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Beaufort Cipher
The Beaufort cipher, created by Sir Francis Beaufort, is a substitution cipher similar to the Vigenère cipher, with a slightly modified enciphering mechanism and tableau. Its most famous application was in a rotor-based cipher machine, the Hagelin M-209. The Beaufort cipher is based on the Beaufort square which is essentially the same as a Vigenère square but in reverse order starting with the letter "Z" in the first row, where the first row and the last column serve the same purpose. Using the cipher To encrypt, first choose the plaintext character from the top row of the tableau; call this column P. Secondly, travel down column P to the corresponding key letter K. Finally, move directly left from the key letter to the left edge of the tableau, the ciphertext encryption of plaintext P with key K will be there. For example if encrypting plain text character "d" with key "m" the steps would be: # find the column with "d" on the top, # travel down that column to find key "m" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Francis Beaufort
Rear-Admiral Sir Francis Beaufort (; 27 May 1774 – 17 December 1857) was an Irish hydrographer, rear admiral of the Royal Navy, and creator of the Beaufort cipher and the Beaufort scale. Early life Francis Beaufort was descended from French Protestant Huguenots, who fled the French Wars of Religion in the sixteenth century. His parents moved to Ireland from London. His father, Daniel Augustus Beaufort, was a Protestant clergyman from Navan, County Meath, Ireland, and a member of the learned Royal Irish Academy. His mother Mary was the daughter and co-heiress of William Waller, of Allenstown House. Francis was born in Navan on 27 May 1774. He had an older brother, William Louis Beaufort and three sisters, Frances, Harriet, and Louisa. His father created and published a new map of Ireland in 1792. Francis grew up in Wales and Ireland until age fourteen. He left school and went to sea, but never stopped his education. By later in life, he had become sufficiently self ... [...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] |
Vigenère Cipher
The Vigenère cipher () is a method of encryption, encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic cipher, polyalphabetic substitution. First described by Giovan Battista Bellaso in 1553, the cipher is easy to understand and implement, but it resisted all attempts to break it until 1863, three centuries later. This earned it the description le chiffrage indéchiffrable (French language, French for 'the indecipherable cipher'). Many people have tried to implement encryption schemes that are essentially Vigenère ciphers. In 1863, Friedrich Kasiski was the first to publish a general method of deciphering Vigenère ciphers. In the 19th century, the scheme was misattributed to Blaise de Vigenère (1523–1596) and so acquired its present name. History The very first well-documented description of a polyalphabetic cipher was by Leon Battista Alberti around 1467 and used a metal cipher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptographic Tableau
In cryptography, the ''tabula recta'' (from Latin ''tabula 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'', 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 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 ciphers based on the Caesar cipher can be described in terms of the ''tabula recta''. The tabu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M-209
In cryptography, the M-209, designated CSP-1500 by the United States Navy (C-38 by the manufacturer) is a portable, mechanical cipher machine used by the US military primarily in World War II, though it remained in active use through the Korean War. The M-209 was designed by Swedish cryptographer Boris Hagelin in response to a request for such a portable cipher machine, and was an improvement of an earlier machine, the C-36. The M-209 is about the size of a lunchbox, in its final form measuring and weighing (plus for the case). It represented a brilliant achievement for pre-electronic technology. It was a rotor machine similar to a telecipher machine, such as the Lorenz cipher and the Geheimfernschreiber. Basic operation Basic operation of the M-209 is relatively straightforward. Six adjustable ''key wheels'' on top of the box each display a letter of the alphabet. These six wheels comprise the external key for the machine, providing an initial state, similar to an initial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NSA DIANA One Time Pad
The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collection, and processing of information and data for foreign and domestic intelligence and counterintelligence purposes, specializing in a discipline known as signals intelligence (SIGINT). The NSA is also tasked with the protection of U.S. communications networks and information systems. The NSA relies on a variety of measures to accomplish its mission, the majority of which are clandestine. The existence of the NSA was not revealed until 1975. The NSA has roughly 32,000 employees. Originating as a unit to decipher coded communications in World War II, it was officially formed as the NSA by President Harry S. Truman in 1952. Between then and the end of the Cold War, it became the largest of the U.S. intelligence organizations in terms of person ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reciprocal Cipher
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between the two keys. The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link. The requirement that both parties have access to the secret key is one of the main drawbacks of symmetric-key encryption, in comparison to public-key encryption (also known as asymmetric-key encryption). However, symmetric-key encryption algorithms are usually better for bulk encryption. They have a smaller key size, which means less storage space and faster transmission. Due to this, asymmetric-key encryption is often used to exchange the secret key for symmetric-key encryption. Types Symmetric-key encryption can use either stream ciphers or block ciphers. * Stream ciphers encrypt the digits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modular Arithmetic
In mathematics, modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" when reaching a certain value, called the modulus. The modern approach to modular arithmetic was developed by Carl Friedrich Gauss in his book ''Disquisitiones Arithmeticae'', published in 1801. A familiar use of modular arithmetic is in the 12-hour clock, in which the day is divided into two 12-hour periods. If the time is 7:00 now, then 8 hours later it will be 3:00. Simple addition would result in , but clocks "wrap around" every 12 hours. Because the hour number starts over at zero when it reaches 12, this is arithmetic ''modulo'' 12. In terms of the definition below, 15 is ''congruent'' to 3 modulo 12, so "15:00" on a 24-hour clock is displayed "3:00" on a 12-hour clock. Congruence Given an integer , called a modulus, two integers and are said to be congruent modulo , if is a divisor of their difference (that is, if there is an integer such that ). Congruence modulo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atbash
Atbash ( he, אתבש; also transliterated Atbaš) is a monoalphabetic substitution cipher originally used to encrypt the Hebrew alphabet. It can be modified for use with any known writing system with a standard collating order. Encryption 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 Latin alphabet would work like this: Due to the fact that there is only one way to perform this, the Atbash cipher provides no communications security, as it lacks any sort of key. If multiple collating orders are available, which one was used in encryption can be used as a key, but this does not provide significantly more security, considering that only a few letters can give away which one was used. History The name derives from the first, last, second, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptographic Algorithms
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or '' -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adversarial behavior. More generally, cryptography is about constructing and analyzing 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 ( data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications. Cryptography prior to the modern age was effectively synonymous wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
