Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Yep - similarly: you live in a neighborhood with a local coffee store. Sure you could use a stolen credit card or a fake $5 bill, but it's not worth the risk of being caught for a $3 coffee. And on the other side, the store can deal with 1% of transactions getting reversed or having a fake bill so they don't change their procedures. Perfection is not necessary in all situations. On Sat, Jun 20, 2015 at 12:02 AM, Eric Lombrozo elombr...@gmail.com wrote: On Jun 19, 2015, at 8:48 PM, Luke Dashjr l...@dashjr.org wrote: On Saturday, June 20, 2015 1:23:03 AM Aaron Voisine wrote: They don't need to be made cryptographically safe, they just have to be safer than, for instance, credit card payments that can be charged back. As long as it's reasonably good in practice, that's fine. They never will be. You can get a decent rate of success merely by making one transaction propagate fast (eg, 1 input, 1 output) and the other slow (eg, 1000 inputs, 1000 outputs) and choosing your peers carefully. The only reason unconfirmed transactions aren't double spent today is because nobody is seriously *trying*. Luke Newspapers are often sold in vending machines that make it possible for anyone to just pay the price of one and take them all…and most of the time they are not that carefully monitored. Why? Because most people have better things to do than try to steal a few newspapers. They probably were much more closely monitored earlier in their history…but once it became clear that despite the obvious attack vector very few people actually try to game it, vendors figured it wasn’t really that big a risk. Same thing applies to people trying to steal a piece of bubble gum at the cash register at a convenience store by double-spending. - Eric Lombrozo -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Jun 20, 2015, at 4:37 PM, justusranv...@riseup.net wrote: Signed PGP part On 2015-06-20 18:20, Jorge Timón wrote: On Fri, Jun 19, 2015 at 6:42 PM, Eric Lombrozo elombr...@gmail.com wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… Non-repudiation can be built on top of the payment protocol layer. Non-repudiation is an intrinsic property of the ECDSA signatures which Bitcoin uses - it's not a feature that needs to be built. There's no way to accidentally sign a transaction and accidentally announce it publicly. There is no form of third-party error that can result in a payee receiving an erroneous contract. Justus, We don’t even have a concept of identity in the Bitcoin protocol, let alone non-repudiation. What good is non-repudiation if there’s no way to even associate a signature with a legal entity? Sure, we could use the ECDSA signatures in transactions as part of a non-repudiation scheme - but the recipient would have to also have a means to establish the identity of the sender and associate it with the the transaction. Furthermore, in light of the fact that there *are* fully legitimate use cases for sending conflicting transactions…and the fact that determination of intent isn’t always entirely clear…we should refrain from attaching any further significance transaction signatures other than that “the sender was willing to have it included in the blockchain if a miner were to have seen it and accepted it…but perhaps the sender would have changed their mind before it actually did get accepted.” - Eric Lombrozo signature.asc Description: Message signed with OpenPGP using GPGMail -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Jun 20, 2015, at 5:27 PM, justusranv...@riseup.net wrote: Signed PGP part On 2015-06-20 19:19, Eric Lombrozo wrote: On Jun 20, 2015, at 4:37 PM, justusranv...@riseup.net wrote: Signed PGP part On 2015-06-20 18:20, Jorge Timón wrote: On Fri, Jun 19, 2015 at 6:42 PM, Eric Lombrozo elombr...@gmail.com wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… Non-repudiation can be built on top of the payment protocol layer. Non-repudiation is an intrinsic property of the ECDSA signatures which Bitcoin uses - it's not a feature that needs to be built. There's no way to accidentally sign a transaction and accidentally announce it publicly. There is no form of third-party error that can result in a payee receiving an erroneous contract. Justus, We don’t even have a concept of identity in the Bitcoin protocol, let alone non-repudiation. What good is non-repudiation if there’s no way to even associate a signature with a legal entity? Sure, we could use the ECDSA signatures in transactions as part of a non-repudiation scheme - but the recipient would have to also have a means to establish the identity of the sender and associate it with the the transaction. Furthermore, in light of the fact that there *are* fully legitimate use cases for sending conflicting transactions…and the fact that determination of intent isn’t always entirely clear…we should refrain from attaching any further significance transaction signatures