Photographs of the codebook were given to the cryptanalysts at the Research Desk and the processed code was kept in red-colored folders (to indicate its Top Secret classification).
[citation needed] In 1930, the Japanese government created a more complex code that was codenamed BLUE, although RED was still being used for low-level communications.
US Military Intelligence COMINT listening stations began monitoring command-to-fleet, ship-to-ship, and land-based communications.
[citation needed] After Japan's ally Germany declared war in the fall of 1939, the German government began sending technical assistance to upgrade their communications and cryptography capabilities.
This accelerated decoding and the addition of more translators on staff in 1942 made it easier and quicker to decipher the traffic intercepted.
No detailed information about the planned attack was even available to the Japanese Foreign Office, as that agency was regarded by the military, particularly its more nationalist members, as insufficiently "reliable".
U.S. access to private Japanese diplomatic communications (even the most secret ones) was less useful than it might otherwise have been because policy in prewar Japan was controlled largely by military groups like the Imperial Way Faction, and not by the Foreign Office.
The Foreign Office itself deliberately withheld from its embassies and consulates much of the information it did have, so the ability to read PURPLE messages was less than definitive regarding Japanese tactical or strategic military intentions.
As a result of the deciphering and typing difficulties at the embassy, the note was delivered late to American Secretary of State Cordell Hull.
When the two Japanese diplomats finally delivered the note, Hull had to pretend to be reading it for the first time, even though he already knew about the attack on Pearl Harbor.
For instance, the Japanese ambassador to Germany, Baron Hiroshi Ōshima, produced long reports for Tokyo which were enciphered on the PURPLE machine.
Much confusion over who in Washington or Hawaii knew what and when, especially as "we were decrypting their messages," has led some to conclude "someone in Washington" knew about the Pearl Harbor attack before it happened, and, since Pearl Harbor was not expecting to be attacked, the "failure to warn Hawaii one was coming must have been deliberate, since it could hardly have been mere oversight".
Nevertheless, the extraordinary experience of reading a foreign government's most closely held communications, sometimes even before the intended recipient, was astonishing.
Internment of "enemy aliens" by the U.S. government began two months prior to Executive Order 9066 on December 8, 1941, immediately after the attack at Pearl Harbor and included Germans and Italians, and not just the Japanese living on the U.S. West Coast.
Those defending the decision to evacuate and relocate when seen in context, notably blogger and investigative reporter Michelle Malkin, point to Magic intercepts as partial justification for EO 9066.
In 1988, Congress passed and President Ronald Reagan signed legislation that apologized for the internment on behalf of the U.S. government.
The legislation said that government actions were based on "race prejudice, war hysteria, and a failure of political leadership".
[8] The following is the actual text of several Magic intercepts translated into English before and during the war and declassified and made public in 1978 by the U.S. government (The Magic Background of Pearl Harbor, Government Printing Office, 8 volumes) Intercept dated January 30, 1941 and noted as translated 2-7-41 Numbered #44 FROM: Tokyo (Matsuoka) TO: Washington (Koshi) (In two parts – complete).
In response to the ordered shift from propaganda efforts to espionage collection, the Japanese consulates throughout the western hemisphere reported their information normally through the use of diplomatic channels, but when time-sensitive through the use of PURPLE encoded messages.
Intercept dated May 9, 1941 and translated 5-19-41 Numbered #067 FROM: Los Angeles (Nakauchi) TO: Tokyo (Gaimudaijin) (In 2 parts – complete).
We are having Nakazawa investigate and summarize information gathered through first hand and newspaper reports, with regard to military movements, labor disputes, communistic activities and other similar matters.
With regard to anti-Jewish movements, we are having investigations made by both prominent Americans and Japanese who are connected with the movie industry which is centered in this area.
From an American, whom we contacted recently, we have received a private report on machinists of German origin who are Communists and members of the labor organizations in the Bremerton Naval Yard and Boeing airplane factory.
Recently we have on two occasions made investigations on the spot of various military establishments and concentration points in various areas.
[citation needed] Those who consider that Executive Order 9066 regarding Japanese American internment was not based on Magic intercepts, argue[citation needed]: One theory is that Stimson wanted DeWitt to provide justifications that could be made public, because the Magic intercepts could not be made public.
This was a fractionating transposition system based on two-letter code groups which stood for common words and phrases.
The groups were written in a square grid according to an irregular pattern and read off vertically, similar to a disrupted columnar transposition.
[12] Ronald Lewin points out that the story repeats the layout and errors of a signal from Admiral Nimitz which Johnston saw while on the transport Barnett.
Galantin, who retired as an Admiral, refers several times to Magic in his 1988 book about his Pacific theater war patrols as captain of the U.S. submarine Halibut.
[15] Neal Stephenson's novel Cryptonomicon includes a fictionalized version of Magic, with the Japanese cryptosystem being named "Indigo" rather than "PURPLE".