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//! ROT13 ("rotate by 13 places"), is a simple implementation of the Caesar cipher. It substitutes //! a letter with the one 13 places after it in the alphabet. //! //! ROT13 is its own inverse. That is, `ROT13(ROT13(message)) = message`. Due to its simplicity, //! this module does not implement the `Cipher` trait. //! use common::substitute; /// Encrypt or decrypt a message using the ROT13 substitute cipher. /// /// # Examples /// Basic usage: /// /// ``` /// use cipher_crypt::ROT13; /// /// let m = "I am my own inverse"; /// assert_eq!(m, ROT13::apply(&ROT13::apply(m))); /// ``` pub fn apply(message: &str) -> String { // The closure below is guarenteed to produce a number less than 26, therefore the // substitution will not return an error and we can unwrap safely. substitute::shift_substitution(message, |i| (i + 13) % 26).unwrap() } #[cfg(test)] mod tests { use super::*; #[test] fn with_emoji(){ let message = "Peace, Freedom and Liberty! 🗡️"; let encrypted = apply(message); let decrypted = apply(&encrypted); assert_eq!(decrypted, message); } #[test] fn alphabet_encrypt(){ let message = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; let encrypted = apply(message); let decrypted = apply(&encrypted); assert_eq!(decrypted, message); } }