From: Troy Benjegerdes <hozer@hozed•org>
To: Mike Hearn <mike@plan99•net>
Cc: Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] Instant / contactless payments
Date: Fri, 7 Mar 2014 13:08:04 -0600 [thread overview]
Message-ID: <20140307190804.GV3180@nl.grid.coop> (raw)
In-Reply-To: <CANEZrP3w9c_UX3dd+7LdWNXCEwjnAG+bYWxqKYo_fzakWQu=Bg@mail.gmail.com>
On Thu, Mar 06, 2014 at 10:45:31AM +0100, Mike Hearn wrote:
> I just did my first contactless nfc payment with a MasterCard. It worked
> very well and was quite delightful - definitely want to be doing more of
> these in future. I think people will come to expect this kind of
> no-friction payment experience and Bitcoin will need to match it, so here
> are some notes on what's involved.
>
> There are two aspects that can be implemented independently of each other:
>
> 1) The physical/NFC layer.
> 2) The risk analysis layer.
>
> A contactless payment needs two things to work: one is a VERY fast, low
> latency communication between payment device (phone in our case) and
> terminal. I couldn't find actual latency specs yet but it felt like using
> an Oyster card, which aims for <400msec.
What matters more than the latency is the *variability*. I would spec this
system for no less than 200ms, and no more than 250ms to be 'standard'.
> ..... so I bet we'd need to optimise the bootup process of the Android
> wallet app. Right now it does slow things like deserialising giant protocol
> buffers and is just generally not optimised for startup time. Loading the
> wallet, reading the payment request over NFC, checking the cert signatures,
> making the trust decision, calculating a transaction, signing it, sending
> it back to the recipient all in under 400 msec would be a tough (but fun)
> programming challenge. Some of the steps can be parallelised and modern
> phones are mostly multicore.
If you have to invoke a java/ios/etc app you are never going to be consistent,
however if you have a GPL linux kernel module (like I proposed for my still
hypothetical 7coin), you should have no trouble meeting those specs.
I'd like to be able to load my java app, tell it to put $50 on my 'instant'/nfc
wallet, and then let the kernel module spend out the $50 whenever the phone
gets swiped by somehting.
If you do this right, every device has a well-known payment address for it's
'instant' wallet, and it should be trivial for merchants to just look at the
blockchain and confirm the instant wallet has a sufficient balance to cover
the transaction.
One more comment... having a bitcoin payment application 'check certs' seems
like a great way to ensure that Visa maintains their market share.
If it's my phone, and I press the hardware payment button, and I only put
$50 on it, I frankly don't care if there's a cert or not. The last thing I
want is a 'certificate validation error' when I'm trying to buy a soda.
----------------------------------------------------------------------------
Troy Benjegerdes 'da hozer' hozer@hozed•org
7 elements earth::water::air::fire::mind::spirit::soul grid.coop
Never pick a fight with someone who buys ink by the barrel,
nor try buy a hacker who makes money by the megahash
next prev parent reply other threads:[~2014-03-07 19:08 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-06 9:45 Mike Hearn
2014-03-06 11:26 ` Andreas Schildbach
2014-03-06 13:44 ` Mike Hearn
2014-03-06 14:51 ` Andreas Schildbach
2014-03-06 16:55 ` [Bitcoin-development] Instant / contactless payments, IsoDep Andreas Schildbach
2014-03-06 17:00 ` Mike Hearn
2014-03-07 8:45 ` Andreas Schildbach
2014-03-07 9:26 ` [Bitcoin-development] Instant / contactless payments Johannes Zweng
2014-03-07 10:00 ` Mike Hearn
2014-03-07 10:23 ` Andreas Schildbach
2014-03-07 11:01 ` Mike Hearn
2014-03-07 12:00 ` Johannes Zweng
2014-03-06 14:20 ` Brooks Boyd
2014-03-06 17:07 ` Mike Hearn
2014-03-06 18:08 ` Brooks Boyd
2014-03-06 18:12 ` Mike Hearn
2014-03-06 18:20 ` Brooks Boyd
2014-03-06 18:24 ` Mike Hearn
2014-03-07 18:07 ` Joel Kaartinen
2014-03-06 14:39 ` Alex Kotenko
2014-03-06 16:46 ` Andreas Schildbach
2014-03-06 16:52 ` Mike Hearn
2014-03-06 18:03 ` Alex Kotenko
2014-03-07 8:59 ` Andreas Schildbach
2014-03-06 17:03 ` Mike Hearn
2014-03-06 18:49 ` Alex Kotenko
2014-03-08 8:52 ` Jan Vornberger
2014-03-10 15:09 ` Alex Kotenko
2014-03-10 19:28 ` Andreas Schildbach
2014-03-10 19:47 ` Alex Kotenko
2014-03-07 19:08 ` Troy Benjegerdes [this message]
2014-03-10 16:04 ` Mike Hearn
2014-03-10 16:14 ` Jean-Paul Kogelman
2014-03-10 16:27 ` Alex Kotenko
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