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 in turn 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.
Electronic order of battle[edit]
Generating an electronic order of battle (EOB) requires identifying SIGINT emitters in an area of interest, determining their geographic location or range of mobility, characterizing their signals, and, where possible, determining their role in the broader organizational order of battle. EOB covers both COMINT and ELINT.
Targeting[edit]
A collection system has to know to look for a particular signal.
"System", in this context, has several nuances.
Targeting is an output of the process of developing collection requirements:
An intelligence need considered in the allocation of intelligence resources. Within the Department of Defense, these collection requirements fulfill the essential elements of information and other intelligence needs of a commander, or an agency.
An established intelligence need, validated against the appropriate allocation of intelligence resources (as a requirement) to fulfill the essential elements of information and other intelligence needs of an intelligence consumer."
Legality[edit]
Since the invention of the radio, the international consensus has been that the radio-waves are no one's property, and thus the interception itself is not illegal. There can however be national laws on who is allowed to collect, store and process radio traffic, and for what purposes. Monitoring traffic in cables (i.e. telephone and Internet) is far more controversial, since it most of the time requires physical access to the cable and thereby violating ownership and expected privacy.
See also[edit]
Central Intelligence Agency Directorate of Science & Technology
COINTELPRO