[Bitcoin-development] Proposal for P2P Wireless (Bluetooth LE) transfer of Payment URI

Thu Feb 5 23:22:47 UTC 2015

I would like to shortly express my opinion:

- Having BT as an alternative is good idea but it must be secure enough
- Signed BIP70 should be enough. I see only two issues regarding BIP70
(but they apply also to TCP/IP, not just BT): key revocations and MITM
attacks by governments.
- Broadcasting faces is very bad idea IMHO.
- Comparing addresses seems complicated but if hash was displayed as a
unique, picture hard to be mistake or long phrase, it could be more
convenient.
- Maybe storing public key (I do NOT mean bitcoin address!) of
merchant after successful transaction is good compromise?

Another idea: I noticed it's extremely easy to compare two strings if
they are the same size (in terms of millimeters, not number of
characters). If the hash of signing key was printed on a sign near the
POS in specified size (90% of smallest available screen?) and phone
would scale correctly, just putting the phone near the sign would be
enough to instantly spot whether the hashes are same.

Maybe instead of hex/base58 hash encoding use colored barcode. But I'm
not sure if it would improve things.

2015-02-05 23:49 GMT+01:00 Roy Badami <roy at gnomon.org.uk>:
> Personally I like the simplicity of tapping two phones together to
> make payment - it should be quicker and easier than scanning QR codes
> and it's a trust model that's hard to misunderstand.
>
> Is NFC good enough for that?  I fear even with NFC it is possible to
> produce a device with longer range than one would expect.  What
> happened to the idea of tapping two devices together and then
> comparing the timing of the tap (as detected by the phones'
> accelerometers) to make spoofing a transaction harder?  I remember
> hearing about that years ago - is that still a thing?
>
> roy
>
> On Thu, Feb 05, 2015 at 02:10:51PM -0800, Eric Voskuil wrote:
>> 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 at 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 at 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 at 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.
>> >
>
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