/*
* Copyright(c) 1997-2001 Id Software, Inc.
* Copyright(c) 1997-1998 Andrew Tridgell
* Copyright(c) 2002 The Quakeforge Project.
* Copyright(c) 2006 Quetoo.
*
* 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

#include "mdfour.h"

/* 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, const 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, 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(const unsigned char *in, int n){
	unsigned char 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);
	}
}

void mdfour_update(struct mdfour *md, const unsigned char *in, int n){
	unsigned int M[16];
	
	if(n == 0)
		mdfour_tail(in, n);
		
	m = md;
	
	while(n >= 64){
		copy64(M, in);
		mdfour64(M);
		in += 64;
		n -= 64;
		m->totalN += 64;
	}
	
	mdfour_tail(in, n);
}

void mdfour_result(struct mdfour *md, unsigned char *out){
	m = md;
	
	copy4(out, m->A);
	copy4(out + 4, m->B);
	copy4(out + 8, m->C);
	copy4(out + 12, m->D);
}

void mdfour(unsigned char *out, const unsigned char *in, int n){
	struct mdfour md;
	
	mdfour_begin(&md);
	mdfour_update(&md, in, n);
	mdfour_result(&md, out);
}