Thursday, June 27, 2013

More on metadata

Image from Quicklabel.
Greenwald via Raw Story:
The Bush email metadata program had restrictions on the scope of the bulk email records the NSA could analyze. Those restrictions are detailed in a legal memorandum written in a 27 November 2007, by assistant attorney general Kenneth Weinstein to his new boss, attorney general Michael Mukasey, who had taken office just a few weeks earlier.
The purpose of that memorandum was to advise Mukasey of the Pentagon’s view that these restrictions were excessive, and to obtain permission for the NSA to expand its “contact chains” deeper into Americans’ email records. The agency, the memo noted, already had “in its databases a large amount of communications metadata associated with persons in the United States”.
But, Wainstein continued, “NSA’s present practice is to ‘stop’ when a chain hits a telephone number or [internet] address believed to be used by a United States person.”
Wainstein told Mukasey that giving NSA broader leeway to study Americans’ online habits would give the surveillance agency, ironically, greater visibility into the online habits of foreigners – NSA’s original mandate.
“NSA believes that it is over-identifying numbers and addresses that belong to United States persons and that modifying its practice to chain through all telephone numbers and addresses, including those reasonably believed to be used by a United States person,” Weinstein wrote, “will yield valuable foreign intelligence information primarily concerning non-United States persons outside the United States.”
"Ironically" is the wrong word there; better would be "paradoxically". I've tried to explain this before with reference to the story about Chicago police practice. The original NSA method was a "profiling" approach which tried to limit its data by marking all the "foreign" numbers first, and it dredged up too many dolphins along with its tuna, so to speak. The method they decided to replace it with was a "network" approach, throwing each dolphin back into the water as it came up on the way to the next tuna. It's paradoxical that starting with fewer limitations should get more narrowly tailored results, but it's true.

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