Black Chamber

The Black Chamber, also known as The Cipher Bureau, was the United States' first peacetime cryptanalytic organization, and a forerunner of the National Security Agency. The only prior codes and cypher organizations maintained by the US government had been some intermittent, and always abandoned, attempts by Armed Forces branches prior to World War I.

Headed by Herbert O. Yardley (1889–1958), the Black Chamber was founded in May 1919 following World War I. Yardley had commanded the Army cryptographic section of Military Intelligence (MI-8) during World War I. MI-8 was disbanded after the war. Jointly funded by the Army and the State Department, the Cipher Bureau was disguised as a New York City commercial code company; it actually produced and sold such codes for business use. Its true mission, however, was to break the communications (chiefly diplomatic) of other nations. Its most notable known success was during the Washington Naval Conference during which it aided American negotiators considerably by providing them with the decrypted traffic of many of the Conference delegations, most notably the Japanese.

According to intelligence historian James Bamford, the Black Chamber secured the cooperation of American telegraph companies, such as Western Union, in illegally turning over the cable traffic of foreign embassies and consulates in Washington and New York. Eventually, "almost the entire American cable industry" was part of this effort. However, these companies eventually withdrew their support—possibly spurred by the Radio Act of 1927, which broadened criminal offenses related to breaching the confidentiality of telegraph messages.

In 1929, the State Department withdrew its share of the funding, the Army declined to bear the entire load, and the Black Chamber closed down. New Secretary of State Henry L. Stimson made this decision, and years later in his memoirs made the oft-quoted comment: "Gentlemen do not read each other's mail." Stimson's ethical reservations about cryptanalysis focused on the targeting of diplomats from America's close allies, not on spying in general. Once he became Secretary of War during World War II, he and the entire US command structure relied heavily on decrypted enemy communications.

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