/*
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 "q_shared.h"
#include "qcommon.h"

typedef struct mdfour_s
{
	uint32_t A, B, C, D;
	uint32_t totalN;
} mdfour_ctx;


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

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

static  mdfour_ctx *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( mdfour_ctx *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( mdfour_ctx *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( mdfour_ctx *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 )
{
	mdfour_ctx md;
	mdfour_begin( &md );
	mdfour_update( &md, in, n );
	mdfour_result( &md, out );
}

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

uint32_t Com_BlockChecksum( const void *buffer, int length )
{
	int				digest[4];
	uint32_t	val;

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

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

	return val;
}