/*

 * FIPS 180-2 SHA-224/256/384/512 implementation

 * Last update: 02/02/2007

 * Issue date:  04/30/2005

 *

 * Copyright (C) 2005, 2007 Olivier Gay <olivier.gay@a3.epfl.ch>

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of the project nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 */

#include <znc/SHA256.h>

#include <string.h>

#define SHFR(x, n) (x >> n)

#define ROTR(x, n) ((x >> n) | (x << ((sizeof(x) << 3) - n)))

#define ROTL(x, n) ((x << n) | (x >> ((sizeof(x) << 3) - n)))

#define CH(x, y, z) ((x & y) ^ (~x & z))

#define MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))

#define SHA256_F1(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))

#define SHA256_F2(x) (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))

#define SHA256_F3(x) (ROTR(x, 7) ^ ROTR(x, 18) ^ SHFR(x, 3))

#define SHA256_F4(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHFR(x, 10))

#define UNPACK32(x, str)                   \

    {                                      \

        *((str)+3) = (uint8_t)((x));       \

        *((str)+2) = (uint8_t)((x) >> 8);  \

        *((str)+1) = (uint8_t)((x) >> 16); \

        *((str)+0) = (uint8_t)((x) >> 24); \

    }

#define PACK32(str, x)                                                    \

    {                                                                     \

        *(x) = ((uint32_t) * ((str)+3)) | ((uint32_t) * ((str)+2) << 8) | \

               ((uint32_t) * ((str)+1) << 16) |                           \

               ((uint32_t) * ((str)+0) << 24);                            \

    }

/* Macros used for loops unrolling */

#define SHA256_SCR(i)                                                          \

    {                                                                          \

        w[i] =                                                                 \

            SHA256_F4(w[i - 2]) + w[i - 7] + SHA256_F3(w[i - 15]) + w[i - 16]; \

    }

#define SHA256_EXP(a, b, c, d, e, f, g, h, j)                     \

    {                                                             \

        t1 = wv[h] + SHA256_F2(wv[e]) + CH(wv[e], wv[f], wv[g]) + \

             sha256_k[j] + w[j];                                  \

        t2 = SHA256_F1(wv[a]) + MAJ(wv[a], wv[b], wv[c]);         \

        wv[d] += t1;                                              \

        wv[h] = t1 + t2;                                          \

    }

uint32_t sha256_h0[8] = {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,

                         0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};

uint32_t sha256_k[64] = {

    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,

    0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,

    0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,

    0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,

    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,

    0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,

    0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,

    0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,

    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,

    0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,

    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

/* SHA-256 functions */

static void sha256_transf(sha256_ctx* ctx, const unsigned char* message,

                          size_t block_nb) {

    uint32_t w[64];

    uint32_t wv[8];

    uint32_t t1, t2;

    const unsigned char* sub_block;

    int i;

    int j;

    for (i = 0; i < (int)block_nb; i++) {

        sub_block = message + (i << 6);

        for (j = 0; j < 16; j++) {

            PACK32(&sub_block[j << 2], &w[j]);

        }

        for (j = 16; j < 64; j++) {

            SHA256_SCR(j);

        }

        for (j = 0; j < 8; j++) {

            wv[j] = ctx->h[j];

        }

        for (j = 0; j < 64; j++) {

            t1 = wv[7] + SHA256_F2(wv[4]) + CH(wv[4], wv[5], wv[6]) +

                 sha256_k[j] + w[j];

            t2 = SHA256_F1(wv[0]) + MAJ(wv[0], wv[1], wv[2]);

            wv[7] = wv[6];

            wv[6] = wv[5];

            wv[5] = wv[4];

            wv[4] = wv[3] + t1;

            wv[3] = wv[2];

            wv[2] = wv[1];

            wv[1] = wv[0];

            wv[0] = t1 + t2;

        }

        for (j = 0; j < 8; j++) {

            ctx->h[j] += wv[j];

        }

    }

}

void sha256(const unsigned char* message, size_t len, unsigned char* digest) {

    sha256_ctx ctx;

    sha256_init(&ctx);

    sha256_update(&ctx, message, len);

    sha256_final(&ctx, digest);

}

void sha256_init(sha256_ctx* ctx) {

    int i;

    for (i = 0; i < 8; i++) {

        ctx->h[i] = sha256_h0[i];

    }

    ctx->len = 0;

    ctx->tot_len = 0;

}

void sha256_update(sha256_ctx* ctx, const unsigned char* message, size_t len) {

    size_t block_nb;

    size_t new_len, rem_len, tmp_len;

    const unsigned char* shifted_message;

    tmp_len = SHA256_BLOCK_SIZE - ctx->len;

    rem_len = len < tmp_len ? len : tmp_len;

    memcpy(&ctx->block[ctx->len], message, rem_len);

    if (ctx->len + len < SHA256_BLOCK_SIZE) {

        ctx->len += len;

        return;

    }

    new_len = len - rem_len;

    block_nb = new_len / SHA256_BLOCK_SIZE;

    shifted_message = message + rem_len;

    sha256_transf(ctx, ctx->block, 1);

    sha256_transf(ctx, shifted_message, block_nb);

    rem_len = new_len % SHA256_BLOCK_SIZE;

    memcpy(ctx->block, &shifted_message[block_nb << 6], rem_len);

    ctx->len = rem_len;

    ctx->tot_len += (block_nb + 1) << 6;

}

void sha256_final(sha256_ctx* ctx, unsigned char* digest) {

    unsigned int block_nb;

    unsigned int pm_len;

    size_t len_b;

    int i;

    block_nb = (1 + ((SHA256_BLOCK_SIZE - 9) < (ctx->len % SHA256_BLOCK_SIZE)));

    len_b = (ctx->tot_len + ctx->len) << 3;

    pm_len = block_nb << 6;

    memset(ctx->block + ctx->len, 0, pm_len - ctx->len);

    ctx->block[ctx->len] = 0x80;

    UNPACK32(len_b, ctx->block + pm_len - 4);

    sha256_transf(ctx, ctx->block, block_nb);

    for (i = 0; i < 8; i++) {

        UNPACK32(ctx->h[i], &digest[i << 2]);

    }

}