other than that “the sender was willing to have it included in the blockchain if a miner were to have seen it and accepted it…but perhaps the sender would have changed their mind before it actually did get accepted.” Bitcoin has no concept of identity, but in any type of commercial transaction the parties involved must know some minimal amount of identity information in order to transact at all. Except for some identifiable special cases, I think a payee is perfectly justified in treating a double spend of a payment sent to them as part of a commercial transaction as a fraud attempt and employing whatever non-Bitcoin recourse mechanisms, if any, they have access to. From the perspective of the network, the obviously correct action for any node or miner is to relay the first version of any transaction they see. The primary purpose of mining is to resolve this otherwise-unresolvable problem of determining which transaction among a set of conflicting transactions happened first. If a node or miner wants to deviate from the obviously correct behaviour, and if they want to avoid harming the value of the network, they should be particularly careful to make sure their deviation from first seen doesn't introduce harmful unintended side effects, like making fraud easier. The contract between the buyer and seller is actually outside the Bitcoin network. Yes, a merchant that gets cheated could seek some other recourse in such an event…but the behavior you’re claiming as “obviously correct” is NOT obviously correct. In fact, there are arguments against this “obviously correct” way even if we were to accept the premise that the signature implies a promise to pay (which I think many reasonable individuals would also dispute). For instance, by relaying conflicting transactions it makes it potentially easier for others to discover the double-spend attempt (of course, this requires wallets to not be lazy about this…perhaps such relays could be flagged or placed in a special message type). - Eric Lombrozo signature.asc Description: Message signed with OpenPGP using GPGMail -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 2015-06-20 19:19, Eric Lombrozo wrote: On Jun 20, 2015, at 4:37 PM, justusranv...@riseup.net wrote: Signed PGP part On 2015-06-20 18:20, Jorge Timón wrote: On Fri, Jun 19, 2015 at 6:42 PM, Eric Lombrozo elombr...@gmail.com wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… Non-repudiation can be built on top of the payment protocol layer. Non-repudiation is an intrinsic property of the ECDSA signatures which Bitcoin uses - it's not a feature that needs to be built. There's no way to accidentally sign a transaction and accidentally announce it publicly. There is no form of third-party error that can result in a payee receiving an erroneous contract. Justus, We don’t even have a concept of identity in the Bitcoin protocol, let alone non-repudiation. What good is non-repudiation if there’s no way to even associate a signature with a legal entity? Sure, we could use the ECDSA signatures in transactions as part of a non-repudiation scheme - but the recipient would have to also have a means to establish the identity of the sender and associate it with the the transaction. Furthermore, in light of the fact that there *are* fully legitimate use cases for sending conflicting transactions…and the fact that determination of intent isn’t always entirely clear…we should refrain from attaching any further significance transaction signatures other than that “the sender was willing to have it included in the blockchain if a miner were to have seen it and accepted it…but perhaps the sender would have changed their mind before it actually did get accepted.” Bitcoin has no concept of identity, but in any type of commercial transaction the parties involved must know some minimal amount of identity information in order to transact at all. Except for some identifiable special cases, I think a payee is perfectly justified in treating a double spend of a payment sent to them as part of a commercial transaction as a fraud attempt and employing whatever non-Bitcoin recourse mechanisms, if any, they have access to. - From the perspective of the network, the obviously correct action for any node or miner is to relay the first version of any transaction they see. The primary purpose of mining is to resolve this otherwise-unresolvable problem of determining which transaction among a set of conflicting transactions happened first. If a node or miner wants to deviate from the obviously correct behaviour, and if they want to avoid harming the value of the network, they should be particularly careful to make sure their deviation from first seen doesn't introduce harmful unintended side effects, like making fraud easier. -BEGIN PGP SIGNATURE- Version: GnuPG v1 iQIcBAEBAgAGBQJVhgTgAAoJECpf2nDq2eYjkksQAJyRVhT2vNQUqlOfH9Z/9EeT LkUm8eg3f1i3xhJVxtLGVJkRmMYmuNtH0lIsH/B3iED732oZSzhwM1F5ky948Mw7 FFG65iUTrXVup9eKZuD7T3/FaQHfC5YME36F4UvEtSUcRDUKmongRGuuw7sNv617 APl3MDwZ8tVWaDb7yZ251is6Fx1l3b6tR4tHUzyIWPyIOuXOsyUaoS1cYJ00YcI5 WIzIXIlRDNpvpIXv4NFtr0BH6BmTCCZOJH3X9Hmtxqrg/dlnfnmc1pZgAyqRXj1d 5of7dYwb+bhHpU9TvcDYprN55Kmida2gTZewfr33rTXcVyjhs5N3bmIRIRrPltMA fFqlKJ7Fo4ldyJ4OEK6upuFHwmQRNL7qr/ODmYg83rJj3BdTzXsJ1l3BRAUBS+cm gc8Q3urxmVyspht+U64GO+ieLA9xb9izFMa+GL8nag0VuHc5J7XDjfzXBT8VK5be 646AZ0tFULNLOBWEJuBRbCRUs90YK2ePpGnAwiZ7HuwHMAC333FYiBuRxgwgn+xv hHMlQWTtrl0zJrxD+pcb5axC7zQdVHVeyNJDi4RF1Wau2NX/itHcUqRr75N8/Si+ GPF8JSnvLlplEsEMBAtbKvg4dn1AOEuJpXtDYrWrzZDs+/wwz5PfQ2oCZ3YRHNx2 po6di9uOSlLq0BJJfSrM =HbNG -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Jun 20, 2015, at 4:47 PM, Eric Lombrozo elombr...