type;
MTRand(RandomAPI& seed)
: rng(gen_seed(seed))
{
}
MTRand()
: rng(gen_seed())
{
}
MTRand(const rand_type::result_type seed)
: rng(seed)
{
}
// Random algorithm name
virtual std::string name() const
{
return "MTRand";
}
// Return true if algorithm is crypto-strength
virtual bool is_crypto() const
{
#ifdef OPENVPN_INSECURE_RANDOM // DO NOT enable in production!
return true;
#else
return false;
#endif
}
// Fill buffer with random bytes
virtual void rand_bytes(unsigned char *buf, size_t size)
{
if (!rndbytes(buf, size))
throw mtrand_error("rand_bytes failed");
}
// Like rand_bytes, but don't throw exception.
// Return true on successs, false on fail.
virtual bool rand_bytes_noexcept(unsigned char *buf, size_t size)
{
return rndbytes(buf, size);
}
rand_type::result_type rand()
{
return rng();
}
private:
bool rndbytes(unsigned char *buf, size_t size)
{
while (size--)
*buf++ = rbs.get_byte(rng);
return true;
}
static rand_type::result_type gen_seed(RandomAPI& seed)
{
return seed.rand_get<rand_type::result_type>();
}
static rand_type::result_type gen_seed()
{
std::random_device rd;
RandomByteStore<decltype(rd)> rbs;
rand_type::result_type ret;
rbs.fill(ret, rd);
return ret;
}
rand_type rng;
RandomByteStore<rand_type> rbs;
};
}
#endif