yeah, I know what you mean.  I do think it's solvable though.<p>one time during undergrad I was talking with Hal Abelson because there was this big stink about the new research building (Stata center) requiring rfid's to get around.  Richard Stallman et al were making a huge ruckus about the privacy implications of not having physical keys.<p>I mentioned some desired attributes of a protocol to let people in without logging it, and started worrying about the implementation details / feasibility.  he said "oh don't worry about implementation.  this building has people in it who can implement anything."  he had this smirk about him.<p>so give it some experts and time and they'll figure it out.