path: root/libdevcore/Keccak256.cpp

/*
    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 SHA3.cpp
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#include <libdevcore/Keccak256.h>

#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;
using namespace dev;

namespace dev
{

namespace
{

/** libkeccak-tiny
 *
 * A single-file implementation of SHA-3 and SHAKE.
 *
 * Implementor: David Leon Gil
 * License: CC0, attribution kindly requested. Blame taken too,
 * but not liability.
 */

/******** The Keccak-f[1600] permutation ********/

/*** Constants. ***/
static const uint8_t rho[24] = \
    { 1,  3,   6, 10, 15, 21,
    28, 36, 45, 55,  2, 14,
    27, 41, 56,  8, 25, 43,
    62, 18, 39, 61, 20, 44};
static const uint8_t pi[24] = \
    {10,  7, 11, 17, 18, 3,
    5, 16,  8, 21, 24, 4,
    15, 23, 19, 13, 12, 2,
    20, 14, 22,  9, 6,  1};
static const uint64_t RC[24] = \
    {1ULL, 0x8082ULL, 0x800000000000808aULL, 0x8000000080008000ULL,
    0x808bULL, 0x80000001ULL, 0x8000000080008081ULL, 0x8000000000008009ULL,
    0x8aULL, 0x88ULL, 0x80008009ULL, 0x8000000aULL,
    0x8000808bULL, 0x800000000000008bULL, 0x8000000000008089ULL, 0x8000000000008003ULL,
    0x8000000000008002ULL, 0x8000000000000080ULL, 0x800aULL, 0x800000008000000aULL,
    0x8000000080008081ULL, 0x8000000000008080ULL, 0x80000001ULL, 0x8000000080008008ULL};

/*** Helper macros to unroll the permutation. ***/
#define rol(x, s) (((x) << s) | ((x) >> (64 - s)))
#define REPEAT6(e) e e e e e e
#define REPEAT24(e) REPEAT6(e e e e)
#define REPEAT5(e) e e e e e
#define FOR5(v, s, e) \
  v = 0;            \
  REPEAT5(e; v += s;)

/*** Keccak-f[1600] ***/
static inline void keccakf(void* state) {
    uint64_t* a = (uint64_t*)state;
    uint64_t b[5] = {0};

    for (int i = 0; i < 24; i++)
    {
        uint8_t x, y;
        // Theta
        FOR5(x, 1,
             b[x] = 0;
             FOR5(y, 5,
                  b[x] ^= a[x + y]; ))
        FOR5(x, 1,
             FOR5(y, 5,
                  a[y + x] ^= b[(x + 4) % 5] ^ rol(b[(x + 1) % 5], 1); ))
        // Rho and pi
        uint64_t t = a[1];
        x = 0;
        REPEAT24(b[0] = a[pi[x]];
                 a[pi[x]] = rol(t, rho[x]);
                 t = b[0];
                 x++; )
        // Chi
        FOR5(y,
           5,
           FOR5(x, 1,
                b[x] = a[y + x];)
           FOR5(x, 1,
                a[y + x] = b[x] ^ ((~b[(x + 1) % 5]) & b[(x + 2) % 5]); ))
        // Iota
        a[0] ^= RC[i];
    }
}

/******** The FIPS202-defined functions. ********/

/*** Some helper macros. ***/

#define _(S) do { S } while (0)
#define FOR(i, ST, L, S) \
  _(for (size_t i = 0; i < L; i += ST) { S; })
#define mkapply_ds(NAME, S)                                          \
  static inline void NAME(uint8_t* dst,                              \
                          const uint8_t* src,                        \
                          size_t len) {                              \
    FOR(i, 1, len, S);                                               \
  }
#define mkapply_sd(NAME, S)                                          \
  static inline void NAME(const uint8_t* src,                        \
                          uint8_t* dst,                              \
                          size_t len) {                              \
    FOR(i, 1, len, S);                                               \
  }

mkapply_ds(xorin, dst[i] ^= src[i])  // xorin
mkapply_sd(setout, dst[i] = src[i])  // setout

#define P keccakf
#define Plen 200

// Fold P*F over the full blocks of an input.
#define foldP(I, L, F) \
  while (L >= rate) {  \
    F(a, I, rate);     \
    P(a);              \
    I += rate;         \
    L -= rate;         \
  }

/** The sponge-based hash construction. **/
inline void hash(
    uint8_t* out,
    size_t outlen,
    const uint8_t* in,
    size_t inlen,
    size_t rate,
    uint8_t delim
)
{
    uint8_t a[Plen] = {0};
    // Absorb input.
    foldP(in, inlen, xorin);
    // Xor in the DS and pad frame.
    a[inlen] ^= delim;
    a[rate - 1] ^= 0x80;
    // Xor in the last block.
    xorin(a, in, inlen);
    // Apply P
    P(a);
    // Squeeze output.
    foldP(out, outlen, setout);
    setout(a, out, outlen);
    memset(a, 0, 200);
}

}

h256 keccak256(bytesConstRef _input)
{
    h256 output;
    // Parameters used:
    // The 0x01 is the specific padding for keccak (sha3 uses 0x06) and
    // the way the round size (or window or whatever it was) is calculated.
    // 200 - (256 / 4) is the "rate"
    hash(output.data(), output.size, _input.data(), _input.size(), 200 - (256 / 4), 0x01);
    return output;
}

}