md4.c

一个功能非常全面的代理服务器源代码程序,

/* 
 * Unix SMB/Netbios implementation.
 * Version 1.9.
 * a implementation of MD4 designed for use in the SMB authentication protocol
 * Copyright (C) Andrew Tridgell 1997
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <string.h>
#include "md4.h"

/* NOTE: This code makes no attempt to be fast! 
 * 
 * It assumes that a int is at least 32 bits long
 */

typedef unsigned int uint32;

static uint32 A, B, C, D;

static uint32
F(uint32 X, uint32 Y, uint32 Z)
{
    return (X & Y) | ((~X) & Z);
}

static uint32
G(uint32 X, uint32 Y, uint32 Z)
{
    return (X & Y) | (X & Z) | (Y & Z);
}

static uint32
H(uint32 X, uint32 Y, uint32 Z)
{
    return X ^ Y ^ Z;
}

static uint32
lshift(uint32 x, int s)
{
    x &= 0xFFFFFFFF;
    return ((x << s) & 0xFFFFFFFF) | (x >> (32 - s));
}

#define ROUND1(a,b,c,d,k,s) a = lshift(a + F(b,c,d) + X[k], s)
#define ROUND2(a,b,c,d,k,s) a = lshift(a + G(b,c,d) + X[k] + (uint32)0x5A827999,s)
#define ROUND3(a,b,c,d,k,s) a = lshift(a + H(b,c,d) + X[k] + (uint32)0x6ED9EBA1,s)

/* this applies md4 to 64 byte chunks */
static void
mdfour64(uint32 * M)
{
    int j;
    uint32 AA, BB, CC, DD;
    uint32 X[16];

    for (j = 0; j < 16; j++)
	X[j] = M[j];

    AA = A;
    BB = B;
    CC = C;
    DD = D;

    ROUND1(A, B, C, D, 0, 3);
    ROUND1(D, A, B, C, 1, 7);
    ROUND1(C, D, A, B, 2, 11);
    ROUND1(B, C, D, A, 3, 19);
    ROUND1(A, B, C, D, 4, 3);
    ROUND1(D, A, B, C, 5, 7);
    ROUND1(C, D, A, B, 6, 11);
    ROUND1(B, C, D, A, 7, 19);
    ROUND1(A, B, C, D, 8, 3);
    ROUND1(D, A, B, C, 9, 7);
    ROUND1(C, D, A, B, 10, 11);
    ROUND1(B, C, D, A, 11, 19);
    ROUND1(A, B, C, D, 12, 3);
    ROUND1(D, A, B, C, 13, 7);
    ROUND1(C, D, A, B, 14, 11);
    ROUND1(B, C, D, A, 15, 19);

    ROUND2(A, B, C, D, 0, 3);
    ROUND2(D, A, B, C, 4, 5);
    ROUND2(C, D, A, B, 8, 9);
    ROUND2(B, C, D, A, 12, 13);
    ROUND2(A, B, C, D, 1, 3);
    ROUND2(D, A, B, C, 5, 5);
    ROUND2(C, D, A, B, 9, 9);
    ROUND2(B, C, D, A, 13, 13);
    ROUND2(A, B, C, D, 2, 3);
    ROUND2(D, A, B, C, 6, 5);
    ROUND2(C, D, A, B, 10, 9);
    ROUND2(B, C, D, A, 14, 13);
    ROUND2(A, B, C, D, 3, 3);
    ROUND2(D, A, B, C, 7, 5);
    ROUND2(C, D, A, B, 11, 9);
    ROUND2(B, C, D, A, 15, 13);

    ROUND3(A, B, C, D, 0, 3);
    ROUND3(D, A, B, C, 8, 9);
    ROUND3(C, D, A, B, 4, 11);
    ROUND3(B, C, D, A, 12, 15);
    ROUND3(A, B, C, D, 2, 3);
    ROUND3(D, A, B, C, 10, 9);
    ROUND3(C, D, A, B, 6, 11);
    ROUND3(B, C, D, A, 14, 15);
    ROUND3(A, B, C, D, 1, 3);
    ROUND3(D, A, B, C, 9, 9);
    ROUND3(C, D, A, B, 5, 11);
    ROUND3(B, C, D, A, 13, 15);
    ROUND3(A, B, C, D, 3, 3);
    ROUND3(D, A, B, C, 11, 9);
    ROUND3(C, D, A, B, 7, 11);
    ROUND3(B, C, D, A, 15, 15);

    A += AA;
    B += BB;
    C += CC;
    D += DD;

    A &= 0xFFFFFFFF;
    B &= 0xFFFFFFFF;
    C &= 0xFFFFFFFF;
    D &= 0xFFFFFFFF;

    for (j = 0; j < 16; j++)
	X[j] = 0;
}

static void
copy64(uint32 * M, unsigned char *in)
{
    int i;

    for (i = 0; i < 16; i++)
	M[i] = (in[i * 4 + 3] << 24) | (in[i * 4 + 2] << 16) |
	    (in[i * 4 + 1] << 8) | (in[i * 4 + 0] << 0);
}

static void
copy4(unsigned char *out, uint32 x)
{
    out[0] = x & 0xFF;
    out[1] = (x >> 8) & 0xFF;
    out[2] = (x >> 16) & 0xFF;
    out[3] = (x >> 24) & 0xFF;
}

/* produce a md4 message digest from data of length n bytes */
void
mdfour(unsigned char *out, unsigned char *in, int n)
{
    unsigned char buf[128];
    uint32 M[16];
    uint32 b = n * 8;
    int i;

    A = 0x67452301;
    B = 0xefcdab89;
    C = 0x98badcfe;
    D = 0x10325476;

    while (n > 64) {
	copy64(M, in);
	mdfour64(M);
	in += 64;
	n -= 64;
    }

    for (i = 0; i < 128; i++)
	buf[i] = 0;
    memcpy(buf, in, n);
    buf[n] = 0x80;

    if (n <= 55) {
	copy4(buf + 56, b);
	copy64(M, buf);
	mdfour64(M);
    } else {
	copy4(buf + 120, b);
	copy64(M, buf);
	mdfour64(M);
	copy64(M, buf + 64);
	mdfour64(M);
    }

    for (i = 0; i < 128; i++)
	buf[i] = 0;
    copy64(M, buf);

    copy4(out, A);
    copy4(out + 4, B);
    copy4(out + 8, C);
    copy4(out + 12, D);

    A = B = C = D = 0;
}