/*
 ***********************************************************************
 **  Message-digest routines:                                         **
 **  To form the message digest for a message M                       **
 **    (1) Initialize a context buffer mdContext using MD5Init        **
 **    (2) Call MD5Update on mdContext and M                          **
 **    (3) Call MD5Final on mdContext                                 **
 **  The message digest is now in mdContext->digest[0...15]           **
 ***********************************************************************
 */

/*
 ***********************************************************************
 ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved.  **
 **                                                                   **
 ** License to copy and use this software is granted provided that    **
 ** it is identified as the "RSA Data Security, Inc. MD5 Message-     **
 ** Digest Algorithm" in all material mentioning or referencing this  **
 ** software or this function.                                        **
 **                                                                   **
 ** License is also granted to make and use derivative works          **
 ** provided that such works are identified as "derived from the RSA  **
 ** Data Security, Inc. MD5 Message-Digest Algorithm" in all          **
 ** material mentioning or referencing the derived work.              **
 **                                                                   **
 ** RSA Data Security, Inc. makes no representations concerning       **
 ** either the merchantability of this software or the suitability    **
 ** of this software for any particular purpose.  It is provided "as  **
 ** is" without express or implied warranty of any kind.              **
 **                                                                   **
 ** These notices must be retained in any copies of any part of this  **
 ** documentation and/or software.                                    **
 ***********************************************************************
 */

#define _DEFAULT_SOURCE
#include "tmd5.h"

/* forward declaration */
static void Transform(uint32_t *buf, uint32_t *in);

static uint8_t PADDING[64] = {0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

/* F, G, H and I are basic MD5 functions */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
/* Rotation is separate from addition to prevent recomputation */
#define FF(a, b, c, d, x, s, ac)                    \
  {                                                 \
    (a) += F((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT((a), (s));                    \
    (a) += (b);                                     \
  }
#define GG(a, b, c, d, x, s, ac)                    \
  {                                                 \
    (a) += G((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT((a), (s));                    \
    (a) += (b);                                     \
  }
#define HH(a, b, c, d, x, s, ac)                    \
  {                                                 \
    (a) += H((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT((a), (s));                    \
    (a) += (b);                                     \
  }
#define II(a, b, c, d, x, s, ac)                    \
  {                                                 \
    (a) += I((b), (c), (d)) + (x) + (uint32_t)(ac); \
    (a) = ROTATE_LEFT((a), (s));                    \
    (a) += (b);                                     \
  }

/* The routine MD5Init initializes the message-digest context
   mdContext. All fields are set to zero.
 */
void tMD5Init(T_MD5_CTX *mdContext) {
  memset(mdContext, 0, sizeof(T_MD5_CTX));

  /* Load magic initialization constants. */
  mdContext->buf[0] = (uint32_t)0x67452301;
  mdContext->buf[1] = (uint32_t)0xefcdab89;
  mdContext->buf[2] = (uint32_t)0x98badcfe;
  mdContext->buf[3] = (uint32_t)0x10325476;
}

/* The routine MD5Update updates the message-digest context to
account for the presence of each of the characters inBuf[0..inLen-1]
in the message whose digest is being computed.
*/
void tMD5Update(T_MD5_CTX *mdContext, uint8_t *inBuf, uint32_t inLen) {
  uint32_t in[16];
  uint32_t mdi;
  uint32_t i, ii;

  /* compute number of bytes mod 64 */
  mdi = (uint32_t)((mdContext->i[0] >> 3) & 0x3F);

  /* update number of bits */
  if ((mdContext->i[0] + ((uint32_t)inLen << 3)) < mdContext->i[0]) mdContext->i[1]++;
  mdContext->i[0] += ((uint32_t)inLen << 3);
  mdContext->i[1] += ((uint32_t)inLen >> 29);

  while (inLen--) {
    /* add new character to buffer, increment mdi */
    mdContext->in[mdi++] = *inBuf++;

