Read and Write file in encrypted format without using encryption

Read File :-

private function readEncryptedFile(objFile:File):String
{
var objFileStream:FileStream = new FileStream();
objFileStream.open(objFile, FileMode.READ);

var objByt:ByteArray = new ByteArray();
objFileStream.readBytes(byt, 0, objFileStream.bytesAvailable);
objByt.uncompress(CompressionAlgorithm.DEFLATE);
var retStr:String = byt.readObject();
return retStr;
}

Write File :-

public function writeEncryptedFile(objFile:File, writeDataStr:String):void
{
var objFileStream:FileStream = new FileStream();
objFileStream.open(objFile, FileMode.WRITE);

var objByt:ByteArray = new ByteArray();
objByt.writeObject(objDataStr);
objByt.position = 0;
objByt.compress(CompressionAlgorithm.DEFLATE);

ojbFileStream.writeBytes(objByt, 0, objByt.length);
objFileStream.close();
}