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Transposition Cipher
In cryptography, a transposition cipher (also known as a permutation 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 cipher, 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 (cryptography), key, scrambling the order of characters like the shuffled pieces of a jigsaw puzzle. The resulting m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Columnar Transposition Example
Double, The Double or Dubble may refer to: Mathematics and computing * Multiplication by 2 * Double precision, a floating-point representation of numbers that is typically 64 bits in length * A double number of the form x+yj, where j^2=+1 * A 2-tuple, or ordered list of two elements, commonly called an ordered pair, denoted (a,b) * Double (manifold), in topology Food and drink * A drink order of two shots of hard liquor in one glass * A "double decker", a hamburger with two patties in a single bun Games * Double, action in games whereby a competitor raises the stakes ** , in contract bridge ** Doubling cube, in backgammon ** Double, doubling a blackjack bet in a favorable situation ** Double, a bet offered by UK bookmakers which combines two selections * Double, villain in the video game ''Mega Man X4'' * A kart racing game '' Mario Kart: Double Dash'' * An arcade action game ''Double Dragon'' Sports * Double (association football), the act of a winning a division and prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anagram
An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once. For example, the word ''anagram'' itself can be rearranged into the phrase "nag a ram"; which is an Easter egg suggestion in Google after searching for the word "anagram". The original word or phrase is known as the ''subject'' of the anagram. Any word or phrase that exactly reproduces the letters in another order is an anagram. Someone who creates anagrams may be called an "anagrammatist", and the goal of a serious or skilled anagrammatist is to produce anagrams that reflect or comment on their subject. Examples Anagrams may be created as a commentary on the subject. They may be a parody, a criticism or satire. For example: * "The New York Times, New York Times" = "monkeys write" * "Church of Scientology" = "rich-chosen goofy cult" * "McDonald's restaurants" = "Uncle Sam's standard rot" An anagram may also be a synonym of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hill Climbing
numerical analysis, hill climbing is a mathematical optimization technique which belongs to the family of local search. It is an iterative algorithm that starts with an arbitrary solution to a problem, then attempts to find a better solution by making an incremental change to the solution. If the change produces a better solution, another incremental change is made to the new solution, and so on until no further improvements can be found. For example, hill climbing can be applied to the travelling salesman problem. It is easy to find an initial solution that visits all the cities but will likely be very poor compared to the optimal solution. The algorithm starts with such a solution and makes small improvements to it, such as switching the order in which two cities are visited. Eventually, a much shorter route is likely to be obtained. Hill climbing finds optimal solutions for convex problems – for other problems it will find only local optima (solutions that cannot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Algorithm
In computer science and operations research, a genetic algorithm (GA) is a metaheuristic inspired by the process of natural selection that belongs to the larger class of evolutionary algorithms (EA). Genetic algorithms are commonly used to generate high-quality solutions to optimization and search problems via biologically inspired operators such as selection, crossover, and mutation. Some examples of GA applications include optimizing decision trees for better performance, solving sudoku puzzles, hyperparameter optimization, and causal inference. Methodology Optimization problems In a genetic algorithm, a population of candidate solutions (called individuals, creatures, organisms, or phenotypes) to an optimization problem is evolved toward better solutions. Each candidate solution has a set of properties (its chromosomes or genotype) which can be mutated and altered; traditionally, solutions are represented in binary as strings of 0s and 1s, but other encod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Distribution
In statistics, the frequency or absolute frequency of an Event (probability theory), event i is the number n_i of times the observation has occurred/been recorded in an experiment or study. These frequencies are often depicted graphically or tabular form. Types The cumulative frequency is the total of the absolute frequencies of all events at or below a certain point in an ordered list of events. The Empirical probability, relative frequency (or ''empirical probability'') of an event is the absolute frequency Normalizing constant, normalized by the total number of events: : f_i = \frac = \frac. The values of f_i for all events i can be plotted to produce a frequency distribution. In the case when n_i = 0 for certain i, pseudocounts can be added. Depicting frequency distributions A frequency distribution shows a summarized grouping of data divided into mutually exclusive classes and the number of occurrences in a class. It is a way of showing unorganized data notably to sh ... [...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] |
Luigi Sacco
