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Tabula Recta
In cryptography, the ''tabula recta'' (from Latin language, Latin ''wikt:tabula#Latin, tabula wikt:rectus#Latin, rēcta'') is a square table of alphabets, each row of which is made by shifting the previous one to the left. The term was invented by the German author and monk Johannes TrithemiusSalomon, Data Privacy, page 63 in 1508, and used in his Trithemius cipher. Trithemius cipher The Trithemius cipher was published by Johannes Trithemius in his book ''Polygraphia (book), Polygraphia'', which is credited with being the first published printed work on cryptology. Trithemius used the ''tabula recta'' to define a polyalphabetic cipher, which was equivalent to Leon Battista Alberti's Alberti cipher disk, cipher disk except that the order of the letters in the target alphabet is not mixed. The ''tabula recta'' is often referred to in discussing pre-computer ciphers, including the Vigenère cipher and Blaise de Vigenère's less well-known autokey cipher. All polyalphabetic ciphe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vigenère Cipher
The Vigenère cipher () is a method of encryption, encrypting alphabetic text where each letter of the plaintext is encoded with a different Caesar cipher, whose increment is determined by the corresponding letter of another text, the key (cryptography), key. For example, if the plaintext is attacking tonight and the key is oculorhinolaryngology, then *the first letter of the plaintext, a, is shifted by 14 positions in the alphabet (because the first letter of the key, o, is the 14th letter of the alphabet, counting from zero), yielding o; *the second letter, t, is shifted by 2 (because the second letter of the key, c, is the 2nd letter of the alphabet, counting from zero) yielding v; *the third letter, t, is shifted by 20 (u), yielding n, with wrap-around; and so on. It is important to note that traditionally spaces and punctuation are removed prior to encryption and reintroduced afterwards. * In this example the tenth letter of the plaintext t is shifted by 14 position ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plaintext
In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. This usually refers to data that is transmitted or stored unencrypted. Overview With the advent of computing, the term ''plaintext'' expanded beyond human-readable documents to mean any data, including binary files, in a form that can be viewed or used without requiring a key or other decryption device. Information—a message, document, file, etc.—if to be communicated or stored in an unencrypted form is referred to as plaintext. Plaintext is used as input to an encryption algorithm; the output is usually termed ciphertext, particularly when the algorithm is a cipher. Codetext is less often used, and almost always only when the algorithm involved is actually a code. Some systems use multiple layers of encryption, with the output of one encryption algorithm becoming "plaintext" input for the next. Secure handling Insecure handling of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giovan Battista Bellaso
Giovan Battista Bellaso (Brescia 1505–...) was an Italian cryptologist. The Vigenère cipher is named after Blaise de Vigenère, although Giovan Battista Bellaso had invented it before Vigenère described his autokey cipher. Biography Bellaso was born of a distinguished family in 1505. His father was Piervincenzo, a patrician of Brescia, owner since the 15th century of a house in town and a suburban estate in Capriano, in a neighborhood called Fenili Belasi (Bellaso's barns), including the Holy Trinity chapel. The chaplain was remunerated each year with a regular salary, and a supply of firewood. The family coat of arms was ‘‘On a blue field three red-tongued gold lion heads in side view”. Bellaso received a degree in civil law at the University of Padua in 1538. The French author, Blaise de Vigenère, reported that he was serving as a secretary in the suite of Cardinal Rodolfo Pio di Carpi and credited him with the invention of the reciprocal table, now calle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerckhoffs's Principle
Kerckhoffs's principle (also called Kerckhoffs's desideratum, assumption, axiom, doctrine or law) of cryptography was stated by the Dutch cryptographer Auguste Kerckhoffs in the 19th century. The principle holds that a cryptosystem should be secure, even if everything about the system, except the key, is public knowledge. This concept is widely embraced by cryptographers, in contrast to security through obscurity, which is not. Kerckhoffs's principle was phrased by the American mathematician Claude Shannon as "the enemy knows the system", i.e., "one ought to design systems under the assumption that the enemy will immediately gain full familiarity with them". In that form, it is called Shannon's maxim. Another formulation by American researcher and professor Steven M. Bellovin is: In other words—design your system assuming that your opponents know it in detail. (A former official at NSA's National Computer Security Center told me that the standard assumption there was that ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key (cryptography)
A key in cryptography is a piece of information, usually a string of numbers or letters that are stored in a file, which, when processed through a cryptographic algorithm, can encode or decode cryptographic data. Based on the used method, the key can be different sizes and varieties, but in all cases, the strength of the encryption relies on the security of the key being maintained. A key's security strength is dependent on its algorithm, the size of the key, the generation of the key, and the process of key exchange. Scope The key is what is used to encrypt data from plaintext to ciphertext. There are different methods for utilizing keys and encryption. Symmetric cryptography Symmetric cryptography refers to the practice of the same key being used for both encryption and decryption. Asymmetric cryptography Asymmetric cryptography has separate keys for encrypting and decrypting. These keys are known as the public and private keys, respectively. Purpose Since the key ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Letter Frequency
