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Félix Delastelle
Félix-Marie Delastelle (2 January 1840 – 2 April 1902) was a French cryptographer, best known for inventing the bifid cipher, first presented in the ''Revue du Génie civil'' in 1895 under the name of "cryptographie nouvelle". This cipher combines fractionation with transposition, and was an early cipher to implement the principles of confusion and diffusion. David Kahn described it as a "system of considerable importance in cryptology." Delastelle's other polygraphic substitution ciphers included the trifid and four-square ciphers.Delastelle, p. 77. The last of these is a variant on the earlier Playfair cipher: Delastelle may have been unaware of Playfair, but he had certainly read of the fractionating cipher described by Pliny Chase Pliny Earle Chase (18 August 1820 in Worcester, Massachusetts – 17 December 1886 in Haverford, Pennsylvania) was an American scientist, mathematician, and educator who contributed to the fields of astronomy, electromagnetism, and cryptogr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bifid Cipher
In classical cryptography, the bifid cipher is a cipher which combines the Polybius square with transposition, and uses fractionation to achieve diffusion. It was invented around 1901 by Felix Delastelle. Operation First, a mixed alphabet Polybius square is drawn up, where the I and the J share their position: 1 2 3 4 5 1 B G W K Z 2 Q P N D S 3 I O A X E 4 F C L U M 5 T H Y V R The message is converted to its coordinates in the usual manner, but they are written vertically beneath: F L E E A T O N C E 4 4 3 3 3 5 3 2 4 3 1 3 5 5 3 1 2 3 2 5 They are then read out in rows: 4 4 3 3 3 5 3 2 4 3 1 3 5 5 3 1 2 3 2 5 Then divided up into pairs again, and the pairs turned back into letters using the square: 44 33 35 32 43 13 55 31 23 25 U A E O L W R I N S In this way, each ciphertext character depends on two plaintext characters, so the bifid is a digraphic cipher, like the Playfair cipher. To decrypt, the procedure is simply reversed. Longer messages are fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transposition Cipher
In cryptography, a transposition cipher is a method of encryption which scrambles the positions of characters (''transposition'') without changing the characters themselves. Transposition ciphers reorder units of plaintext (typically characters or groups of characters) according to a regular system to produce a ciphertext which is a permutation of the plaintext. They differ from substitution ciphers, which do not change the position of units of plaintext but instead change the units themselves. Despite the difference between transposition and substitution operations, they are often combined, as in historical ciphers like the ADFGVX cipher or complex high-quality encryption methods like the modern Advanced Encryption Standard (AES). General principle Plaintexts can be rearranged into a ciphertext using a key, scrambling the order of characters like the shuffled pieces of a jigsaw puzzle. The resulting message is hard to decipher without the key because there are many ways the char ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confusion And Diffusion
In cryptography, confusion and diffusion are two properties of the operation of a secure cipher identified by Claude Shannon in his 1945 classified report ''A Mathematical Theory of Cryptography'.'' These properties, when present, work to thwart the application of statistics and other methods of cryptanalysis. These concepts are also important in the design of secure hash functions and pseudorandom number generators where decorrelation of the generated values is the main feature. Definition Confusion Confusion means that each binary digit (bit) of the ciphertext should depend on several parts of the key, obscuring the connections between the two. The property of confusion hides the relationship between the ciphertext and the key. This property makes it difficult to find the key from the ciphertext and if a single bit in a key is changed, the calculation of most or all of the bits in the ciphertext will be affected. Confusion increases the ambiguity of ciphertext and it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substitution Cipher
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. The receiver deciphers the text by performing the inverse substitution process to extract the original message. Substitution ciphers can be compared with transposition ciphers. In a transposition cipher, the units of the plaintext are rearranged in a different and usually quite complex order, but the units themselves are left unchanged. By contrast, in a substitution cipher, the units of the plaintext are retained in the same sequence in the ciphertext, but the units themselves are altered. There are a number of different types of substitution cipher. If the cipher operates on single letters, it is termed a simple substitution cipher; a cipher that operates on larger groups of letters ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trifid Cipher
