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 *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];
}