/*
	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 "shared.h"
#include "common.h"

struct mdfour
{
	uint32_t A, B, C, D;
	uint32_t 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(uint32_t *M)
{
	int j;
	uint32_t AA, BB, CC, DD;
	uint32_t X[16];
	uint32_t 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(uint32_t *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,uint32_t 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];
	uint32_t M[16];
	uint32_t b;

	m->totalN += n;

	b = m->totalN * 8;

	Com_Memset(buf, 0, 128);
	if(n)
		Com_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)
{
	uint32_t 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;
}
