/* sha3-permute.c

   The sha3 permutation function (aka Keccak).

   Copyright (C) 2012 Niels Möller

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle 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 copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
*/

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include "sha3.h"
#include "sha3-internal.h"

#include "macros.h"

#define SHA3_ROUNDS 24

/* For fat builds */
#if HAVE_NATIVE_sha3_permute
void
_nettle_sha3_permute_c(struct sha3_state *state);
#define nettle_sha3_permute _nettle_sha3_permute_c
#endif

void
sha3_permute (struct sha3_state *state)
{
  static const uint64_t rc[SHA3_ROUNDS] = {
    0x0000000000000001ULL, 0X0000000000008082ULL,
    0X800000000000808AULL, 0X8000000080008000ULL,
    0X000000000000808BULL, 0X0000000080000001ULL,
    0X8000000080008081ULL, 0X8000000000008009ULL,
    0X000000000000008AULL, 0X0000000000000088ULL,
    0X0000000080008009ULL, 0X000000008000000AULL,
    0X000000008000808BULL, 0X800000000000008BULL,
    0X8000000000008089ULL, 0X8000000000008003ULL,
    0X8000000000008002ULL, 0X8000000000000080ULL,
    0X000000000000800AULL, 0X800000008000000AULL,
    0X8000000080008081ULL, 0X8000000000008080ULL,
    0X0000000080000001ULL, 0X8000000080008008ULL,
  };

  /* Original permutation:
     
       0,10,20, 5,15,
      16, 1,11,21, 6,
       7,17, 2,12,22,
      23, 8,18, 3,13,
      14,24, 9,19, 4

     Rotation counts:

       0,  1, 62, 28, 27,
      36, 44,  6, 55, 20,
       3, 10, 43, 25, 39,
      41, 45, 15, 21,  8,
      18,  2, 61, 56, 14,
  */

  /* In-place implementation. Permutation done as a long sequence of
     25 moves "following" the permutation.

      T <--  1
      1 <--  6
      6 <--  9
      9 <-- 22
     22 <-- 14
     14 <-- 20
     20 <--  2
      2 <-- 12
     12 <-- 13
     13 <-- 19
     19 <-- 23
     23 <-- 15
     15 <--  4
      4 <-- 24
     24 <-- 21
     21 <--  8
      8 <-- 16
     16 <--  5
      5 <--  3
      3 <-- 18
     18 <-- 17
     17 <-- 11
     11 <--  7
      7 <-- 10
     10 <--  T

  */
  uint64_t C[5], D[5], T, X;
  unsigned i, y;

#define A state->a

  C[0] = A[0] ^ A[5+0] ^ A[10+0] ^ A[15+0] ^ A[20+0];
  C[1] = A[1] ^ A[5+1] ^ A[10+1] ^ A[15+1] ^ A[20+1];
  C[2] = A[2] ^ A[5+2] ^ A[10+2] ^ A[15+2] ^ A[20+2];
  C[3] = A[3] ^ A[5+3] ^ A[10+3] ^ A[15+3] ^ A[20+3];
  C[4] = A[4] ^ A[5+4] ^ A[10+4] ^ A[15+4] ^ A[20+4];

  for (i = 0; i < SHA3_ROUNDS; i++)
    {
      D[0] = C[4] ^ ROTL64(1, C[1]);
      D[1] = C[0] ^ ROTL64(1, C[2]);
      D[2] = C[1] ^ ROTL64(1, C[3]);
      D[3] = C[2] ^ ROTL64(1, C[4]);
      D[4] = C[3] ^ ROTL64(1, C[0]);

      A[0] ^= D[0];
      X = A[ 1] ^ D[1];     T = ROTL64(1, X);
      X = A[ 6] ^ D[1]; A[ 1] = ROTL64 (44, X);
      X = A[ 9] ^ D[4]; A[ 6] = ROTL64 (20, X);
      X = A[22] ^ D[2]; A[ 9] = ROTL64 (61, X);
      X = A[14] ^ D[4]; A[22] = ROTL64 (39, X);
      X = A[20] ^ D[0]; A[14] = ROTL64 (18, X);
      X = A[ 2] ^ D[2]; A[20] = ROTL64 (62, X);
      X = A[12] ^ D[2]; A[ 2] = ROTL64 (43, X);
      X = A[13] ^ D[3]; A[12] = ROTL64 (25, X);
      X = A[19] ^ D[4]; A[13] = ROTL64 ( 8, X);
      X = A[23] ^ D[3]; A[19] = ROTL64 (56, X);
      X = A[15] ^ D[0]; A[23] = ROTL64 (41, X);
      X = A[ 4] ^ D[4]; A[15] = ROTL64 (27, X);
      X = A[24] ^ D[4]; A[ 4] = ROTL64 (14, X);
      X = A[21] ^ D[1]; A[24] = ROTL64 ( 2, X);
      X = A[ 8] ^ D[3]; A[21] = ROTL64 (55, X); /* row 4 done */
      X = A[16] ^ D[1]; A[ 8] = ROTL64 (45, X);
      X = A[ 5] ^ D[0]; A[16] = ROTL64 (36, X);
      X = A[ 3] ^ D[3]; A[ 5] = ROTL64 (28, X);
      X = A[18] ^ D[3]; A[ 3] = ROTL64 (21, X); /* row 0 done */
      X = A[17] ^ D[2]; A[18] = ROTL64 (15, X);
      X = A[11] ^ D[1]; A[17] = ROTL64 (10, X); /* row 3 done */
      X = A[ 7] ^ D[2]; A[11] = ROTL64 ( 6, X); /* row 1 done */
      X = A[10] ^ D[0]; A[ 7] = ROTL64 ( 3, X);
      A[10] = T;				/* row 2 done */

      D[0] = ~A[1] & A[2];
      D[1] = ~A[2] & A[3];
      D[2] = ~A[3] & A[4];
      D[3] = ~A[4] & A[0];
      D[4] = ~A[0] & A[1];

      A[0] ^= D[0] ^ rc[i]; C[0] = A[0];
      A[1] ^= D[1]; C[1] = A[1];
      A[2] ^= D[2]; C[2] = A[2];
      A[3] ^= D[3]; C[3] = A[3];
      A[4] ^= D[4]; C[4] = A[4];

      for (y = 5; y < 25; y+= 5)
	{
	  D[0] = ~A[y+1] & A[y+2];
	  D[1] = ~A[y+2] & A[y+3];
	  D[2] = ~A[y+3] & A[y+4];
	  D[3] = ~A[y+4] & A[y+0];
	  D[4] = ~A[y+0] & A[y+1];

	  A[y+0] ^= D[0]; C[0] ^= A[y+0];
	  A[y+1] ^= D[1]; C[1] ^= A[y+1];
	  A[y+2] ^= D[2]; C[2] ^= A[y+2];
	  A[y+3] ^= D[3]; C[3] ^= A[y+3];
	  A[y+4] ^= D[4]; C[4] ^= A[y+4];
	}
    }
#undef A
}