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Polyalphabetic Cipher
A polyalphabetic cipher is a substitution cipher, 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. History The work of Al-Qalqashandi (1355–1418), based on the earlier work of Ibn al-Durayhim (1312–1359), contained the first published discussion of the substitution and transposition of ciphers, as well as the first description of a polyalphabetic cipher, in which each plaintext letter is assigned more than one substitute. However, it has been claimed that polyalphabetic ciphers may have been developed by the Arab cryptologist Al Kindi (801–873) centuries earlier. The Alberti cipher by Leon Battista Alberti around 1467 was an early polyalphabetic cipher. Alberti used a mixed alphabet to encrypt a message, but whenever he wanted to, he would switch to a ... [...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 lett ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classical Ciphers
Classical may refer to: European antiquity *Classical antiquity, a period of history from roughly the 7th or 8th century B.C.E. to the 5th century C.E. centered on the Mediterranean Sea *Classical architecture, architecture derived from Greek and Roman architecture of classical antiquity *Classical mythology, the body of myths from the ancient Greeks and Romans *Classical tradition, the reception of classical Greco-Roman antiquity by later cultures *Classics, study of the language and culture of classical antiquity, particularly its literature *Classicism, a high regard for classical antiquity in the arts Music and arts *Classical ballet, the most formal of the ballet styles *Classical music, a variety of Western musical styles from the 9th century to the present *Classical guitar, a common type of acoustic guitar *Classical Hollywood cinema, a visual and sound style in the American film industry between 1927 and 1963 *Classical Indian dance, various codified art forms whose theor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topics In Cryptography
The following outline is provided as an overview of and topical guide to cryptography: Cryptography (or cryptology) – practice and study of hiding information. Modern cryptography intersects the disciplines of mathematics, computer science, and engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce. Essence of cryptography * Cryptographer * Encryption/decryption * Cryptographic key * Cipher * Ciphertext * Plaintext * Code * Tabula recta * Alice and Bob Uses of cryptographic techniques * Commitment schemes * Secure multiparty computation * Electronic voting * Authentication * Digital signatures * Crypto systems * Dining cryptographers problem * Anonymous remailer * Pseudonymity * Onion routing * Digital currency * Secret sharing * Indistinguishability obfuscation Branches of cryptography * Multivariate cryptography * Post-quantum cryptography * Quantum cryptography * Steganography * Visual cryptography * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Kahn (writer)
David Kahn (February 7, 1930 – January 23, 2024) was an American historian, journalist, and writer. He wrote extensively on the history of cryptography and military intelligence. Kahn's first published book, '' The Codebreakers - The Story of Secret Writing'' (1967), has been widely considered to be a definitive account of the history of cryptography. Biography David Kahn was born in New York City to Florence Abraham Kahn, a glass manufacturer, and Jesse Kahn, a lawyer, and grew up in Great Neck, NY on Long Island. Kahn said he traced his interest in cryptography to reading Fletcher Pratt's '' Secret and Urgent'' (1939) as a boy. Kahn was a founding editor of the '' Cryptologia'' journal. In 1969, Kahn married Susanne Fiedler; they divorced in 1994. They have two sons, Oliver and Michael.* Kahn attended Bucknell University. After graduation, he worked as a reporter at ''Newsday''. He also served as an editor at the ''International Herald Tribune'' in Paris in the 1960 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abramo Colorni
Abramo Colorni (Abram or Abraham, Colorno or Calorno, sometimes Colorini, 1544–1599) was an Italian-Jewish polymath and Renaissance man. An engineer, architect, mathematician, chiromancer, cryptographer, alchemist, inventor, Magic (supernatural), magus (magician) and merchant, Colorni spent nine years as a Court Jew for Rudolf II. He is the author of the 1593 treatise on cryptography, ''Scotographia''. As court alchemist, he was a major player in cultural transfer from Italy to Baden-Wurttemberg and Prague. He was born in, and died in, Mantua, Italy. Sometimes thought of as a charlatan, a genius "Jewish Leonardo da Vinci, Leonardo" or "Jewish Baron von Munchhausen", or a ''professore de’ secreti'', "professor of secrets", he was also known as a clockmaker, for his magic tricks and escapology, and invented a new kind of revolver. Biography A Orthodox Judaism, devout Jew whose ancestors migrated from Rhineland, Germanic lands to Italy, Colorni was described as a Jewish Daeda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kasiski Examination
