Re: [Bitcoin-development] Bitcoin-development Digest, Vol 32, Issue 57
This will easily create too much data in the block chain. I think it's probably better to trust online wallets to handle complex financial transactions such a debits or credits. If Bitcoin achieves Visa-levels of popularity, that would mean one megabyte of transactions per second (even assuming script isn't used), or ~30 terabytes per year. After a decade the Bitcoin blockchain can only be stored by Amazon or Google or the Web Archive, even assuming Kryder's Law continues. If the Bitcoin blockchain instead becomes cheque clearinghouse style transaction system, many problems involving blockchain growth become negligible. Sure, this is supposed to be a trustless system, but there's a reason why everyone relies on trust in the real world. On Tue, Jan 28, 2014 at 7:13 PM, < bitcoin-development-requ...@lists.sourceforge.net> wrote: > Send Bitcoin-development mailing list submissions to > bitcoin-development@lists.sourceforge.net > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.sourceforge.net/lists/listinfo/bitcoin-development > or, via email, send a message with subject or body 'help' to > bitcoin-development-requ...@lists.sourceforge.net > > You can reach the person managing the list at > bitcoin-development-ow...@lists.sourceforge.net > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Bitcoin-development digest..." > > > Today's Topics: > >1. Re: BIP70: PaymentACK semantics (Peter Todd) >2. Re: Extension for BIP-0070 to support recurring payments > (Stephane Brossier) > > > -- > > Message: 1 > Date: Tue, 28 Jan 2014 16:12:18 -0500 > From: Peter Todd > Subject: Re: [Bitcoin-development] BIP70: PaymentACK semantics > To: Mike Hearn > Cc: Andreas Schildbach , Bitcoin Dev > > Message-ID: <20140128211218.GE22059@savin> > Content-Type: text/plain; charset="us-ascii" > > On Tue, Jan 28, 2014 at 06:33:28PM +0100, Mike Hearn wrote: > > In practice this should only be an issue if a payment is submitted and > > fails, which should be rare. Barring internal server errors and screwups > on > > the merchants side, the only reasons for a rejection at submit time would > > be the imperfect fungibility of bitcoins, e.g. you try and pay with a > huge > > dust tx or one that's invalid/too low fee/etc. > > > > So I think we have a bit of time to figure this out. But yes - once you > > broadcast, you probably accept that there might be a more painful path to > > resolve issues if something goes wrong, I guess. Right now BitPay has a > > support system where you can file a ticket if you pay the bitcoins and > they > > don't recognise it or the tx never confirms or whatever. It's grotty > manual > > work but they do it. Not broadcasting unless you "have" to seems like an > > optimisation that can reduce pain without much additional complexity. > > That's the reason you use a model where things happen atomicly: the > funds either can or can't be transferred, so if the merchant screws up > due to a server failure at worst the wallet can always send the > original, signed, payment request and transaction details proving to the > merchant that they agreed. Since the asked for txouts exist in the > blockchain they must either refund the money, or ship the goods. > > Wallet software can handle that kind of worst-case failure by > automatically sending the original payment request back to the merchant. > At worst all customer support has to do is tell the customer "Sorry > about that; we didn't get your payment. Please start your wallet up and > hit the 'resend transaction' button in your wallet and we'll clear that > right up." > > Keep in mind that we're probably going to see fraudsters figuring out > ways to make payment servers fail. This means conversely that a customer > calling up a merchant and saying "Hey! Something didn work but the > wallet says I paid!" is going to be treated more suspiciously. By using > atomic protocols the issue of did or didn't they pay becomes much more > black and white, and failure resistant. That's exactly what we keep > saying Bitcoin offers that PayPal doesn't. > > -- > 'peter'[:-1]@petertodd.org > 85c725a905444d271c56fdee4e4ec7f27bdb2e777c872925 > -- next part -- > A non-text attachment was scrubbed... > Name: not available > Type: application/pgp-signature > Size: 685 bytes > Desc: Digital signature > > -- > > Message: 2 > Date: Tue, 28 Jan 2014 18:47:20 -0800 > From: Stephane Brossier > Subject: Re: [Bitcoin-development] Extension for BIP-0070 to support > recurring payments > To: "bitcoin-development@lists.sourceforge.net" > > Cc: Pierre-Alexandre Meyer , PikaPay > > Message-ID: > Content-Type: text/plain; charset="windows-1252" > > >From what I have seen so far, there seems to be an agreement that
