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To: bitcoin-development@lists.sourceforge.net
From: Andreas Schildbach <andreas@schildbach.de>
Date: Thu, 06 Mar 2014 15:51:09 +0100
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Subject: Re: [Bitcoin-development] Instant / contactless payments
Precedence: list

On 03/06/2014 02:44 PM, Mike Hearn wrote:

>     I'm not sure if iso-dep is the way to go here. Afaik as soon as you pick
>     up the phone the connection breaks.
> 
> If the phone isn't willing to immediately authorise then it'd have to
> fall back to HTTPS or Bluetooth as normal.

Ok, that would be an option.

>     Besides, how do you plan to risk-analyse the memo field?
> 
> I guess only the amount and destination are relevant for risk analysis.

The memo field (and its logical evolution, an invoice) also needs to be
verified, since its part of the contract. Imagine sitting in a
restaurant and you're being presented the bill, most people will do a
quick scan of the meals and drinks consumed (and non-malignant errors
are frequent in that business).

>     It's already very short if you can do without Android Beam, e.g. on
>     Android 2.3.
> 
> I think IsoDep based protocols must bypass Beam - when I scan my
> e-passport there's no beam animation.

Everything except Beam bypasses Beam (-:  Beam is an Android-specific
protocol. I assume it would also be possible to write an own NDEF
implementation on top of the low level NFC APIs. I want to try as soon
as I have a second NFC-capable phone, preferably Android 4.4.

>     Even the current ~10 second roundtrip is a huge improvement to the
>     status quo. I recently tried to buy a subway ticket and it took me 7
>     full minutes (just for the payment process)!
> 
> Then that subway kind of sucks ;)

You can't really blame the subway for a broken payment process.

> Have you been to London and used Oyster?

Yes, it was a complete disaster. Obtaining a ticket took even longer --
ca. 45 minutes. Boarding the train took some additional seconds,
compared to no overhead in Germany where we simply don't have any gates.

On top of that, you walk more (in tunnels) than you get driven around,
get tracked on each movement and if you want to get your (monetary)
change, you need to wait for another 45 minutes.

The upside is, when going by public transport in England I always feel
like Mr. Freeman in City 17  (-: