X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;f=arcfour.c;h=5dcb84fb4e4ec7b44e6d34b8c81dbb821ff037c4;hb=5ac75cfae217122b540c1a6d258054230dc534c3;hp=863b7ac8782a83519895379d72b9ba7f746dde32;hpb=3c995d0a8faeb9d37927d48e20fc45d839e066ea;p=avr-crypto-lib.git

diff --git a/arcfour.c b/arcfour.c
index 863b7ac..5dcb84f 100644
--- a/arcfour.c
+++ b/arcfour.c
@@ -1,12 +1,31 @@
-/* 
- * File:		arcfour.c
- * Author:	Daniel Otte
- * Date: 	07.06.2006
- * License: GPL
+/* 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
+ * 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"
 
@@ -14,30 +33,31 @@
  * 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];
 }