/***************************************************************************************
 *
 *  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
 *
 *  By downloading, copying, installing or using the software you agree to this license.
 *  If you do not agree to this license, do not download, install, 
 *  copy or use the software.
 *
 *  Copyright (C) 2014-2022, Happytimesoft Corporation, all rights reserved.
 *
 *  Redistribution and use in binary forms, with or without modification, are permitted.
 *
 *  Unless required by applicable law or agreed to in writing, software distributed 
 *  under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 *  CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
 *  language governing permissions and limitations under the License.
 *
****************************************************************************************/

#include "sys_inc.h"
#include "rfc_md5.h"

/***************************************************************************************/
static void MD5Transform(uint32[4], uint8[64]);
static void Encode(uint8 *, uint32 *, uint32);
static void Decode(uint32 *, uint8 *, uint32);
static void MD5_memcpy(uint8 *, uint8 *, uint32);
static void MD5_memset(uint8 *, int, uint32);

/***************************************************************************************/
static uint8 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.
*/
HT_API 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.
*/
HT_API void MD5Update(MD5_CTX * context, uint8 * input, uint32 inputLen)
{
	uint32 i, index, partLen;
	
	/* Compute number of bytes mod 64 */
	index = (uint32)((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) 
	{
		MD5_memcpy((uint8 *)&context->buffer[index], (uint8 *)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 */
	MD5_memcpy((uint8 *)&context->buffer[index], (uint8 *)&input[i], inputLen-i);
}

/* MD5 finalization. Ends an MD5 message-digest operation, writing the
the message digest and zeroizing the context.
*/
HT_API void MD5Final(uint8 digest[16], MD5_CTX * context)
{
	uint8 bits[8];
	uint32 index, padLen;
	
	/* Save number of bits */
	Encode(bits, context->count, 8);
	
	/* Pad out to 56 mod 64.
	*/
	index = (uint32)((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.
	*/
	MD5_memset((uint8 *)context, 0, sizeof (*context));
}

/* MD5 basic transformation. Transforms state based on block.
*/
static void MD5Transform(uint32 state[4], uint8 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.*/
	MD5_memset((uint8 *)x, 0, sizeof (x));
}

/* Encodes input (uint32) into output (uint8). Assumes len is
a multiple of 4.
*/
static void Encode(uint8 * output, uint32 * input, uint32 len)
{
	uint32 i, j;
	
	for (i = 0, j = 0; j < len; i++, j += 4) 
	{
		output[j] = (uint8)(input[i] & 0xff);
		output[j+1] = (uint8)((input[i] >> 8) & 0xff);
		output[j+2] = (uint8)((input[i] >> 16) & 0xff);
		output[j+3] = (uint8)((input[i] >> 24) & 0xff);
	}
}

/* Decodes input (uint8) into output (uint32). Assumes len is
a multiple of 4.
*/
static void Decode(uint32 * output, uint8 * input, uint32 len)
{
	uint32 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);
	}	
}

/* Note: Replace "for loop" with standard memcpy if possible.
*/

static void MD5_memcpy(uint8 * output, uint8 * input, uint32 len)
{
	uint32 i;
	
	for (i = 0; i < len; i++)
	{
		output[i] = input[i];
	}	
}

/* Note: Replace "for loop" with standard memset if possible.
*/
static void MD5_memset(uint8 * output, int value, uint32 len)
{
	uint32 i;
	
	for (i = 0; i < len; i++)
	{
		((char *)output)[i] = (char)value;
	}	
}


/* Digests a string and prints the result.
*/
HT_API void MD5String(uint8 * string, uint32 len, uint8 * result)
{
	MD5_CTX context;
	
	MD5Init(&context);
	MD5Update(&context, string, len);
	MD5Final(result, &context);
}

HT_API void BinToHexStr(HASH Bin, HASHHEX Hex)
{
	uint16 i;
	uint8 j;
	
	for (i = 0; i < HASHLEN; i++) 
	{
		j = (Bin[i] >> 4) & 0xf;

		if (j <= 9)
		{
			Hex[i*2] = (j + '0');
		}	
		else
		{
			Hex[i*2] = (j + 'a' - 10);
		}
		
		j = Bin[i] & 0xf;

		if (j <= 9)
		{
			Hex[i*2+1] = (j + '0');
		}	
		else
		{
			Hex[i*2+1] = (j + 'a' - 10);
		}	
	};
	
	Hex[HASHHEXLEN] = '\0';
};

HT_API BOOL HexStrToBin(char * str, HASH Bin)
{
	int i;

	if (strlen(str) != HASHHEXLEN)
	{
		return FALSE;
	}
	
	for (i=0; i<HASHLEN; i++)
	{
		if (str[i*2] >= '0' && str[i*2] <= '9')
		{
			Bin[i] = (str[i*2] - '0') << 4;
		}	
		else if (str[i*2] >= 'a' && str[i*2] <= 'z')
		{
			Bin[i] = (str[i*2] - 'a') << 4;
		}	
		else
		{
			return FALSE;
        }
        
		if (str[i*2+1] >= '0' && str[i*2+1] <= '9')
		{
			Bin[i] |= (str[i*2+1] - '0');
		}	
		else if (str[i*2+1] >= 'a' && str[i*2+1] <= 'z')
		{
			Bin[i] |= str[i*2+1] - 'a';
		}	
		else
		{
			return FALSE;
		}	
	}

	return TRUE;
}