NationMaster - Encyclopedia: Straddling checkerboard

In cryptography, a straddling checkerboard is a device for converting an alphabetic plaintext into digits whilst simultaneously achieving fractionation (a simple form of information diffusion) and homophony (a simple method for suppressing peaks of the frequency distribution). Cryptography has had a long and colourful history. ... An alphabet is a complete standardized set of letters â€” basic written symbols â€” each of which roughly represents a phoneme of a spoken language, either as it exists now or as it may have been in the past. ... The plain text term has shit a different meaning. ... A numeral is a symbol or group of symbols that represents a number. ... In classical cryptography, a transposition cipher changes one character from the plaintext to another (to decrypt the reverse is done). ... Homophony is music in which the top line has a dominant melody, and all the voices accompany it with chords in the same rhythm. ... In statistics, a frequency distribution is a list of the values that a variable takes in a sample. ...

The first row is set up with the eight highest frequency letters, leaving two blank spots. It has no row label. The second and third rows are labelled with whichever two digits didn't get a letter in the top row, and then filled out with the rest of the alphabet. (This can be scrambled by a key word, or simply done in order - relying on another stage of the cipher for security). Since there are 30 slots in our grid, and we missed two letters in the first row, there will end up being two spare in the other rows. It doesn't matter where these spares go, so long as sender and receiver use the same system.

To encipher, a letter on the top row is simply replaced by the number labelling its column. Letters on the other rows are replaced by their row number, then column number. Like so:

The resulting message, 3113212731223655, may be sent directly (if the table was set up with a key word), but usually is first input into a second cipher stage, such as transposition or substitution. As a simple example, we will add a secret key number (say, 0452) by non-carrying addition: In classical cryptography, a transposition cipher changes one character from the plaintext to another (to decrypt the reverse is done). ... In cryptography, a substitution cipher is a method of encryption by which units of plaintext are substituted with ciphertext according to a regular system; the units may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. ...

Deciphering is simply the reverse of this process. Although the size of groups can vary, deciphering is unambiguous because whenever the next element to be deciphered starts with a 2 or a 6, it is a pair; otherwise, it is a singleton.

Cipher that use a straddling checkerboard are the VIC cipher and SECOM The VIC cipher was a pencil and paper cipher used by the Soviet spy Reino Hayhanen, codenamed VICTOR. It was arguably the most complex hand-operated cipher ever seen. ...

Categories: Cryptography In cryptography, the ADFGVX cipher was a field cipher used by the German Army during World War I. ADFGVX was in fact an extension of an earlier cipher called ADFGX. Invented by Colonel Fritz Nebel and introduced in March 1918, the cipher was a fractionating transposition cipher which combined a... The Affine cipher is a special case of the more general substitution cipher. ... Atbash is a simple substitution cipher for the Hebrew alphabet. ... An autokey cipher, or self-synchronizing stream cipher, is a cipher which incorporates the message (the plaintext) into the key. ... In classical cryptography, the bifid cipher is a cipher which combines the Polybius square with transposition, and uses fractionation to achieve diffusion. ... A book cipher is a cipher in which the key is the identity of a book. ... The action of a Caesar cipher is to move each letter a number of places down the alphabet. ... The Four-square cipher is a manual symmetric encryption technique. ... Hills cipher machine, from figure 4 of the patent In classical cryptography, the Hill cipher is a polygraphic substitution cipher based on linear algebra. ... In classical cryptography, a permutation cipher is a transposition cipher in which the key is a permutation. ... The Pigpen Cipher is a simple substitution cipher exchanging letters for symbols, using a grid. ... The Playfair system was invented by Charles Wheatstone, first described in 1854. ... A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. ... The Reihenschieber was a hand cipher system used by Germany. ... In classical cryptography, the runnning key cipher is a type of polyalphabetic substitution cipher in which a text, typically from a book, is used to provide a very long key stream. ... In cryptography, a substitution cipher is a method of encryption by which units of plaintext are substituted with ciphertext according to a regular system; the units may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. ... In classical cryptography, a transposition cipher changes one character from the plaintext to another (to decrypt the reverse is done). ... In classical cryptography, the trifid cipher is a cipher invented around 1901 by Felix Delastelle, which extends the concept of the bifid cipher to a third dimension, allowing each symbol to be fractionated into 3 elements instead of two. ... The Two-square cipher is a manual symmetric encryption technique. ... The VigenÃ¨re cipher is named for Blaise de VigenÃ¨re (pictured), although the cipher had been invented earlier by Giovan Batista Belaso. ... In mathematics, physics and signal processing, frequency analysis is a method to decompose a function, wave, or signal into its frequency components so that it is possible to have the frequency spectrum. ... In cryptography, coincidence counting is the technique (invented by William F. Friedman) of putting two texts side-by-side and counting the number of times that a letter appears next to itself in both copies. ... A cryptogram is a type of word puzzle popularly printed in some newspapers and magazines. ... In cryptography, the Polybius square is a device invented by the Ancient Greek historian and scholar Polybius, described in Hist. ... This article is about the encryption device; for the Dune character, see Scytale (Dune). ... Tabula recta In cryptography, the tabula recta is a square table of alphabets, each one made by shifting the previous one to the left. ...