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


V key = ‘]kYV}(!7P$n5_0i R:?jOWtF/=-pe'AD&@r6%ZXs"v*N[#wSl9zq2^+g;LoB`aGh{3.HIu4fbK)mU8|dMET><,Qc\C1yxJ’
 
F encode(s)
   V r = ‘’
   L(c) s
      r ‘’= :key[c.code - 32]
   R r
 
F decode(s)
   V r = ‘’
   L(c) s
      r ‘’= Char(code' :key.index(c) + 32)
   R r
 
V s = ‘The quick brown fox jumps over the lazy dog, who barks VERY loudly!’
V enc = encode(s)
print(‘Encoded:  ’enc)
print(‘Decoded:  ’decode(enc))