●●●●● ●●●● ●●0 Playfair Cipher ●●● ●●●● the large number of keys in a monoalphabetic cipher cannot provide enough security o one approach of improving security is to encrypt multiple letters of plaintext o the playfair cipher is an example invented by Charles Wheatstone in 1854, but named after his friend Baron Playfair o another approach is polyalphabetic substitution cipher COMP4690. HKBUCOMP4690, HKBU 18 Playfair Cipher ⚫ the large number of keys in a monoalphabetic cipher cannot provide enough security ⚫ one approach of improving security is to encrypt multiple letters of plaintext ⚫ the Playfair Cipher is an example ⚫ invented by Charles Wheatstone in 1854, but named after his friend Baron Playfair ⚫ another approach is polyalphabetic substitution cipher