┌────────────────────────────────────────────────────┐
│        Encipher or Decipher a string of text.      │
└────────────────────────────────────────────────────┘

This routine requires that you supply two strings of
characters. The first is the text to be encrypted, and
the second is one or more keywords which are used to
encipher the text. Thereafter, the text cannot be
decrypted until you supply the same key string again.

The encryption algorithm XORs (eXclusive ORs) the key
string with string to be encrypted. This allows you to
reverse the procedure and decrypt the text, simply by
calling the routine a second time.