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To decrypt, the process is reversed. Unlike the otherwise very similar Vigenère cipher, the Beaufort cipher is a reciprocal cipher, that is, decryption and encryption algorithms are the same. This obviously reduces errors in handling the table which makes it useful for encrypting larger volumes of messages by hand, for example in the manual ...
The four-square cipher is a manual symmetric encryption technique. [1] It was invented by the French cryptographer Felix Delastelle . The technique encrypts pairs of letters ( digraphs ), and falls into a category of ciphers known as polygraphic substitution ciphers .
The design had the cipher alphabet and number disks coupled by friction, and there was often slippage when trying to decipher a message. Unlike any other Code-O-Graph, the cipher-key settings utilized a pointer on the back, and a number scale from 1 through 26. Each would increment the positioning of the two scales. 1941 Key-O-Matic Code-O-Graph
The pigpen cipher uses graphical symbols assigned according to a key similar to the above diagram. [1]The pigpen cipher (alternatively referred to as the masonic cipher, Freemason's cipher, Rosicrucian cipher, Napoleon cipher, and tic-tac-toe cipher) [2] [3] is a geometric simple substitution cipher, which exchanges letters for symbols which are fragments of a grid.
The Polybius square is also used as a basic cipher called the Polybius cipher. This cipher is quite insecure by modern standards, as it is a substitution cipher with characters being substituted for pairs of digits, which is easily broken through frequency analysis. [2]
A book cipher is a cipher in which each word or letter in the plaintext of a message is replaced by some code that locates it in another text, the key. A simple version of such a cipher would use a specific book as the key, and would replace each word of the plaintext by a number that gives the position where that word occurs in that book.
In the history of cryptography, a grille cipher was a technique for encrypting a plaintext by writing it onto a sheet of paper through a pierced sheet (of paper or cardboard or similar). The earliest known description is due to Jacopo Silvestri in 1526. [ 1 ]
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 .