@gmail.com wrote: On Jun 20, 2015, at 4:16 PM, Jorge Timón jti...@jtimon.cc wrote: On Fri, Jun 19, 2015 at 5:37 PM, Eric Lombrozo elombr...@gmail.com wrote: The Bitcoin network was designed (or should be designed) with the requirement that it can withstand deliberate double-spend attacks that can come from anywhere at any time… I disagree with this premise. Please, don't take this as an argument from authority fallacy, but I will cite Satoshi to express what I think the assumptions while using the system should be: As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. I can't say for sure what was meant by attacking the network in this context but I personally mean trying to rewrite valid and proof-of-work-timestamped history. Unconfirmed transactions are simply not part of history yet. Ordering unconfirmed transactions in a consensus compatible way without a universal clock is impossible, that's why we're using proof of work in the first place. Alternative policies are NOT attacks on the network. Just to be clear, Jorge, I wasn’t suggesting that unconfirmed transactions are part of any sort of global consensus. In fact, they very much AREN’T. Which is exactly why it is extremely dangerous to accept unconfirmed transactions as final unless you clearly have assessed the risks and it makes sense for the particular business use case. - Eric Lombrozo I think the misunderstanding was in perhaps my earlier statement seemed like I was suggesting that it’s the protocol’s responsibility to protect merchants from double-spends. On the contrary - I think we agree - the protocol CANNOT make any guarantees to ANYONE until we do converge on a history. The “design” I speak of here is more on the merchant side. - Eric Lombrozo signature.asc Description: Message signed with OpenPGP using GPGMail -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
It seems to me that FSS RBF must enforce identical OP_RETURN data on the output scripts as the first seen transaction, as well, to safely continue support for various other applications built atop the blockchain. Is there a canonical implementation of FSS RBF around somewhere I can review? Best, -jp -- Jeffrey Paul +1 (312) 361-0355 5539 AD00 DE4C 42F3 AFE1 1575 0524 43F4 DF2A 55C2 On 19.06.2015, at 15:52, Chun Wang 1240...@gmail.com wrote: Before F2Pool's launch, I performed probably the only successful bitcoin double spend in the March 2013 fork without any mining power. [ https://bitcointalk.org/index.php?topic=152348.0 ] I know how bad the full RBF is. We are going to switch to FSS RBF in a few hours. Sorry. On Fri, Jun 19, 2015 at 9:44 PM, Peter Todd p...@petertodd.org wrote: On Fri, Jun 19, 2015 at 09:33:05AM -0400, Stephen Morse wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Specifically the following is what I told them: We are interested in the replace-by-fee patch, but I am not following the development closely, more background info is needed, like what the difference between standard and zeroconf versions? Thanks. Great! Basically both let you replace one transaction with another that pays a higher fee. First-seen-safe replace-by-fee adds the additional criteria that all outputs of the old transaction still need to be paid by the new transaction, with = as many Bitcoins. Basically, it makes sure that if someone was paid by tx1, then tx2 will still pay them. I've written about how wallets can use RBF and FSS-RBF to more efficiently use the blockchain on the bitcoin-development mailing list: http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07813.html http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07829.html Basically, for the purpose of increasing fees, RBF is something like %50 cheaper than CPFP, and FSS-RBF is something like %25 cheaper. In addition, for ease of implementation, my new FSS-RBF has a number of other restrictions. For instance, you can't replace multiple transactions with one, you can't replace a transaction whose outputs have already been spent, you can't replace a transaction with one that spends additional unconfirmed inputs, etc. These restrictions aren't set in stone, but they do make the code simpler and less likely to have bugs. In comparison my previous standard RBF patch can replace