What we tried for our experiment was simple: you turn in your RFID card at the end of the meeting, and it is randomly re-used for the next one, i.e., a new number is assigned each meeting. Unfortunately, we only got a relatively small fraction of RFID badges back, if I recall correctly, as people presumably forgot to turn them in. On Aug 7, 2013, at 1:28 PM, Ted Lemon <Ted.Lemon@xxxxxxxxxxx> wrote: > On Aug 7, 2013, at 1:24 PM, Scott Brim <scott.brim@xxxxxxxxx> wrote: >> I keep my passport in a "cage" when I'm not handing it to someone. >> I'm not concerned about my phone. > > Likewise. The point being, handing everyone in IETF an RFID tag probably doesn't have new privacy implications for most of them, and giving them a faraday cage, as was done in Hiroshima, addresses the remaining implications for those people who do not carry powered-on cell phones or laptops for privacy reasons. If you carry a powered on cell phone, I don't think you can argue that carrying an RFID tag with a simple number in it makes things any worse. > > Actually, the main argument I'd make against IETF RFID tags is that it's more plastic to throw out. > >