ROT13 is a very simple “encryption” achieved by shifting each letter with the 13th letter further in the alphabet (with wrap-around). That is, in English alphabet, A becomes N, B becomes O, N becomes A, etc.
This encryption (or a more general form of it, where rotation can be by any number, with or without wrap-around) was once used for military communications by Julius Caesar.
It’s used today in the Internet (and once, in Usenet) mostly to hide spoilers (similar to writing the solution in upside-down in magazines), and to hide E-mail addresses (to prevent spam-bots from collecting them). Many times, email addresses are written as “my DOT name AT provider DOT com”, to trick spam-bots and make it difficult for them to identify the string as an E-mail address. This trick, however, is so common that bots can (and should, if to give advice to spammers) be programmed to read them. Maybe you would like to consider writing your E-mail in ROT13 instead ;-)
What is beautiful about ROT13, is that the same transformation which encrypts the text, is the transformation used to decrypt it (This is true in the case of English alphabet, because it has 26 letters, which is twice 13). This kind of cipher is called a Reciprocal cipher.
So, if you want to encrypt you email address in ROT13, you can do the following:
Run the following in a unix terminal:
echo “My.Email@Provider.com” | tr A-Za-z N-ZA-Mn-za-m
The output will be the “encrypted” email address. “Zl.Rznvy@Cebivqre.pbz” In the example
Then write this as your email address:
My Email: echo “Zl.Rznvy@Cebivqre.pbz” | tr A-Za-z N-ZA-Mn-za-m
Now you can be sure that bots won’t know your E-mail address, and will sound like a geek. Be warned that only geeks will be able to email you ;-)
(Obvious) Note: Don’t use ROT13 or similar to encrypt sensitive data, or it will be easily accessed, and worse: you’ll become a joke.