/*
 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdint.h>
#include <string.h>
#include <assert.h>

#define ROL64(a, offset) ((offset) ? (((a) << offset) | ((a) >> (64-offset))) \
                                   : a)

static void Theta(uint64_t A[5][5])
{
    uint64_t C[5], D[5];
    size_t y;

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

    D[0] = ROL64(C[1], 1) ^ C[4];
    D[1] = ROL64(C[2], 1) ^ C[0];
    D[2] = ROL64(C[3], 1) ^ C[1];
    D[3] = ROL64(C[4], 1) ^ C[2];
    D[4] = ROL64(C[0], 1) ^ C[3];

    for (y = 0; y < 5; y++) {
        A[y][0] ^= D[0];
        A[y][1] ^= D[1];
        A[y][2] ^= D[2];
        A[y][3] ^= D[3];
        A[y][4] ^= D[4];
    }
}

static void Rho(uint64_t A[5][5])
{
    static const unsigned char rhotates[5][5] = {
        {  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 }
    };
    size_t y;

    for (y = 0; y < 5; y++) {
        A[y][0] = ROL64(A[y][0], rhotates[y][0]);
        A[y][1] = ROL64(A[y][1], rhotates[y][1]);
        A[y][2] = ROL64(A[y][2], rhotates[y][2]);
        A[y][3] = ROL64(A[y][3], rhotates[y][3]);
        A[y][4] = ROL64(A[y][4], rhotates[y][4]);
    }
}

static void Pi(uint64_t A[5][5])
{
    uint64_t T[5][5];

    /*
     * T = A
     * A[y][x] = T[x][(3*y+x)%5]
     */
    memcpy(T, A, sizeof(T));

    A[0][0] = T[0][0];
    A[0][1] = T[1][1];
    A[0][2] = T[2][2];
    A[0][3] = T[3][3];
    A[0][4] = T[4][4];

    A[1][0] = T[0][3];
    A[1][1] = T[1][4];
    A[1][2] = T[2][0];
    A[1][3] = T[3][1];
    A[1][4] = T[4][2];

    A[2][0] = T[0][1];
    A[2][1] = T[1][2];
    A[2][2] = T[2][3];
    A[2][3] = T[3][4];
    A[2][4] = T[4][0];

    A[3][0] = T[0][4];
    A[3][1] = T[1][0];
    A[3][2] = T[2][1];
    A[3][3] = T[3][2];
    A[3][4] = T[4][3];

    A[4][0] = T[0][2];
    A[4][1] = T[1][3];
    A[4][2] = T[2][4];
    A[4][3] = T[3][0];
    A[4][4] = T[4][1];
}

static void Chi(uint64_t A[5][5])
{
    uint64_t C[5];
    size_t y;

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

        A[y][0] = C[0];
        A[y][1] = C[1];
        A[y][2] = C[2];
        A[y][3] = C[3];
        A[y][4] = C[4];
    }
}

static void Iota(uint64_t A[5][5], size_t i)
{
    static const uint64_t iotas[] = {
        0x0000000000000001U, 0x0000000000008082U, 0x800000000000808aU,
        0x8000000080008000U, 0x000000000000808bU, 0x0000000080000001U,
        0x8000000080008081U, 0x8000000000008009U, 0x000000000000008aU,
        0x0000000000000088U, 0x0000000080008009U, 0x000000008000000aU,
        0x000000008000808bU, 0x800000000000008bU, 0x8000000000008089U,
        0x8000000000008003U, 0x8000000000008002U, 0x8000000000000080U,
        0x000000000000800aU, 0x800000008000000aU, 0x8000000080008081U,
        0x8000000000008080U, 0x0000000080000001U, 0x8000000080008008U
    };

    assert(i < (sizeof(iotas) / sizeof(iotas[0])));
    A[0][0] ^= iotas[i];
}

void KeccakF1600(uint64_t A[5][5])
{
    size_t i;

    for (i = 0; i < 24; i++) {
        Theta(A);
        Rho(A);
        Pi(A);
        Chi(A);
        Iota(A, i);
    }
}

