求密码学英文文献
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发布时间：2023-04-15 05:00
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热心网友
时间：2023-10-14 10:20
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 I
James 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 Breaking
Though 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 procere 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 concted massive espionage in America, including espionage related to nuclear armament.
Code Making
Dramatic 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 ties 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.
热心网友
时间：2023-10-14 10:21
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