ROT13 is a simple Caesar cipher for obscuring text by replacing each letter with the letter thirteen places down the alphabet. A becomes N, B becomes O and so on. The algorithm is used in online forums as a means of hiding joke punchlines, puzzle solutions, movie and story spoilers 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 originated in Usenet Internet discussions in the early 1980s, and has become a de facto standard. As a Caesar cipher, ROT13 provides no real cryptographic security and is not used for such; in fact it is often used as the canonical example of weak encryption. Because ROT13 scrambles only letters, more complex schemes have been proposed to handle numbers and punctuation, or arbitrary binary data. (more...)
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