Usage
ROT13 was in use in the net.jokes newsgroup by the early 1980s. It is used to hide potentially offensive jokes, or to obscure an answer to a puzzle or other spoiler. A shift of thirteen was chosen over other values, such as three as in the original Caesar cipher, because thirteen is the value for which encoding and decoding are equivalent, thereby allowing the convenience of a single command for both. ROT13 is typically supported as a built-in feature to newsreading software. Email addresses are also sometimes encoded with ROT13 to hide them from less sophisticated spam bots.
ROT13 is an example of the encryption algorithm known as a Caesar cipher, attributed to Julius Caesar in the 1st century BC.
ROT13 is not intended to be used where secrecy is of any concern—the use of a constant shift means that the encryption effectively has no key, and decryption requires no more knowledge than the fact that ROT13 is in use. Even without this knowledge, the algorithm is easily broken through frequency analysis. Because of its utter unsuitability for real secrecy, ROT13 has become a catchphrase to refer to any conspicuously weak encryption scheme; a critic might claim that "56-bit DES is little better than ROT13 these days". Also, in a play on real terms like "double DES", the terms "double ROT13", "ROT26", or "2ROT13" crop up with humorous intent, including a spoof academic paper "On the 2ROT13 Encryption Algorithm". As applying ROT13 to an already ROT13-encrypted text restores the original plaintext, ROT26 is equivalent to no encryption at all. By extension, triple-ROT13 (used in joking analogy with 3DES) is equivalent to regular ROT13.
In December 1999, it was found that Netscape Communicator used ROT-13 as part of an insecure scheme to store email passwords. In 2001, Russian programmer Dimitry Sklyarov demonstrated that an eBook vendor, New Paradigm Research Group (NPRG), used ROT13 to encrypt their documents; it has been speculated that NPRG may have mistaken the ROT13 toy example—provided with the Adobe eBook software development kit—for a serious encryption scheme. Windows XP uses ROT13 on some of its registry keys.
The ROT13 encryption is used to cipher cache hints on Geocaching.com.
Read more about this topic: ROT13
Famous quotes containing the word usage:
“I am using it [the word ‘perceive’] here in such a way that to say of an object that it is perceived does not entail saying that it exists in any sense at all. And this is a perfectly correct and familiar usage of the word.”
—A.J. (Alfred Jules)
“Pythagoras, Locke, Socrates—but pages
Might be filled up, as vainly as before,
With the sad usage of all sorts of sages,
Who in his life-time, each was deemed a bore!
The loftiest minds outrun their tardy ages.”
—George Gordon Noel Byron (1788–1824)
“...Often the accurate answer to a usage question begins, “It depends.” And what it depends on most often is where you are, who you are, who your listeners or readers are, and what your purpose in speaking or writing is.”
—Kenneth G. Wilson (b. 1923)