multiple transactions with one, can replace long chains of transactions, etc. It's willing to do more computation before deciding if a transaction should be replaced, with more complex logic; it probably has a higher chance of having a bug or DoS attack. You've probably seen the huge controversy around zeroconf with regard to standard replace-by-fee. While FSS RBF doesn't make zeroconf any safer, it also doesn't make it any more dangerous, so politically with regard to zeroconf it makes no difference. You *can* still use it doublespend by taking advantage of how different transactions are accepted differently, but that's true of *every* change we've ever made to Bitcoin Core - by upgrading to v0.10 from v0.9 you've also broken zeroconf in the same way. Having said that... honestly, zeroconf is pretty broken already. Only with pretty heroic measures like connecting to a significant fraction of the Bitcoin network at once, as well as connecting to getblocktemplate supporting miners to figure out what transactions are being mined, are services having any hope of avoiding getting ripped off. For the average user their wallets do a terrible job of showing whether or not an unconfirmed transaction will go through. For example, Schildbach's Bitcoin wallet for Android has no code at all to detect double-spends until they get mined, and I've been able to trick it into showing completely invalid transactions. In fact, currently Bitcoin XT will relay invalid transactions that are doublepsends, and Schildbach's wallet displays them as valid, unconfirmed, payments. It's really no surprise to me that nearly no-one in the Bitcoin ecosystem accepts unconfirmed transactions without some kind of protection that doesn't rely on first-seen-safe mempool behavior. For instance, many ATM's these days know who their customers are due to AML requirements, so while you can deposit Bitcoins and get your funds instantly, the protection for the ATM operator is that they can go to the police if you rip them off; I've spoken to ATM operators who didn't do this who've lost hundreds or even thousands of dollars before giving up on zeroconf. My big worry with zeroconf is a service like Coinbase or Shapeshift coming to rely on it, and then
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Friday, 19 June 2015, at 9:18 am, Adrian Macneil wrote: If full-RBF sees any significant adoption by miners, then it will actively harm bitcoin adoption by reducing or removing the ability for online or POS merchants to accept bitcoin payments at all. Retail POS merchants probably should not be accepting vanilla Bitcoin payments, as Bitcoin alone does not (and cannot) guarantee the irreversibility of a transaction until it has been buried several blocks deep in the chain. Retail merchants should be requiring a co-signature from a mutually trusted co-signer that vows never to sign a double-spend. The reason we don't yet see such technology permeating the ecosystem is because, to date, zero-conf transactions have been irreversible enough, but this has only been a happy accident; it was never promised, and it should not be relied upon. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
What retail needs is escrowed microchannel hubs (what lightning provides, for example), which enable untrusted instant payments. Not reliance on single-signer zeroconf transactions that can never be made safe. They don't need to be made cryptographically safe, they just have to be safer than, for instance, credit card payments that can be charged back. As long as it's reasonably good in practice, that's fine. Aaron Voisine co-founder and CEO breadwallet.com On Fri, Jun 19, 2015 at 6:09 PM, Mark Friedenbach m...@friedenbach.org wrote: What retail needs is escrowed microchannel hubs (what lightning provides, for example), which enable untrusted instant payments. Not reliance on single-signer zeroconf transactions that can never be made safe. On Fri, Jun 19, 2015 at 5:47 PM, Andreas Petersson andr...@petersson.at wrote: I have some experience here. If you are seriously suggesting these measures, you might as well kill retail transactions altogether. In practice, if a retail place starts to accept bitcoin they have a similar situation as with cash, only that the fraud potential is much lower. (e.g. 100-dollar bill for a sandwich might turn out fake later) and the fraud frequency is also much lower. 0-conf concerns were never a problem in practice. except for 2-way atms i have never heard of a problem that was caused by double spends. while adding these measures is generally positive, requiring them means excluding 99.9% of the potential users. so you might as well not do it. RBF as implemented by F2Pool just flat out lowers Bitcoins utility value. So it's a bad thing. for any online or automated system, waiting for a handful of confirmations was always recommended practice. Am 19.06.2015 um 22:39 schrieb Matt Whitlock: Retail POS merchants probably should not be accepting vanilla Bitcoin payments, as Bitcoin alone does not (and cannot) guarantee the irreversibility of a transaction until it has been buried several blocks deep in the chain. Retail merchants should be requiring a co-signature from a mutually trusted co-signer that vows never to sign a double-spend. