Although the spoken Japanese and Chinese languages differ, they share a common written language. Written Japanese, which originated in the ninth century, was derived from Chinese and uses ideographs. The written language was simplified by introducing the kana phonetic system, containing 48 basic syllables. Of the two kana versions developed, hirigana and katagana, the latter was favored for telegraphic communications due to the ease of reproducing its kana symbols.
In order to write Japanese using the Roman alphabet A,B,. . .,Z, each kana symbol is assigned a Roman letter counterpart Romaji. The Hepburn Romaji system used by Japan during World War II still remains in use today. The Hepburn-frequencies {f(t)} of the letters A,B, . . .,Z derived from a sample of Romanized Japanese is given in Table 7.1. The sample’s index of coincidence s2
P25
t¼0 f 2(t) ¼ 0:0819 is much larger than the value s2 0.06875 for English. The letters L, Q, and X do not occur in the Romanized Japanese text.
A new cipher machine was introduced by the Japanese Foreign Office in 1930. Designated RED by the United States, Angooki Taipu A would soon be followed by other colors of the rainbow – PURPLE, CORAL, and JADE. The diagnosis and cryptanalysis of RED by the Army Signal Intelligence Service started in 1935 and was completed in one year.
RED was replaced in 1940 by Angooki Taipu B, designated PURPLE; its cryptanalysis was completed just before the bombing of Pearl Harbor. Intelligence gleaned from PURPLE traffic gave the United States a decisive edge in World War II.
In order to write Japanese using the Roman alphabet A,B,. . .,Z, each kana symbol is assigned a Roman letter counterpart Romaji. The Hepburn Romaji system used by Japan during World War II still remains in use today. The Hepburn-frequencies {f(t)} of the letters A,B, . . .,Z derived from a sample of Romanized Japanese is given in Table 7.1. The sample’s index of coincidence s2
P25
t¼0 f 2(t) ¼ 0:0819 is much larger than the value s2 0.06875 for English. The letters L, Q, and X do not occur in the Romanized Japanese text.
A new cipher machine was introduced by the Japanese Foreign Office in 1930. Designated RED by the United States, Angooki Taipu A would soon be followed by other colors of the rainbow – PURPLE, CORAL, and JADE. The diagnosis and cryptanalysis of RED by the Army Signal Intelligence Service started in 1935 and was completed in one year.
RED was replaced in 1940 by Angooki Taipu B, designated PURPLE; its cryptanalysis was completed just before the bombing of Pearl Harbor. Intelligence gleaned from PURPLE traffic gave the United States a decisive edge in World War II.
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