The trifid cipher is a classical cipher invented by Félix Delastelle and described in 1902. 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 trifid cipher uses a table to ''fractionate'' each plaintext letter into a trigram, mixes the constituents of the trigrams, and then applies the table in reverse to turn these mixed trigrams into ciphertext letters. Delastelle notes that the most practical system uses three symbols for the trigrams:In order to split letters into three parts, it is necessary to represent them by a group of three signs or numbers. Knowing that ''n'' objects, combined in trigrams in all possible ways, give ''n'' × ''n'' × ''n'' = ''n''3, we recognize that three is the only value for ''n''; two would only give 23 = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Four-square Cipher
The four-square cipher is a manual symmetric encryption technique. It was invented by the French cryptographer Felix Delastelle. The technique encrypts pairs of letters (''digraphs''), and thus falls into a category of ciphers known as polygraphic substitution ciphers. This adds significant strength to the encryption when compared with monographic substitution ciphers which operate on single characters. The use of digraphs makes the four-square technique less susceptible to frequency analysis attacks, as the analysis must be done on 676 possible digraphs rather than just 26 for monographic substitution. The frequency analysis of digraphs is possible, but considerably more difficult - and it generally requires a much larger ciphertext in order to be useful. Using four-square The four-square cipher uses four 5 by 5 (5x5) matrices arranged in a square. Each of the 5 by 5 matrices contains the letters of the alphabet (usually omitting "Q" or putting both "I" and "J" in the same ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Playfair Cipher
The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is a manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair for promoting its use. The technique encrypts pairs of letters (''bigrams'' or ''digrams''), instead of single letters as in the simple substitution cipher and rather more complex Vigenère cipher systems then in use. The Playfair is thus significantly harder to break since the frequency analysis used for simple substitution ciphers does not work with it. The frequency analysis of bigrams is possible, but considerably more difficult. With 600 possible bigrams rather than the 26 possible monograms (single symbols, usually letters in this context), a considerably larger cipher text is required in order to be useful. History The Playfair cipher was the first cipher to encrypt pairs of letters in cryptologic history. Wheat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliny Chase
Pliny Earle Chase (18 August 1820 in Worcester, Massachusetts – 17 December 1886 in Haverford, Pennsylvania) was an American scientist, mathematician, and educator who contributed to the fields of astronomy, electromagnetism, and cryptography, among others. Biography He graduated at Harvard in 1839, then taught in Philadelphia and engaged in business for many years, but employed his leisure in physical and philological studies. In 1863 he was elected a member of the American Antiquarian Society and the American Philosophical Society. In 1864 the Magellanic gold medal of the American Philosophical Society was awarded him for his ''Numerical Relations of Gravity and Magnetism''. The results of other mathematical and physical researches were published from time to time in the ''Proceedings'' of the American Philosophical Society, and brought him a worldwide reputation as a man of unusual scientific powers and attainments. In 1871 he became a member of the faculty of Haverfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Cryptographers
French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with France ** French cuisine, cooking traditions and practices Fortnite French places Arts and media * The French (band), a British rock band * "French" (episode), a live-action episode of ''The Super Mario Bros. Super Show!'' * ''Française'' (film), 2008 * French Stewart (born 1964), American actor Other uses * French (surname), a surname (including a list of people with the name) * French (tunic), a particular type of military jacket or tunic used in the Russian Empire and Soviet Union * French's, an American brand of mustard condiment * French catheter scale, a unit of measurement of diameter * French Defence, a chess opening * French kiss, a type of kiss involving the tongue See also * France (other) * Franch, a surname * French ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1840 Births
__NOTOC__ Year 184 ( CLXXXIV) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Eggius and Aelianus (or, less frequently, year 937 ''Ab urbe condita''). The denomination 184 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place China * The Yellow Turban Rebellion and Liang Province Rebellion break out in China. * The Disasters of the Partisan Prohibitions ends. * Zhang Jue leads the peasant revolt against Emperor Ling of Han of the Eastern Han Dynasty. Heading for the capital of Luoyang, his massive and undisciplined army (360,000 men), burns and destroys government offices and outposts. * June – Ling of Han places his brother-in-law, He Jin, in command of the imperial army and sends them to attack the Yellow Turban rebels. * Winter – Zha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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