[tptacek]

New Yorker:

Pilot tests of ThinThread proved almost too successful, according to a former intelligence expert who analyzed it. “It was nearly perfect,” the official says. “But it processed such a large amount of data that it picked up more Americans than the other systems.” Though ThinThread was intended to intercept foreign communications, it continued documenting signals when a trail crossed into the U.S. This was a big problem: federal law forbade the monitoring of domestic communications without a court warrant. And a warrant couldn’t be issued without probable cause and a known suspect. In order to comply with the law, Binney installed privacy controls and added an “anonymizing feature,” so that all American communications would be encrypted until a warrant was issued. The system would indicate when a pattern looked suspicious enough to justify a warrant.

But this was before 9/11, and the N.S.A.’s lawyers deemed ThinThread too invasive of Americans’ privacy. In addition, concerns were raised about whether the system would function on a huge scale, although preliminary tests had suggested that it would. In the fall of 2000, [General Michael Hayden, the director of the N.S.A.,] decided not to use ThinThread, largely because of his legal advisers’ concerns… .

I'm sure it discarded some things, but the basic technical control that ThinThread appeared to have that Trailblazer (and PRISM) lacked is cryptographic authorization controls.

[krek]

The New Yorker's Mayer is paraphrasing an anonymous source, which she then counter-points in the very next sentence of the article with a quote from NSA historian Matthew Aid, who says: “The resistance to ThinThread was just standard bureaucratic politics. ThinThread was small, cost-effective, easy to understand, and protected the identity of Americans.” [1]

That's what Binney and Drake have said all along.

[1] http://www.newyorker.com/reporting/2011/05/23/110523fa_fact_...

[tptacek]

I think if you read my comments you'll find that I'm not denying that ThinThread had a goal of protecting the identity of Americans. The problem is that the collections programs underpinning PRISM and XKEYSCORE also have that goal. The problem isn't the technology.