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  2. Hill cipher - Wikipedia

    en.wikipedia.org/wiki/Hill_cipher

    Hill's cipher machine, from figure 4 of the patent. In classical cryptography, the Hill cipher is a polygraphic substitution cipher based on linear algebra.Invented by Lester S. Hill in 1929, it was the first polygraphic cipher in which it was practical (though barely) to operate on more than three symbols at once.

  3. Polygraphic substitution - Wikipedia

    en.wikipedia.org/wiki/Polygraphic_substitution

    This was followed up over the next fifty years with the closely related four-square and two-square ciphers, which are slightly more cumbersome but offer slightly better security. [1] In 1929, Lester S. Hill developed the Hill cipher, which uses matrix algebra to encrypt blocks of any desired length. However, encryption is very difficult to ...

  4. Lester S. Hill - Wikipedia

    en.wikipedia.org/wiki/Lester_S._Hill

    Lester S. Hill (1891–1961) was an American mathematician and educator who was interested in applications of mathematics to communications.He received a bachelor's degree (1911) and a master's degree (1913) from Columbia College and a Ph.D. from Yale University (1926).

  5. Aristocrat Cipher - Wikipedia

    en.wikipedia.org/wiki/Aristocrat_Cipher

    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 ]

  6. National Cipher Challenge - Wikipedia

    en.wikipedia.org/wiki/National_Cipher_Challenge

    The National Cipher Challenge is an annual cryptographic competition organised by the University of Southampton School of Mathematics. Competitors attempt to break cryptograms published on the competition website. [ 1 ]

  7. Known-plaintext attack - Wikipedia

    en.wikipedia.org/wiki/Known-plaintext_attack

    Classical ciphers are typically vulnerable to known-plaintext attack. For example, a Caesar cipher can be solved using a single letter of corresponding plaintext and ciphertext to decrypt entirely. A general monoalphabetic substitution cipher needs several character pairs and some guessing if there are fewer than 26 distinct pairs.

  8. Category:Classical ciphers - Wikipedia

    en.wikipedia.org/wiki/Category:Classical_ciphers

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  9. Unicity distance - Wikipedia

    en.wikipedia.org/wiki/Unicity_distance

    In cryptography, unicity distance is the length of an original ciphertext needed to break the cipher by reducing the number of possible spurious keys to zero in a brute force attack. That is, after trying every possible key , there should be just one decipherment that makes sense, i.e. expected amount of ciphertext needed to determine the key ...