The Playfair Cipher Back to Crack the Ciphers In 1854, Sir Charles Wheatstone invented the cipher known as "Playfair," named for his friend Lyon Playfair, first Baron Playfair of St. Andrews, who ...

Like the Playfair, the Double Playfair cipher uses 5x5 squares. In this case two keywords are chosen, and each square is filled in the same way as the Playfair.