+/* arcfour.c */
+/*
+ This file is part of the Crypto-avr-lib/microcrypt-lib.
+ Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
+
+ 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 3 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, see <http://www.gnu.org/licenses/>.
+*/
/*
- * File: arcfour.c
- * Author: Daniel Otte
- * Date: 07.06.2006
- * License: GPL
+ * File: arcfour.c
+ * Author: Daniel Otte
+ * email: daniel.otte@rub.de
+ * Date: 2006-06-07
+ * License: GPLv3 or later
* Description: Implementation of the ARCFOUR (RC4 compatible) stream cipher algorithm.
*
*/
* length is length of key in bytes!
*/
-void arcfour_init(arcfour_ctx_t *c, uint8_t *key, uint8_t length){
+void arcfour_init(const void *key, uint8_t length_B, arcfour_ctx_t *ctx){
uint8_t t;
- unsigned x,y=0;
+ uint16_t x,y=0;
for(x=0; x<= 255; ++x)
- c->s[x]=x;
+ ctx->s[x]=x;
for(x=0; x<= 255; ++x){
- y += c->s[x] + key[x % length];
+ y += ctx->s[x] + ((uint8_t*)key)[x % length_B];
y &= 0xff;
- t = c->s[y];
- c->s[y] = c->s[x];
- c->s[x] = t;
- };
-
- c->i = c->j = 0;
+ /* ctx->s[y] <--> ctx->s[x] */
+ t = ctx->s[y];
+ ctx->s[y] = ctx->s[x];
+ ctx->s[x] = t;
+ }
+ ctx->i = ctx->j = 0;
}
-uint8_t arcfour_gen(arcfour_ctx_t *c){
+uint8_t arcfour_gen(arcfour_ctx_t *ctx){
uint8_t t;
- c->i++;
- c->j += c->s[c->i];
- t = c->s[c->j];
- c->s[c->j] = c->s[c->i];
- c->s[c->i] = t;
- return c->s[(c->s[c->j] + c->s[c->i]) & 0xff];
+ ctx->i++;
+ ctx->j += ctx->s[ctx->i];
+ /* ctx->s[i] <--> ctx->s[j] */
+ t = ctx->s[ctx->j];
+ ctx->s[ctx->j] = ctx->s[ctx->i];
+ ctx->s[ctx->i] = t;
+ return ctx->s[(ctx->s[ctx->j] + ctx->s[ctx->i]) & 0xff];
}