/** Encrypt and decrypt data using the Xor cipher.
 *  Xor stands for "exclusive or".  This is a technique that manipulates
 *  the binary representation of the characters.  One interesting feature
 *  is that the encryption and decryption functions are the same.
 *  And, like the Caesar cipher, there is a 'key' value we perform the
 *  operation with.
 */

public class Xor implements Encryption
{
  // private String plaintext;
  // private String ciphertext;
  private static int key = 7;


  /** encrypt -- Go through each character of the string and add the key
   *  value.
   */
  public void encrypt(String plaintext)
  {
    String ciphertext = "";
    for(int i = 0; i < plaintext.length(); ++i)
      ciphertext += (char) (plaintext.charAt(i) ^ key);
    System.out.println(ciphertext);
  }

  /** decrypt -- this is exactly the inverse of encrypt
   */
  public void decrypt(String ciphertext)
  {
    String plaintext = "";
    for (int i = 0; i < ciphertext.length(); ++i)
      plaintext += (char) (ciphertext.charAt(i) ^ key);
    System.out.println(plaintext);
  }
}