●●●●● ●●●● ●●0 Playfair Key Matrix ●●● ●●●● ●a5X5matrⅸ k of letters based on a keyword First, fill in letters of keyword (sans duplicates) Second. fill rest of matrix with other letters e I and j count as one letter E.g., using the keyword MONARCHY MO NAR C H Y B D EFG工R L P Q ST U V X Z COMP4690. HKBUCOMP4690, HKBU 19 Playfair Key Matrix ⚫ a 5x5 matrix of letters based on a keyword ⚫ First, fill in letters of keyword (sans duplicates) ⚫ Second, fill rest of matrix with other letters ⚫ I and J count as one letter ⚫ E.g., using the keyword MONARCHY M O N A R C H Y B D E F G I K L P Q S T U V W X Z