NationMaster - Encyclopedia: Book cipher

A book cipher is a cipher in which the key is the identity of a book. This article is about algorithms for encryption and decryption. ...

Traditionally book ciphers work by replacing words in the plaintext of a message with the location of words from a book. In this mode, book ciphers are more properly called codes. In the context of cryptography, a code is a method used to transform a message into an obscured form, preventing those not in on the secret from understanding what is actually transmitted. ...

This can have problems as if a word appears in the plaintext that doesn't appear in the book then it can't be encoded. An alternative approach which gets around this problem is to replace individual letters rather than words, in which case the book cipher is properly a cipher. However, if needed often, this has the side effect of creating a larger ciphertext.

Perhaps the most famous use of a book cipher is in the Beale ciphers. The Beale ciphers are a set of three ciphertexts, one of which allegedly states the location of a buried treasure of gold and silver estimated to be worth over 20 million US dollars in todays money. ...

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. ...

Categories: Cryptography stubs | Classical ciphers 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 in Hebrew. ... 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. ... 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). ... 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). ... Tabula recta In cryptography, the tabula recta is a square table of alphabets, each one made by shifting the previous one to the left. ...