Re: [Bitcoin-development] Extension for BIP-0070 to support recurring payments
From what I have seen so far, there seems to be an agreement that this is a nice feature to add. We are pretty new to that community and so we don't know exactly what the process is, and in particular how we reach consensus via email. I am certainly open to follow 'the way' if there is one, but one solution would be to follow Mike's suggestion on providing a (prototype) implementation first and then defining/refining the BIP. Odinn also suggested a possible retribution for our time through crowd-sourcing which I am interested to pursue if that makes sense. We have quite some experience on the subscription side of things and while we are growing our knowledge on the Bitcoin technology (and ecosystem at large) we would benefit from: * some feedbacks on the high level proposal * additional requirements we might have missed So, below is a high level description of what we have in mind. If this sounds reasonable, we could start working on an implementation. I. Abstract --- This describes a protocol to enable recurring payments in bitcoins and can be seen as an extension of BIP-0070. The main goal here is to have the customer subscribe to a service of some kind (that is, agreeing on the terms of that subscription contract), and then have the wallet make recurring payments without any intervention from the customer as long as the payments match what the customer agreed on paying. An example of such service would be an online streaming website, to which a user pays a fixed recurring monthly fee to access videos (a.k.a. resources). Note that there is also usage based billing: for example, the user may need to purchase additional access for premium videos (overage charges). This type of billing is more complicated and there are many variations to it used in the industry (pre-paid, …). For the sake of discussion, we’ll focus on fixed recurring payments only, but we will keep usage in mind to make sure the protocol will be able to support it as well. II. Motivation -- Subscription based services have been growing in the past few years and so the intent it to make it possible for customers to pay in bitcoins. Bitcoin’s push model presents new advantages for the customer compared to traditional payment methods: the user has control over the subscription (for example, there is no need to call the merchant to explicitly cancel the credit card payments). It also opens the door to subscription management tools in wallets (e.g. Hive apps), which would give user an overview of what they are paying each month. III. Flow of Operations Creation of the subscription: - - - - - - - - - - - - - - - - - - - - - - 1. The customer clicks 'subscribe' -> A message is sent to the merchant. 2. The merchant sends back a message to the wallet with the details of the subscription such as the amount to be paid. In reality, there will be more information but for the purpose of the prototype implementation this is sufficient. 3. The wallet prompts the customer for authorization. 4. The customer authorizes (or denies) it. 5. The wallet sends the confirmation to the merchant. 6. The merchant confirms the subscription was created. Ongoing payments: - - - - - - - - - - - - - - - - From that time on and since Bitcoin is a 'push' model, the wallet is responsible to poll the merchant for due payments associated with that subscription. Note that the merchant could specify hints to the wallet on when to poll (specific dates) or not during the registration of the subscription. Note that we can't simply have the wallet push X bitcoins every month: the user account on the merchant side may have gotten credits, invoice adjustments, etc. since the last invoice, so the amount to pay for a given billing period may be lower than the regular amount. It could even be zero if the user decides to make a one-time payment to the merchant directly using a different wallet. Hence, the wallet needs to get the latest invoice balance to make sure how much it should pay. This also opens the door for the support of overage charges. Quick note on the implementation on the merchant side: an entitlement system is a piece of logic on the merchant side which grants the user access to certain resources depending on the account status (unpaid invoices, etc.). This goes often hand in hand with a dunning system, which progressively restricts access as the user's account is more and more overdue. Since wallets can be offline for an extended period of time, payments may be missed and lead to an overdue state (e.g. extra fees, service degraded). It is the responsibility of the customer to ensure the wallet is up often enough for payments to happen. In that recurring phase where the wallet polls the merchant, the wallet is responsible to check that payments match the subscription contract; that is, the amount, frequency of payments, … match what
