solidity/libdevcore/SwarmHash.cpp
2019-06-27 12:48:51 +02:00

117 lines
3.0 KiB
C++

/*
This file is part of solidity.
solidity 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.
solidity 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 solidity. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file SwarmHash.cpp
*/
#include <libdevcore/SwarmHash.h>
#include <libdevcore/Keccak256.h>
using namespace std;
using namespace dev;
namespace
{
bytes toLittleEndian(size_t _size)
{
bytes encoded(8);
for (size_t i = 0; i < 8; ++i)
encoded[i] = (_size >> (8 * i)) & 0xff;
return encoded;
}
h256 swarmHashSimple(bytesConstRef _data, size_t _size)
{
return keccak256(toLittleEndian(_size) + _data.toBytes());
}
h256 swarmHashIntermediate(string const& _input, size_t _offset, size_t _length)
{
bytesConstRef ref;
bytes innerNodes;
if (_length <= 0x1000)
ref = bytesConstRef(_input).cropped(_offset, _length);
else
{
size_t maxRepresentedSize = 0x1000;
while (maxRepresentedSize * (0x1000 / 32) < _length)
maxRepresentedSize *= (0x1000 / 32);
for (size_t i = 0; i < _length; i += maxRepresentedSize)
{
size_t size = std::min(maxRepresentedSize, _length - i);
innerNodes += swarmHashIntermediate(_input, _offset + i, size).asBytes();
}
ref = bytesConstRef(&innerNodes);
}
return swarmHashSimple(ref, _length);
}
h256 bmtHash(bytesConstRef _data)
{
if (_data.size() <= 64)
return keccak256(_data);
size_t midPoint = _data.size() / 2;
return keccak256(
bmtHash(_data.cropped(0, midPoint)).asBytes() +
bmtHash(_data.cropped(midPoint)).asBytes()
);
}
h256 chunkHash(bytesConstRef const _data, bool _forceHigherLevel = false)
{
bytes dataToHash;
if (_data.size() < 0x1000)
dataToHash = _data.toBytes();
else if (_data.size() == 0x1000 && !_forceHigherLevel)
dataToHash = _data.toBytes();
else
{
size_t maxRepresentedSize = 0x1000;
while (maxRepresentedSize * (0x1000 / 32) < _data.size())
maxRepresentedSize *= (0x1000 / 32);
// If remaining size is 0x1000, but maxRepresentedSize is not,
// we have to still do one level of the chunk hashes.
bool forceHigher = maxRepresentedSize > 0x1000;
for (size_t i = 0; i < _data.size(); i += maxRepresentedSize)
{
size_t size = std::min(maxRepresentedSize, _data.size() - i);
dataToHash += chunkHash(_data.cropped(i, size), forceHigher).asBytes();
}
}
dataToHash.resize(0x1000, 0);
return keccak256(toLittleEndian(_data.size()) + bmtHash(&dataToHash).asBytes());
}
}
h256 dev::bzzr0Hash(string const& _input)
{
return swarmHashIntermediate(_input, 0, _input.size());
}
h256 dev::bzzr1Hash(bytes const& _input)
{
if (_input.empty())
return h256{};
return chunkHash(&_input);
}