/*

 * This code implements the MD5 message-digest algorithm.

 * The algorithm is due to Ron Rivest.  This code was

 * written by Colin Plumb in 1993, no copyright is claimed.

 * This code is in the public domain; do with it what you wish.

 *

 * Equivalent code is available from RSA Data Security, Inc.

 * This code has been tested against that, and is equivalent,

 * except that you don't need to include two pages of legalese

 * with every copy.

 *

 * To compute the message digest of a chunk of bytes, declare an

 * MD5Context structure, pass it to MD5Init, call MD5Update as

 * needed on buffers full of bytes, and then call MD5Final, which

 * will fill a supplied 16-byte array with the digest.

 * ----------------------------------------------------------------------------

 * libjpeg-turbo Modifications:

 * Copyright (C)2018, D. R. Commander.  All Rights Reserved.

 *

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

 * modification, are permitted provided that the following conditions are met:

 *

 * - Redistributions of source code must retain the above copyright notice,

 *   this list of conditions and the following disclaimer.

 * - 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.

 * - Neither the name of the libjpeg-turbo 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDERS 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 <string.h>             /* for memcpy() */</string.h>

#include "md5.h"

#if (BYTE_ORDER == LITTLE_ENDIAN)

#define byteReverse(buf, len)   /* Nothing */

#else

/*

 * Note: this code is harmless on little-endian machines.

 */

static void byteReverse(unsigned char *buf, unsigned int longs)

{

  uint32 t;

  do {

    t = (uint32)((unsigned int)buf[3] << 8 | buf[2]) << 16 |

        ((unsigned int)buf[1] << 8 | buf[0]);

    *(uint32 *)buf = t;

    buf += 4;

  } while (--longs);

}

#endif

/*

 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious

 * initialization constants.

 */

void MD5Init(struct MD5Context *ctx)

{

  ctx->buf[0] = 0x67452301;

  ctx->buf[1] = 0xefcdab89;

  ctx->buf[2] = 0x98badcfe;

  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;

  ctx->bits[1] = 0;

}

/*

 * Update context to reflect the concatenation of another buffer full

 * of bytes.

 */

void MD5Update(struct MD5Context *ctx, unsigned char *buf, unsigned int len)

{

  uint32 t;

  /* Update bitcount */

  t = ctx->bits[0];

  if ((ctx->bits[0] = t + ((uint32)len << 3)) < t)

    ctx->bits[1]++;             /* Carry from low to high */

  ctx->bits[1] += len >> 29;

  t = (t >> 3) & 0x3f;          /* Bytes already in shsInfo->data */

  /* Handle any leading odd-sized chunks */

  if (t) {

    unsigned char *p = (unsigned char *)ctx->in + t;

    t = 64 - t;

    if (len < t) {

      memcpy(p, buf, len);

      return;

    }

    memcpy(p, buf, t);

    byteReverse(ctx->in, 16);

    MD5Transform(ctx->buf, (uint32 *)ctx->in);

    buf += t;

    len -= t;

  }

  /* Process data in 64-byte chunks */

  while (len >= 64) {

    memcpy(ctx->in, buf, 64);

    byteReverse(ctx->in, 16);

    MD5Transform(ctx->buf, (uint32 *)ctx->in);

    buf += 64;

    len -= 64;

  }

  /* Handle any remaining bytes of data. */

  memcpy(ctx->in, buf, len);

}

/*

 * Final wrapup - pad to 64-byte boundary with the bit pattern

 * 1 0* (64-bit count of bits processed, MSB-first)

 */

void MD5Final(unsigned char digest[16], struct MD5Context *ctx)

{

  unsigned int count;

  unsigned char *p;

  uint32 *in32 = (uint32 *)ctx->in;

  /* Compute number of bytes mod 64 */

  count = (ctx->bits[0] >> 3) & 0x3F;

  /* Set the first char of padding to 0x80.  This is safe since there is

     always at least one byte free */

  p = ctx->in + count;

  *p++ = 0x80;

  /* Bytes of padding needed to make 64 bytes */

  count = 64 - 1 - count;

  /* Pad out to 56 mod 64 */

  if (count < 8) {

    /* Two lots of padding:  Pad the first block to 64 bytes */

    memset(p, 0, count);

    byteReverse(ctx->in, 16);

    MD5Transform(ctx->buf, (uint32 *)ctx->in);

    /* Now fill the next block with 56 bytes */

    memset(ctx->in, 0, 56);

  } else {

    /* Pad block to 56 bytes */

    memset(p, 0, count - 8);

  }

  byteReverse(ctx->in, 14);

  /* Append length in bits and transform */

  in32[14] = ctx->bits[0];

  in32[15] = ctx->bits[1];

  MD5Transform(ctx->buf, (uint32 *)ctx->in);

  byteReverse((unsigned char *)ctx->buf, 4);

  memcpy(digest, ctx->buf, 16);

  memset(ctx, 0, sizeof(struct MD5Context));     /* In case it's sensitive */

}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */

#define F1(x, y, z)  (z ^ (x & (y ^ z)))

#define F2(x, y, z)  F1(z, x, y)

#define F3(x, y, z)  (x ^ y ^ z)

#define F4(x, y, z)  (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */

#define MD5STEP(f, w, x, y, z, data, s) \

  ( w += f(x, y, z) + data,  w = w << s | w >> (32 - s),  w += x )

/*

 * The core of the MD5 algorithm, this alters an existing MD5 hash to

 * reflect the addition of 16 longwords of new data.  MD5Update blocks

 * the data and converts bytes into longwords for this routine.

 */

void MD5Transform(uint32 buf[4], uint32 in[16])

{

  register uint32 a, b, c, d;

  a = buf[0];

  b = buf[1];

  c = buf[2];

  d = buf[3];

  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);

  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);

  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);

  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);

  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);

  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);

  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);

  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);

  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);

  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);

  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);

  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);

  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);

  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);

  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);

  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);

  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);

  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);

  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);

  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);

  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);

  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);

  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);

  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);

  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);

  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);

  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);

  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);

  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);

  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);

  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);

  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);

  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);

  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);

  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);

  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);

  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);

  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);

  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);

  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);

  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);

  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);

  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);

  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);

  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);

  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);

  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);

  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);

  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);

  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);

  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);

  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);

  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);

  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);

  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);

  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);

  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);

  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);

  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);

  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);

  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

  buf[0] += a;

  buf[1] += b;

  buf[2] += c;

  buf[3] += d;

}