/*
 * SHA3_absorb can be called multiple times, but at each invocation
 * largest multiple of |r| out of |len| bytes are processed. Then
 * remaining amount of bytes are returned. This is done to spare caller
 * trouble of calculating the largest multiple of |r|, effectively the
 * blocksize. It is commonly (1600 - 256*n)/8, e.g. 168, 136, 104, 72,
 * but can also be (1600 - 448)/8 = 144. All this means that message
 * padding and intermediate sub-block buffering, byte- or bitwise, is
 * caller's reponsibility.
 */
size_t SHA3_absorb(uint64_t A[5][5], const unsigned char *inp, size_t len,
                   size_t r)
{
    uint64_t *A_flat = (uint64_t *)A;
    size_t i, w = r / 8;

    while (len >= r) {
        for (i = 0; i < w; i++) {
            A_flat[i] ^= (uint64_t)inp[0]       | (uint64_t)inp[1] << 8  |
                         (uint64_t)inp[2] << 16 | (uint64_t)inp[3] << 24 |
                         (uint64_t)inp[4] << 32 | (uint64_t)inp[5] << 40 |
                         (uint64_t)inp[6] << 48 | (uint64_t)inp[7] << 56;
            inp += 8;
        }
        KeccakF1600(A);
        len -= r;
    }

    return len;
}

/*
 * SHA3_squeeze is called once at the end to generate |out| hash value
 * of |len| bytes.
 */
void SHA3_squeeze(uint64_t A[5][5], unsigned char *out, size_t len, size_t r)
{
    uint64_t *A_flat = (uint64_t *)A;
    size_t i, rem, w = r / 8;

    while (len >= r) {
        for (i = 0; i < w; i++) {
            uint64_t Ai = A_flat[i];

            out[0] = (unsigned char)(Ai);
            out[1] = (unsigned char)(Ai >> 8);
            out[2] = (unsigned char)(Ai >> 16);
            out[3] = (unsigned char)(Ai >> 24);
            out[4] = (unsigned char)(Ai >> 32);
            out[5] = (unsigned char)(Ai >> 40);
            out[6] = (unsigned char)(Ai >> 48);
            out[7] = (unsigned char)(Ai >> 56);
            out += 8;
        }
        len -= r;
        if (len)
            KeccakF1600(A);
    }

    rem = len % 8;
    len /= 8;

    for (i = 0; i < len; i++) {
        uint64_t Ai = A_flat[i];

        out[0] = (unsigned char)(Ai);
        out[1] = (unsigned char)(Ai >> 8);
        out[2] = (unsigned char)(Ai >> 16);
        out[3] = (unsigned char)(Ai >> 24);
        out[4] = (unsigned char)(Ai >> 32);
        out[5] = (unsigned char)(Ai >> 40);
        out[6] = (unsigned char)(Ai >> 48);
        out[7] = (unsigned char)(Ai >> 56);
        out += 8;
    }

    if (rem) {
        uint64_t Ai = A_flat[i];

        for (i = 0; i < rem; i++) {
            *out++ = (unsigned char)Ai;
            Ai >>= 8;
        }
    }
}

#ifdef SELFTEST
/*
 * Post-padding one-shot implementations would look as following:
 *
 * SHA3_224     SHA3_sponge(inp, len, out, 224/8, (1600-448)/8);
 * SHA3_256     SHA3_sponge(inp, len, out, 256/8, (1600-512)/8);
 * SHA3_384     SHA3_sponge(inp, len, out, 384/8, (1600-768)/8);
 * SHA3_512     SHA3_sponge(inp, len, out, 512/8, (1600-1024)/8);
 * SHAKE_128    SHA3_sponge(inp, len, out, d, (1600-256)/8);
 * SHAKE_256    SHA3_sponge(inp, len, out, d, (1600-512)/8);
 */

void SHA3_sponge(const unsigned char *inp, size_t len,
                 unsigned char *out, size_t d, size_t r)
{
    uint64_t A[5][5];

    memset(A, 0, sizeof(A));
    SHA3_absorb(A, inp, len, r);
    SHA3_squeeze(A, out, d, r);
}

