md4c.c

算法源代码比较经典

/* Modifications Copyright (c) J.S.A.Kapp 1994 - 1995.

	 MD4 Component Of RSAEURO using RSA Data Security, Inc.
	 MD4 Message Digest Algorithm.

	 All Trademarks Acknowledged.

	 Future versions may not use this modified RSADSI implementation
	 of MD4.
*/

/* Copyright (C) 1990-2, 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. MD4 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. MD4 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 "rsaeuro.h"
#include "md4.h"

/* Constants for MD4Transform routine. */
#define S11 3
#define S12 7
#define S13 11
#define S14 19
#define S21 3
#define S22 5
#define S23 9
#define S24 13
#define S31 3
#define S32 9
#define S33 11
#define S34 15

static void MD4Transform PROTO_LIST ((UINT4 [4], unsigned char [64]));
static void Encode PROTO_LIST ((unsigned char *, UINT4 *, unsigned int));
static void Decode PROTO_LIST ((UINT4 *, 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 and H are basic MD4 functions. */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

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

/* FF, GG and HH are transformations for rounds 1, 2 and 3 */
/* Rotation is separate from addition to prevent recomputation */

#define FF(a, b, c, d, x, s) { \
		(a) += F ((b), (c), (d)) + (x); \
		(a) = ROTATE_LEFT ((a), (s)); \
	}
#define GG(a, b, c, d, x, s) { \
		(a) += G ((b), (c), (d)) + (x) + (UINT4)0x5a827999; \
		(a) = ROTATE_LEFT ((a), (s)); \
	}
#define HH(a, b, c, d, x, s) { \
		(a) += H ((b), (c), (d)) + (x) + (UINT4)0x6ed9eba1; \
		(a) = ROTATE_LEFT ((a), (s)); \
	}

/* MD4 initialization. Begins an MD4 operation, writing a new context. */
void MD4Init(context)
MD4_CTX *context;               /* 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;
}

/* MD4 block update operation. Continues an MD4 message-digest
	 operation, processing another message block, and updating the context.
*/

void MD4Update(context, input, inputLen)
MD4_CTX *context;               /* context */
unsigned char *input;           /* input block */
unsigned int inputLen;          /* length of input block */
{
	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] += ((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) {
		R_memcpy((POINTER)&context->buffer[index], (POINTER)input, partLen);
		MD4Transform(context->state, context->buffer);

		for(i = partLen; i + 63 < inputLen; i += 64)
			MD4Transform(context->state, &input[i]);

		index = 0;
	}
	else
		i = 0;

	/* Buffer remaining input */
	R_memcpy((POINTER)&context->buffer[index], (POINTER)&input[i], inputLen-i);
}

/* MD4 finalization. Ends an MD4 message-digest operation, writing the
	 the message digest and zeroizing the context. */

void MD4Final(digest, context)
unsigned char digest[16];       /* message digest */
MD4_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);
	MD4Update(context, PADDING, padLen);

	/* Append length (before padding) */
	MD4Update(context, bits, 8);
	/* Store state in digest */
	Encode(digest, context->state, 16);

	/* Zeroize sensitive information. */

	R_memset((POINTER)context, 0, sizeof (*context));

}

/* MD4 basic transformation. Transforms state based on block. */

static void MD4Transform(state, block)
UINT4 state[4];
unsigned char block[64];
{
	UINT4 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); /* 1 */
	FF(d, a, b, c, x[ 1], S12); /* 2 */
	FF(c, d, a, b, x[ 2], S13); /* 3 */
	FF(b, c, d, a, x[ 3], S14); /* 4 */
	FF(a, b, c, d, x[ 4], S11); /* 5 */
	FF(d, a, b, c, x[ 5], S12); /* 6 */
	FF(c, d, a, b, x[ 6], S13); /* 7 */
	FF(b, c, d, a, x[ 7], S14); /* 8 */
	FF(a, b, c, d, x[ 8], S11); /* 9 */
	FF(d, a, b, c, x[ 9], S12); /* 10 */
	FF(c, d, a, b, x[10], S13); /* 11 */
	FF(b, c, d, a, x[11], S14); /* 12 */
	FF(a, b, c, d, x[12], S11); /* 13 */
	FF(d, a, b, c, x[13], S12); /* 14 */
	FF(c, d, a, b, x[14], S13); /* 15 */
	FF(b, c, d, a, x[15], S14); /* 16 */

			/* Round 2 */
	GG(a, b, c, d, x[ 0], S21); /* 17 */
	GG(d, a, b, c, x[ 4], S22); /* 18 */
	GG(c, d, a, b, x[ 8], S23); /* 19 */
	GG(b, c, d, a, x[12], S24); /* 20 */
	GG(a, b, c, d, x[ 1], S21); /* 21 */
	GG(d, a, b, c, x[ 5], S22); /* 22 */
	GG(c, d, a, b, x[ 9], S23); /* 23 */
	GG(b, c, d, a, x[13], S24); /* 24 */
	GG(a, b, c, d, x[ 2], S21); /* 25 */
	GG(d, a, b, c, x[ 6], S22); /* 26 */
	GG(c, d, a, b, x[10], S23); /* 27 */
	GG(b, c, d, a, x[14], S24); /* 28 */
	GG(a, b, c, d, x[ 3], S21); /* 29 */
	GG(d, a, b, c, x[ 7], S22); /* 30 */
	GG(c, d, a, b, x[11], S23); /* 31 */
	GG(b, c, d, a, x[15], S24); /* 32 */

			/* Round 3 */
	HH(a, b, c, d, x[ 0], S31); /* 33 */
	HH(d, a, b, c, x[ 8], S32); /* 34 */
	HH(c, d, a, b, x[ 4], S33); /* 35 */
	HH(b, c, d, a, x[12], S34); /* 36 */
	HH(a, b, c, d, x[ 2], S31); /* 37 */
	HH(d, a, b, c, x[10], S32); /* 38 */
	HH(c, d, a, b, x[ 6], S33); /* 39 */
	HH(b, c, d, a, x[14], S34); /* 40 */
	HH(a, b, c, d, x[ 1], S31); /* 41 */
	HH(d, a, b, c, x[ 9], S32); /* 42 */
	HH(c, d, a, b, x[ 5], S33); /* 43 */
	HH(b, c, d, a, x[13], S34); /* 44 */
	HH(a, b, c, d, x[ 3], S31); /* 45 */
	HH(d, a, b, c, x[11], S32); /* 46 */
	HH(c, d, a, b, x[ 7], S33); /* 47 */
	HH(b, c, d, a, x[15], S34); /* 48 */

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

	/* Clear sensitive information. */
	R_memset((POINTER)x, 0, sizeof (x));
}

/* Encodes input (UINT4) into output (unsigned char). Assumes len is
	 a multiple of 4. */

static void Encode(output, input, len)
unsigned char *output;
UINT4 *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 (UINT4). Assumes len is
	 a multiple of 4. */

static void Decode(output, input, len)
UINT4 *output;
unsigned char *input;
unsigned int len;
{
	unsigned int 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);
}