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The Caesar cipher is named for Julius Caesar, who used an alphabet where decrypting would shift three letters to the left. The Caesar cipher is named after Julius Caesar , who, according to Suetonius , used it with a shift of three (A becoming D when encrypting, and D becoming A when decrypting) to protect messages of military significance. [ 4 ]
The Atbash cipher is a particular type of monoalphabetic cipher formed by taking the alphabet (or abjad, syllabary, etc.) and mapping it to its reverse, so that the first letter becomes the last letter, the second letter becomes the second to last letter, and so on. For example, the Hebrew alphabet would work like this:
For this encipherment Alberti used a decoder device, his cipher disk, which implemented a polyalphabetic substitution with mixed alphabets. Johannes Trithemius—in his book Polygraphiae libri sex (Six books of polygraphia), which was published in 1518 after his death—invented a progressive key polyalphabetic cipher called the Trithemius ...
To decode a message, You apply the same substitution rules, but this time on the ROT13 encrypted text. (Any other character, for example numbers, symbols, punctuation or whitespace, are left unchanged.) Because there are 26 letters in the Latin alphabet and 26 = 2 × 13, the ROT13 function is its own inverse: [2]
In a K2 Aristocrat Cipher, the ciphertext alphabet is constructed by placing the keyword at the beginning of the alphabet, followed by the remaining letters in their standard order, omitting those already used in the keyword. This method ensures that each letter in the plaintext is substituted by a different letter in the ciphertext.
This is termed a substitution alphabet. The cipher alphabet may be shifted or reversed (creating the Caesar and Atbash ciphers, respectively) or scrambled in a more complex fashion, in which case it is called a mixed alphabet or deranged alphabet. Traditionally, mixed alphabets may be created by first writing out a keyword, removing repeated ...
The trifid cipher is a classical cipher invented by Félix Delastelle and described in 1902. [1] Extending the principles of Delastelle's earlier bifid cipher, it combines the techniques of fractionation and transposition to achieve a certain amount of confusion and diffusion: each letter of the ciphertext depends on three letters of the plaintext and up to three letters of the key.
"The Alphabet Cipher" was a brief study published by Lewis Carroll in 1868, describing how to use the alphabet to send encrypted codes. [1] It was one of four ciphers he invented between 1858 and 1868, and one of two polyalphabetic ciphers he devised during that period and used to write letters to his friends.