md5.cpp

md5 加密的C/C++完美实现。 估计是现在最好的md5加密实现了

/*
 * md5.cpp
 *
 * RSA data security. Md5 message-digest algorithm
 * rfc1321.txt
 *
 * author: [e-mail]
 */
#include "md5.h"

// 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

// Padding bits
static const 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) + (UINT4)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}

#define GG(a, b, c, d, x, s, ac) { \
	(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}

#define HH(a, b, c, d, x, s, ac) { \
	(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}

#define II(a, b, c, d, x, s, ac) { \
	(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}

// Replace "for loop" with standard memcpy if possible.
static void MD5_memcpy(BYTE* output, const BYTE* input, UINT4 len) 
{
	UINT4 i;
	if (output == NULL || input == NULL) {
		return;
	}
	for (i = 0; i < len; i++) {
		output[i] = input[i];
	}
}

// Replace "for loop" with standard memset if possible.
static void MD5_memset(BYTE* output, BYTE value, UINT4 len) 
{
	UINT4 i;
	if (output == NULL) {
		return;
	}
	for (i = 0; i < len; i++) {
		output[i] = value;
	}
}

// Encodes input (UINT4) into output (BYTE).
// Assumes len is a multiple of 4.
static void Encode(BYTE* output, const UINT4* input, UINT4 len) 
{
	UINT4 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 (UINT4).
// Assumes len is a multiple of 4.
static void Decode(UINT4* output, const BYTE* input, UINT4 len) 
{
	UINT4 i, j;
	for (i = 0, j = 0; j < len; i++, j += 4)
	{
		output[i] = ((UINT4) input[j]) 
			| (((UINT4) input[j + 1]) << 8 )
			| (((UINT4) input[j + 2]) << 16)
			| (((UINT4) input[j + 3]) << 24);
	}
}

// MD5 basic transformation. 
// Transforms state based on block.
static void MD5Transform(UINT4 state[4], const BYTE block[64]) 
{
	UINT4 a = state[0], b = state[1], c = state[2], d = state[3];
	UINT4 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;
	MD5_memset((BYTE*)x, 0x00, sizeof(x));
}

// MD5 initialization. Begins an MD5 operation, writing a new context.
// context: MD5_CTX.
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.
// context:  MD5_CTX
// input:    input block
// inputLen: length of input block
void MD5Update(MD5_CTX* context, const BYTE* input, UINT4 inputLen) 
{
	UINT4 i, index, partLen;
	//Compute number of bytes mod 64
	index = (UINT4) ((context->count[0] >> 3) & 0x3F);
	//Update number of bits
	if ((context->count[0] += ((UINT4) inputLen << 3)) 
		< ((UINT4) inputLen << 3)) {
		context->count[1]++;
	}
	context->count[1] += ((UINT4) inputLen >> 29);
	partLen = 64 - index;
	//Transform as many times as possible
	if (inputLen >= partLen) {
		MD5_memcpy(&context->buffer[index], 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(&context->buffer[index], &input[i], inputLen - i);
}

// MD5 finalization. Ends an MD5 message-digest operation,
// writing the message digest and zeroizing the context.
// digest:  message digest.
// context: MD5_CTX.
void MD5Final(BYTE digest[16], MD5_CTX* context)
{
	BYTE bits[8];
	UINT4 index, padLen;
	//Save number of bits
	Encode(bits, context->count, 8);
	//Pad out to 56 mod 64.
	index = (UINT4) ((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((BYTE*)context, 0x00, sizeof(*context));
}