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Saturday, June 20, 2015 1:23:03 AM Aaron Voisine wrote: They don't need to be made cryptographically safe, they just have to be safer than, for instance, credit card payments that can be charged back. As long as it's reasonably good in practice, that's fine. They never will be. You can get a decent rate of success merely by making one transaction propagate fast (eg, 1 input, 1 output) and the other slow (eg, 1000 inputs, 1000 outputs) and choosing your peers carefully. The only reason unconfirmed transactions aren't double spent today is because nobody is seriously *trying*. Luke -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
What retail needs is escrowed microchannel hubs (what lightning provides, for example), which enable untrusted instant payments. Not reliance on single-signer zeroconf transactions that can never be made safe. On Fri, Jun 19, 2015 at 5:47 PM, Andreas Petersson andr...@petersson.at wrote: I have some experience here. If you are seriously suggesting these measures, you might as well kill retail transactions altogether. In practice, if a retail place starts to accept bitcoin they have a similar situation as with cash, only that the fraud potential is much lower. (e.g. 100-dollar bill for a sandwich might turn out fake later) and the fraud frequency is also much lower. 0-conf concerns were never a problem in practice. except for 2-way atms i have never heard of a problem that was caused by double spends. while adding these measures is generally positive, requiring them means excluding 99.9% of the potential users. so you might as well not do it. RBF as implemented by F2Pool just flat out lowers Bitcoins utility value. So it's a bad thing. for any online or automated system, waiting for a handful of confirmations was always recommended practice. Am 19.06.2015 um 22:39 schrieb Matt Whitlock: Retail POS merchants probably should not be accepting vanilla Bitcoin payments, as Bitcoin alone does not (and cannot) guarantee the irreversibility of a transaction until it has been buried several blocks deep in the chain. Retail merchants should be requiring a co-signature from a mutually trusted co-signer that vows never to sign a double-spend. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
It all comes down to managing risk. If you’ve got a decent risk model with capped losses and safe recovery mechanisms…and it’s still profitable…it’s fine. But most payment processors and merchants right now probably don’t have particularly good risk models and are making many dangerous assumptions…and probably would not be able to gracefully handle very many risk scenarios. - Eric Lombrozo On Jun 19, 2015, at 6:23 PM, Aaron Voisine vois...@gmail.com wrote: What retail needs is escrowed microchannel hubs (what lightning provides, for example), which enable untrusted instant payments. Not reliance on single-signer zeroconf transactions that can never be made safe. They don't need to be made cryptographically safe, they just have to be safer than, for instance, credit card payments that can be charged back. As long as it's reasonably good in practice, that's fine. Aaron Voisine co-founder and CEO breadwallet.com http://breadwallet.com/ On Fri, Jun 19, 2015 at 6:09 PM, Mark Friedenbach m...@friedenbach.org mailto:m...@friedenbach.org wrote: What retail needs is escrowed microchannel hubs (what lightning provides, for example), which enable untrusted instant payments. Not reliance on single-signer zeroconf transactions that can never be made safe. On Fri, Jun 19, 2015 at 5:47 PM, Andreas Petersson andr...@petersson.at mailto:andr...@petersson.at wrote: I have some experience here. If you are seriously suggesting these measures, you might as well kill retail transactions altogether. In practice, if a retail place starts to accept bitcoin they have a similar situation as with cash, only that the fraud potential is much lower. (e.g. 100-dollar bill for a sandwich might turn out fake later) and the fraud frequency is also much lower. 0-conf concerns were never a problem in practice. except for 2-way atms i have never heard of a problem that was caused by double spends. while adding these measures is generally positive, requiring them means excluding 99.9% of the potential users. so you might as well not do it. RBF as implemented by F2Pool just flat out lowers Bitcoins utility value. So it's a bad thing. for any online or automated system, waiting for a handful of confirmations was always recommended practice. Am 19.06.2015 um 22:39 schrieb Matt Whitlock: Retail POS merchants probably should not be accepting vanilla Bitcoin payments, as Bitcoin alone does not (and cannot) guarantee the irreversibility of a transaction until it has been buried several blocks deep in the chain. Retail merchants should be requiring a co-signature from a mutually trusted co-signer that vows never to sign a double-spend. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net mailto:Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net mailto:Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development signature.asc Description: Message signed with OpenPGP using GPGMail -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
