/* Taken from ReHash (www.reichlsoft.de.vu) and released
 * under GPL/LGPL with permission from ReHash author
 * Dominik Reichl <dominik.reichl@t-online.de>, Germany
 */

/*
 **********************************************************************
 ** MD5.cpp                                                          **
 **                                                                  **
 ** - Style modified by Tony Ray, January 2001                       **
 **   Added support for randomizing initialization constants         **
 ** - Style modified by Dominik Reichl, April 2003                   **
 **   Optimized code                                                 **
 **                                                                  **
 ** MD5.c                                                            **
 ** RSA Data Security, Inc. MD5 Message Digest Algorithm             **
 ** Created: 2/17/90 RLR                                             **
 ** Revised: 1/91 SRD,AJ,BSK,JT Reference C Version                  **
 **********************************************************************
 */

/*
 **********************************************************************
 ** MD5.h -- Header file for implementation of MD5                   **
 ** RSA Data Security, Inc. MD5 Message Digest Algorithm             **
 ** Created: 2/17/90 RLR                                             **
 ** Revised: 12/27/90 SRD,AJ,BSK,JT Reference C version              **
 ** Revised (for MD5): RLR 4/27/91                                   **
 **   -- G modified to have y&~z instead of y&z                      **
 **   -- FF, GG, HH modified to add in last register done            **
 **   -- Access pattern: round 2 works mod 5, round 3 works mod 3    **
 **   -- distinct additive constant for each step                    **
 **   -- round 4 added, working mod 7                                **
 **********************************************************************
 */

/*
 **********************************************************************
 ** 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.                                   **
 **********************************************************************
 */

#include <stdio.h>
#include <stdlib.h>

#include "md5.h"

/* Typedef a 32 bit type */
#ifndef UINT4
typedef unsigned long int UINT4;
#endif

/* Data structure for MD5 (Message Digest) computation */
typedef struct {
	UINT4 		i[2];           /* Number of _bits_ handled mod 2^64 	*/
	UINT4 		buf[4];         /* Scratch buffer 			*/
	unsigned char 	in[64];         /* Input buffer 			*/
	unsigned char 	digest[16];     /* Actual digest after MD5Final call 	*/
} MD5_CTX;

/* Padding */
static unsigned char MD5_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
};

/* MD5_F, MD5_G and MD5_H are basic MD5 functions: selection, majority, parity */
#define MD5_F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define MD5_G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define MD5_H(x, y, z) ((x) ^ (y) ^ (z))
#define MD5_I(x, y, z) ((y) ^ ((x) | (~z)))

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

/* MD5_FF, MD5_GG, MD5_HH, and MD5_II transformations for rounds 1, 2, 3, and 4 */
/* Rotation is separate from addition to prevent recomputation */
#define MD5_FF(a, b, c, d, x, s, ac) {(a) += MD5_F ((b), (c), (d)) + (x) + (UINT4)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }
#define MD5_GG(a, b, c, d, x, s, ac) {(a) += MD5_G ((b), (c), (d)) + (x) + (UINT4)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }
#define MD5_HH(a, b, c, d, x, s, ac) {(a) += MD5_H ((b), (c), (d)) + (x) + (UINT4)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }
#define MD5_II(a, b, c, d, x, s, ac) {(a) += MD5_I ((b), (c), (d)) + (x) + (UINT4)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b); }

/* Constants for transformation */
#define MD5_S11 7  /* Round 1 */
#define MD5_S12 12
#define MD5_S13 17
#define MD5_S14 22
#define MD5_S21 5  /* Round 2 */
#define MD5_S22 9
#define MD5_S23 14
#define MD5_S24 20
#define MD5_S31 4  /* Round 3 */
#define MD5_S32 11
#define MD5_S33 16
#define MD5_S34 23
#define MD5_S41 6  /* Round 4 */
#define MD5_S42 10
#define MD5_S43 15
#define MD5_S44 21

/* Basic MD5 step. MD5_Transform buf based on in */
static void MD5_Transform (UINT4 *buf, UINT4 *in)
{
	UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];

