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/*
This file is part of cpp-ethereum.
cpp-ethereum 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.
cpp-ethereum 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 cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file ProofOfWork.cpp
* @author Gav Wood <i@gavwood.com>
* @date 2014
*/
#if !ETH_LANGUAGES
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#include <boost/detail/endian.hpp>
#include <chrono>
#include <array>
#include <random>
#include <thread>
#include <libethcore/CryptoHeaders.h>
#include <libdevcore/Common.h>
#include "ProofOfWork.h"
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using namespace std;
using namespace std::chrono;
namespace dev
{
namespace eth
{
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template <class _T>
static inline void update(_T& _sha, u256 const& _value)
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{
int i = 0;
for (u256 v = _value; v; ++i, v >>= 8) {}
byte buf[32];
bytesRef bufRef(buf, i);
toBigEndian(_value, bufRef);
_sha.Update(buf, i);
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}
template <class _T>
static inline void update(_T& _sha, h256 const& _value)
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{
int i = 0;
byte const* data = _value.data();
for (; i != 32 && data[i] == 0; ++i);
_sha.Update(data + i, 32 - i);
}
template <class _T>
static inline h256 get(_T& _sha)
{
h256 ret;
_sha.TruncatedFinal(&ret[0], 32);
return ret;
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}
h256 DaggerEvaluator::node(h256 const& _root, h256 const& _xn, uint_fast32_t _L, uint_fast32_t _i)
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{
if (_L == _i)
return _root;
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u256 m = (_L == 9) ? 16 : 3;
CryptoPP::SHA3_256 bsha;
for (uint_fast32_t k = 0; k < m; ++k)
{
CryptoPP::SHA3_256 sha;
update(sha, _root);
update(sha, _xn);
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update(sha, (u256)_L);
update(sha, (u256)_i);
update(sha, (u256)k);
uint_fast32_t pk = (uint_fast32_t)(u256)get(sha) & ((1 << ((_L - 1) * 3)) - 1);
auto u = node(_root, _xn, _L - 1, pk);
update(bsha, u);
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}
return get(bsha);
}
h256 DaggerEvaluator::eval(h256 const& _root, h256 const& _nonce)
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{
h256 extranonce = (u256)_nonce >> 26; // with xn = floor(n / 2^26) -> assuming this is with xn = floor(N / 2^26)
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CryptoPP::SHA3_256 bsha;
for (uint_fast32_t k = 0; k < 4; ++k)
{
//sha256(D || xn || i || k) -> sha256(D || xn || k) - there's no 'i' here!
CryptoPP::SHA3_256 sha;
update(sha, _root);
update(sha, extranonce);
update(sha, _nonce);
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update(sha, (u256)k);
uint_fast32_t pk = (uint_fast32_t)(u256)get(sha) & 0x1ffffff; // mod 8^8 * 2 [ == mod 2^25 ?! ] [ == & ((1 << 25) - 1) ] [ == & 0x1ffffff ]
auto u = node(_root, extranonce, 9, pk);
update(bsha, u);
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}
return get(bsha);
}
}
}
#endif