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JN-25
The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well. Every Japanese code was eventually broken, and the intelligence gathered made possible such operations as the victorious American ambush of the Japanese Navy at Midway in 1942 (by breaking code JN-25b) and the shooting down of Japanese admiral Isoroku Yamamoto a year later in Operation Vengeance. The Imperial Japanese Navy (IJN) used many codes and ciphers. All of these cryptosystems were known differently by different organizations; the names listed below are those given by Western cryptanalytic operations. Red code The Red Book code was an IJN code book system used in World War I and after. It was called "Red Book" because the American photographs made of it were bound in red covers.Greg Goebel"US Codebreakers In The Shadow Of War" 2018. It should not be confu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Station HYPO
Station , also known as Fleet Radio Unit Pacific () was the United States Navy signals monitoring and cryptographic intelligence unit in Hawaii during World War II. It was one of two major Allied signals intelligence units, called Fleet Radio Units in the Pacific theaters, along with in Melbourne, Australia. The station took its initial name from the phonetic code at the time for "H" for Heʻeia, Hawaii radio tower. The precise importance and role of in penetrating the Japanese naval codes has been the subject of considerable controversy, reflecting internal tensions amongst US Navy cryptographic stations. was under the control of the OP-20-G Naval Intelligence section in Washington. Before the attack on Pearl Harbor of December 7, 1941, and for some time afterward, was in the basement of the Old Administration Building at Pearl Harbor. Later on, a new building was constructed for the station, though it had been reorganized and renamed by then. Background Cryptic problems fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Station CAST
Station CAST was the United States Navy signals monitoring and cryptographic intelligence fleet radio unit at Cavite Navy Yard in the Philippines, until Cavite was captured by the Japanese forces in 1942, during World War II. It was an important part of the Allied intelligence effort, addressing Japanese communications as the War expanded from China into the rest of the Pacific theaters. As Japanese advances in the Philippines threatened CAST, its staff and services were progressively transferred to Corregidor in Manila Bay, and eventually to a newly formed US-Australian station, FRUMEL in Melbourne, Australia. STATION CAST had originally been located at Shanghai but had been evacuated to Cavite in early 1941 as part of the US Navy's disengagement with China. Prior to the war, CAST was the US Navy's Far East cryptographic operation, under the OP-20-G Naval Intelligence section in Washington. It was located at the Navy Yard in Manila and moved into the tunnels on Corregidor, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Far East Combined Bureau
The Far East Combined Bureau, an outstation of the British Government Code and Cypher School, was set up in Hong Kong in March 1935, to monitor Japanese, and also Chinese and Russian (Soviet) intelligence and radio traffic. Later it moved to Singapore, Colombo (Ceylon), Kilindini (Kenya), then returned to Colombo. Hong Kong The FECB was located in an office block in the Naval dockyard, with an armed guard at the door (which negated any attempt at secrecy). The intercept site was on Stonecutters Island, four miles across the harbour, and manned by a dozen RAF and RN ratings (plus later four Army signallers). The codebreaking or Y section had Japanese, Chinese and Russian interpreters, under RN Paymaster Arthur (Harry) Shaw, with Dick Thatcher and Neil Barnham. The FECB was headed by the Chief of Intelligence Staff (COIS) Captain John Waller, later by Captain F. J. Wylie. Shaw had been dealing direct with GC&CS and the C-in-C Far East in Shanghai, but found that Waller expected tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Rochefort
Joseph John Rochefort (May 12, 1900 – July 20, 1976) was an American naval officer and cryptanalyst. He was a major figure in the United States Navy's cryptographic and intelligence operations from 1925 to 1946, particularly in the Battle of Midway. His contributions and those of his team were pivotal to victory in the Pacific War. Early career Rochefort was born in Dayton, Ohio. In 1917, he joined the United States Navy while still in high school in Los Angeles, without obtaining a diploma. He enlisted in the Navy in 1918, lying that he was born in 1898 so as to appear almost 21 and eligible for the service. This adjustment lasted his entire career. He was commissioned as an ensign after a 14 June 1919 graduation from the US Navy's Steam Engineering School at Stevens Institute of Technology, and later in 1919 became engineering officer of the tanker USS ''Cuyama''. A fellow officer observed that Rochefort had a penchant for solving crossword puzzles and adept skills at playi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operation Vengeance
Operation Vengeance was the American military operation to kill Admiral Isoroku Yamamoto of the Imperial Japanese Navy on April 18, 1943, during the Solomon Islands campaign in the Pacific Theater of World War II. Yamamoto, commander of the Combined Fleet of the Imperial Japanese Navy, was killed on Bougainville Island when his transport bomber aircraft was shot down by United States Army Air Forces fighter aircraft operating from Kukum Field on Guadalcanal. The mission of the U.S. aircraft was specifically to kill Yamamoto and was based on United States Navy intelligence on Yamamoto's itinerary in the Solomon Islands area. The death of Yamamoto reportedly damaged the morale of Japanese naval personnel, raised the morale of the Allied forces, and was intended as revenge by U.S. leaders, who blamed Yamamoto for the attack on Pearl Harbor that initiated the war between Imperial Japan and the United States. The U.S. pilots claimed to have shot down three twin-engine bombers and two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of Midway
