vigenere加密

  1. //! Vigenère Cipher
  2. //!
  3. //! # Algorithm
  4. //!
  5. //! Rotate each ascii character by the offset of the corresponding key character.
  6. //! When we reach the last key character, we start over from the first one.
  7. //! This implementation does not rotate unicode characters.
  9. /// Vigenère cipher to rotate plain_text text by key and return an owned String.
  10. pub fn vigenere(plain_text: &str, key: &str) -> String {
  11.     // Remove all unicode and non-ascii characters from key
  12.     let key: String = key.chars().filter(|&c| c.is_ascii_alphabetic()).collect();
  13.     key.to_ascii_lowercase();
  15.     let key_len = key.len();
  16.     if key_len == 0 {
  17.         return String::from(plain_text);
  18.     }
  20.     let mut index = 0;
  22.     plain_text
  23.         .chars()
  24.         .map(|c| {
  25.             if c.is_ascii_alphabetic() {
  26.                 let first = if c.is_ascii_lowercase() { b'a' } else { b'A' };
  27.                 let shift = key.as_bytes()[index % key_len] - b'a';
  28.                 index += 1;
  29.                 // modulo the distance to keep character range
  30.                 (first + (c as u8 + shift - first) % 26) as char
  31.             } else {
  32.                 c
  33.             }
  34.         })
  35.         .collect()
  36. }
  38. #[cfg(test)]
  39. mod tests {
  40.     use super::*;
  42.     #[test]
  43.     fn empty() {
  44.         assert_eq!(vigenere("", "test"), "");
  45.     }
  47.     #[test]
  48.     fn vigenere_base() {
  49.         assert_eq!(
  50.             vigenere("LoremIpsumDolorSitAmet", "base"),
  51.             "MojinIhwvmVsmojWjtSqft"
  52.         );
  53.     }
  55.     #[test]
  56.     fn vigenere_with_spaces() {
  57.         assert_eq!(
  58.             vigenere(
  59.                 "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",
  60.                 "spaces"
  61.             ),
  62.             "Ddrgq ahhuo hgddr uml sbev, ggfheexwljr chahxsemfy tlkx."
  63.         );
  64.     }
  66.     #[test]
  67.     fn vigenere_unicode_and_numbers() {
  68.         assert_eq!(
  69.             vigenere("1 Lorem ⏳ ipsum dolor sit amet Ѡ", "unicode"),
  70.             "1 Fbzga ⏳ ltmhu fcosl fqv opin Ѡ"
  71.         );
  72.     }
  74.     #[test]
  75.     fn vigenere_unicode_key() {
  76.         assert_eq!(
  77.             vigenere("Lorem ipsum dolor sit amet", "😉 key!"),
  78.             "Vspoq gzwsw hmvsp cmr kqcd"
  79.         );
  80.     }
  82.     #[test]
  83.     fn vigenere_empty_key() {
  84.         assert_eq!(vigenere("Lorem ipsum", ""), "Lorem ipsum");
  85.     }
  86. }