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Atbash is a simple substitution cipher possible with any known alphabet. It emerged around 500-600 BCE. It works by substituting the letters of an alphabet with another.


English alphabets in order is the constant.

CONSTANT = 'abcdefghijklmnopqrstuvwxyz'

A random shuffle of the constant is the ciper.

Example cipher: zyxwvutsrqponmlkjihgfedcba

Using the cipher, strings can be encypted. When the cipher and encrypted string is given it possible to decrypt the encrypted text.

Example 1

CONSTANT       = 'abcdefghijklmnopqrstuvwxyz'
cipher         = 'zodvqukgwefbyitmrsplhacxnj'
encrypted text = 'dzs'
original text  = 'car'

Example 2

CONSTANT       = 'abcdefghijklmnopqrstuvwxyz'
cipher         = 'xipmuzfkbrlwotjancqgveshdy'
encrypted text = 'skd qj qucbjvq?'
original text  = 'why so serious?'

The challenge

CONSTANT       = 'abcdefghijklmnopqrstuvwxyz'
cipher         = 'oephjizkxdawubnytvfglqsrcm'
encrypted text = 'knlfgnb, sj koqj o yvnewju'
original text  = ?
  1. Decrypt the given encrypted text.
  2. Any character other than what you have in the constant doesn't have to be replaced.
  3. Add test/spec to your solution.

Time: 30 mins

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