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The history of cryptology in Japan shows two things. First, the fact that substitution ciphers existed makes the failure of the Japanese to improve on the substitution cipher or to invent the transposition cipher much harder to explain. Second, the lack of a strong cryptographic tradition suggests – almost requires – a correspondingly weak ...
In cryptography, a substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth.
In a substitution cipher, letters, or groups of letters, are systematically replaced throughout the message for other letters, groups of letters, or symbols. A well-known example of a substitution cipher is the Caesar cipher. To encrypt a message with the Caesar cipher, each letter of message is replaced by the letter three positions later in ...
De Furtivis Literarum Notis (On the Secret Symbols of Letters) is a 1563 book on cryptography written by Giambattista della Porta. [1]The book includes three sets of cypher discs for coding and decoding messages, [2] [3] a substitution cipher improving on the work of Al-Qalqashandi, [4] and one of the earliest known music substitution ciphers.
The Aristocrat Cipher is a type of monoalphabetic substitution cipher in which plaintext is replaced with ciphertext and encoded into assorted letters, numbers, and symbols based on a keyword. The formatting of these ciphers generally includes a title, letter frequency, keyword indicators, and the encoder's nom de plume . [ 1 ]
The main classical cipher types are transposition ciphers, which rearrange the order of letters in a message (e.g., 'hello world' becomes 'ehlol owrdl' in a trivially simple rearrangement scheme), and substitution ciphers, which systematically replace letters or groups of letters with other letters or groups of letters (e.g., 'fly at once ...
The running key cipher is a polyalphabetic substitution, the book cipher is a homophonic substitution. Perhaps the distinction is most clearly made by the fact that a running cipher would work best of all with a book of random numbers, whereas such a book (containing no text) would be useless for a book cipher.
600-500 – Hebrew scholars make use of simple monoalphabetic substitution ciphers (such as the Atbash cipher) c. 400 – Spartan use of scytale (alleged) c. 400 – Herodotus reports use of steganography in reports to Greece from Persia (tattoo on shaved head) 100-1 A.D.- Notable Roman ciphers such as the Caesar cipher.