//
// --------------------------------------------------------------------------
//  Gurux Ltd
//
//
//
// Filename:        $HeadURL$
//
// Version:         $Revision$,
//                  $Date$
//                  $Author$
//
// Copyright (c) Gurux Ltd
//
//---------------------------------------------------------------------------
//
//  DESCRIPTION
//
// This file is a part of Gurux Device Framework.
//
// Gurux Device Framework is Open Source 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; version 2 of the License.
// Gurux Device Framework 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.
//
// More information of Gurux products: http://www.gurux.org
//
// This code is licensed under the GNU General Public License v2.
// Full text may be retrieved at http://www.gnu.org/licenses/gpl-2.0.txt
//---------------------------------------------------------------------------

#include "../include/GXDLMSSha256.h"

const unsigned int 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 };

#define SHA2_SHFR(x, n)    (x >> n)
#define SHA2_ROTR(x, n)   ((x >> n) | (x << ((sizeof(x) << 3) - n)))
#define SHA2_ROTL(x, n)   ((x << n) | (x >> ((sizeof(x) << 3) - n)))
#define SHA2_CH(x, y, z)  ((x & y) ^ (~x & z))
#define SHA2_MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
#define SHA256_F1(x) (SHA2_ROTR(x,  2) ^ SHA2_ROTR(x, 13) ^ SHA2_ROTR(x, 22))
#define SHA256_F2(x) (SHA2_ROTR(x,  6) ^ SHA2_ROTR(x, 11) ^ SHA2_ROTR(x, 25))
#define SHA256_F3(x) (SHA2_ROTR(x,  7) ^ SHA2_ROTR(x, 18) ^ SHA2_SHFR(x,  3))
#define SHA256_F4(x) (SHA2_ROTR(x, 17) ^ SHA2_ROTR(x, 19) ^ SHA2_SHFR(x, 10))
#define SHA2_UNPACK32(x, str)                 \
{                                             \
    *((str) + 3) = (unsigned char) ((x)      );       \
    *((str) + 2) = (unsigned char) ((x) >>  8);       \
    *((str) + 1) = (unsigned char) ((x) >> 16);       \
    *((str) + 0) = (unsigned char) ((x) >> 24);       \
}
#define SHA2_PACK32(str, x)                   \
{                                             \
    *(x) =   ((unsigned int) *((str) + 3)      )    \
           | ((unsigned int) *((str) + 2) <<  8)    \
           | ((unsigned int) *((str) + 1) << 16)    \
           | ((unsigned int) *((str) + 0) << 24);   \
}

void CGXDLMSSha256::Transform(unsigned int *h, const unsigned char *message, unsigned int block_nb)
{
    unsigned int w[64];
    unsigned int wv[8];
    unsigned int 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++)
        {
            SHA2_PACK32(&sub_block[j << 2], &w[j]);
        }
        for (j = 16; j < 64; j++)
        {
            w[j] = SHA256_F4(w[j - 2]) + w[j - 7] + SHA256_F3(w[j - 15]) + w[j - 16];
        }
        for (j = 0; j < 8; j++)
        {
            wv[j] = h[j];
        }
        for (j = 0; j < 64; j++) {
            t1 = wv[7] + SHA256_F2(wv[4]) + SHA2_CH(wv[4], wv[5], wv[6])
                + sha256_k[j] + w[j];
            t2 = SHA256_F1(wv[0]) + SHA2_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++)
        {
            h[j] += wv[j];
        }
    }
}

int CGXDLMSSha256::Update(unsigned int *h, unsigned char *block, CGXByteBuffer&  data, unsigned int *len, unsigned int *totalLen)
{
    unsigned int block_nb;
    unsigned int new_len, rem_len, tmp_len;
    const unsigned char *shifted_message;
    tmp_len = 64 - (data.GetSize() - data.GetPosition());
    rem_len = data.GetSize() < tmp_len ? data.GetSize() : tmp_len;
    memcpy(&block[data.GetPosition()], data.GetData(), rem_len);
    if (data.GetSize() - data.GetPosition() < 64)
    {
        data.SetPosition(data.GetSize());
        return 0;
    }
    new_len = *len - rem_len;
    block_nb = new_len / 64;
    shifted_message = data.GetData() + rem_len;
    Transform(h, block, 1);
    Transform(h, shifted_message, block_nb);
    rem_len = new_len % 64;
    memcpy(block, &shifted_message[block_nb << 6], rem_len);
    *len = rem_len;
    *totalLen += (block_nb + 1) << 6;
    return 0;
}

int CGXDLMSSha256::Final(unsigned int *h, unsigned char *block, unsigned char *digest, unsigned int len, unsigned int totalLen)
{
    unsigned int block_nb;
    unsigned int pm_len;
    unsigned int len_b;
    int i;
    block_nb = (1 + ((64 - 9) < (len % 64)));
    len_b = (totalLen + len) << 3;
    pm_len = block_nb << 6;
    memset(block + len, 0, pm_len - len);
    block[len] = 0x80;
    SHA2_UNPACK32(len_b, block + pm_len - 4);
    Transform(h, block, block_nb);
    for (i = 0; i < 8; i++)
    {
        SHA2_UNPACK32(h[i], &digest[i << 2]);
    }
    return 0;
}

int CGXDLMSSha256::Encrypt(CGXByteBuffer& data, CGXByteBuffer& digest)
{
    unsigned int len = data.GetSize(), totalLen = 0;
    unsigned int h[8] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
    unsigned char block[128];
    digest.Capacity(32);
    digest.SetSize(32);
    Update((unsigned int*)&h, block, data, &len, &totalLen);
    return Final(h, block, digest.GetData(), len, totalLen);
}