Black room
Part of a communications center used by state officials for surveillance
title: "Black room" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["privacy-of-telecommunications", "postal-infrastructure", "locations-in-the-history-of-espionage", "louis-xviii"] description: "Part of a communications center used by state officials for surveillance" topic_path: "engineering" source: "https://en.wikipedia.org/wiki/Black_room" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Part of a communications center used by state officials for surveillance ::
NOTOC
A black room is part of a communication center (e.g. a post office) used by state officials to conduct clandestine interception and surveillance of communications. Typically, all letters or communications pass through the black room before being passed to the recipient. This practice had been in vogue since the establishment of postal and telegraph services, and was frequently used in France by the ministers of Louis XVIII and his followers as the cabinet noir (French for "black room").
In modern American network operations centers, optical splitters divert a percentage of the laser light from all incoming and outgoing fiber-optic cables to the secret room. An example is Room 641A in the SBC Communications building in San Francisco.
The term black room or black chamber has also been used to refer to any place or organisation dedicated to code-breaking.
References
References
- "Black Chamber at espionageinfo".
- {{cite EB1911
- Mark Klein. (31 December 2005). "AT&T's Implementation of NSA Spying on American Citizens".
- "National Security Agency Central Security Service > About Us > Cryptologic Heritage > Center for Cryptologic History > Pearl Harbor Review > The Black Chamber".
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