北京美克
密码: [ mì mǎ ] 1. password2. code其它相关解释:
蒙古无双皇帝
从美国百科大全书里搜到，希望能有所帮助。翻译就算了吧……Cryptology, the technology of making and breaking codes and ciphers, has furnished America with excellent protection for its transmitted documents and with its best intelligence.Revolution to World War IJames Lovell, a member of the Continental Congress who may be considered America's first cryptanalyst, solved British cryptograms for the rebels. One of them enabled Washington to alert the French admiral Comte de Grasse to blockade Yorktown, which then surrendered. Edgar Allan Poe popularized cryptology in 1843 with his story "The Gold Bug." During the Civil War, the Union utilized a word-transposition cipher; the South, a letter-substitution. The State Department printed its first cable code in 1867. In 1878, the New York Tribune solved and published encrypted telegrams showing that Democrats had bought electoral votes for Samuel J. Tilden in 1876. Though the Republican candidate, Rutherford B. Hayes, had nevertheless won the presidency, the disclosures helped lead to Republican gains in the midterm elections and to a Republican president, James A. Garfield, in 1880.Code BreakingThough some army officers investigated cryptology, the United States had no official cryptanalytic bureau until World War I. U.S. involvement in the war came about in part through codebreaking: Britain had cryptanalyzed a German offer to Mexico to make joint war on the United States; five weeks after newspapers headlined this, Congress declared war on Germany. In the spring of 1917, the Army's Military Intelligence Section established a codebreaking agency, called MI-8, placing a charismatic former State Department code clerk, Herbert O. Yardley, in charge. One of its solutions convicted a German spy. The American Expeditionary Forces had its own codebreaking unit, G.2 A.6, to solve German front-line codes, and its own Code Compilation Section, which printed and distributed new codes every few weeks. In 1919, MI-8 evolved into the joint Army-State Cipher Bureau under Yardley. During the Washington naval disarmament conference of 1921–1922, it solved Japanese diplomatic messages that helped America compel Tokyo to accept the equivalent of a battleship-and-a-half less than it wanted. America, Japan, and other nations saved millions that would otherwise have been spent on warships.In 1929, Secretary of State Henry L. Stimson withdrew the Bureau's funds, on the ground that "gentlemen do not read each other's mail." Yardley, jobless in the Depression, awoke America to the importance of cryptology in his best-selling The American Black Chamber (1931). His bureau's work was assumed by the army's tiny Signal Intelligence Service (SIS) under the brilliant cryptologist William F. Friedman. During World War I, Friedman, at the Riverbank Laboratories, a think tank near Chicago, had broken new paths for cryptanalysis; soon after he joined the War Department as a civilian employee in 1921, he reconstructed the locations and starting positions of the rotors in a cipher machine. His work placed the United States at the forefront of world cryptology. Beginning in 1931, he expanded the SIS, hiring mathematicians first. By 1940, a team under the cryptanalyst Frank B. Rowlett had reconstructed the chief Japanese diplomatic cipher machine, which the Americans called purple. These solutions could not prevent Pearl Harbor because no messages saying anything like "We will attack Pearl Harbor" were ever transmitted; the Japanese diplomats themselves were not told of the attack. Later in the war, however, the solutions of the radiograms of the Japanese ambassador in Berlin, enciphered in purple, provided the Allies with what Army Chief of Staff General George C. Marshall called "our main basis of information regarding Hitler's intentions in Europe." One revealed details of Hitler's Atlantic Wall defenses.The U.S. Navy's OP-20-G, established in 1924 under Lieutenant Laurence F. Safford, solved Japanese naval codes. This work flowered when the solutions of its branch in Hawaii made possible the American victory at Midway in 1942, the midair shootdown of Admiral Isoroku Yamamoto in 1943, and the sinking of Japanese freighters throughout the Pacific war, strangling Japan. Its headquarters in Washington cooperated with the British code breaking agency, the Government Code and Cypher School, at Bletchley Park, northwest of London, to solve U-boat messages encrypted in the Enigma rotor cipher machine. This enabled Allied convoys