

Show HN: Instant confirmation via Bitcoin payment protocol - BrokenPipe
https://greenaddress.it

======
BrokenPipe
Hello:)

Author of the BIP draft for the Instant Confirmation Payment Protocol aka
BIP70 extension and founder of GreenAddress.

You can find the draft here [https://github.com/greenaddress/bips/blob/bip-
payment-reques...](https://github.com/greenaddress/bips/blob/bip-payment-
request-instant-confirmations/bip-payment-request-instant-
confirmations.mediawiki)

Bitcoin dev mailing list discussion
[http://comments.gmane.org/gmane.comp.bitcoin.devel/5628](http://comments.gmane.org/gmane.comp.bitcoin.devel/5628)

Reddit discussion
[http://www.reddit.com/r/Bitcoin/comments/284me8/instant_conf...](http://www.reddit.com/r/Bitcoin/comments/284me8/instant_confirmation_via_payment_protocol_bip70/)

The aim of this extension is to reduce risk by allowing, via a third party,
instant confirmation of bitcoin transactions.

Questions, comments and in general any feedback is very welcome!

Cheers! Lawrence

~~~
wdewind
It seems that much of the "bitcoin is great because it is feeless" stuff is
going to get eaten up by the services/fraud reduction layer put on top of it,
by stuff like this. Right now, including miner fees, it seems like the
transaction cost of bitcoin is actually as high, if not higher, than most
credit cards.

How do you see the fees finalizing? Will there still be a significant cost
reduction for in person transactions once the industry has matured a bit more?
(equivalent of CC transactions in terms of ease of use).

Either way, this is a cool idea, best of luck to you.

~~~
LyndsySimon
Some of those things are worth paying for. The revolutionary thing about
Bitcoin (from a financial systems perspective) is that those things are
optional. If I don't want or need instant confirms, I don't have to use them.

Another important thing to note is that you're likely a member of a very
privileged class, by virtue of being on HN. You likely have a bank account and
a credit card. Not everyone is so lucky, and Bitcoin serves many of the same
needs you fulfill with the traditional financial system.

Then you have remittance. Imagine you are a Somali immigrant living in
Michigan, and you'd like to send money to your brother in Xamar. How do you do
that? It's legal, but to my knowledge no US Bank operates in the region.
Bitcoin world's as easily to your brother as it does to anyone else.

~~~
dublinben
Bitcoin users are an even more privileged class of the already privileged
population. They have regular access to a private computer, and robust
internet access. That is not the case for most people in the world.

~~~
BrokenPipe
Do you think the banking industry will support the unbanked faster than a
stable and accessible internet will reach them?

~~~
dublinben
If the wild success of M-Pesa is any indication, then the traditional finance
industry will reach the next billion consumers well before an obscure
technology like Bitcoin will.

~~~
mike_hearn
Given that M-PESA is run by a telephone company, is it the traditional
financial industry or not? It can be argued both ways. SafariCom effectively
runs a bank, but it is nonetheless primarily a technology company.

------
tyho
Which merchants currently accept your key for instant confirmations? From the
bitcoin wiki: [green addresses] are generally considered a bad idea and not
advisable to implement.

~~~
BrokenPipe
An ATM bitcoin to cash manufacturer is testing the functionality right now and
another one is planning to integrate it when they implement the payment
protocol.

There's also other users that can check either inside the GreenAddress wallet
or at [https://greenaddress.it/instant](https://greenaddress.it/instant)

it's called GreenAddress because when I thought about the concept, end of 2012
beginning of 2013 it wasn't yet associated with the bad reputation or MtGox
double spends and I felt anyhow that it could be improved (which I think we
did).

The modus operandi of the platform is different from the original GreenAddress
concept as the instant confirmation comes out of band and is based on
multisignature allowing the system to prevent users double spends.

However, like the original GreenAddress concept, it is based on third party
trust, there is no magic bullet.

~~~
tyho
How could you prevent somebody signing a transaction using your service,
waiting until the nLockTime has expired, then creating a transaction that is
not signed by you but valid due to the nLockTime expiry? They would then be in
a position to double spend because they could use a transaction that is
verified by you to buy something instantly (cash from an ATM for example) and
redirect the same funds back to their own control using the single signature
transaction with a high chance of success.

~~~
BrokenPipe
We only provide instant confirmations for bitcoins we know that are going to
get included in a block long before the nlocktime will expire allowing you to
spend them.

~~~
tyho
How long before, because that would make it impossible for people to spend
their coins at all during that period, which could be annoying.

Also, does this mean that to verify a transaction can be considered instant,
the merchant has to check with your servers and there is no way of verifying
this independently? Isn't this a serious privacy problem?

~~~
BrokenPipe
We don't provide instant confirmation but that does not mean you can't spend
your funds without it.

The minimum is 1 day or 144 blocks, default to 90 days, max is max block size.

~~~
mikemoka
Hi Lawrence,

probably that is the right step toward solving the transaction speed,albeit by
a slightly more centralized workaround,it reminds me of a comment I made
almost a year from now:

[https://news.ycombinator.com/item?id=6130813](https://news.ycombinator.com/item?id=6130813)

great job ;)

~~~
BrokenPipe
cheers!

------
abrkn
"...or analysing transaction network propagation."

Haven't we already agreed this is meaningless?

~~~
BrokenPipe
I think we did, good point.

It should be removed imho. Especially since the instant confirmation with a
monitor couldn't really be synchronous without .. wait for it, waiting.

good catch!

------
nijiko
Yay, easy way to confirm false transactions :D

~~~
BrokenPipe
Not really, the payment protocol gives you back the full transaction that can
be checked by the merchant.

The 'instant' comes from trusting a third party that temporarily controls
enough keys to block the funds before they can get double spent but long
enough that the tx can be confirmed.

------
HostFat
I hope to see it soon on my lovely iphone!

~~~
BrokenPipe
For the record I know HostFat does not have an iPhone and he is a friend. I
think.

------
dublinben
I would be incredibly careful of trusting any new BTC trust protocols this
week, with the ongoing 51% threat from GHash.

[http://arstechnica.com/security/2014/06/bitcoin-security-
gua...](http://arstechnica.com/security/2014/06/bitcoin-security-guarantee-
shattered-by-anonymous-miner-with-51-network-power/)

~~~
BrokenPipe
reminds me of this comment on reddit

[http://www.reddit.com/r/Bitcoin/comments/284me8/instant_conf...](http://www.reddit.com/r/Bitcoin/comments/284me8/instant_confirmation_via_payment_protocol_bip70/ci7dsej)

Not to dismiss the 51% issue but that would affect all transactions, this
-'instant protocol' is on top of bitcoin, not in replacement of.