Re: [Bitcoin-development] BIP70: PaymentACK semantics
On Tue, Jan 28, 2014 at 06:33:28PM +0100, Mike Hearn wrote: > In practice this should only be an issue if a payment is submitted and > fails, which should be rare. Barring internal server errors and screwups on > the merchants side, the only reasons for a rejection at submit time would > be the imperfect fungibility of bitcoins, e.g. you try and pay with a huge > dust tx or one that's invalid/too low fee/etc. > > So I think we have a bit of time to figure this out. But yes - once you > broadcast, you probably accept that there might be a more painful path to > resolve issues if something goes wrong, I guess. Right now BitPay has a > support system where you can file a ticket if you pay the bitcoins and they > don't recognise it or the tx never confirms or whatever. It's grotty manual > work but they do it. Not broadcasting unless you "have" to seems like an > optimisation that can reduce pain without much additional complexity. That's the reason you use a model where things happen atomicly: the funds either can or can't be transferred, so if the merchant screws up due to a server failure at worst the wallet can always send the original, signed, payment request and transaction details proving to the merchant that they agreed. Since the asked for txouts exist in the blockchain they must either refund the money, or ship the goods. Wallet software can handle that kind of worst-case failure by automatically sending the original payment request back to the merchant. At worst all customer support has to do is tell the customer "Sorry about that; we didn't get your payment. Please start your wallet up and hit the 'resend transaction' button in your wallet and we'll clear that right up." Keep in mind that we're probably going to see fraudsters figuring out ways to make payment servers fail. This means conversely that a customer calling up a merchant and saying "Hey! Something didn work but the wallet says I paid!" is going to be treated more suspiciously. By using atomic protocols the issue of did or didn't they pay becomes much more black and white, and failure resistant. That's exactly what we keep saying Bitcoin offers that PayPal doesn't. -- 'peter'[:-1]@petertodd.org 85c725a905444d271c56fdee4e4ec7f27bdb2e777c872925 signature.asc Description: Digital signature -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] BIP70: PaymentACK semantics
In practice this should only be an issue if a payment is submitted and fails, which should be rare. Barring internal server errors and screwups on the merchants side, the only reasons for a rejection at submit time would be the imperfect fungibility of bitcoins, e.g. you try and pay with a huge dust tx or one that's invalid/too low fee/etc. So I think we have a bit of time to figure this out. But yes - once you broadcast, you probably accept that there might be a more painful path to resolve issues if something goes wrong, I guess. Right now BitPay has a support system where you can file a ticket if you pay the bitcoins and they don't recognise it or the tx never confirms or whatever. It's grotty manual work but they do it. Not broadcasting unless you "have" to seems like an optimisation that can reduce pain without much additional complexity. On Tue, Jan 28, 2014 at 6:23 PM, Peter Todd wrote: > On Tue, Jan 28, 2014 at 07:53:14AM -0500, Gavin Andresen wrote: > > On Tue, Jan 28, 2014 at 6:42 AM, Mike Hearn wrote: > > > > > Yeah, that's the interpretation I think we should go with for now. > There > > > was a reason why this isn't specified and I forgot what it was - some > > > inability to come to agreement on when to broadcast vs when to submit > via > > > HTTP, I think. > > > > > > > If the wallet software is doing automatic CoinJoin (for example), then > > typically one or several of the other participants will broadcast the > > transaction as soon as it is complete. > > > > If the spec said that wallets must not broadcast until they receive a > > PaymentACK (if a payment_url is specified), then you'd have to violate > the > > spec to do CoinJoin. > > > > And even if you don't care about CoinJoin, not broadcasting the > transaction > > as soon as the inputs are signed adds implementation complexity (should > you > > retry if payment_url is unavailable? how many times? if you eventually > > unlock the probably-not-quite-spent-yet inputs, should you double-spend > > them to yourself just in case the merchant eventually gets around to > > broadcasting the transaction, or should you just unlock them and squirrel > > away the failed Payment so if the merchant does eventually broadcast you > > have a record of why the