Station CAST

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Station CAST was the

FRUMEL in Melbourne, Australia.[1]

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, as Japanese attacks increased. STATION CAST possessed one of the PURPLE machines produced by the US Army.

Cryptanalytic problems facing the United States in the Pacific prior to World War II were largely

Bainbridge Island
, etc.) were tasked and staffed for signals interception and traffic analysis.

PURPLE diplomatic traffic

The US Army

PURPLE traffic, eventually called MAGIC, were rather capriciously distributed to high level officials in Washington, and in general, poorly used.[citation needed] SIS was able to build several PURPLE machine equivalents and the distribution of those machines has since been thought controversial. One was sent to Station CAST. After the US entered the War, two went to Bletchley Park, the center of British cryptographic work. One was sent to the Far East Combined Bureau (FECB) at Singapore, and was lost during the fall of Singapore [2]

Japanese Navy crypto systems: JN-25

Stations HYPO and CAST were assigned responsibility for work on Japanese Navy systems, and after the agreement with the United Kingdom and Netherlands to share the effort, worked with crypto groups in Hong Kong then Singapore (Far East Combined Bureau) and Batavia (Kamer 14 or Room 14).

Prior to the

FECB
as the additives were not changed. Most references cite about 10% of messages partially (or sometimes completely) decrypted prior to 1 December 1941, at which time a new edition of the system went into effect and sent all the cryptanalysts back to the beginning.

After 7 December 1941, there was considerably more JN-25 traffic as the Japanese Navy operational tempo increased and geographically expanded, and progress against it went better. The

FECB
contribution stopped until the crypto station could be relocated from Singapore to Ceylon, but CAST, HYPO, and the Dutch at Batavia, in conjunction with OP-20-G, made steady progress.

CAST during and after the invasion of the Philippines

Station CAST and its personnel and equipment were moved from Manila to the tunnels on Corregidor as the Japanese approached and spent the next months working there. Eventually, they destroyed their equipment (some

South West Pacific Area (command)
.

References

  1. ^ Parker, Frederick D. A Priceless Advantage: U.S. Navy Communications Intelligence and the Battles of Coral Sea, Midway, and the Aleutians. Fort Meade MD: Center for Cryptologic History, National Security Agency, 1993.
  2. ISBN 0-593-04642-0
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