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Playfair cipher. The Playfair cipher uses a 5×5 grid of letters, and encrypts a message by breaking the text into pairs of letters and swapping them according to their positions in a rectangle within that grid: "HI" becomes "BM". The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is a manual symmetric encryption technique ...
The Two-square cipher, also called double Playfair, is a manual symmetric encryption technique. [1] It was developed to ease the cumbersome nature of the large encryption/decryption matrix used in the four-square cipher while still being slightly stronger than the single-square Playfair cipher . The technique encrypts pairs of letters ...
Polybius square. The Polybius square, also known as the Polybius checkerboard, is a device invented by the ancient Greeks Cleoxenus and Democleitus, and made famous by the historian and scholar Polybius. [ 1] The device is used for fractionating plaintext characters so that they can be represented by a smaller set of symbols, which is useful ...
When operating on 2 symbols at once, a Hill cipher offers no particular advantage over Playfair or the bifid cipher, and in fact is weaker than either, and slightly more laborious to operate by pencil-and-paper. As the dimension increases, the cipher rapidly becomes infeasible for a human to operate by hand.
4 4 3 3 3 5 3 2 4 3 1 3 5 5 3 1 2 3 2 5 Then divided up into pairs again, and the pairs turned back into letters using the square: 44 33 35 32 43 13 55 31 23 25 U A E O L W R I N S In this way, each ciphertext character depends on two plaintext characters, so the bifid is a digraphic cipher, like the Playfair cipher. To decrypt, the procedure ...
Félix-Marie Delastelle (2 January 1840 – 2 April 1902) was a French cryptographer, best known for inventing the bifid cipher, [1] first presented in the Revue du Génie civil in 1895 under the name of "cryptographie nouvelle". This cipher combines fractionation with transposition, and was an early cipher to implement the principles of ...
Joseph Oswald Mauborgne (February 26, 1881 – June 7, 1971) co-invented the one-time pad with Gilbert Vernam of Bell Labs. In 1914 he published the first recorded solution of the Playfair cipher. Mauborgne became a Major General in the United States Army, and from October 1937 to his retirement in 1941 was the Army's 12th Chief Signal Officer ...
Polygraphic substitution. Polygraphic substitution is a cipher in which a uniform substitution is performed on blocks of letters. When the length of the block is specifically known, more precise terms are used: for instance, a cipher in which pairs of letters are substituted is bigraphic . As a concept, polygraphic substitution contrasts with ...