Converter for ROT5/ROT13/ROT18/ROT47

This web page allows you to encode/decode a piece of text according to the algorithms ROT5, ROT13, ROT18 or ROT47.

The ROT algorithms are simple Caesar ciphers (also known as shift ciphers). They are not designed to provide any cryptographic security, but to provide an easy means to obscure pieces of text such as messages posted in an online forum or in the Usenet. For example, you want to post the solution of a puzzle. With regard to readers who want to solve the puzzle on their own, you should reveal the solution only ROT encoded. By that, it is guaranteed that those readers who have (accidentally) chosen to read your message will not find out the solution.

The four ROT algorithms ROT5, ROT13, ROT18 and ROT47 vary in the characters that can be encoded/decoded:

  • ROT5 covers the numbers 0-9.

  • ROT13 covers the 26 upper and lower case letters of the Latin alphabet (A-Z, a-z).

  • ROT18 is a combination of ROT5 and ROT13.

  • ROT47 covers all printable ASCII characters, except empty spaces. Besides numbers and the letters of the Latin alphabet, the following characters are included:

Applying ROT algorithms is fairly simple. For example, the most used algorithm ROT13 only requires replacing each upper or lower case letter with a letter 13 places down the alphabet, wrapping back to the beginning if necessary. This procedure results in the following lookup table for upper case letters -- the table for lower case letters is the same, aside from the letters being lower case:


The corresponding lookup table for the algorithm ROT5 reads:

Plain: 0123456789
ROT5 : 5678901234

The algorithm ROT47 finally shifts the characters 33 to 126 of the ASCII table by 47 positions.

The following tool now allows you to encrypt/decrypt a piece of text according to the algorithms ROT5, ROT13, ROT18 or ROT47:

Note: The converter is released under the GNU General Public License (GPL) and requires JavaScript to be enabled in your browser.

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