coins were spent). > > Also users don't have infinite unspent txouts in their wallets - if they > need to make two payments in a row and run out their wallet software is > (currently) going to spend the change txout and either be forced to > broadcast both transactions anyway, or the second payment-protocol-using > recipient will do so on their behalf. (in the future they might also do > a replacement tx replacing the first with a single tx paying both to > save on fees, again with the same problem) > > Anyway what you want is payment atomicity: the customer losing control > of the funds must be atomic with respect to the payment going through. > From that point of view it's unfortunate that Payment message contains > refund_to, memo, etc. That information should have been provided to the > merchant prior to them providing the list of addresses to pay. > > -- > 'peter'[:-1]@petertodd.org > 85c725a905444d271c56fdee4e4ec7f27bdb2e777c872925 > -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] BIP70: PaymentACK semantics
On Tue, Jan 28, 2014 at 07:53:14AM -0500, Gavin Andresen wrote: > On Tue, Jan 28, 2014 at 6:42 AM, Mike Hearn wrote: > > > Yeah, that's the interpretation I think we should go with for now. There > > was a reason why this isn't specified and I forgot what it was - some > > inability to come to agreement on when to broadcast vs when to submit via > > HTTP, I think. > > > > If the wallet software is doing automatic CoinJoin (for example), then > typically one or several of the other participants will broadcast the > transaction as soon as it is complete. > > If the spec said that wallets must not broadcast until they receive a > PaymentACK (if a payment_url is specified), then you'd have to violate the > spec to do CoinJoin. > > And even if you don't care about CoinJoin, not broadcasting the transaction > as soon as the inputs are signed adds implementation complexity (should you > retry if payment_url is unavailable? how many times? if you eventually > unlock the probably-not-quite-spent-yet inputs, should you double-spend > them to yourself just in case the merchant eventually gets around to > broadcasting the transaction, or should you just unlock them and squirrel > away the failed Payment so if the merchant does eventually broadcast you > have a record of why the coins were spent). Also users don't have infinite unspent txouts in their wallets - if they need to make two payments in a row and run out their wallet software is (currently) going to spend the change txout and either be forced to broadcast both transactions anyway, or the second payment-protocol-using recipient will do so on their behalf. (in the future they might also do a replacement tx replacing the first with a single tx paying both to save on fees, again with the same problem) Anyway what you want is payment atomicity: the customer losing control of the funds must be atomic with respect to the payment going through. From that point of view it's unfortunate that Payment message contains refund_to, memo, etc. That information should have been provided to the merchant prior to them providing the list of addresses to pay. -- 'peter'[:-1]@petertodd.org 85c725a905444d271c56fdee4e4ec7f27bdb2e777c872925 signature.asc Description: Digital signature -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] BIP70: PaymentACK semantics
> > And even if you don't care about CoinJoin, not broadcasting the > transaction as soon as the inputs are signed adds implementation complexity > (should you retry if payment_url is unavailable? how many times? > I guess a lot of wallets just won't broadcast at all and try to submit via the URL. If they don't succeed, then the transaction is just never committed to the wallet. Doesn't seem like a big deal. Payment submission is online, interactive. If it fails, you keep the coins. This seems simple and straightforward. If someone really wanted to do a real-time coinjoin, they can build the transaction together and submit it via payment_url, and broadcast as well. If the merchant has an issue with the payment for some reason (e.g. request is expired or the tx is non-standard), well, you'll have to sort it out with them manually. -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] BIP70: PaymentACK semantics
