The Playfair cipher or Playfair square is a manual symmetric encryption technique and was the first literal digraph substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair who promoted the use of the cipher.
The technique encrypts pairs of letters (digraphs), instead of single letters as in the simple substitution cipher and rather more complex Vigenère cipher systems then in use. The Playfair is thus significantly harder to break since the frequency analysis used for simple substitution ciphers does not work with it. Frequency analysis can still be undertaken, but on the 600 possible digraphs rather than the 26 possible monographs. The frequency analysis of digraphs is possible, but considerably more difficult – and it generally requires a much larger ciphertext in order to be useful.
Other articles related to "playfair cipher":
... Sayers gives a blow-by-blow account of the cracking of a Playfair cipher ... In the film National Treasure Book of Secrets, a treasure hunt clue is encoded as Playfair cipher ... In the audio book Rogue Angel God of Thunder, a Playfair cipher clue is used to send Anja Creed to Venice ...
Famous quotes containing the word cipher:
“It is not an arbitrary decree of God, but in the nature of man, that a veil shuts down on the facts of to-morrow; for the soul will not have us read any other cipher than that of cause and effect. By this veil, which curtains events, it instructs the children of men to live in to-day.”
—Ralph Waldo Emerson (18031882)