At one time, this was the term for the cipher departments of various
countries. These became common in the 1700's with the creation of
more complex
ciphers and the
industrialization of
cryptology.
While every European government had one, the most celebrated black
chamber was the Geheim Kabinets-Kanzlei in Vienna.
This government organization ran on a strict and rigorous schedule.
It was critical that the black chamber not interrupt the smooth
running of the postal service. Messages that were to be delivery
at the embassy in Vienna were first sent to the black chamber at 7am.
There, seals were melted and a team of stenographers copied all the
messages. If it was necessary, a linguist was called in for strange
scripts. Within three hours, the letters were returned to the envelope
and resealed and sent back to the post office to be properly delivered.
Mail in transit through Vienna arrived at the chamber at 10am, and
mail leaving the embassy for outside destinations arrived at 4pm.
All these messages were copied before being sent on their way.
Once a message was copied, it was passed to a cryptanalyst. Teams
of cryptanalysts sat in little kiosks (and you thought the
cubical environment was bad?) who then attacked the message.
As well as supplying the emperor of Austria with intelligence, the Viennese Black Chamber also sold the information harvested to other European powers.
There is a story of a man who put a live flea in the letter he sent to test if anyone had tampered with it. In reality, he didn't put the flea in the letter. However, when his friend opened it, a flea jumped out, as described in the encrypted message.
The Black Chamber still exists today. Governments attempt to read encrypted messages of enemy states as well as friendly states. An exception to this was made in the United States in 1929 when Henry L. Stimson (just appointed as secretary of defense) said: "A gentleman does not read other people's letters." At this point, he withdraw financial support from America's black chamber. Following this, the United Sates Army established its own cipher section.
In 1952, President Harry S. Truman established the NSA. Its existence was secret for many years. This agency is charged with monitoring the information services of powers that might endanger national security. The NSA employees over 40,000 people, and more mathematicians than any other organization in the world.