    /* transform if necessary */
    if (mdi == 0x40) {
      for (i = 0, ii = 0; i < 16; i++, ii += 4)
        in[i] = (((uint32_t)mdContext->in[ii + 3]) << 24) | (((uint32_t)mdContext->in[ii + 2]) << 16) |
                (((uint32_t)mdContext->in[ii + 1]) << 8) | ((uint32_t)mdContext->in[ii]);
      Transform(mdContext->buf, in);
      mdi = 0;
    }
  }
}

/* The routine MD5Final terminates the message-digest computation and
ends with the desired message digest in mdContext->digest[0...15].
*/
void tMD5Final(T_MD5_CTX *mdContext) {
  uint32_t in[16];
  uint32_t mdi;
  uint32_t i, ii;
  uint32_t padLen;

  /* save number of bits */
  in[14] = mdContext->i[0];
  in[15] = mdContext->i[1];

  /* compute number of bytes mod 64 */
  mdi = (uint32_t)((mdContext->i[0] >> 3) & 0x3F);

  /* pad out to 56 mod 64 */
  padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
  tMD5Update(mdContext, PADDING, padLen);

  /* append length in bits and transform */
  for (i = 0, ii = 0; i < 14; i++, ii += 4)
    in[i] = (((uint32_t)mdContext->in[ii + 3]) << 24) | (((uint32_t)mdContext->in[ii + 2]) << 16) |
            (((uint32_t)mdContext->in[ii + 1]) << 8) | ((uint32_t)mdContext->in[ii]);
  Transform(mdContext->buf, in);

  /* store buffer in digest */
  for (i = 0, ii = 0; i < 4; i++, ii += 4) {
    mdContext->digest[ii] = (uint8_t)(mdContext->buf[i] & 0xFF);
    mdContext->digest[ii + 1] = (uint8_t)((mdContext->buf[i] >> 8) & 0xFF);
    mdContext->digest[ii + 2] = (uint8_t)((mdContext->buf[i] >> 16) & 0xFF);
    mdContext->digest[ii + 3] = (uint8_t)((mdContext->buf[i] >> 24) & 0xFF);
  }
}

/* Basic MD5 step. Transforms buf based on in.
 */
static void Transform(uint32_t *buf, uint32_t *in) {
  uint32_t a = buf[0], b = buf[1], c = buf[2], d = buf[3];

/* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22

  FF(a, b, c, d, in[0], S11, 3614090360U);  /* 1 */
  FF(d, a, b, c, in[1], S12, 3905402710U);  /* 2 */
  FF(c, d, a, b, in[2], S13, 606105819U);   /* 3 */
  FF(b, c, d, a, in[3], S14, 3250441966U);  /* 4 */
  FF(a, b, c, d, in[4], S11, 4118548399U);  /* 5 */
  FF(d, a, b, c, in[5], S12, 1200080426U);  /* 6 */
  FF(c, d, a, b, in[6], S13, 2821735955U);  /* 7 */
  FF(b, c, d, a, in[7], S14, 4249261313U);  /* 8 */
  FF(a, b, c, d, in[8], S11, 1770035416U);  /* 9 */
  FF(d, a, b, c, in[9], S12, 2336552879U);  /* 10 */
  FF(c, d, a, b, in[10], S13, 4294925233U); /* 11 */
  FF(b, c, d, a, in[11], S14, 2304563134U); /* 12 */
  FF(a, b, c, d, in[12], S11, 1804603682U); /* 13 */
  FF(d, a, b, c, in[13], S12, 4254626195U); /* 14 */
  FF(c, d, a, b, in[14], S13, 2792965006U); /* 15 */
  FF(b, c, d, a, in[15], S14, 1236535329U); /* 16 */