to dodge wolf packs and so help win the Battle of the Atlantic. Teams of American cryptanalysts and tabulating machine engineers went to the British agency to cooperate in solving German Enigma and other cipher systems, shortening the land war in Europe. No other source of information—not spies, aerial photographs, or prisoner interrogations—provided such trustworthy, high-level, voluminous, detailed, and prompt intelligence as code breaking.At the San Francisco conference of 1945, which created the United Nations, the United States used information from code breaking to get its way on important matters, such as its desire, despite French opposition, for a veto procedure in the Security Council. In the 1940s, the United States began solving Soviet spy messages. Disclosed in 1995, these solutions, codenamed venona, showed that the Soviet Union had conducted massive espionage in America, including espionage related to nuclear armament.Code MakingDramatic though code breaking is, more important than getting other people's secrets is keeping one's own. America has excelled in this as well. The first law specifying the duties of the Post Office, 20 February 1792 made it a crime for its employees to open mail, thus protecting privacy before European countries did. Thomas Jefferson invented an ingenious cipher system but filed and forgot it; the U.S. Army adopted an independent invention of it in 1922 that was used until World War II. In 1917, an engineer at the American Telephone & Telegraph Company, Gilbert S. Vernam, devised the first online cipher machine. Based on a teletypewriter, it electromechanically added the on-off impulses of the plain-text message to those of a key tape and transmitted the resultant ciphertext. This mechanism, the first binary device in cryptology, was perfected by Major Joseph O. Mauborgne, who, by making the key tape random and prohibiting more than a single use of it, created the only theoretically unbreakable cipher, the one-time tape. Also in 1917, an amateur inventor, Edward H. Hebern of California, devised the first rotor cipher machine before three Europeans independently had the same idea. In the 1930s, Rowlett and Friedman irregularized the turning of rotors. Their cipher machine, the sigaba, armored U.S. Army and Navy communications against the technology of the time; none of its messages were broken by Axis powers. During World War II, Navajos in the Marine Corps translated English-language orders into their language for walkie-talkie transmission; the Japanese never understood them. In 1943, AT&T engineers built a radiotelephone scrambler, sigsaly, that used a one-time key and proved invulnerable to German eavesdropping. Another AT&T employee, Claude E. Shannon, the conceiver of information theory, provided cryptology with a theoretical underpinning in his article "Communication Theory of Secrecy Systems," published in 1949.In 1976, the National Institute of Standards and Technology promulgated a Data Encryption Standard so computers could intercommunicate securely; it was replaced on 26 May 2002 by the Advanced Encryption Standard. Also in 1976, an electrical engineering student, Whitfield Diffie, aided by Professor Martin Hellman, both of Stanford University, devised the most important advance in cryptography since the invention of cryptography itself: public-key cryptography. This permitted people to communicate in secret without prearrangement and ultimately opened the way to online Electronic Commerce.
十米之上
密码: [ mì mǎ ] 1. password2. code其它相关解释:
继续改一个
密钥：分为加密密钥和解密密钥。明文：没有进行加密，能够直接代表原文含义的信息。密文：经过加密处理处理之后，隐藏原文含义的信息。加密：将明文转换成密文的实施过程。解密：将密文转换成明文的实施过程。密码算法：密码系统采用的加密方法和解密方法，随着基于数学密码技术的发展，加密方法一般称为加密算法，解密方法一般称为解密算法。直到现代以前，密码学几乎专指加密(encryption）算法：将普通信息（明文,plaintext）转换成难以理解的资料（密文,ciphertext）的过程；解密(decryption）算法则是其相反的过程：由密文转换回明文；加解密包含了这两种算法，一般加密即同时指称加密(encrypt或encipher）与解密(decrypt或decipher）的技术。加解密的具体运作由两部分决定：一个是算法，另一个是密钥。密钥是一个用于加解密算法的秘密参数，通常只有通讯者拥有。历史上，密钥通常未经认证或完整性测试而被直接使用在密码机上。密码协议（cryptographic protocol）是使用密码技术的通信协议（communication protocol）。近代密码学者多认为除了传统上的加解密算法，密码协议也一样重要，两者为密码学研究的两大课题。在英文中，cryptography和cryptology都可代表密码学，前者又称密码术。但更严谨地说，前者（cryptography）指密码技术的使用，而后者（cryptology）指研究密码的学科，包含密码术与密码分析。密码分析（cryptanalysis）是研究如何破解密码学的学科。但在实际使用中，通常都称密码学（英文通常称cryptography），而不具体区分其含义。口语上，编码（code）常意指加密或隐藏信息的各种方法。然而，在密码学中，编码有更特定的意义：它意指以码字（code word）取代特定的明文。例如，以‘苹果派’（apple pie）替换‘拂晓攻击’（attack at dawn）。编码已经不再被使用在严谨的密码学，它在信息论或通讯原理上有更明确的意义。在汉语口语中，电脑系统或网络使用的个人帐户口令（password）也常被以密码代称，虽然口令亦属密码学研究的范围，但学术上口令与密码学中所称的钥匙（key）并不相同，即使两者间常有密切的关连。