Luigi Sacco (1 August 1883 in Alba – 5 December 1970 in Rome) was an Italian general and cryptanalyst. At the entrance of Italy into WWI, he was a captain serving with radio-telegraphy troops. As specialist in direction finding Direction finding (DF), radio direction finding (RDF), or radiogoniometry is the use of radio waves to determine the direction to a radio source. The source may be a cooperating radio transmitter or may be an inadvertent source, a naturall ... he led the effort to locate and intercept Austro-Hungarian radiograms on the frontline, but due to a lack cryptanalysts they weren't being decrypted, so in 1916 he had to learn cryptanalysis himself. After the war he wrote books on cryptography. Bibliography ''Manual of Cryptology'' ''("Manuale di Crittografia")'' (1936) References People from Alba, Piedmont Italian military personnel of World War II Italian Army generals Italian cryptographers 1970 deaths 1883 births {{Italy-mil-bio-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rasterschlüssel 44
Rasterschlüssel 44 (abbr. RS 44) was a manual cipher system, used by the German Wehrmacht during the Second World War. The cipher was designed by the astronomer and sometime cryptographer Walter Fricke while working as a conscript in Section IIb, of Group 2 of OKW/Chi and introduced in March 1944 and the Allied forces codebreakers had considerable difficulties in breaking it. Cryptanalysis, if successful, generally required a 40 letter crib (known plaintext) and some two weeks, making the tactical information outdated before it could be exploited. The combination of strength and ease of use made RS 44 an ideal hand cipher. Design The cipher is a transposition based grille cipher, consisting of a grid with 25 columns and 24 rows. Each row contains 10 randomly placed white cells (to be filled with text) and 15 black cells. The columns are labeled with shuffled digraphs and numbers and the rows with digraphs. The key sheet also contains two letter substitution alphabets to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VIC Cipher
The VIC cipher was a pencil and paper cipher used by the Soviet Union, Soviet spy Reino Häyhänen, codenamed "VICTOR". If the cipher were to be given a modern technical name, it would be known as a "straddling bipartite monoalphabetic substitution superenciphered by modified double transposition." David Kahn"Number One From Moscow" 1993. However, by general classification it is part of the Nihilist cipher, Nihilist family of ciphers. It was arguably the most complex hand-operated cipher ever seen, when it was first discovered. The initial analysis done by the American National Security Agency (NSA) in 1953 did not absolutely conclude that it was a hand cipher, but its placement in a hollowed out Nickel (United States coin), 5¢ coin (later known as the Hollow Nickel Case) implied it could be decoded using pencil and paper. The VIC cipher remained unbroken until more information about its structure was available. Although certainly not as complex or secure as modern computer op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Office Of Strategic Services
The Office of Strategic Services (OSS) was the first intelligence agency of the United States, formed during World War II. The OSS was formed as an agency of the Joint Chiefs of Staff (JCS) to coordinate espionage activities behind enemy lines for all branches of the United States Armed Forces. Other OSS functions included the use of propaganda, subversion, and post-war planning. The OSS was dissolved a month after the end of the war. Intelligence tasks were shortly later resumed and carried over by its successors, the Strategic Services Unit (SSU), the United States Department of State, Department of State's Bureau of Intelligence and Research (INR), and the Central Intelligence Group (CIG), the intermediary precursor to the independent Central Intelligence Agency (CIA). On December 14, 2016, the organization was collectively honored with a Congressional Gold Medal. Origin Before the OSS, the various departments of the executive branch, including the United States Departm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Operations Executive
Special Operations Executive (SOE) was a British organisation formed in 1940 to conduct espionage, sabotage and reconnaissance in German-occupied Europe and to aid local Resistance during World War II, resistance movements during World War II. SOE personnel operated in all territories occupied or attacked by the Axis powers, except where demarcation lines were agreed upon with Britain's principal Allies of World War II, Allies, the United States and the Soviet Union. SOE made use of neutral territory on occasion, or made plans and preparations in case neutral countries were attacked by the Axis. The organisation directly employed or controlled more than 13,000 people, of whom 3,200 were women. Both men and women served as agents in Axis-occupied countries. The organisation was dissolved in 1946. A memorial to those who served in SOE was unveiled in 1996 on the wall of the west cloister of Westminster Abbey by the Queen Elizabeth The Queen Mother, Queen Mother, and in 2009 on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maquis (World War II)
The Maquis () were rural guerrilla bands of French and Belgian Resistance fighters, called ''maquisards'', during World War II. Initially, they were composed of young, mostly working-class men who had escaped into the mountains and woods to avoid conscription into Vichy France's (STO; 'Compulsory Work Service') which provided forced labor for Germany. To avoid capture and deportation to Germany, they became increasingly organized into active resistance groups. They had an estimated to members in autumn of 1943 and approximately members in June 1944. Meaning The maquis made up one component of the mosaic of the resistance in France and Belgium. The maquis refers to the organization of bands of resistance guerrillas which emerged in rural France, mainly in the south. The maquis were emergent in 1943 and were also active in 1944. Originally the word came from the kind of terrain in which the armed resistance groups hid, high ground in southeastern France covered with scrub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
