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 ...

The Playfair cipher is an incredibLe code system that is both difficult to decrypt without a computer and easily solvable by hand. You might be familiar with the Cryptoquip in the comics section of a ...

Q: If I encrypt my .class files and use a custom classloader to load and decrypt them on the fly, will this prevent decompilation? A: The problem of preventing Java byte-code decompilation is almost ...

The Double Playfair is an extension of the Playfair to use two separate keys and to encipher each pair of letters twice. The German police made the mistake in late 1941 of switching from the rather ...