/* Round 2 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20

  GG(a, b, c, d, in[1], S21, 4129170786U);  /* 17 */
  GG(d, a, b, c, in[6], S22, 3225465664U);  /* 18 */
  GG(c, d, a, b, in[11], S23, 643717713U);  /* 19 */
  GG(b, c, d, a, in[0], S24, 3921069994U);  /* 20 */
  GG(a, b, c, d, in[5], S21, 3593408605U);  /* 21 */
  GG(d, a, b, c, in[10], S22, 38016083U);   /* 22 */
  GG(c, d, a, b, in[15], S23, 3634488961U); /* 23 */
  GG(b, c, d, a, in[4], S24, 3889429448U);  /* 24 */
  GG(a, b, c, d, in[9], S21, 568446438U);   /* 25 */
  GG(d, a, b, c, in[14], S22, 3275163606U); /* 26 */
  GG(c, d, a, b, in[3], S23, 4107603335U);  /* 27 */
  GG(b, c, d, a, in[8], S24, 1163531501U);  /* 28 */
  GG(a, b, c, d, in[13], S21, 2850285829U); /* 29 */
  GG(d, a, b, c, in[2], S22, 4243563512U);  /* 30 */
  GG(c, d, a, b, in[7], S23, 1735328473U);  /* 31 */
  GG(b, c, d, a, in[12], S24, 2368359562U); /* 32 */

/* Round 3 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23

  HH(a, b, c, d, in[5], S31, 4294588738U);  /* 33 */
  HH(d, a, b, c, in[8], S32, 2272392833U);  /* 34 */
  HH(c, d, a, b, in[11], S33, 1839030562U); /* 35 */
  HH(b, c, d, a, in[14], S34, 4259657740U); /* 36 */
  HH(a, b, c, d, in[1], S31, 2763975236U);  /* 37 */
  HH(d, a, b, c, in[4], S32, 1272893353U);  /* 38 */
  HH(c, d, a, b, in[7], S33, 4139469664U);  /* 39 */
  HH(b, c, d, a, in[10], S34, 3200236656U); /* 40 */
  HH(a, b, c, d, in[13], S31, 681279174U);  /* 41 */
  HH(d, a, b, c, in[0], S32, 3936430074U);  /* 42 */
  HH(c, d, a, b, in[3], S33, 3572445317U);  /* 43 */
  HH(b, c, d, a, in[6], S34, 76029189U);    /* 44 */
  HH(a, b, c, d, in[9], S31, 3654602809U);  /* 45 */
  HH(d, a, b, c, in[12], S32, 3873151461U); /* 46 */
  HH(c, d, a, b, in[15], S33, 530742520U);  /* 47 */
  HH(b, c, d, a, in[2], S34, 3299628645U);  /* 48 */

/* Round 4 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21

  II(a, b, c, d, in[0], S41, 4096336452U);  /* 49 */
  II(d, a, b, c, in[7], S42, 1126891415U);  /* 50 */
  II(c, d, a, b, in[14], S43, 2878612391U); /* 51 */
  II(b, c, d, a, in[5], S44, 4237533241U);  /* 52 */
  II(a, b, c, d, in[12], S41, 1700485571U); /* 53 */
  II(d, a, b, c, in[3], S42, 2399980690U);  /* 54 */
  II(c, d, a, b, in[10], S43, 4293915773U); /* 55 */
  II(b, c, d, a, in[1], S44, 2240044497U);  /* 56 */
  II(a, b, c, d, in[8], S41, 1873313359U);  /* 57 */
  II(d, a, b, c, in[15], S42, 4264355552U); /* 58 */
  II(c, d, a, b, in[6], S43, 2734768916U);  /* 59 */
  II(b, c, d, a, in[13], S44, 1309151649U); /* 60 */
  II(a, b, c, d, in[4], S41, 4149444226U);  /* 61 */
  II(d, a, b, c, in[11], S42, 3174756917U); /* 62 */
  II(c, d, a, b, in[2], S43, 718787259U);   /* 63 */
  II(b, c, d, a, in[9], S44, 3951481745U);  /* 64 */

  buf[0] += a;
  buf[1] += b;
  buf[2] += c;
  buf[3] += d;
}