/* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
/* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */

/* sha256.c
 *
 * Copyright (C) 2006-2014 wolfSSL Inc.
 *
 * This file is part of CyaSSL.
 *
 * CyaSSL 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 2 of the License, or
 * (at your option) any later version.
 *
 * CyaSSL 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include "crypto/wolfssl/sha256.h"
#include "api.h"

#define XMEMSET memset
#define XMEMCPY memcpy

#ifndef rotlFixed
static inline word32 rotlFixed(word32 x, word32 y)
{
    return (x << y) | (x >> (sizeof(y) * 8 - y));
}
#endif /* rotlFixed */

#ifndef rotrFixed
static inline word32 rotrFixed(word32 x, word32 y)
{
    return (x >> y) | (x << (sizeof(y) * 8 - y));
}
#endif /* rotrFixed */

#ifndef min
static inline word32 min(word32 a, word32 b)
{
     return a > b ? b : a;
}
#endif /* min */

static inline word32 ByteReverseWord32(word32 value)
{
    /* 6 instructions with rotate instruction, 8 without */
    value = ((value & 0xFF00FF00) >> 8) | ((value & 0x00FF00FF) << 8);
    return rotlFixed(value, 16U);
}

static inline void ByteReverseWords(word32 *out, const word32 *in,
                                    word32 byteCount)
{
    word32 count = byteCount/(word32)sizeof(word32), i;

    for (i = 0; i < count; i++)
        out[i] = ByteReverseWord32(in[i]);
}

int SHA256Init(SHA256 *sha256)
{
    sha256->digest[0] = 0x6A09E667L;
    sha256->digest[1] = 0xBB67AE85L;
    sha256->digest[2] = 0x3C6EF372L;
    sha256->digest[3] = 0xA54FF53AL;
    sha256->digest[4] = 0x510E527FL;
    sha256->digest[5] = 0x9B05688CL;
    sha256->digest[6] = 0x1F83D9ABL;
    sha256->digest[7] = 0x5BE0CD19L;

    sha256->buffLen = 0;
    sha256->loLen   = 0;
    sha256->hiLen   = 0;

    return 0;
}

#define XTRANSFORM(S,B)  Transform((S))

static const word32 K[64] = {
    0x428A2F98L, 0x71374491L, 0xB5C0FBCFL, 0xE9B5DBA5L, 0x3956C25BL,
    0x59F111F1L, 0x923F82A4L, 0xAB1C5ED5L, 0xD807AA98L, 0x12835B01L,
    0x243185BEL, 0x550C7DC3L, 0x72BE5D74L, 0x80DEB1FEL, 0x9BDC06A7L,
    0xC19BF174L, 0xE49B69C1L, 0xEFBE4786L, 0x0FC19DC6L, 0x240CA1CCL,
    0x2DE92C6FL, 0x4A7484AAL, 0x5CB0A9DCL, 0x76F988DAL, 0x983E5152L,
    0xA831C66DL, 0xB00327C8L, 0xBF597FC7L, 0xC6E00BF3L, 0xD5A79147L,
    0x06CA6351L, 0x14292967L, 0x27B70A85L, 0x2E1B2138L, 0x4D2C6DFCL,
    0x53380D13L, 0x650A7354L, 0x766A0ABBL, 0x81C2C92EL, 0x92722C85L,
    0xA2BFE8A1L, 0xA81A664BL, 0xC24B8B70L, 0xC76C51A3L, 0xD192E819L,
    0xD6990624L, 0xF40E3585L, 0x106AA070L, 0x19A4C116L, 0x1E376C08L,
    0x2748774CL, 0x34B0BCB5L, 0x391C0CB3L, 0x4ED8AA4AL, 0x5B9CCA4FL,
    0x682E6FF3L, 0x748F82EEL, 0x78A5636FL, 0x84C87814L, 0x8CC70208L,
    0x90BEFFFAL, 0xA4506CEBL, 0xBEF9A3F7L, 0xC67178F2L
};

#define Ch(x,y,z)       (z ^ (x & (y ^ z)))
#define Maj(x,y,z)      (((x | y) & z) | (x & y))
#define S(x, n)         rotrFixed(x, n)
#define R(x, n)         (((x)&0xFFFFFFFFU)>>(n))
#define Sigma0(x)       (S(x, 2) ^ S(x, 13) ^ S(x, 22))
#define Sigma1(x)       (S(x, 6) ^ S(x, 11) ^ S(x, 25))
#define Gamma0(x)       (S(x, 7) ^ S(x, 18) ^ R(x, 3))
#define Gamma1(x)       (S(x, 17) ^ S(x, 19) ^ R(x, 10))

#define RND(a,b,c,d,e,f,g,h,i) \
     t0 = h + Sigma1(e) + Ch(e, f, g) + K[i] + W[i]; \
     t1 = Sigma0(a) + Maj(a, b, c); \
     d += t0; \
     h  = t0 + t1;


static int Transform(SHA256 *sha256)
{
    word32 S[8], t0, t1;
    int i;

    word32 W[64];