	/* Round 1 */
	MD5_FF ( a, b, c, d, in[ 0], MD5_S11, (UINT4) 3614090360u); /* 1 */
	MD5_FF ( d, a, b, c, in[ 1], MD5_S12, (UINT4) 3905402710u); /* 2 */
	MD5_FF ( c, d, a, b, in[ 2], MD5_S13, (UINT4)  606105819u); /* 3 */
	MD5_FF ( b, c, d, a, in[ 3], MD5_S14, (UINT4) 3250441966u); /* 4 */
	MD5_FF ( a, b, c, d, in[ 4], MD5_S11, (UINT4) 4118548399u); /* 5 */
	MD5_FF ( d, a, b, c, in[ 5], MD5_S12, (UINT4) 1200080426u); /* 6 */
	MD5_FF ( c, d, a, b, in[ 6], MD5_S13, (UINT4) 2821735955u); /* 7 */
	MD5_FF ( b, c, d, a, in[ 7], MD5_S14, (UINT4) 4249261313u); /* 8 */
	MD5_FF ( a, b, c, d, in[ 8], MD5_S11, (UINT4) 1770035416u); /* 9 */
	MD5_FF ( d, a, b, c, in[ 9], MD5_S12, (UINT4) 2336552879u); /* 10 */
	MD5_FF ( c, d, a, b, in[10], MD5_S13, (UINT4) 4294925233u); /* 11 */
	MD5_FF ( b, c, d, a, in[11], MD5_S14, (UINT4) 2304563134u); /* 12 */
	MD5_FF ( a, b, c, d, in[12], MD5_S11, (UINT4) 1804603682u); /* 13 */
	MD5_FF ( d, a, b, c, in[13], MD5_S12, (UINT4) 4254626195u); /* 14 */
	MD5_FF ( c, d, a, b, in[14], MD5_S13, (UINT4) 2792965006u); /* 15 */
	MD5_FF ( b, c, d, a, in[15], MD5_S14, (UINT4) 1236535329u); /* 16 */

	/* Round 2 */
	MD5_GG ( a, b, c, d, in[ 1], MD5_S21, (UINT4) 4129170786u); /* 17 */
	MD5_GG ( d, a, b, c, in[ 6], MD5_S22, (UINT4) 3225465664u); /* 18 */
	MD5_GG ( c, d, a, b, in[11], MD5_S23, (UINT4)  643717713u); /* 19 */
	MD5_GG ( b, c, d, a, in[ 0], MD5_S24, (UINT4) 3921069994u); /* 20 */
	MD5_GG ( a, b, c, d, in[ 5], MD5_S21, (UINT4) 3593408605u); /* 21 */
	MD5_GG ( d, a, b, c, in[10], MD5_S22, (UINT4)   38016083u); /* 22 */
	MD5_GG ( c, d, a, b, in[15], MD5_S23, (UINT4) 3634488961u); /* 23 */
	MD5_GG ( b, c, d, a, in[ 4], MD5_S24, (UINT4) 3889429448u); /* 24 */
	MD5_GG ( a, b, c, d, in[ 9], MD5_S21, (UINT4)  568446438u); /* 25 */
	MD5_GG ( d, a, b, c, in[14], MD5_S22, (UINT4) 3275163606u); /* 26 */
	MD5_GG ( c, d, a, b, in[ 3], MD5_S23, (UINT4) 4107603335u); /* 27 */
	MD5_GG ( b, c, d, a, in[ 8], MD5_S24, (UINT4) 1163531501u); /* 28 */
	MD5_GG ( a, b, c, d, in[13], MD5_S21, (UINT4) 2850285829u); /* 29 */
	MD5_GG ( d, a, b, c, in[ 2], MD5_S22, (UINT4) 4243563512u); /* 30 */
	MD5_GG ( c, d, a, b, in[ 7], MD5_S23, (UINT4) 1735328473u); /* 31 */
	MD5_GG ( b, c, d, a, in[12], MD5_S24, (UINT4) 2368359562u); /* 32 */

	/* Round 3 */
	MD5_HH ( a, b, c, d, in[ 5], MD5_S31, (UINT4) 4294588738u); /* 33 */
	MD5_HH ( d, a, b, c, in[ 8], MD5_S32, (UINT4) 2272392833u); /* 34 */
	MD5_HH ( c, d, a, b, in[11], MD5_S33, (UINT4) 1839030562u); /* 35 */
	MD5_HH ( b, c, d, a, in[14], MD5_S34, (UINT4) 4259657740u); /* 36 */
	MD5_HH ( a, b, c, d, in[ 1], MD5_S31, (UINT4) 2763975236u); /* 37 */
	MD5_HH ( d, a, b, c, in[ 4], MD5_S32, (UINT4) 1272893353u); /* 38 */
	MD5_HH ( c, d, a, b, in[ 7], MD5_S33, (UINT4) 4139469664u); /* 39 */
	MD5_HH ( b, c, d, a, in[10], MD5_S34, (UINT4) 3200236656u); /* 40 */
	MD5_HH ( a, b, c, d, in[13], MD5_S31, (UINT4)  681279174u); /* 41 */
	MD5_HH ( d, a, b, c, in[ 0], MD5_S32, (UINT4) 3936430074u); /* 42 */
	MD5_HH ( c, d, a, b, in[ 3], MD5_S33, (UINT4) 3572445317u); /* 43 */
	MD5_HH ( b, c, d, a, in[ 6], MD5_S34, (UINT4)   76029189u); /* 44 */
	MD5_HH ( a, b, c, d, in[ 9], MD5_S31, (UINT4) 3654602809u); /* 45 */
	MD5_HH ( d, a, b, c, in[12], MD5_S32, (UINT4) 3873151461u); /* 46 */
	MD5_HH ( c, d, a, b, in[15], MD5_S33, (UINT4)  530742520u); /* 47 */
	MD5_HH ( b, c, d, a, in[ 2], MD5_S34, (UINT4) 3299628645u); /* 48 */

