Diff: arc4.c

Revision:

0:5045d2638c29

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/arc4.c	Sat Feb 05 01:09:17 2011 +0000
@@ -0,0 +1,76 @@
+/* arc4.c
+ *
+ * Copyright (C) 2006-2009 Sawtooth Consulting Ltd.
+ *
+ * This file is part of CyaSSL.
+ *
+ * CyaSSL 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * CyaSSL 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+
+#include "arc4.h"
+
+
+
+void Arc4SetKey(Arc4* arc4, const byte* key, word32 length)
+{
+    word32 i;
+    word32 keyIndex = 0, stateIndex = 0;
+
+    arc4->x = 1;
+    arc4->y = 0;
+
+    for (i = 0; i < ARC4_STATE_SIZE; i++)
+        arc4->state[i] = i;
+
+    for (i = 0; i < ARC4_STATE_SIZE; i++) {
+        word32 a = arc4->state[i];
+        stateIndex += key[keyIndex] + a;
+        stateIndex &= 0xFF;
+        arc4->state[i] = arc4->state[stateIndex];
+        arc4->state[stateIndex] = a;
+
+        if (++keyIndex >= length)
+            keyIndex = 0;
+    }
+}
+
+
+static INLINE word32 MakeByte(word32* x, word32* y, byte* s)
+{
+    word32 a = s[*x], b;
+    *y = (*y+a) & 0xff;
+
+    b = s[*y];
+    s[*x] = b;
+    s[*y] = a;
+    *x = (*x+1) & 0xff;
+
+    return s[(a+b) & 0xff];
+}
+
+
+void Arc4Process(Arc4* arc4, byte* out, const byte* in, word32 length)
+{
+    word32 x = arc4->x;
+    word32 y = arc4->y;
+
+    while(length--)
+        *out++ = *in++ ^ MakeByte(&x, &y, arc4->state);
+
+    arc4->x = x;
+    arc4->y = y;
+}
+