Substitution Cipher Implementation - File Encryption/Decryption



Task

Encrypt a input/source file by replacing every upper/lower case alphabets of the source file with another predetermined upper/lower case alphabets or symbols and save it into another output/encrypted file and then again convert that output/encrypted file into original/decrypted file.

This type of Encryption/Decryption scheme is often called a Substitution Cipher.



Related tasks

 Caesar cipher
 Rot-13
 Vigenère Cipher/Cryptanalysis


See also

 Wikipedia: Substitution cipher


def key: 
  "]kYV}(!7P$n5_0i R:?jOWtF/=-pe'AD&@r6%ZXs\"v*N[#wSl9zq2^+g;LoB`aGh{3.HIu4fbK)mU8|dMET><,Qc\\C1yxJ";
 
def encode:
  (key|explode) as $key
  | explode as $exploded
  | reduce range(0;length) as $i ([];
        . + [$key[ $exploded[$i] - 32]] ) 
  | implode;
 
def decode:
  (key|explode) as $key
  | explode as $exploded
  | reduce range(0;length) as $i ([];
       $exploded[$i] as $c
       | . + [ $key | index($c) + 32] )
  | implode ;
 
def task:
  "The quick brown fox jumps over the lazy dog, who barks VERY loudly!"
   | encode as $encoded
   |"Encoded:  \($encoded)",
    "Decoded:  \($encoded|decode)" ;
 
task