f1600_c.c

//  f1600_c.c
//  2018-06-29  Markku-Juhani O. Saarinen <markku@teserakt.io>

//  (c) 2018 Copyright Teserakt AG

//  The original tiny_sha3 compression function (2011-11-19) for comparison.

#include "sha3.h"

#ifndef ROTL64
#define ROTL64(x, y) (((x) << (y)) | ((x) >> (64 - (y))))
#endif

// update the state with given number of rounds

void keccak_f1600(void *state, uint8_t rc)
{
    // constants
    const uint64_t keccakf_rndc[24] = {
        0x0000000000000001, 0x0000000000008082, 0x800000000000808a,
        0x8000000080008000, 0x000000000000808b, 0x0000000080000001,
        0x8000000080008081, 0x8000000000008009, 0x000000000000008a,
        0x0000000000000088, 0x0000000080008009, 0x000000008000000a,
        0x000000008000808b, 0x800000000000008b, 0x8000000000008089,
        0x8000000000008003, 0x8000000000008002, 0x8000000000000080,
        0x000000000000800a, 0x800000008000000a, 0x8000000080008081,
        0x8000000000008080, 0x0000000080000001, 0x8000000080008008
    };
    const int keccakf_rotc[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
    };
    const int keccakf_piln[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
    };

    // variables
    int i, j, r;
    uint64_t t, bc[5], *st = (uint64_t *) state;

    // actual iteration
    for (r = 0; r < rc; r++) {


        // Theta
        for (i = 0; i < 5; i++)
            bc[i] = st[i] ^ st[i + 5] ^ st[i + 10] ^ st[i + 15] ^ st[i + 20];

        for (i = 0; i < 5; i++) {
            t = bc[(i + 4) % 5] ^ ROTL64(bc[(i + 1) % 5], 1);
            for (j = 0; j < 25; j += 5)
                st[j + i] ^= t;
        }

        // Rho Pi
        t = st[1];
        for (i = 0; i < 24; i++) {
            j = keccakf_piln[i];
            bc[0] = st[j];
            st[j] = ROTL64(t, keccakf_rotc[i]);
            t = bc[0];
        }

        //  Chi
        for (j = 0; j < 25; j += 5) {
            for (i = 0; i < 5; i++)
                bc[i] = st[j + i];
            for (i = 0; i < 5; i++)
                st[j + i] ^= (~bc[(i + 1) % 5]) & bc[(i + 2) % 5];
        }

        //  Iota
        st[0] ^= keccakf_rndc[r];
    }
}