//----------------------------------------------------------------------------
// MD5 clone.
//----------------------------------------------------------------------------
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <assert.h>
#include <stdlib.h>
#include "md52.h"
///#define ASM
#define LITTLE_ENDIAN


//----------------------------------------------------------------------------
// This code implements the MD5 message-digest algorithm.  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.
//
// 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.
//----------------------------------------------------------------------------
#ifdef LITTLE_ENDIAN
#define byteReverse(buf, len)	// Do nothing.
#else
void byteReverse(unsigned char *buf, unsigned longs);
#ifndef ASM
// Note: this code is harmless on big-endian machines.
void byteReverse(unsigned char *buf, unsigned longs)
{
	uint32 t;
	do 
	{
		t = (((((buf[3] << 8) | buf[2]) << 8) | buf[1]) << 8) | buf[0];
		*(uint32 *)buf = t;
		buf += 4;
	} 
	while (--longs);
}
#endif
#endif


//----------------------------------------------------------------------------
// Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
// initialization constants.
//----------------------------------------------------------------------------
void MD5Init2(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 MD5Update2(struct MD5Context *ctx, unsigned char *buf, unsigned 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);
		Transform2(ctx->buf, (uint32 *)ctx->in);
		buf += t;
		len -= t;
	}

	// Process data in SHS_BLOCKSIZE chunks
	while (len >= 64) 
	{
		memcpy(ctx->in, buf, 64);
		byteReverse(ctx->in, 16);
		Transform2(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 MD5Final2(unsigned char digest[16], struct MD5Context *ctx)
{
	unsigned count;
	unsigned char *p;

	// 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);
		Transform2(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.
	((uint32 *)ctx->in)[ 14 ] = ctx->bits[0];
	((uint32 *)ctx->in)[ 15 ] = ctx->bits[1];

	Transform2(ctx->buf, (uint32 *)ctx->in);
	memcpy(digest, ctx->buf, 16);
	byteReverse(digest, 4);
}


#ifndef ASM

//----------------------------------------------------------------------------
// 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 Transform2(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;
}

#endif


//----------------------------------------------------------------------------
// Hash a string.
//----------------------------------------------------------------------------
BOOL MD5HashText(LPCSTR sText, BYTE Hash[MD5_HASH_SIZE])
{
	struct MD5Context Context;

	MD5Init2(&Context);
	MD5Update2(&Context, (BYTE*)sText, strlen(sText));
	MD5Final2(Hash, &Context);

	return TRUE;
}


//----------------------------------------------------------------------------
// Convert a Hash value to something we can print.
//----------------------------------------------------------------------------
void MD5HashToStr(BYTE buf[MD5_HASH_SIZE], LPSTR sText)
{
	char sByte[4];
	wsprintf(sText, "%02x", *buf++);
	for (int i = 0; i < MD5_HASH_SIZE - 1; i++)
	{
		wsprintf(sByte, " %02x", *buf++);
		strcat(sText, sByte);
	}
}


//----------------------------------------------------------------------------
// Convert a String representation of a hash back to a hash.
//----------------------------------------------------------------------------
void MD5StrToHash(LPCSTR sText, BYTE buf[MD5_HASH_SIZE])
{
	assert(strlen(sText) == 2 * MD5_HASH_SIZE);

	char sByte[5] = "0xNN";
	char* sEnd = NULL;

	for (int i = 0; i < MD5_HASH_SIZE; i++)
	{
		sByte[2] = sText[i * 2];
		sByte[3] = sText[i * 2 + 1];

		buf[i] = (BYTE)strtol(sByte, &sEnd, 16);
	}
}