The Playfair cipher is an incredibLe code system that is both difficult to decrypt without a computer and easily solvable by hand. Here's how to solve it.

In 1854, Sir Charles Wheatstone invented the cipher known as "Playfair," named for his friend Lyon Playfair, first Baron Playfair of St. Andrews, who popularized and promoted the cipher. Its ...

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.