#include "MD5.h"

#include <cassert>
#include <cstring>

using namespace std;

/******************************************************************************/

/*
	MD5C.C - 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.
*/

/******************************************************************************/

/* 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 void MD5Transform (unsigned long [4], unsigned char [64]);
static void Encode (unsigned char *, unsigned long *, unsigned int);
static void Decode (unsigned long *, unsigned char *, unsigned int);

static unsigned char 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) + (unsigned long)(ac); \
     (a) = ROTATE_LEFT ((a), (s)); \
     (a) += (b); \
     }
#define GG(a, b, c, d, x, s, ac) { \
     (a) += G ((b), (c), (d)) + (x) + (unsigned long)(ac); \
     (a) = ROTATE_LEFT ((a), (s)); \
     (a) += (b); \
     }
#define HH(a, b, c, d, x, s, ac) { \
     (a) += H ((b), (c), (d)) + (x) + (unsigned long)(ac); \
     (a) = ROTATE_LEFT ((a), (s)); \
     (a) += (b); \
     }
#define II(a, b, c, d, x, s, ac) { \
     (a) += I ((b), (c), (d)) + (x) + (unsigned long)(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, /* context */
					unsigned char *input, /* input block */
					unsigned int inputLen) /* length of input block */
{
	using namespace std;

     unsigned int i, index, partLen;

       /* Compute number of bytes mod 64 */
       index = (unsigned int)((context->count[0] >> 3) & 0x3F);

       /* Update number of bits */
       if ((context->count[0] += ((unsigned long)inputLen << 3))
        < ((unsigned long)inputLen << 3))
      context->count[1]++;
       context->count[1] += ((unsigned long)inputLen >> 29);

     partLen = 64 - index;

       /* Transform as many times as possible.

*/
     if (inputLen >= partLen) {
	 std::memcpy (&context->buffer[index], input, partLen);	// AUDIT: From public MD5 code, assumed safe.
     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 */
	 std::memcpy (&context->buffer[index], &input[i], inputLen-i);	// AUDIT: From public MD5 code, assumed safe.

}

/* MD5 finalization. Ends an MD5 message-digest operation, writing the
     the message digest and zeroizing the context.

      */

void MD5Final (	unsigned char digest[16], /* message digest */
				MD5_CTX *context /* context */)
{
     unsigned char bits[8];
     unsigned int index, padLen;

       /* Save number of bits */
       Encode (bits, context->count, 8);

       /* Pad out to 56 mod 64.

*/
     index = (unsigned int)((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.

*/
	assert ( sizeof(*context) == sizeof(MD5_CTX) );
    memset ( context, 0, sizeof (*context) );	// AUDIT: Safe, using sizeof destination.
}

/* MD5 basic transformation. Transforms state based on block.

      */

static void MD5Transform (	unsigned long state[4],
							unsigned char block[64])
{
     unsigned long 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 (x, 0, sizeof (x));
}

/* Encodes input (unsigned long) into output (unsigned char). Assumes len is
     a multiple of 4.

      */

static void Encode (	unsigned char *output,
						unsigned long *input,
						unsigned int len)
{
     unsigned int i, j;

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

/* Decodes input (unsigned char) into output (unsigned long). Assumes len is
     a multiple of 4.

      */

static void Decode (	unsigned long *output,
						unsigned char *input,
						unsigned int len)
{
     unsigned int i, j;

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