I did some super lightweight encryption. I used rot-X where X was over the printed charset. So I had punctuation and whatnot in mine.

A slightly taller fence, but it wasn't hard to do and it passes for small/light encryption. I'd have to double check but I think I was rotating over 96 characters instead of 13.

Oh, and one more thing. Using 'rot' encryption means that your encrypt and decrypt are the same routine. Which is nice. But it's pretty shoddy encryption.