From signal to report: how SIGINT works

1. Requirement

   The NSA says it produces intelligence in response to formal requirements from those with an official need for it (intelligence requirement). In the US, the national intelligence priorities (NIPF) determine where to start looking. NATO doctrine AJP-2 calls this stage direction: setting the requirements and planning the collection.

2. Interception

   According to AJP-2, SIGINT is intelligence derived from foreign electromagnetic signals and emissions. It covers communications (COMINT) and non-communication emissions, such as those of radars (ELINT). The NSA stresses that it is concerned with the signals of foreign targets. In Poland, signals intelligence is one of the tasks of the Foreign Intelligence Agency (AW), which carries it out outside the country.

3. Processing

   The raw signal has to be turned into something that can be read and handled by machines. The NSA calls this one of the biggest tasks in the whole cycle; thresholds and filters weed out signals with no intelligence value. The traffic alone says something: traffic analysis draws conclusions from the patterns and volume of messages, and direction finding locates the transmitter.

4. Cryptanalysis

   Intercepted messages are often in foreign languages and protected by codes, the NSA notes. Reading ciphers without knowing the key is the work of cryptanalysis. The classic example is Enigma: GCHQ calls Rejewski’s bomb the first electromechanical device to support cryptanalysis.

5. Analysis

   According to the NSA, experts make sense of the processed data, drawing on knowledge of the target and on the customers’ needs. AJP-2 breaks this work into steps: collation, evaluation of the reliability of the source and the credibility of the information, analysis, integration and interpretation. A fuller picture comes from combining SIGINT with other sources – all-source intelligence.

6. Report

   The result reaches the customers as finished intelligence – and in time for them to act on it. According to the NSA, several reviewers check each report, and reports do not reveal sources or methods; sanitisation serves the same purpose. Allies share results, among other ways through the Five Eyes.

7. Oversight

   In the US, the NSA is overseen by, among others, the congressional intelligence committees, the FISC court (see FISA), the Department of Justice and an Inspector General. GCHQ is overseen by IPCO, the IPT tribunal and the parliamentary ISC. In Poland, the heads of the ABW and the AW report to the Prime Minister, and their activities are subject to scrutiny by the Sejm, including through the Special Services Committee. Operational control is ordered by a court at the request of the Head of the ABW, after written consent from the National Prosecutor; the AW may use it only through the Head of the ABW.

↺ The customers of the reports set new requirements and the cycle starts again.