Signals intelligence

Signals intelligence (SIGINT) is intelligence-gathering by interception of signals, whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication (electronic intelligence—abbreviated to ELINT). Signals intelligence is a subset of intelligence collection management.

As sensitive information is often encrypted, signals intelligence often involves the use of cryptanalysis to decipher the messages. Traffic analysis—the study of who is signaling whom and in what quantity—is also used to derive information.

History

Origins

Electronic interception appeared as early as 1900, during the Boer Wars. The Royal Navy had installed wireless sets produced by Marconi on board their ships in the late 1890s and some limited wireless signalling was used by the British Army. Some wireless sets were captured by the Boers, and were used to make vital transmissions. Since the British were the only people transmitting at the time, no special interpretation of the signals that were intercepted by the British was necessary.