[1] Classic Encryption Techniques [1-1] Substitution cipher [1-2] Transposition cipher [1-1] Substitution cipher Monoalphabetic Cipher Caesar Cipher - Monoalphabetic Cipher : mapping plaintext character one-to-one with other characters - Assign numbers from 0 to 25 to english character and combine them with a secret key to perform a modulo operation - K : secret key (shift interval of plaintext)..