/*
 * The QUAFFLER library
 * Copyright (c) 2006 Clifford Wolf <clifford@clifford.at>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include "quaffler.h"

void qfl_ofb_init(unsigned char *sbox)
{
	int i, j, k;

	for (i=0; i<256; i++)
		sbox[i] = i;

	for (i=0; i<256; i++) {
		j = qfl_os_unix_rand() % 256;
		k = sbox[i];
		sbox[i] = sbox[j];
		sbox[j] = k;
	}

	sbox[256] = 0;
	sbox[257] = 0;
}

void qfl_ofb_recover(unsigned char *sbox)
{
	unsigned char map[256];
	int i;

	for (i=0; i<256; i++)
		map[i] = 0;

	for (i=0; i<256; i++)
		map[sbox[i]] = 1;

	for (i=0; i<256; i++)
		if (!map[i]) {
			sbox[255] = i;
			break;
		}

	sbox[256] = 0;
	sbox[257] = 0;
}

void qfl_ofb_xor(unsigned char *sbox, unsigned char *data, int len)
{
	int i = sbox[256];
	int j = sbox[257];
	unsigned char t;

	while (len-- > 0)
	{
		i = (i+1) & 255;
		j = (j+sbox[i]) & 255;

		t = sbox[i];
		sbox[i] = sbox[j];
		sbox[j] = t;

		*(data++) ^= sbox[(sbox[i]+sbox[j]) & 255];
	}

	sbox[256] = i;
	sbox[257] = j;
}