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The D'Agapeyeff cipher is an unsolved cipher that appears in the first edition of Codes and Ciphers, an elementary book on cryptography published by the Russian-born English cryptographer and cartographer Alexander D'Agapeyeff in 1939. Offered as a "challenge cipher" at the end of the book, the ciphertext is:
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 DIANA crypto system, used by U.S ...
A six-bit character code is a character encoding designed for use on computers with word lengths a multiple of 6. Six bits can only encode 64 distinct characters, so these codes generally include only the upper-case letters, the numerals, some punctuation characters, and sometimes control characters.
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 .
Nyctography (in Nyctography:) is a form of substitution cipher writing created by Lewis Carroll (Charles Lutwidge Dodgson) in 1891. It is written with a nyctograph (a device invented by Carroll) and uses a system of dots and strokes all based on a dot placed in the upper left corner.
ROT13 is a special case of the Caesar cipher which was developed in ancient Rome, used by Julius Caesar in the 1st century BC. [1] An early entry on the Timeline of cryptography . ROT13 can be referred by "Rotate13", "rotate by 13 places", hyphenated "ROT-13" or sometimes by its autonym "EBG13".
The most obvious and, in principle at least, simplest way of cracking a code is to steal the codebook through bribery, burglary, or raiding parties — procedures sometimes glorified by the phrase "practical cryptography" — and this is a weakness for both codes and ciphers, though codebooks are generally larger and used longer than cipher ...
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