exercism-perl5

Repository for my Perl 5 Exercism exercises
git clone git://git.samirparikh.com/exercism-perl5
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      1 # Atbash Cipher
      2 
      3 Welcome to Atbash Cipher on Exercism's Perl 5 Track.
      4 If you need help running the tests or submitting your code, check out `HELP.md`.
      5 
      6 ## Instructions
      7 
      8 Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
      9 
     10 The Atbash cipher is a simple substitution cipher that relies on
     11 transposing all the letters in the alphabet such that the resulting
     12 alphabet is backwards. The first letter is replaced with the last
     13 letter, the second with the second-last, and so on.
     14 
     15 An Atbash cipher for the Latin alphabet would be as follows:
     16 
     17 ```text
     18 Plain:  abcdefghijklmnopqrstuvwxyz
     19 Cipher: zyxwvutsrqponmlkjihgfedcba
     20 ```
     21 
     22 It is a very weak cipher because it only has one possible key, and it is
     23 a simple monoalphabetic substitution cipher. However, this may not have
     24 been an issue in the cipher's time.
     25 
     26 Ciphertext is written out in groups of fixed length, the traditional group size
     27 being 5 letters, and punctuation is excluded. This is to make it harder to guess
     28 things based on word boundaries.
     29 
     30 ## Examples
     31 
     32 - Encoding `test` gives `gvhg`
     33 - Decoding `gvhg` gives `test`
     34 - Decoding `gsvjf rxpyi ldmul cqfnk hlevi gsvoz abwlt` gives `thequickbrownfoxjumpsoverthelazydog`
     35 
     36 ## Source
     37 
     38 ### Created by
     39 
     40 - @bistik
     41 
     42 ### Contributed to by
     43 
     44 - @dnmfarrell
     45 - @kytrinyx
     46 - @m-dango
     47 - @rfilipo
     48 
     49 ### Based on
     50 
     51 Wikipedia - http://en.wikipedia.org/wiki/Atbash