/*
md5.ec - RSA Data Security, Inc., MD5 message-digest algorithm

Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. 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.
*/

// MD5 context.
struct MD5_CTX
{
   uint32 state[4];        // state (ABCD)
   uint32 count[2];        // number of bits, modulo 2^64 (lsb first)
   byte buffer[64];        // input buffer
};

// Constants for MD5Transform routine.

#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

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

// 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)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) { \
 (a) += G ((b), (c), (d)) + (x) + (uint32)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) { \
 (a) += H ((b), (c), (d)) + (x) + (uint32)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) { \
 (a) += I ((b), (c), (d)) + (x) + (uint32)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \
 (a) += (b); \
  }

// MD5 initialization. Begins an MD5 operation, writing a new context.
void MD5Init(MD5_CTX context)
{
  context.count[0] = context.count[1] = 0;

  // Load magic initialization constants.
  context.state[0] = 0x67452301;
  context.state[1] = 0xefcdab89;
  context.state[2] = 0x98badcfe;
  context.state[3] = 0x10325476;
}

// MD5 block update operation. Continues an MD5 message-digest operation, processing another message block, and updating the context.
void MD5Update(MD5_CTX context, byte *input, uint inputLen)
{
   uint i, index, partLen;

   // Compute number of bytes mod 64
   index = (uint)((context.count[0] >> 3) & 0x3F);

   // Update number of bits
   if ((context.count[0] += ((uint32)inputLen << 3)) < ((uint32)inputLen << 3))
      context.count[1]++;
   context.count[1] += ((uint32)inputLen >> 29);

   partLen = 64 - index;

   // Transform as many times as possible.
   if (inputLen >= partLen)
   {
      memcpy((byte *)&context.buffer[index], (byte *)input, partLen);
      MD5Transform (context.state, context.buffer);

      for (i = partLen; i + 63 < inputLen; i += 64)
         MD5Transform (context.state, &input[i]);

      index = 0;
   }
   else
      i = 0;

   // Buffer remaining input
   memcpy((byte *)&context.buffer[index], (byte *)&input[i],
   inputLen-i);
}

// MD5 finalization. Ends an MD5 message-digest operation, writing the the message digest and zeroizing the context.
void MD5Final(byte digest[16], MD5_CTX context)
{
   byte bits[8];
   uint index, padLen;

   // Save number of bits
   Encode (bits, context.count, 8);

   // Pad out to 56 mod 64.

   index = (uint)((context.count[0] >> 3) & 0x3f);
   padLen = (index < 56) ? (56 - index) : (120 - index);
   MD5Update (context, PADDING, padLen);

   // Append length (before padding)
   MD5Update (context, bits, 8);

   // Store state in digest
   Encode (digest, context.state, 16);

   // Zeroize sensitive information.
   memset ((byte *)context, 0, sizeof(MD5_CTX));
}

// MD5 basic transformation. Transforms state based on block.
static void MD5Transform(uint32 state[4], byte block[64])
{
   uint32 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

   Decode (x, block, 64);

   // Round 1
   FF (a, b, c, d, x[ 0], S11, 0xd76aa478); // 1
   FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); // 2
   FF (c, d, a, b, x[ 2], S13, 0x242070db); // 3
   FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); // 4
   FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); // 5
   FF (d, a, b, c, x[ 5], S12, 0x4787c62a); // 6
   FF (c, d, a, b, x[ 6], S13, 0xa8304613); // 7
   FF (b, c, d, a, x[ 7], S14, 0xfd469501); // 8
   FF (a, b, c, d, x[ 8], S11, 0x698098d8); // 9
   FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); // 10
   FF (c, d, a, b, x[10], S13, 0xffff5bb1); // 11
   FF (b, c, d, a, x[11], S14, 0x895cd7be); // 12
   FF (a, b, c, d, x[12], S11, 0x6b901122); // 13
   FF (d, a, b, c, x[13], S12, 0xfd987193); // 14
   FF (c, d, a, b, x[14], S13, 0xa679438e); // 15
   FF (b, c, d, a, x[15], S14, 0x49b40821); // 16