In cryptanalysis, Kasiski examination (also known as Kasiski's test or Kasiski's method) is a method of attacking polyalphabetic substitution ciphers, such as the Vigenère cipher. It was first published by Friedrich Kasiski in 1863, but seems to have been independently discovered by Charles Babbage as early as 1846. How it works In polyalphabetic substitution ciphers where the substitution alphabets are chosen by the use of a keyword, the Kasiski examination allows a cryptanalyst to deduce the length of the keyword. Once the length of the keyword is discovered, the cryptanalyst lines up the ciphertext in ''n'' columns, where ''n'' is the length of the keyword. Then each column can be treated as the ciphertext of a monoalphabetic substitution cipher. As such, each column can be attacked with frequency analysis. Similarly, where a rotor stream cipher machine has been used, this method may allow the deduction of the length of individual rotors. The Kasiski examination involves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptanalysis
Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown. In addition to mathematical analysis of cryptographic algorithms, cryptanalysis includes the study of side-channel attacks that do not target weaknesses in the cryptographic algorithms themselves, but instead exploit weaknesses in their implementation. Even though the goal has been the same, the methods and techniques of cryptanalysis have changed drastically through the history of cryptography, adapting to increasing cryptographic complexity, ranging from the pen-and-paper methods of the past, through machines like the British Bombes and Colossus computers at Bletchley Park in World War II, to the mathematically advanced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Kasiski
Major Friedrich Wilhelm Kasiski (29 November 1805 – 22 May 1881) was a German infantry officer, cryptographer and archeologist. Kasiski was born in Schlochau, Kingdom of Prussia (now Człuchów, Poland). Military service Kasiski enlisted in East Prussia's 33rd Infantry Regiment on 20 March 1823 at the age of 17. In May 1824, he was promoted to the rank of master sergeant, and eight months later was commissioned as a second lieutenant in February 1825. It took fourteen years to earn his next promotion when, in May 1839, he advanced to the rank of first lieutenant. His next advancement was quicker, promoted to captain in November 1842. Kasiski finally retired from active service with the rank of major on 17 February 1852. Between 1860 and 1868 he was the commander of a National Guard battalion. Cryptography In 1863, Kasiski published a 95-page book on cryptography, ''Die Geheimschriften und die Dechiffrir-Kunst'' (German, "Secret writing and the Art of Deciphering"). This wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crimean War
The Crimean War was fought between the Russian Empire and an alliance of the Ottoman Empire, the Second French Empire, the United Kingdom of Great Britain and Ireland, and the Kingdom of Sardinia (1720–1861), Kingdom of Sardinia-Piedmont from October 1853 to February 1856. Geopolitical causes of the war included the "Eastern question" (Decline and modernization of the Ottoman Empire, the decline of the Ottoman Empire, the "sick man of Europe"), expansion of Imperial Russia in the preceding Russo-Turkish wars, and the British and French preference to preserve the Ottoman Empire to maintain the European balance of power, balance of power in the Concert of Europe. The flashpoint was a dispute between France and Russia over the rights of Catholic Church, Catholic and Eastern Orthodox Church, Orthodox minorities in Palestine (region), Palestine. After the Sublime Porte refused Nicholas I of Russia, Tsar Nicholas I's demand that the Empire's Orthodox subjects were to be placed unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Babbage
Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Babbage is considered by some to be "List of pioneers in computer science, father of the computer". He is credited with inventing the first mechanical computer, the difference engine, that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in his analytical engine, programmed using a principle openly borrowed from the Jacquard loom. As part of his computer work, he also designed the first Printer (computing), computer printers. He had a broad range of interests in addition to his work on computers covered in his 1832 book ''Economy of Manufactures and Machinery''. He was an important figure in the social scene in London, and is credited with importing the "scientific soirée" from France with hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
