ROTator lets you encode or decode messages in "ROT 13" format, or in any other rotational letter-substitution format.

Long before the Internet became popular or the World Wide Web existed, computer enthusiasts used a simple cipher known as ROT 13 to disguise the text of their Usenet postings. Sometimes they used ROT 13 to protect innocent eyes against dirty jokes, or to obfuscate other messages that might be deemed objectionable by unknown viewers. This was when the Internet was virtually a private network for scientists and academics, not the free-for-all it is today.

ROT 13 was never intended to be secure encryption. It's just a simple letter-substitution cipher. It's called "ROT 13" because each letter in the alphabet is rotated 13 positions to the right. In other words, "A" becomes "N," "B becomes "O,", and so on. If the rotation goes past "Z," it wraps back around to the beginning of the alphabet and continues. Since the alphabet has 26 letters, and since 13 is half of 26, you can decode a ROT 13 message merely by encoding it using ROT 13 again. The second rotation cancels out the first one and restores the original text. Numerals and punctuation marks are unaffected. ROT 13 is sometimes known as "Caesar's cipher" because Julius Caesar used a similar method to encrypt his secret messages.

My ROTator applet, written in the JavaScript programming language, lets you encode and decode text in ROT 13. It also allows encoding and decoding in any rotational format. ROTator lets you rotate the letters left or right, and you can rotate them by any number of letters from 1 to 26. (Of course, ROT 26 would wrap completely around the alphabet and yield the same text you started with, but it's included for completeness.)

You can use ROTator to encode or decode ROT 13 messages, or you can use it as a simple encryption tool. If you choose a nonstandard rotational value or direction — such as ROT 12 left — it'll really throw somebody who's expecting ROT 13. When they try to decode the message, it gets even more scrambled!

[Clear All Text] This button deletes all text in the window.

[Restore Original Text] This button is really an undo function; it reverses the last rotation and restores the previous text.

[ROTate Letters Left] When you select this option, clicking the ROTate Text button will shift the letters left, toward "A" instead of "Z."

[ROTate Letters Right] When you select this option, clicking the ROTate Text button will shift the letters right, toward "Z" instead of "A." This the default setting.

[Letter Rotation] The list box lets you choose the number of letters to shift left or right. You can choose any value from ROT 1 to ROT 26. (Although, as noted above, ROT 26 wraps completely around the alphabet and has no visible effect.) The default setting is ROT 13.