# include <stdio.h>

int main()
{
    /*
     * This is 5-bit SHAKE128 test from http://csrc.nist.gov/groups/ST/toolkit/examples.html#aHashing
     */
    unsigned char test[168] = { '\xf3', '\x3' };
    unsigned char out[512];
    size_t i;
    static const unsigned char result[512] = {
        0x2E, 0x0A, 0xBF, 0xBA, 0x83, 0xE6, 0x72, 0x0B,
        0xFB, 0xC2, 0x25, 0xFF, 0x6B, 0x7A, 0xB9, 0xFF,
        0xCE, 0x58, 0xBA, 0x02, 0x7E, 0xE3, 0xD8, 0x98,
        0x76, 0x4F, 0xEF, 0x28, 0x7D, 0xDE, 0xCC, 0xCA,
        0x3E, 0x6E, 0x59, 0x98, 0x41, 0x1E, 0x7D, 0xDB,
        0x32, 0xF6, 0x75, 0x38, 0xF5, 0x00, 0xB1, 0x8C,
        0x8C, 0x97, 0xC4, 0x52, 0xC3, 0x70, 0xEA, 0x2C,
        0xF0, 0xAF, 0xCA, 0x3E, 0x05, 0xDE, 0x7E, 0x4D,
        0xE2, 0x7F, 0xA4, 0x41, 0xA9, 0xCB, 0x34, 0xFD,
        0x17, 0xC9, 0x78, 0xB4, 0x2D, 0x5B, 0x7E, 0x7F,
        0x9A, 0xB1, 0x8F, 0xFE, 0xFF, 0xC3, 0xC5, 0xAC,
        0x2F, 0x3A, 0x45, 0x5E, 0xEB, 0xFD, 0xC7, 0x6C,
        0xEA, 0xEB, 0x0A, 0x2C, 0xCA, 0x22, 0xEE, 0xF6,
        0xE6, 0x37, 0xF4, 0xCA, 0xBE, 0x5C, 0x51, 0xDE,
        0xD2, 0xE3, 0xFA, 0xD8, 0xB9, 0x52, 0x70, 0xA3,
        0x21, 0x84, 0x56, 0x64, 0xF1, 0x07, 0xD1, 0x64,
        0x96, 0xBB, 0x7A, 0xBF, 0xBE, 0x75, 0x04, 0xB6,
        0xED, 0xE2, 0xE8, 0x9E, 0x4B, 0x99, 0x6F, 0xB5,
        0x8E, 0xFD, 0xC4, 0x18, 0x1F, 0x91, 0x63, 0x38,
        0x1C, 0xBE, 0x7B, 0xC0, 0x06, 0xA7, 0xA2, 0x05,
        0x98, 0x9C, 0x52, 0x6C, 0xD1, 0xBD, 0x68, 0x98,
        0x36, 0x93, 0xB4, 0xBD, 0xC5, 0x37, 0x28, 0xB2,
        0x41, 0xC1, 0xCF, 0xF4, 0x2B, 0xB6, 0x11, 0x50,
        0x2C, 0x35, 0x20, 0x5C, 0xAB, 0xB2, 0x88, 0x75,
        0x56, 0x55, 0xD6, 0x20, 0xC6, 0x79, 0x94, 0xF0,
        0x64, 0x51, 0x18, 0x7F, 0x6F, 0xD1, 0x7E, 0x04,
        0x66, 0x82, 0xBA, 0x12, 0x86, 0x06, 0x3F, 0xF8,
        0x8F, 0xE2, 0x50, 0x8D, 0x1F, 0xCA, 0xF9, 0x03,
        0x5A, 0x12, 0x31, 0xAD, 0x41, 0x50, 0xA9, 0xC9,
        0xB2, 0x4C, 0x9B, 0x2D, 0x66, 0xB2, 0xAD, 0x1B,
        0xDE, 0x0B, 0xD0, 0xBB, 0xCB, 0x8B, 0xE0, 0x5B,
        0x83, 0x52, 0x29, 0xEF, 0x79, 0x19, 0x73, 0x73,
        0x23, 0x42, 0x44, 0x01, 0xE1, 0xD8, 0x37, 0xB6,
        0x6E, 0xB4, 0xE6, 0x30, 0xFF, 0x1D, 0xE7, 0x0C,
        0xB3, 0x17, 0xC2, 0xBA, 0xCB, 0x08, 0x00, 0x1D,
