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Japanese army and diplomatic codes
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Japanese army and diplomatic codes
Japanese army and diplomatic codes. This article is on Japanese army and diplomatic ciphers and codes used up to and during World War II, to supplement the article on Japanese naval codes. The diplomatic codes were significant militarily, particularly those from diplomats in Germany.
Japanese army (IJA) and diplomatic codes were studied at Arlington Hall (US), Bletchley Park (UK), Central Bureau or CBB (Australian, US; in Melbourne, then Brisbane), the FECB (British Far East Combined Bureau) at Hong Kong, Singapore, Kilindi then Colombo and the British Wireless Experimental Centre in Delhi.
Arlington Hall had initially delayed study of the Army codes until 1942 because of the "high payoff" from diplomatic codes, but were not successful until 1943. Then, with success on Army codes in April, the increasing workload was put under Solomon Kullback in branch B-II in September. Other mainly diplomatic work was put under Frank Rowlett in B-III. Branch B-I translated Japanese.
Initially, "brute-force" IBM runs on Army codes from April 1942 to the end of the year did not work. but U.S. Army Sgt. Joe Richard noticed that the system for 2468 changed every three weeks, so the messages could be arranged by IBM tabulators by group and time period. Richard was assisted at Central Bureau by Major Harry Clark and by the head, Abraham "Abe" Sinkov, and broke 2468 on 6 April 1943, for which he was awarded the Legion of Merit. Wilfrid Noyce at the Wireless Experimental Centre had realised that the first letter of the third group of each message was not random and that other groups were paired in "doublets".
At first, Arlington Hall could not find the non-randomness until Richard told them it changed about every four weeks. With this tip Arlington Hall broke the code, as did the Wireless Experimental Centre. It used a 10×10 conversion square with the plaintext digits 0-9 across the top, key digits down the side, and the table contained the cipher text digits. As well as "kana", the Chinese Telegraph Code was used to explain places or words, and the code groups 1951 or 5734 indicated that the CTC follows; an "absurd security flaw" as it was like "Stop" as a key.[clarification needed] The CTC code group was often preceded by the "kana" groups for the same character.
Many of the Army codes were known to the Allies by their four-figure discriminant numbers. The SIS at Arlington Hall gave them three-letter codes, e.g., JEM. A conference at Arlington Hall in early 1944 decided on the allocation of high-level army codes.
The Army Water Transport Code senpaku angoshu 2 (2468 or JEK) was used by the Water Transport organization, the Army's own Navy, when moving troops around the Pacific. Ships signalled their noontime position, course, speed and other movement items. As the Japanese relied extensively on sea transport for isolated garrisons, the information assisted in planning air raids and action against Japanese air raids, and, through the American Seventh Fleet, submarine attacks. Breaking it in 1943 gave the Allies insight into other Army codes.
A three-figure reciphered air-to-ground code used by the IJA, kuuchi renraku kanji-hyoo 2-goo was known to the British as BULBUL. First broken by the Bletchley Park air section, it provided vital tactical information, so work on it was carried out in India at the Wireless Experimental Centre in Delhi. Traffic from the army operational flying units based around Meiktila in Burma was particularly valuable, aided by a book and some additive sheets from a Japanese aircraft shot down over India. By November 1944 many messages predicting air raids were intercepted, decoded and sent out as intelligence in ninety minutes. On one occasion Allied night fighters got the lot and all night we could hear Mingaladon air base calling for its lost children.
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Japanese army and diplomatic codes
Japanese army and diplomatic codes. This article is on Japanese army and diplomatic ciphers and codes used up to and during World War II, to supplement the article on Japanese naval codes. The diplomatic codes were significant militarily, particularly those from diplomats in Germany.
Japanese army (IJA) and diplomatic codes were studied at Arlington Hall (US), Bletchley Park (UK), Central Bureau or CBB (Australian, US; in Melbourne, then Brisbane), the FECB (British Far East Combined Bureau) at Hong Kong, Singapore, Kilindi then Colombo and the British Wireless Experimental Centre in Delhi.
Arlington Hall had initially delayed study of the Army codes until 1942 because of the "high payoff" from diplomatic codes, but were not successful until 1943. Then, with success on Army codes in April, the increasing workload was put under Solomon Kullback in branch B-II in September. Other mainly diplomatic work was put under Frank Rowlett in B-III. Branch B-I translated Japanese.
Initially, "brute-force" IBM runs on Army codes from April 1942 to the end of the year did not work. but U.S. Army Sgt. Joe Richard noticed that the system for 2468 changed every three weeks, so the messages could be arranged by IBM tabulators by group and time period. Richard was assisted at Central Bureau by Major Harry Clark and by the head, Abraham "Abe" Sinkov, and broke 2468 on 6 April 1943, for which he was awarded the Legion of Merit. Wilfrid Noyce at the Wireless Experimental Centre had realised that the first letter of the third group of each message was not random and that other groups were paired in "doublets".
At first, Arlington Hall could not find the non-randomness until Richard told them it changed about every four weeks. With this tip Arlington Hall broke the code, as did the Wireless Experimental Centre. It used a 10×10 conversion square with the plaintext digits 0-9 across the top, key digits down the side, and the table contained the cipher text digits. As well as "kana", the Chinese Telegraph Code was used to explain places or words, and the code groups 1951 or 5734 indicated that the CTC follows; an "absurd security flaw" as it was like "Stop" as a key.[clarification needed] The CTC code group was often preceded by the "kana" groups for the same character.
Many of the Army codes were known to the Allies by their four-figure discriminant numbers. The SIS at Arlington Hall gave them three-letter codes, e.g., JEM. A conference at Arlington Hall in early 1944 decided on the allocation of high-level army codes.
The Army Water Transport Code senpaku angoshu 2 (2468 or JEK) was used by the Water Transport organization, the Army's own Navy, when moving troops around the Pacific. Ships signalled their noontime position, course, speed and other movement items. As the Japanese relied extensively on sea transport for isolated garrisons, the information assisted in planning air raids and action against Japanese air raids, and, through the American Seventh Fleet, submarine attacks. Breaking it in 1943 gave the Allies insight into other Army codes.
A three-figure reciphered air-to-ground code used by the IJA, kuuchi renraku kanji-hyoo 2-goo was known to the British as BULBUL. First broken by the Bletchley Park air section, it provided vital tactical information, so work on it was carried out in India at the Wireless Experimental Centre in Delhi. Traffic from the army operational flying units based around Meiktila in Burma was particularly valuable, aided by a book and some additive sheets from a Japanese aircraft shot down over India. By November 1944 many messages predicting air raids were intercepted, decoded and sent out as intelligence in ninety minutes. On one occasion Allied night fighters got the lot and all night we could hear Mingaladon air base calling for its lost children.