3 This file is part of the Crypto-avr-lib/microcrypt-lib.
4 Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
22 * email: daniel.otte@rub.de
24 * License: GPLv3 or later
25 * Description: Implementation of the ARCFOUR (RC4 compatible) stream cipher algorithm.
33 * length is length of key in bytes!
36 void arcfour_init(arcfour_ctx_t *c, uint8_t *key, uint8_t length){
39 for(x=0; x<= 255; ++x)
42 for(x=0; x<= 255; ++x){
43 y += c->s[x] + key[x % length];
53 uint8_t arcfour_gen(arcfour_ctx_t *c){
58 c->s[c->j] = c->s[c->i];
60 return c->s[(c->s[c->j] + c->s[c->i]) & 0xff];