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The Vigenère cipher is simple enough to be a field cipher if it is used in conjunction with cipher disks. [13] The Confederate States of America, for example, used a brass cipher disk to implement the Vigenère cipher during the American Civil War. The Confederacy's messages were far from secret, and the Union regularly cracked its messages.
Sometimes values are reported without the normalizing denominator, for example 0.067 = 1.73/26 for English; such values may be called κ p ("kappa-plaintext") rather than IC, with κ r ("kappa-random") used to denote the denominator 1/c (which is the expected coincidence rate for a uniform distribution of the same alphabet, 0.0385=1/26 for ...
For example, consider the plaintext: the man and the woman retrieved the letter from the post office The word "the" is a repeated string, appearing multiple times. If we line up the plaintext with a 5-character keyword "beads " : bea dsb ead sbe adsbe adsbeadsb ead sbeads bead sbe adsb eadsbe the man and the woman retrieved the letter from the ...
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 ...
It is very similar to the Vigenère cipher, making many scholars call Bellaso its inventor, although unlike the modern Vigenère cipher Bellaso didn't use 26 different "shifts" (different Caesar's ciphers) for every letter, instead opting for 13 shifts for pairs of letters. The system is still periodic although the use of one or more long ...
An autokey cipher (also known as the autoclave cipher) is a cipher that incorporates the message (the plaintext) into the key. The key is generated from the message in some automated fashion, sometimes by selecting certain letters from the text or, more commonly, by adding a short primer key to the front of the message.
A polyalphabetic cipher is a substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case. The Enigma machine is more complex but is still fundamentally a polyalphabetic substitution cipher.
Tabula recta. In cryptography, the tabula recta (from Latin tabula rēcta) is a square table of alphabets, each row of which is made by shifting the previous one to the left.. The term was invented by the German author and monk Johannes Trithemius [1] in 1508, and used in his Trithemius ciph