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Steganographic
Steganography ( ) is the practice of representing information within another message or physical object, in such a manner that the presence of the information is not evident to human inspection. In computing/electronic contexts, a computer file, message, image, or video is concealed within another file, message, image, or video. The word ''steganography'' comes from Greek ''steganographia'', which combines the words ''steganós'' (), meaning "covered or concealed", and ''-graphia'' () meaning "writing". The first recorded use of the term was in 1499 by Johannes Trithemius in his '' Steganographia'', a treatise on cryptography and steganography, disguised as a book on magic. Generally, the hidden messages appear to be (or to be part of) something else: images, articles, shopping lists, or some other cover text. For example, the hidden message may be in invisible ink between the visible lines of a private letter. Some implementations of steganography that lack a shared secret are f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
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 synony ... [...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 Dutch-born 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 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 se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histiaeus
Histiaeus (, died 493 BC), the son of Lysagoras, was a Greek ruler of Miletus in the late 6th century BC. Histiaeus was tyrant of Miletus under Darius I, king of Persia, who had subjugated Miletus and the other Ionian states in Asia Minor, and who generally appointed Greeks as tyrants to rule the Greek cities of Ionia in his territory. Scythian campaign of Darius I (circa 513 BC) According to Herodotus,Herodotus. (2003). " The Histories, Book 5." Trans. Aubrey De Selincourt. Rev. John Marincola. London: Penguin Group. Histiaeus, along with the other Chiefs/Tyrants under Darius' rule, took part in the Persian expedition against the Scythians, and was put in charge of defending the bridge that Darius' troops had placed across the Danube River. The Scythians attempted to persuade Histiaeus and the others to abandon the bridge; one faction, led by Miltiades of Athens, at that time tyrant of the Chersonese, wanted to follow the Scythians' advice. However, Histiaeus argu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Espionage
Espionage, spying, or intelligence gathering is the act of obtaining secret or confidential information ( intelligence) from non-disclosed sources or divulging of the same without the permission of the holder of the information for a tangible benefit. A person who commits espionage is called an ''espionage agent'' or ''spy''. Any individual or spy ring (a cooperating group of spies), in the service of a government, company, criminal organization, or independent operation, can commit espionage. The practice is clandestine, as it is by definition unwelcome. In some circumstances, it may be a legal tool of law enforcement and in others, it may be illegal and punishable by law. Espionage is often part of an institutional effort by a government or commercial concern. However, the term tends to be associated with state spying on potential or actual enemies for military purposes. Spying involving corporations is known as industrial espionage. One of the most effective ways t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microdot Camera Markiv
A microdot is text or an image substantially reduced in size to prevent detection by unintended recipients. Microdots are normally circular and around in diameter but can be made into different shapes and sizes and made from various materials such as polyester or metal. The name comes from the fact that the microdots have often been about the size and shape of a typographical dot, such as a period or the tittle of a lowercase ''i'' or ''j''. Microdots are, fundamentally, a steganographic approach to message protection. History In 1870 during the Franco-Prussian War, Paris was under siege and messages were sent by carrier pigeon. Parisian photographer René Dagron used microfilm to permit each pigeon to carry a high volume of messages, as pigeons can carry little weight. Improvement in technology since then has made even more miniaturization possible. At the International Congress of Photography in Paris in 1925 Emanuel Goldberg presented a method of producing extreme red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postage Stamp
A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the face or address-side of any item of mail—an envelope or other postal cover (e.g., packet, box, mailing cylinder)—that they wish to send. The item is then processed by the postal system, where a postmark or cancellation mark—in modern usage indicating date and point of origin of mailing—is applied to the stamp and its left and right sides to prevent its reuse. The item is then delivered to its addressee. Always featuring the name of the issuing nation (with the exception of the United Kingdom), a denomination of its value, and often an illustration of persons, events, institutions, or natural realities that symbolize the nation's traditions and values, every stamp is printed on a piece of usually rectangular, but sometimes triangu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yarn
Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for needlework. Yarn can be made of a number of natural or synthetic materials, and comes in a variety of colors and thicknesses (referred to as "weights"). Although yarn may be dyed different colours, most yarns are solid coloured with a uniform hue. Etymology The word yarn comes from Middle English, from the Old English ''gearn'', akin to Old High German ''garn'', "yarn," Dutch "garen," Italian ''chordē'', "string," and Sanskrit ''hira'', "band." History The human production of yarn is known to have existed since the Stone Age and earlier prehistory, with ancient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null Cipher
A null cipher, also known as concealment cipher, is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material. Today it is regarded as a simple form of steganography, which can be used to hide ciphertext. This is one of 3 categories of cipher used in classical cryptography along with Substitution ciphers and Transposition cipher, Transposition ciphers. Classical cryptography In classical cryptography, a ''null'' is intended to confuse the cryptanalyst. In the most common form of a null cipher, the 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 com ... is included within the ciphertext and one needs to discard certain characters in order to decrypt the message (such as first letter, last letter, third letter of every second word, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ave Maria Cipher
''Alta Velocidad Española'' (''AVE'') is a service of high-speed rail in Spain operated by Renfe, the Spanish national railway company, at speeds of up to . As of December 2021, the Spanish high-speed rail network, on part of which the AVE service runs, is the longest HSR network in Europe with and the second longest in the world, after China's. AVE trains run on a network of high-speed rail track owned and managed by ADIF (''Administrador de Infraestructuras Ferroviarias''), where other high speed (, Alvia, Avlo) and mid-speed ( Altaria) services also operate. The first line was opened in 1992, connecting the cities of Madrid, Córdoba and Seville. Unlike the rest of the Iberian broad gauge network, the AVE uses standard gauge. This permits direct connections to outside Spain through the link to the French network at the Perthus Tunnel. AVE trains are operated by Renfe, but private companies may be able to operate trains in the future using other brands, in accordance wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