	/* Round 4 */
	MD5_II ( a, b, c, d, in[ 0], MD5_S41, (UINT4) 4096336452u); /* 49 */
	MD5_II ( d, a, b, c, in[ 7], MD5_S42, (UINT4) 1126891415u); /* 50 */
	MD5_II ( c, d, a, b, in[14], MD5_S43, (UINT4) 2878612391u); /* 51 */
	MD5_II ( b, c, d, a, in[ 5], MD5_S44, (UINT4) 4237533241u); /* 52 */
	MD5_II ( a, b, c, d, in[12], MD5_S41, (UINT4) 1700485571u); /* 53 */
	MD5_II ( d, a, b, c, in[ 3], MD5_S42, (UINT4) 2399980690u); /* 54 */
	MD5_II ( c, d, a, b, in[10], MD5_S43, (UINT4) 4293915773u); /* 55 */
	MD5_II ( b, c, d, a, in[ 1], MD5_S44, (UINT4) 2240044497u); /* 56 */
	MD5_II ( a, b, c, d, in[ 8], MD5_S41, (UINT4) 1873313359u); /* 57 */
	MD5_II ( d, a, b, c, in[15], MD5_S42, (UINT4) 4264355552u); /* 58 */
	MD5_II ( c, d, a, b, in[ 6], MD5_S43, (UINT4) 2734768916u); /* 59 */
	MD5_II ( b, c, d, a, in[13], MD5_S44, (UINT4) 1309151649u); /* 60 */
	MD5_II ( a, b, c, d, in[ 4], MD5_S41, (UINT4) 4149444226u); /* 61 */
	MD5_II ( d, a, b, c, in[11], MD5_S42, (UINT4) 3174756917u); /* 62 */
	MD5_II ( c, d, a, b, in[ 2], MD5_S43, (UINT4)  718787259u); /* 63 */
	MD5_II ( b, c, d, a, in[ 9], MD5_S44, (UINT4) 3951481745u); /* 64 */

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

/* Set pseudoRandomNumber to zero for RFC MD5 implementation */
void MD5Init (MD5_CTX *mdContext, unsigned long pseudoRandomNumber)
{
	mdContext->i[0] = mdContext->i[1] = (UINT4)0;

	/* Load magic initialization constants */
	mdContext->buf[0] = (UINT4)0x67452301 + (pseudoRandomNumber * 11);
	mdContext->buf[1] = (UINT4)0xefcdab89 + (pseudoRandomNumber * 71);
	mdContext->buf[2] = (UINT4)0x98badcfe + (pseudoRandomNumber * 37);
	mdContext->buf[3] = (UINT4)0x10325476 + (pseudoRandomNumber * 97);
}

void MD5Update (MD5_CTX *mdContext, unsigned char *inBuf, unsigned int inLen)
{
	UINT4 		in[16];
	int 		mdi = 0;
	unsigned int 	i = 0, ii = 0;

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

	/* Update number of bits */
	if ((mdContext->i[0] + ((UINT4)inLen << 3)) < mdContext->i[0]) mdContext->i[1]++;
	mdContext->i[0] += ((UINT4)inLen << 3);
	mdContext->i[1] += ((UINT4)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] = (((UINT4)mdContext->in[ii+3]) << 24) |
					(((UINT4)mdContext->in[ii+2]) << 16) |
					(((UINT4)mdContext->in[ii+1]) << 8) |
					((UINT4)mdContext->in[ii]);

			MD5_Transform (mdContext->buf, in);
			mdi = 0;
		}
	}
}

void MD5Final (MD5_CTX *mdContext)
{
	UINT4 		in[16];
	int 		mdi = 0;
	unsigned int 	i = 0, ii = 0, padLen = 0;

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

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

	/* Pad out to 56 mod 64 */
	padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
	MD5Update (mdContext, MD5_PADDING, padLen);

	/* Append length in bits and transform */
	for (i = 0, ii = 0; i < 14; i++, ii += 4)
		in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
			(((UINT4)mdContext->in[ii+2]) << 16) |
			(((UINT4)mdContext->in[ii+1]) <<  8) |
			((UINT4)mdContext->in[ii]);
	MD5_Transform (mdContext->buf, in);

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

void CalculateMD5(unsigned char *buffer, int length, unsigned char *checksum)
{
	int 		i;
	MD5_CTX 	m_md5;

	MD5Init(&m_md5, 0);
	MD5Update(&m_md5, buffer, length);
	MD5Final(&m_md5);

	for (i = 0; i < 16; i++) sprintf(checksum+i*2,"%02X", m_md5.digest[i]);
}
