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ROT13 encoder and decoder
ROT13 encoder and decoder

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ROT13 encoder


About ROT13

ROT13 ("rotate by 13 places", sometimes hyphenated ROT-13) is a simple letter substitution cipher that replaces a letter with the letter 13 letters after it in the alphabet. ROT13 is an example of the Caesar cipher, developed in ancient Rome.

In the basic Latin alphabet, ROT13 is its own inverse; that is, to undo ROT13, the same algorithm is applied, so the same action can be used for encoding and decoding. The algorithm provides virtually no cryptographic security, and is often cited as a canonical example of weak encryption.

ROT13 is used in online forums as a means of hiding spoilers, punchlines, puzzle solutions, and offensive materials from the casual glance. ROT13 has been described as the "Usenet equivalent of a magazine printing the answer to a quiz upside down". ROT13 has inspired a variety of letter and word games on-line, and is frequently mentioned in newsgroup conversations.

Some example of its usage

  • Used to hide potentially offensive jokes
  • Obscure an answer to a puzzle or other spoiler.
  • Encode email address from spam bots
  • Encode easy password to something very hard
  • Many newsreaders include ROT13 decoding features, though it's use seems to be declining.