ROT47

ROT47 is a simple substitution cipher that applies a 47-position rotation to all printable ASCII characters. Unlike ROT13, which rotates only letters, ROT47 operates on the 94 characters from the exclamation mark '!' (ASCII 33) to the tilde '~' (ASCII 126). Each character in that range is replaced by the character 47 positions later in the sequence, wrapping around to the start when necessary. For characters outside this range, such as spaces and control characters, ROT47 leaves them unchanged.

Formally, for a character c with ASCII code between 33 and 126, the encoded character c' is 33 + ((ord(c) - 33 + 47) mod 94). The operation is symmetric: applying ROT47 twice yields the original text, since 2*47 = 94, which is equivalent to a full cycle.

ROT47 is designed as a playful obfuscation rather than a secure cipher. It is easy to reverse and provides no meaningful cryptographic security. It has been used in some online forums and message boards to obscure spoilers, jokes, or text to bypass simple filters, but it should not be considered encryption.

See also ROT13, Caesar cipher, obfuscation.