Bullrun (decryption program)

Bullrun (stylized BULLRUN) is a clandestine, highly classified program to crack encryption of online communications and data, which is run by the United States National Security Agency (NSA). The British Government Communications Headquarters (GCHQ) has a similar program codenamed Edgehill. According to the BULLRUN classification guide published by The Guardian, the program uses multiple methods including computer network exploitation,interdiction, industry relationships, collaboration with other intelligence community entities, and advanced mathematical techniques.

Information about the program's existence was leaked in 2013 by Edward Snowden. Although Snowden's documents do not contain technical information on exact cryptanalytic capabilities because Snowden did not have clearance access to such information, they do contain a 2010 GCHQ presentation which claims that "vast amounts of encrypted Internet data which have up till now been discarded are now exploitable". A number of technical details regarding the program found in Snowden's documents were additionally censored by the press at the behest of US intelligence officials. Out of all the programs that have been leaked by Snowden, the Bullrun Decryption Program is by far the most expensive. Snowden claims that since 2011, expenses devoted to Bullrun amount to $800 million. The leaked documents reveal that Bullrun seeks to "defeat the encryption used in specific network communication technologies".

According to the NSA's BULLRUN Classification Guide, BULLRUN is not a Sensitive Compartmented Information (SCI) control system or compartment, but the codeword has to be shown in the classification line, after all other classification and dissemination markings. Furthermore, any details about specific cryptographic successes were recommend to be additionally restricted (besides being marked Top Secret//SI) with Exceptionally Controlled Information labels; a non-exclusive list of possible BULLRUN ECI labels was given as: APERIODIC, AMBULANT, AUNTIE, PAINTEDEAGLE, PAWLEYS, PITCHFORD, PENDLETON, PICARESQUE, and PIEDMONT without any details as to what these labels mean.

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