|
SIGINT stands for Signals Intelligence, and refers to intelligence-gathering
by interception of signals, whether by radio interception or other means.
It became far more central to military (and to some extent diplomatic) intelligence generally with the mechanization of armies,
development of blitzkrieg tactics, use of submarine and commerce raiders warfare, and the development of practicable wireless
communications. For example, failure to properly protect its communications fatally compromised the Russian Army in its
advance early in WWI and led to the disastrous defeat by the Germans under Ludendorff and Hindenburg at the
Battle of Tannenberg. Similarly, the
interception and decryption of the Zimmerman telegram was an
important factor in the US decision to enter the War.
On the negative side, the inability of British commanders to take seriously traffic analysis information from intercepts was instrumental in the failure to achieve more than they did
at the Battle of Jutland, thus losing what might have been a
major opportunity.
The use of SIGINT had important implications during WWII as well. Early on, Admiralty dismissal of SIGINT information (also
traffic analysis in this instance) contributed to the loss of HMS Glorious
in 1940. The Allied ability to intercept and decrypt the German Enigma (Ultra) and Japanese Purple (Magic) traffic proved to be a great military advantage. Perhaps most dramatically, Japanese Naval
intercepts yeilded information which gave Admiral Nimitz the upper hand
in the ambush that resulted in the Japanese Navy's defeat at the Battle
of Midway, six months after the Pearl Harbor
disaster.
As sensitive information is often encrypted, SIGINT often involves the use of cryptanalysis. However, traffic analysis can produce information, often valuable information, even when the
messages themselves cannot be decrypted.
Past and Present SIGINT Activities
other meanings
In UNIX and similar operating
systems (such as Linux, BSD, OS-9 and UniFLEX)
SIGINT stands for Signal Interrupt or Signal Interactive. It refers to the
signal sent to a UNIX process by the kernel when the user on the process's terminal presses the interrupt the running process key (typically Control-C, but on some systems, the
"delete" character or "break" key (though not an ASCII character but an electrical condition
on a serial port).
|