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source/com/hurlant/crypto/symmetric/PKCS5.as

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+/**
+ * PKCS5
+ * 
+ * A padding implementation of PKCS5.
+ * Copyright (c) 2007 Henri Torgemane
+ * 
+ * See LICENSE.txt for full license information.
+ */
+package com.hurlant.crypto.symmetric
+{
+	import flash.utils.ByteArray;
+	
+	public class PKCS5 implements IPad
+	{
+		private var blockSize:uint;
+		
+		public function PKCS5(blockSize:uint=0) {
+			this.blockSize = blockSize;
+		}
+		
+		public function pad(a:ByteArray):void {
+			var c:uint = blockSize-a.length%blockSize;
+			for (var i:uint=0;i<c;i++){
+				a[a.length] = c;
+			}
+		}
+		public function unpad(a:ByteArray):void {
+			var c:uint = a.length%blockSize;
+			if (c!=0) throw new Error("PKCS#5::unpad: ByteArray.length isn't a multiple of the blockSize");
+			c = a[a.length-1];
+			for (var i:uint=c;i>0;i--) {
+				var v:uint = a[a.length-1];
+				a.length--;
+				if (c!=v) throw new Error("PKCS#5:unpad: Invalid padding value. expected ["+c+"], found ["+v+"]");
+			}
+			// that is all.
+		}
+
+		public function setBlockSize(bs:uint):void {
+			blockSize = bs;
+		}
+
+	}
+}