aboutsummaryrefslogtreecommitdiffstats
path: root/libdevcore/SwarmHash.cpp
blob: 583d84b1f14229ff0bab2dc4990f164ea0d2288c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
/*
    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 SwarmHash.cpp
 */

#include <libdevcore/SwarmHash.h>

#include <libdevcore/SHA3.h>

using namespace std;
using namespace dev;


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 dev::swarmHash(bytes const& _input)
{
    bytes data = _input;
    size_t lastChunkSize = 0;
    size_t level = 0;
    do
    {
        bytes innerNodes;
        size_t i = 0;
        do
        {
            size_t bytes = std::min<size_t>(0x1000, data.size() - i);
            size_t size = bytes << (7 * level);
            if (i + 0x1000 >= data.size())
            {
                // last node
                size = level == 0 ? bytes : ((bytes - 32) << (7 * level)) + lastChunkSize;
                lastChunkSize = size;
            }
            innerNodes += swarmHashSimple(bytesConstRef(_input.data() + i, bytes), size).asBytes();
            i += 0x1000;
        }
        while (i < data.size());
        data = std::move(innerNodes);
        level++;
    }
    while (data.size() > 32);
    return h256(data);
}