A MITM can receive the initial broadcast and then spoof it by jamming the original. You then only see one.

e

On Feb 5, 2015, at 2:07 PM, Paul Puey <paul@airbitz.co> wrote:

So if you picked up the BLE broadcast request. All you know is that *someone* within 100m is requesting bitcoin at a certain address. Not necessarily who. The *name* is both optional, and possibly just a *handle* of the user. If I'm sitting 5 ft away from someone at dinner and wanted to pay them via BLE, I might see "Monkey Dude" on my list and simply ask him "is that you?" If so, I send it. If there are two "Monkey Dude's" Then I have to bother with the address prefix, but not otherwise.

On Thu, Feb 5, 2015 at 1:46 PM, Eric Voskuil <eric@voskuil.org> wrote:
BLE has an advertised range of over 100m. 

http://www.bluetooth.com/Pages/low-energy-tech-info.aspx

In the case of mass surveillance that range could most likely be extended dramatically by the reviewer. I've seen  WiFi ranges of over a mile with a strong (not FCC approved) receiver.

WiFi hotspots don't have strong identity or a guaranteed position, so they can't be trusted for location.

e

On Feb 5, 2015, at 1:36 PM, Mike Hearn <mike@plan99.net> wrote:

This sounds horrible. You could basically monitor anyone with a wallet in a highly populated area and track them super easily by doing facial recognition.

We're talking about BLE, still? The radio tech that runs in the so called "junk bands" because propagation is so poor?

My watch loses its connection to my phone if I just put it down and walk around my apartment. I'm all for reasonable paranoia, but Bluetooth isn't going to be enabling mass surveillance any time soon. It barely goes through air, let alone walls.

Anyway, whatever. I'm just bouncing around ideas for faster user interfaces. You could always switch it off or set it to be triggered by the presence of particular wifi hotspots, if you don't mind an initial bit of setup.

Back on topic - the debate is interesting, but I think to get this to the stage of being a BIP we'd need at least another wallet to implement it? Then I guess a BIP would be useful regardless of the design issues. The prefix matching still feels flaky to me but it's hard to know if you could really swipe payments out of the air in practice, without actually trying it.