        0x34, 0x77, 0xB7, 0xA7, 0x0A, 0x57, 0x6D, 0x20,
        0x86, 0x90, 0x33, 0x58, 0x9D, 0x85, 0xA0, 0x1D,
        0xDB, 0x2B, 0x66, 0x46, 0xC0, 0x43, 0xB5, 0x9F,
        0xC0, 0x11, 0x31, 0x1D, 0xA6, 0x66, 0xFA, 0x5A,
        0xD1, 0xD6, 0x38, 0x7F, 0xA9, 0xBC, 0x40, 0x15,
        0xA3, 0x8A, 0x51, 0xD1, 0xDA, 0x1E, 0xA6, 0x1D,
        0x64, 0x8D, 0xC8, 0xE3, 0x9A, 0x88, 0xB9, 0xD6,
        0x22, 0xBD, 0xE2, 0x07, 0xFD, 0xAB, 0xC6, 0xF2,
        0x82, 0x7A, 0x88, 0x0C, 0x33, 0x0B, 0xBF, 0x6D,
        0xF7, 0x33, 0x77, 0x4B, 0x65, 0x3E, 0x57, 0x30,
        0x5D, 0x78, 0xDC, 0xE1, 0x12, 0xF1, 0x0A, 0x2C,
        0x71, 0xF4, 0xCD, 0xAD, 0x92, 0xED, 0x11, 0x3E,
        0x1C, 0xEA, 0x63, 0xB9, 0x19, 0x25, 0xED, 0x28,
        0x19, 0x1E, 0x6D, 0xBB, 0xB5, 0xAA, 0x5A, 0x2A,
        0xFD, 0xA5, 0x1F, 0xC0, 0x5A, 0x3A, 0xF5, 0x25,
        0x8B, 0x87, 0x66, 0x52, 0x43, 0x55, 0x0F, 0x28,
        0x94, 0x8A, 0xE2, 0xB8, 0xBE, 0xB6, 0xBC, 0x9C,
        0x77, 0x0B, 0x35, 0xF0, 0x67, 0xEA, 0xA6, 0x41,
        0xEF, 0xE6, 0x5B, 0x1A, 0x44, 0x90, 0x9D, 0x1B,
        0x14, 0x9F, 0x97, 0xEE, 0xA6, 0x01, 0x39, 0x1C,
        0x60, 0x9E, 0xC8, 0x1D, 0x19, 0x30, 0xF5, 0x7C,
        0x18, 0xA4, 0xE0, 0xFA, 0xB4, 0x91, 0xD1, 0xCA,
        0xDF, 0xD5, 0x04, 0x83, 0x44, 0x9E, 0xDC, 0x0F,
        0x07, 0xFF, 0xB2, 0x4D, 0x2C, 0x6F, 0x9A, 0x9A,
        0x3B, 0xFF, 0x39, 0xAE, 0x3D, 0x57, 0xF5, 0x60,
        0x65, 0x4D, 0x7D, 0x75, 0xC9, 0x08, 0xAB, 0xE6,
        0x25, 0x64, 0x75, 0x3E, 0xAC, 0x39, 0xD7, 0x50,
        0x3D, 0xA6, 0xD3, 0x7C, 0x2E, 0x32, 0xE1, 0xAF,
        0x3B, 0x8A, 0xEC, 0x8A, 0xE3, 0x06, 0x9C, 0xD9
    };

    test[167] = '\x80';
    SHA3_sponge(test, sizeof(test), out, sizeof(out), sizeof(test));

    /*
     * Rationale behind keeping output [formatted as below] is that
     * one should be able to redirect it to a file, then copy-n-paste
     * final "output val" from official example to another file, and
     * compare the two with diff(1).
     */
    for (i = 0; i < sizeof(out);) {
        printf("%02X", out[i]);
        printf(++i % 16 && i != sizeof(out) ? " " : "\n");
    }

    if (memcmp(out,result,sizeof(out))) {
        fprintf(stderr,"failure\n");
        return 1;
    } else {
        fprintf(stderr,"success\n");
        return 0;
    }
}
#endif