trait Text {
    val text:List[Int]
    override def toString: String

    def xor(other:Text) = {
      val xorText = (text zip other.text) map { case (a,b) => a^b }
    }
  }

  class PlainText(val text:List[Int]) extends Text       {
    override def toString: String = text.map(_.toChar).mkString(" ")
  }

  class CypherText(val text:List[Int]) extends Text       {
    override def toString: String = text.map("%x".format(_)).mkString(" ")
  }