Substitution Cipher Implementation - File Encryption/Decryption


;Task:
Encrypt an 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:
* [[wp:Substitution_cipher|Wikipedia: Substitution cipher]]
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