It does seem to be legal, for now. That doesn't mean that the US government is unwilling to, say, question you every time you fly: http://en.wikipedia.org/wiki/

It does seem to be legal, for now. That doesn't mean that the US government is unwilling to, say, question you every time you fly: http://en.wikipedia.org/wiki/Jacob_Appelbaum#Investigation_and_Detainment http://en.wikipedia.org/wiki/Jacob_Appelbaum#Investigation_a.... (Note that Jacob was more involved than simply running a mirror, though.)