Letter frequency is the number of times letters of the alphabet appear on average in written language. Letter frequency analysis dates back to the Arab mathematician Al-Kindi (c. AD 801–873), who formally developed the method to break ciphers. Letter frequency analysis gained importance in Europe with the development of movable type in AD 1450, wherein one must estimate the amount of type required for each letterform. Linguists use letter frequency analysis as a rudimentary technique for language identification, where it is particularly effective as an indication of whether an unknown writing system is alphabetic, syllabic, or ideographic. The use of letter frequencies and frequency analysis plays a fundamental role in cryptograms and several word puzzle games, including hangman, ''Scrabble'', '' Wordle'' and the television game show '' Wheel of Fortune''. One of the earliest descriptions in classical literature of applying the knowledge of English letter frequency to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caesar Cipher
In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code, or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, would be replaced by , would become , and so on. The method is named after Julius Caesar, who used it in his private correspondence. The encryption step performed by a Caesar cipher is often incorporated as part of more complex schemes, such as the Vigenère cipher, and still has modern application in the ROT13 system. As with all single-alphabet substitution ciphers, the Caesar cipher is easily broken and in modern practice offers essentially no communications security. Example The transformation can be represented by aligning two alphabets; the cipher is the plain alphabet rotated left or right by some number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autokey Cipher
An autokey cipher (also known as the autoclave cipher) is a cipher that incorporates the message (the plaintext) into the key. The key is generated from the message in some automated fashion, sometimes by selecting certain letters from the text or, more commonly, by adding a short ''primer key'' to the front of the message. There are two forms of autokey cipher: ''key-autokey'' and ''text-autokey'' ciphers. A key-autokey cipher uses previous members of the keystream to determine the next element in the keystream. A text-autokey uses the previous message text to determine the next element in the keystream. History This cipher was invented in 1586 by Blaise de Vigenère with a reciprocal table of ten alphabets. Vigenère's version used an agreed-upon letter of the alphabet as a primer, making the key by writing down that letter and then the rest of the message. More popular autokeys use a tabula recta, a square with 26 copies of the alphabet, the first line starting with 'A', th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blaise De Vigenère
Blaise de Vigenère (5 April 1523 – 19 February 1596) () was a French diplomat, cryptographer, translator and alchemist. Biography Vigenère was born into a respectable family in the village of Saint-Pourçain in Bourbonnais. When he was 12, his father, Jehan (modern spelling Jean) de Vigenère, arranged for him to have a classical education in Paris. Registered at the university at 14, he quit after three years without a known degree.Sarazin 1997, p. 18. From 1539 to around 1545, he worked under Gilbert Bayard, a first secretary to King Francis I, who had fiefs in Bourbonnais. In 1545, he accompanied the French envoy Louis Adhémar de Monteil, Count of Grignan, to the Diet of Worms as a junior secretary. After the diet's rupture, he traveled in Europe.Moreri 1759 vol. 10, p. 606 ("Vigenere, Blaise de") In 1547, he quit the court and entered the service of the House of Nevers. He would remain associated with it until at least a year before his death in 1596. At first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alberti Cipher Disk
Alberti may refer to: Leon Battista Alberti, the Renaissance architect Places * Alberti Partido, a partido of Buenos Aires Province, Argentina * Alberti, Buenos Aires, the main town of the partido * Alberti (Buenos Aires Underground), a railway station Other uses * Alberti (surname) Alberti is an Italian surname that derives from the given name Alberto, Latin translation of Germanic Albert (given name), Albert. It may refer to: *Alberti (family), Florentine family *Achille Alberti (1860–1943), Italian sculptor *Aída Alberti ... * Alberti bass, a musical accompaniment figuration, usually in the left hand on a keyboard instrument * Alberti cipher, an early polyalphabetic cipher (late 15th century) * Alberti (family), Florentine political family See also * Albertis (other) * Albertoni, a surname * D'Albertis (other) {{disambiguation, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), adversarial behavior. More generally, cryptography is about constructing and analyzing Communication protocol, protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engineering, digital signal processing, physics, and others. Core concepts related to information security (confidentiality, data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, Smart card#EMV, chip-based payment cards, digital currencies, password, computer passwords, and military communications. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
