[Doctor Stochastic]

They should be able to trace the paper. Probably to a batch of 500,000,000 sheets produced for Wal-Mart, Staples, Office Max, Office Depot, and others. Of course, being A4, this would limit things a bit. (A4 is used in the US too, nice aspect ratio for use in copying.)

[Alamo-Girl]

LOL! Ok, so maybe the paper won't tell them much - but microscopic things on the paper might tell them something. I don't know - but I strongly suspect the NSA knows a lot more than they are revealing and probably for good reason.