   // Round 2
   GG (a, b, c, d, x[ 1], S21, 0xf61e2562); // 17
   GG (d, a, b, c, x[ 6], S22, 0xc040b340); // 18
   GG (c, d, a, b, x[11], S23, 0x265e5a51); // 19
   GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); // 20
   GG (a, b, c, d, x[ 5], S21, 0xd62f105d); // 21
   GG (d, a, b, c, x[10], S22,  0x2441453); // 22
   GG (c, d, a, b, x[15], S23, 0xd8a1e681); // 23
   GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); // 24
   GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); // 25
   GG (d, a, b, c, x[14], S22, 0xc33707d6); // 26
   GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); // 27
   GG (b, c, d, a, x[ 8], S24, 0x455a14ed); // 28
   GG (a, b, c, d, x[13], S21, 0xa9e3e905); // 29
   GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); // 30
   GG (c, d, a, b, x[ 7], S23, 0x676f02d9); // 31
   GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); // 32

   // Round 3
   HH (a, b, c, d, x[ 5], S31, 0xfffa3942); // 33
   HH (d, a, b, c, x[ 8], S32, 0x8771f681); // 34
   HH (c, d, a, b, x[11], S33, 0x6d9d6122); // 35
   HH (b, c, d, a, x[14], S34, 0xfde5380c); // 36
   HH (a, b, c, d, x[ 1], S31, 0xa4beea44); // 37
   HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); // 38
   HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); // 39
   HH (b, c, d, a, x[10], S34, 0xbebfbc70); // 40
   HH (a, b, c, d, x[13], S31, 0x289b7ec6); // 41
   HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); // 42
   HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); // 43
   HH (b, c, d, a, x[ 6], S34,  0x4881d05); // 44
   HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); // 45
   HH (d, a, b, c, x[12], S32, 0xe6db99e5); // 46
   HH (c, d, a, b, x[15], S33, 0x1fa27cf8); // 47
   HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); // 48

   // Round 4
   II (a, b, c, d, x[ 0], S41, 0xf4292244); // 49
   II (d, a, b, c, x[ 7], S42, 0x432aff97); // 50
   II (c, d, a, b, x[14], S43, 0xab9423a7); // 51
   II (b, c, d, a, x[ 5], S44, 0xfc93a039); // 52
   II (a, b, c, d, x[12], S41, 0x655b59c3); // 53
   II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); // 54
   II (c, d, a, b, x[10], S43, 0xffeff47d); // 55
   II (b, c, d, a, x[ 1], S44, 0x85845dd1); // 56
   II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); // 57
   II (d, a, b, c, x[15], S42, 0xfe2ce6e0); // 58
   II (c, d, a, b, x[ 6], S43, 0xa3014314); // 59
   II (b, c, d, a, x[13], S44, 0x4e0811a1); // 60
   II (a, b, c, d, x[ 4], S41, 0xf7537e82); // 61
   II (d, a, b, c, x[11], S42, 0xbd3af235); // 62
   II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); // 63
   II (b, c, d, a, x[ 9], S44, 0xeb86d391); // 64

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

   // Zeroize sensitive information.
   memset ((byte *)x, 0, sizeof (x));
}

// Encodes input (uint32) into output (byte). Assumes len is a multiple of 4.
static void Encode(byte *output, uint32 *input, uint len)
{
   uint i, j;

   for (i = 0, j = 0; j < len; i++, j += 4)
   {
      output[j] = (byte)(input[i] & 0xff);
      output[j+1] = (byte)((input[i] >> 8) & 0xff);
      output[j+2] = (byte)((input[i] >> 16) & 0xff);
      output[j+3] = (byte)((input[i] >> 24) & 0xff);
   }
}

// Decodes input (byte) into output (uint32). Assumes len is a multiple of 4.
static void Decode(uint32 *output, byte *input, uint len)
{
   uint i, j;

   for (i = 0, j = 0; j < len; i++, j += 4)
      output[i] = ((uint32)input[j]) | (((uint32)input[j+1]) << 8) | (((uint32)input[j+2]) << 16) | (((uint32)input[j+3]) << 24);
}

void MD5Digest(char * string, int len, char * output)
{
   byte bytes[16];
   int c;
   MD5_CTX ctx;
   MD5Init(&ctx);
   MD5Update(&ctx, string, len);
   MD5Final(bytes, &ctx);
   len = 0;
   for(c = 0; c<16; c++)
   {
      sprintf(output + len, "%02x", bytes[c]);
      len += 2;      
   }
}