Substitution Cipher

Tags

cryptography

A [see page 9, form] of cipher that encrypts a message \( \subset \textit{M} \) by applying the substitution process (mapping one character to another) to each character \( \subset A \) in the alphabet.

The encryption function for a substitution cipher is bijective, meaning the decryption process is simply encryption applied in reverse.

The general issue with substitution-cipher based encryptions is that:

Structure (of any type) in the plaintext reveals itself in the ciphertext