The Battle of Midway was a major naval battle in the Pacific Theater of World War II that took place on 4–7 June 1942, six months after Japan's attack on Pearl Harbor and one month after the Battle of the Coral Sea. The U.S. Navy under Admirals Chester W. Nimitz, Frank J. Fletcher, and Raymond A. Spruance defeated an attacking fleet of the Imperial Japanese Navy under Admirals Isoroku Yamamoto, Chūichi Nagumo, and Nobutake Kondō north of Midway Atoll, inflicting devastating damage on the Japanese fleet. Military historian John Keegan called it "the most stunning and decisive blow in the history of naval warfare", while naval historian Craig Symonds called it "one of the most consequential naval engagements in world history, ranking alongside Salamis, Trafalgar, and Tsushima Strait, as both tactically decisive and strategically influential". Hoping to lure the American aircraft carriers into a trap and occupying Midway was part of an overall "barrier" strategy to extend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnes Driscoll
Agnes Meyer Driscoll (July 24, 1889 – September 16, 1971), known as "Miss Aggie" or "Madame X'", was an American cryptanalyst during both World War I and World War II and was known as “the first lady of naval cryptology." Early years Born in Geneseo, Illinois, in 1889, Driscoll moved with her family to Westerville, Ohio, in 1895 where her father, Gustav Meyer, had taken a job teaching music at Otterbein College. In 1909, he donated the family home to the Anti-Saloon League, which had recently moved its headquarters to Westerville. The home was later donated to the Westerville Public Library and is now home to the Anti-Saloon League Museum and the Westerville Local History Center. Education Driscoll attended Otterbein College from 1907 to 1909. In 1911, she received a Bachelor of Arts degree from the Ohio State University, having majored in mathematics and physics and studied foreign languages, statistics and music. She was fluent in English, French, German, Latin and Japanese. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attack On Pearl Harbor
The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, just before 8:00a.m. (local time) on Sunday, December 7, 1941. The United States was a neutral country at the time; the attack led to its formal entry into World War II the next day. The Japanese military leadership referred to the attack as the Hawaii Operation and Operation AI, and as Operation Z during its planning. Japan intended the attack as a preventive action. Its aim was to prevent the United States Pacific Fleet from interfering with its planned military actions in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and those of the United States. Over the course of seven hours there were coordinated Japanese attacks on the US-held Philippines, Guam, and Wake Island and on the British Empire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Code Book
A codebook is a type of document used for gathering and storing cryptography codes. Originally codebooks were often literally , but today codebook is a byword for the complete record of a series of codes, regardless of physical format. Cryptography In cryptography, a codebook is a document used for implementing a code. A codebook contains a lookup table for coding and decoding; each word or phrase has one or more strings which replace it. To decipher messages written in code, corresponding copies of the codebook must be available at either end. The distribution and physical security of codebooks presents a special difficulty in the use of codes, compared to the secret information used in ciphers, the key, which is typically much shorter. The United States National Security Agency documents sometimes use ''codebook'' to refer to block ciphers; compare their use of ''combiner-type algorithm'' to refer to stream ciphers. Codebook come in two forms, one-part or two-part: * In o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoroku Yamamoto
was a Marshal Admiral of the Imperial Japanese Navy (IJN) and the commander-in-chief of the Combined Fleet during World War II until he was killed. Yamamoto held several important posts in the IJN, and undertook many of its changes and reorganizations, especially its development of naval aviation. He was the commander-in-chief during the early years of the Pacific War and oversaw major engagements including the attack on Pearl Harbor and the Battle of Midway. Yamamoto was killed in April 1943 after American code breakers identified his flight plans, enabling the United States Army Air Forces to shoot down his plane. His death was a major blow to Japanese military morale during World War II. Family background Yamamoto was born in Nagaoka, Niigata. His father, Sadayoshi Takano (高野 貞吉), was an intermediate-rank ''samurai'' of the Nagaoka Domain. " Isoroku" is an old Japanese term meaning "56"; the name referred to his father's age at Isoroku's birth. In 1916, Iso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Japanese Ship Naming Conventions
Japanese ship names follow different conventions from those typical in the West. Merchant ship names often contain the word ''maru'' at the end (meaning ''circle''), while warships are never named after people, but rather after objects such as mountains, islands, weather phenomena, or animals. Merchant ships The word is often attached to Japanese ship names. The first ship known to follow this practice was the ''Nippon Maru'', flagship of ''daimyō'' Toyotomi Hideyoshi's 16th century fleet. Several theories purport to explain this practice: *The most common is that ships were thought of as floating castles, and the word referred to the defensive "circles" or ''maru'' that protected the castle. *The suffix ''-maru'' is often applied to words representing something beloved, and sailors applied this suffix to their ships. *The term ''maru'' is used in divination and represents perfection or completeness, or the ship as "a small world of its own". *The myth of '' Hakudo Maru'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crib (cryptanalysis)
The known-plaintext attack (KPA) is an attack model for cryptanalysis where the attacker has access to both the plaintext (called a crib), and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books. The term "crib" originated at Bletchley Park, the British World War II decryption operation, where it was defined as: History The usage "crib" was adapted from a slang term referring to cheating (e.g., "I cribbed my answer from your test paper"). A "crib" originally was a literal or interlinear translation of a foreign-language text—usually a Latin or Greek text—that students might be assigned to translate from the original language. The idea behind a crib is that cryptologists were looking at incomprehensible ciphertext, but if they had a clue about some word or phrase that might be expected to be in the ciphertext, they would have a "wedge," a test to break into it. If their otherwise random attacks on the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