On Tue, Jan 28, 2014 at 1:53 PM, Gavin Andresen wrote: > On Tue, Jan 28, 2014 at 6:42 AM, Mike Hearn wrote: >> >> Yeah, that's the interpretation I think we should go with for now. There >> was a reason why this isn't specified and I forgot what it was - some >> inability to come to agreement on when to broadcast vs when to submit via >> HTTP, I think. > > > If the wallet software is doing automatic CoinJoin (for example), then > typically one or several of the other participants will broadcast the > transaction as soon as it is complete. > > If the spec said that wallets must not broadcast until they receive a > PaymentACK (if a payment_url is specified), then you'd have to violate the > spec to do CoinJoin. You cannot prevent transactions from being broadcasted, but an ACK can still mean "You're now relieved of the responsibility of getting the transaction confirmed". That's independent from being allowed to broadcast it. > And even if you don't care about CoinJoin, not broadcasting the transaction > as soon as the inputs are signed adds implementation complexity (should you > retry if payment_url is unavailable? how many times? if you eventually > unlock the probably-not-quite-spent-yet inputs, should you double-spend them > to yourself just in case the merchant eventually gets around to broadcasting > the transaction, or should you just unlock them and squirrel away the failed > Payment so if the merchant does eventually broadcast you have a record of > why the coins were spent). If a payment_url is unavailable, you should imho retry. If you broadcasted, and the payment_url is unavailable, you should *certainly* retry. Otherwise the recipient cannot rely on receiving memo and refund address, which would imho make these fields completely useless. I still like suggesting not broadcasting if a payment_uri to minimize that risk further, but as you say - there are enough cases where you cannot enforce that anyway. -- Pieter -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] BIP70: PaymentACK semantics
On Tue, Jan 28, 2014 at 6:42 AM, Mike Hearn wrote: > Yeah, that's the interpretation I think we should go with for now. There > was a reason why this isn't specified and I forgot what it was - some > inability to come to agreement on when to broadcast vs when to submit via > HTTP, I think. > If the wallet software is doing automatic CoinJoin (for example), then typically one or several of the other participants will broadcast the transaction as soon as it is complete. If the spec said that wallets must not broadcast until they receive a PaymentACK (if a payment_url is specified), then you'd have to violate the spec to do CoinJoin. And even if you don't care about CoinJoin, not broadcasting the transaction as soon as the inputs are signed adds implementation complexity (should you retry if payment_url is unavailable? how many times? if you eventually unlock the probably-not-quite-spent-yet inputs, should you double-spend them to yourself just in case the merchant eventually gets around to broadcasting the transaction, or should you just unlock them and squirrel away the failed Payment so if the merchant does eventually broadcast you have a record of why the coins were spent). -- -- Gavin Andresen -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] BIP70: PaymentACK semantics
Yeah, that's the interpretation I think we should go with for now. There was a reason why this isn't specified and I forgot what it was - some inability to come to agreement on when to broadcast vs when to submit via HTTP, I think. On Mon, Jan 27, 2014 at 11:39 PM, Kevin Greene wrote: > >> Should the wallet broadcast the transaction to the bitcoin network when > it > >> receives an ACK, or always assume that the merchant server will do that? > > > > In my opinion, that should be the primary meaning of receiving an ACK: > > acknowledgement that the receiver takes responsibility for getting the > > transaction confirmed (to the extent possible, of course). > > Ok, so if there is no > payment > _url specified in the PaymentRequest, then the wallet is responsible for > broadcasting > the transaction to the bitcoin network > . > Otherwise, the wallet should > rely on the merchant server to broadcast. > > > On Mon, Jan 27, 2014 at 2:17 PM, Pieter Wuille wrote: > >> On Mon, Jan 27, 2014 at 11:03 PM, Kevin Greene >> wrote: >> > +1 for an error field. >> >> Agree, I think we need a way for client applications to interpret the >> response. >> >> > Should the wallet broadcast the transaction to the bitcoin network when >> it >> > receives an ACK, or always assume that the merchant server will do that? >> >> In my opinion, that should be the primary meaning of receiving an ACK: >> acknowledgement that the receiver takes responsibility for getting the >> transaction confirmed (to the extent possible, of course). > > >> >> -- >> Pieter >> > > -- WatchGuard Dimension instantly turns raw network data into actionable security intelligence. It gives you real-time visual feedback on key security issues and trends. Skip the complicated setup - simply import a virtual appliance and go from zero to informed in seconds. http://pubads.g.doubleclick.net/gampad/clk?id=123612991&iu=/4140/ostg.clktrk___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