    /* Copy context->state[] to working vars */
    for (i = 0; i < 8; i++)
        S[i] = sha256->digest[i];

    for (i = 0; i < 16; i++)
        W[i] = sha256->buffer[i];

    for (i = 16; i < 64; i++)
        W[i] = Gamma1(W[i-2]) + W[i-7] + Gamma0(W[i-15]) + W[i-16];

    for (i = 0; i < 64; i += 8) {
        RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],i+0);
        RND(S[7],S[0],S[1],S[2],S[3],S[4],S[5],S[6],i+1);
        RND(S[6],S[7],S[0],S[1],S[2],S[3],S[4],S[5],i+2);
        RND(S[5],S[6],S[7],S[0],S[1],S[2],S[3],S[4],i+3);
        RND(S[4],S[5],S[6],S[7],S[0],S[1],S[2],S[3],i+4);
        RND(S[3],S[4],S[5],S[6],S[7],S[0],S[1],S[2],i+5);
        RND(S[2],S[3],S[4],S[5],S[6],S[7],S[0],S[1],i+6);
        RND(S[1],S[2],S[3],S[4],S[5],S[6],S[7],S[0],i+7);
    }

    /* Add the working vars back into digest state[] */
    for (i = 0; i < 8; i++) {
        sha256->digest[i] += S[i];
    }

    return 0;
}

static inline void AddLength(SHA256 *sha256, word32 len)
{
    word32 tmp = sha256->loLen;
    if ( (sha256->loLen += len) < tmp)
        sha256->hiLen++;                       /* carry low to high */
}

int SHA256Update(SHA256 *sha256, const byte *data, word32 len)
{
    /* do block size increments */
    byte *local = (byte*)sha256->buffer;

    while (len) {
        word32 add = min(len, SHA256_BLOCK_SIZE - sha256->buffLen);
        XMEMCPY(&local[sha256->buffLen], data, add);

        sha256->buffLen += add;
        data            += add;
        len             -= add;

        if (sha256->buffLen == SHA256_BLOCK_SIZE) {
            int ret;

            ByteReverseWords(sha256->buffer, sha256->buffer,
                             SHA256_BLOCK_SIZE);

            ret = XTRANSFORM(sha256, local);
            if (ret != 0)
                return ret;

            AddLength(sha256, SHA256_BLOCK_SIZE);
            sha256->buffLen = 0;
        }
    }

    return 0;
}

int SHA256Final(SHA256 *sha256, byte *hash)
{
    byte *local = (byte*)sha256->buffer;
    int ret;

    AddLength(sha256, sha256->buffLen);  /* before adding pads */

    local[sha256->buffLen++] = 0x80;     /* add 1 */

    /* pad with zeros */
    if (sha256->buffLen > SHA256_PAD_SIZE) {
        XMEMSET(&local[sha256->buffLen], 0, SHA256_BLOCK_SIZE - sha256->buffLen);
        sha256->buffLen += SHA256_BLOCK_SIZE - sha256->buffLen;

        ByteReverseWords(sha256->buffer, sha256->buffer, SHA256_BLOCK_SIZE);

        ret = XTRANSFORM(sha256, local);
        if (ret != 0)
            return ret;

        sha256->buffLen = 0;
    }
    XMEMSET(&local[sha256->buffLen], 0, SHA256_PAD_SIZE - sha256->buffLen);

    /* put lengths in bits */
    sha256->hiLen = (sha256->loLen >> (8*sizeof(sha256->loLen) - 3)) +
                 (sha256->hiLen << 3);
    sha256->loLen = sha256->loLen << 3;

    /* store lengths */
    ByteReverseWords(sha256->buffer, sha256->buffer, SHA256_BLOCK_SIZE);
    /* ! length ordering dependent on digest endian type ! */
    XMEMCPY(&local[SHA256_PAD_SIZE], &sha256->hiLen, sizeof(word32));
    XMEMCPY(&local[SHA256_PAD_SIZE + sizeof(word32)], &sha256->loLen,
            sizeof(word32));

    ret = XTRANSFORM(sha256, local);
    if (ret != 0)
        return ret;

    ByteReverseWords(sha256->digest, sha256->digest, SHA256_DIGEST_SIZE);
    XMEMCPY(hash, sha256->digest, SHA256_DIGEST_SIZE);

    return SHA256Init(sha256);  /* reset state */
}

int SHA256Hash(const byte * data, word32 len, byte * hash)
{
    int ret = 0;
    SHA256 sha256;

    if ((ret = SHA256Init(&sha256)) != 0)
        return ret;
    if ((ret = SHA256Update(&sha256, data, len)) != 0)
        return ret;
    else if ((ret = SHA256Final(&sha256, hash)) != 0)
        return ret;

    return 0;
}