一种简易的数字加密方法

这是我无意中写的一个简易的加密方法，现在放出来，其实是因为没有用了，不过是提醒自己，数字要加密而已，所以将这个放了出来，大家也可以看看，有好的加密方法的朋友，可以交流一下

	public function NumberConvert()
		{		
		}
		
		public static function getNum(str:String):String{
			if(str==null)return null;
			var _num:String="";
			for(var	 i:int=0;i<str.length;i++){
				var tmp:String= str.charAt(i);
				_num=_num+strToNum(tmp);
			}
			return _num;
		}
		
		
		public static function getString(num:String):String{
			if(num==null) return null;
			var _str:String="";
			for(var i:int=0;i<num.length;i++){
				var tmp:String=num.charAt(i);
				_str=_str+numToStr(tmp);
			}
			return _str;
		}
		
		private static function numToStr(tmp :String):String{
		switch (tmp)
			{
				case "0":
					return "I";
					break;
				case "1":
					return "O";
					break;
				case "2":
					return "x";
					break;
				case "3":
					return "l";
					break;
				case "4":
					return "C";
					break;
				case "5":
					return "Z";
					break;
				case "6":
					return "D";
					break;
				case "7":
					return "F";
					break;
				case "8":
					return "S";
					break;
				case "9":
					return "T";
					break;
				case ".":
					return "^";
					break;
				default :
					return "error";
					break;
			}
		}
		
		private static function strToNum(str:String):String{
			switch (str)
			{
				case "I":
					return "0";
					break;
				case "O":
					return "1";
					break;
				case "x":
					return "2";
					break;
				case "l":
					return "3";
					break;
				case "C":
					return "4";
					break;
				case "Z":
					return "5";
					break;
				case "D":
					return "6";
					break;
				case "F":
					return "7";
					break;
				case "S":
					return "8";
					break;
				case "T":
					return "9";
					break;
				case "^":
					return ".";
					break;
				default :
					return "error";
					break;
			}
		}