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// -*-c++-*-
/* $Id: arc4.h,v 1.2 1998/11/10 21:36:06 dm Exp $ */
/*
*
* Copyright (C) 1998 David Mazieres (dm@uun.org)
*
* 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, 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
*
*/
#ifndef _ARC4_H_
#define _ARC4_H_
#include "sysconf.h"
/* Arcfour random stream generator. This code is derived from section
* 17.1 of Applied Cryptography, second edition, which describes a
* stream cipher allegedly compatible with RSA Labs "RC4" cipher (the
* actual description of which is a trade secret). The same algorithm
* is used as a stream cipher called "arcfour" in Tatu Ylonen's ssh
* package.
*
* RC4 is a registered trademark of RSA Laboratories.
*/
class arc4 {
u_char i;
u_char j;
u_char s[256];
void _setkey (const u_char *key, size_t len);
public:
arc4 () { reset (); }
~arc4 () { i = j = 0; bzero (s, sizeof (s)); }
void reset ();
void setkey (const void *key, size_t len);
u_char getbyte () {
i = i + 1 & 0xff;
u_char si = s[i];
j = j + si & 0xff;
u_char sj = s[j];
s[i] = sj;
s[j] = si;
return s[si + sj & 0xff];
}
};
#endif /* _ARC4_H_ */
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