📅 Original date posted:2014-03-07
📝 Original message: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 at 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
Troy Benjegerdes [ARCHIVE] /
npub1m6…rdjn5
2023-06-07 15:14:56
in reply to nevent1q…y7fz
Author Public Key
npub1m6p5kgcd428x6pxyfege98zjmlwrdhp0gyz6pdnsvrvalscddnxqurdjn5Published at
2023-06-07 15:14:56Event JSON
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"content": "📅 Original date posted:2014-03-07\n📝 Original message:On Thu, Mar 06, 2014 at 10:45:31AM +0100, Mike Hearn wrote:\n\u003e I just did my first contactless nfc payment with a MasterCard. It worked\n\u003e very well and was quite delightful - definitely want to be doing more of\n\u003e these in future. I think people will come to expect this kind of\n\u003e no-friction payment experience and Bitcoin will need to match it, so here\n\u003e are some notes on what's involved.\n\u003e \n\u003e There are two aspects that can be implemented independently of each other:\n\u003e \n\u003e 1) The physical/NFC layer.\n\u003e 2) The risk analysis layer.\n\u003e \n\u003e A contactless payment needs two things to work: one is a VERY fast, low\n\u003e latency communication between payment device (phone in our case) and\n\u003e terminal. I couldn't find actual latency specs yet but it felt like using\n\u003e an Oyster card, which aims for \u003c400msec.\n\nWhat matters more than the latency is the *variability*. I would spec this\nsystem for no less than 200ms, and no more than 250ms to be 'standard'.\n\n\u003e ..... so I bet we'd need to optimise the bootup process of the Android\n\u003e wallet app. Right now it does slow things like deserialising giant protocol\n\u003e buffers and is just generally not optimised for startup time. Loading the\n\u003e wallet, reading the payment request over NFC, checking the cert signatures,\n\u003e making the trust decision, calculating a transaction, signing it, sending\n\u003e it back to the recipient all in under 400 msec would be a tough (but fun)\n\u003e programming challenge. Some of the steps can be parallelised and modern\n\u003e phones are mostly multicore.\n\nIf you have to invoke a java/ios/etc app you are never going to be consistent,\nhowever if you have a GPL linux kernel module (like I proposed for my still\nhypothetical 7coin), you should have no trouble meeting those specs. \n\nI'd like to be able to load my java app, tell it to put $50 on my 'instant'/nfc\nwallet, and then let the kernel module spend out the $50 whenever the phone \ngets swiped by somehting.\n\nIf you do this right, every device has a well-known payment address for it's\n'instant' wallet, and it should be trivial for merchants to just look at the\nblockchain and confirm the instant wallet has a sufficient balance to cover\nthe transaction.\n\nOne more comment... having a bitcoin payment application 'check certs' seems\nlike a great way to ensure that Visa maintains their market share. \n\nIf it's my phone, and I press the hardware payment button, and I only put \n$50 on it, I frankly don't care if there's a cert or not. The last thing I\nwant is a 'certificate validation error' when I'm trying to buy a soda.\n\n----------------------------------------------------------------------------\nTroy Benjegerdes 'da hozer' hozer at hozed.org\n7 elements earth::water::air::fire::mind::spirit::soul grid.coop\n\n Never pick a fight with someone who buys ink by the barrel,\n nor try buy a hacker who makes money by the megahash",
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