md4.c

/*
    mdfour.c

    An implementation of MD4 designed for use in the samba SMB
    authentication protocol

    Copyright (C) 1997-1998  Andrew Tridgell

    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:

        Free Software Foundation, Inc.
        59 Temple Place - Suite 330
        Boston, MA  02111-1307, USA

    $Id: mdfour.c,v 1.1 2002/08/23 22:03:27 abster Exp $
*/

#include "kmap2.h"
//#include "zip.h" //compress


struct mdfour
{
	unsigned int A, B, C, D;
	unsigned int totalN;
};


/* NOTE: This code makes no attempt to be fast!

   It assumes that a int is at least 32 bits long
*/

static struct mdfour *m;

#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))
#define lshift(x, s) (((x) << (s)) | ((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] + 0x5A827999, s)
#define ROUND3(a, b, c, d, k, s) a = lshift(a + H(b, c, d) + X[k] + 0x6ED9EBA1, s)

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

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

	A  = m->A;
	B  = m->B;
	C  = m->C;
	D  = m->D;
	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;

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

	m->A = A;
	m->B = B;
	m->C = C;
	m->D = D;
}

static void copy64(unsigned int *M, byte *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(byte *out, unsigned int x)
{
	out[0] = x & 0xFF;
	out[1] = (x >> 8) & 0xFF;
	out[2] = (x >> 16) & 0xFF;
	out[3] = (x >> 24) & 0xFF;
}

void mdfour_begin(struct mdfour *md)
{
	md->A      = 0x67452301;
	md->B      = 0xefcdab89;
	md->C      = 0x98badcfe;
	md->D      = 0x10325476;
	md->totalN = 0;
}


static void mdfour_tail(byte *in, int n)
{
	byte buf[128];
	unsigned int M[16];
	unsigned int b;

	m->totalN += n;

	b = m->totalN * 8;

	memset(buf, 0, 128);
	if(n) 
		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);
	}
}

static void mdfour_update(struct mdfour *md, byte *in, int n)
{
	unsigned int M[16];

	m = md;

	if(n == 0) 
		mdfour_tail(in, n);

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

	mdfour_tail(in, n);
}


static void mdfour_result(struct mdfour *md, byte *out)
{
	m = md;

	copy4(out, m->A);
	copy4(out + 4, m->B);
	copy4(out + 8, m->C);
	copy4(out + 12, m->D);
}

static void mdfour(byte *out, byte *in, int n)
{
	struct mdfour md;

	mdfour_begin(&md);
	mdfour_update(&md, in, n);
	mdfour_result(&md, out);
}

//===================================================================

unsigned Com_BlockChecksum(const void *buffer, int length)
{
	int digest[4];
	unsigned val;

	mdfour((byte *)digest, (byte *)buffer, length);

	val = digest[0] ^ digest[1] ^ digest[2] ^ digest[3];

	return val;
}