/* arcfour.c */
/*
- This file is part of the Crypto-avr-lib/microcrypt-lib.
+ This file is part of the AVR-Crypto-Lib.
Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
This program is free software: you can redistribute it and/or modify
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
* email: daniel.otte@rub.de
* Date: 2006-06-07
* License: GPLv3 or later
* Description: Implementation of the ARCFOUR (RC4 compatible) stream cipher algorithm.
- *
+ *
*/
-
+
#include <stdint.h>
#include "arcfour.h"
* length is length of key in bytes!
*/
-void arcfour_init(arcfour_ctx_t *ctx, void *key, uint8_t length_B){
+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)
ctx->s[x]=x;
-
+
for(x=0; x<= 255; ++x){
y += ctx->s[x] + ((uint8_t*)key)[x % length_B];
y &= 0xff;
+ /* 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 t;
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;