derivekey.scala

  def deriveKey(masterKey: String, allowedOperations: String) = {
    def bytesToString(bytes: Array[Byte]) = {
      bytes.map({byte => Integer.toString(byte.toInt, 16)}).mkString
    }

    val masterKeyBytes: Array[Byte] = {
      masterKey.map({ char =>
        Integer.parseInt(char.toString, 16).toByte
      }).toArray
    }
    val cipher: Cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
    val secretKey: SecretKeySpec = new SecretKeySpec(masterKeyBytes, "AES")

    cipher.init(Cipher.ENCRYPT_MODE, secretKey)
    val ivString = bytesToString(cipher.getIV)
    val jsonDescription: String = s"""{"allowed_operations":"${allowedOperations}"}"""
    val cipherText = bytesToString(cipher.doFinal(jsonDescription.getBytes("UTF-8")))
    ivString ++ cipherText
  }