Cipher disk
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A cipher disk is an enciphering and deciphering tool developed in 1470 by the Italian architect and author Leon Battista Alberti. He constructed a device, consisting of two concentric circular plates
A metal cipher disk
Reconstruction of an Aeneas cipher disk, 5th century BC, Thessaloniki Science Center and Technology Museum
Modern representation of the Union Cipher Disk, from the American Civil War, which was 3.75 inches (95 mm) in diameter and made of light yellow heavy card stock. It consisted of two concentric disks of unequal size revolving on a central pivot. The disks were divided along their outer edges into 30 equal compartments. The smaller inner disk contained letters, terminations and word pauses, while the outer disk contained groups of signal numbers. For easier recognition, the number eight represented two. The initials A.J.M. represent the Chief Signal Officer General
Substitution cipher
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In cryptography, a substitution cipher is a method of encrypting that creates the ciphertext by replacing units of the plaintext in a defined manner, with the help of a key; the "units" may be single
Cipher disk
…alphabet would be positioned next to the "Q" in the cipher alphabet). The entire message is then encoded according to this key. In addition to simple substitution ciphers, the cipher disk opened the way for convenient polyalphabetic ciphers. An easy way to do this is for the sender and the recipient to agree that a certain…
The forged nomenclator message used in the Babington Plot in 1586
A French nomenclator code table
Enigma cipher machine as used by the German military in World War II