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


class SubstitutionCipher{
   // 92 characters: " !"#$%&" ... "xyz{|}", doesn't include "~"
   const KEY="]kYV}(!7P$n5_0i R:?jOWtF/=-pe'AD&@r6%ZXs\"v*N"
             "[#wSl9zq2^+g;LoB`aGh{3.HIu4fbK)mU8|dMET><,Qc\\C1yxJ";
   fcn encode(s){ s.apply(fcn(c){ try{ KEY[c.toAsc()-32] }catch{ c } }) }
   fcn decode(s){ s.apply(fcn(c){ try{ (KEY.index(c)+32).toChar() }catch{ c } }) }
}