/*-
 * Copyright (c) 2010
 *	Thorsten Glaser <tg@mirbsd.org>
 *
 * Provided that these terms and disclaimer and all copyright notices
 * are retained or reproduced in an accompanying document, permission
 * is granted to deal in this work without restriction, including un-
 * limited rights to use, publicly perform, distribute, sell, modify,
 * merge, give away, or sublicence.
 *
 * This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
 * the utmost extent permitted by applicable law, neither express nor
 * implied; without malicious intent or gross negligence. In no event
 * may a licensor, author or contributor be held liable for indirect,
 * direct, other damage, loss, or other issues arising in any way out
 * of dealing in the work, even if advised of the possibility of such
 * damage or existence of a defect, except proven that it results out
 * of said person's immediate fault when using the work as intended.
 *-
 * Arcfour cipher re-implementation from (alledged) spec description.
 * Base cipher operation: initialise state and get byte of keystream.
 */

#include <libckern.h>

__RCSID("$MirOS: src/kern/c/arcfour_base.c,v 1.1 2010/09/12 17:10:49 tg Exp $");

void
arcfour_init(struct arcfour_status *c)
{
	register uint8_t i = 0;

	do {
		c->S[i] = i;
	} while (++i);

	c->i = c->j = 0;
}

uint8_t
arcfour_byte(struct arcfour_status *c)
{
	register uint8_t i, j, si, sj;

	i = ++(c->i);
	si = c->S[i];
	j = (c->j += si);
	sj = c->S[j];
	c->S[i] = sj;
	c->S[j] = si;
	return (c->S[(uint8_t)(si + sj)]);
}