I have some experience here. If you are seriously suggesting these measures, you might as well kill retail transactions altogether. In practice, if a retail place starts to accept bitcoin they have a similar situation as with cash, only that the fraud potential is much lower. (e.g. 100-dollar bill for a sandwich might turn out fake later) and the fraud frequency is also much lower. 0-conf concerns were never a problem in practice. except for 2-way atms i have never heard of a problem that was caused by double spends. while adding these measures is generally positive, requiring them means excluding 99.9% of the potential users. so you might as well not do it. RBF as implemented by F2Pool just flat out lowers Bitcoins utility value. So it's a bad thing. for any online or automated system, waiting for a handful of confirmations was always recommended practice. Am 19.06.2015 um 22:39 schrieb Matt Whitlock: Retail POS merchants probably should not be accepting vanilla Bitcoin payments, as Bitcoin alone does not (and cannot) guarantee the irreversibility of a transaction until it has been buried several blocks deep in the chain. Retail merchants should be requiring a co-signature from a mutually trusted co-signer that vows never to sign a double-spend. 0xAA4EDEEF.asc Description: application/pgp-keys -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 09:37:49PM +0800, Chun Wang wrote: Hello. We recognize the problem. We will switch to FSS RBF soon. Thanks. No worries, let me know if you have any issues. You have my phone number. While my own preference - and a number of other devs - is full-RBF, either one is a good step forward for Bitcoin. -- 'peter'[:-1]@petertodd.org 03188926be14e5fbe2f8f9c63c9fb8e2ba4b14ab04f1c9ab signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 09:33:03AM -0400, Gavin Andresen wrote: I just sent the following email to F2Pool: I was disappointed to see Peter Todd claiming that you have (or will?) run his replace-by-fee patch. I strongly encourage you to wait until most wallet software supports replace-by-fee before doing that, because until that happens replace-by-fee just makes it easier to steal from bitcoin-accepting merchants. Do you mean just full-RBF, or FSS-RBF as well? Speaking of, could we get a confirmation that Coinbase is, or is not, one of the merchant service providers trying to get hashing power contracts with mining pools for guaranteed transaction acceptance? IIRC you are still an advisor to them. This is a serious concern for the reasons I outlined in my post. Equally if anyone else from Coinbase would like to chime in that'd be great. -- 'peter'[:-1]@petertodd.org 0d7110f3a176228445ed710afd332291384992ed89c5c1a7 signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Before F2Pool's launch, I performed probably the only successful bitcoin double spend in the March 2013 fork without any mining power. [ https://bitcointalk.org/index.php?topic=152348.0 ] I know how bad the full RBF is. We are going to switch to FSS RBF in a few hours. Sorry. On Fri, Jun 19, 2015 at 9:44 PM, Peter Todd p...@petertodd.org wrote: On Fri, Jun 19, 2015 at 09:33:05AM -0400, Stephen Morse wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Specifically the following is what I told them: We are interested in the replace-by-fee patch, but I am not following the development closely, more background info is needed, like what the difference between standard and zeroconf versions? Thanks. Great! Basically both let you replace one transaction with another that pays a higher fee. First-seen-safe replace-by-fee adds the additional criteria that all outputs of the old transaction still need to be paid by the new transaction, with = as many Bitcoins. Basically, it makes sure that if someone was paid by tx1, then tx2 will still pay them. I've written about how wallets can use RBF and FSS-RBF to more efficiently use the blockchain on the bitcoin-development mailing list: http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07813.html http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07829.html Basically, for the purpose of increasing fees, RBF is something like %50 cheaper than CPFP, and FSS-RBF is something like %25 cheaper. In addition, for ease of implementation, my new FSS-RBF has a number of other restrictions. For instance, you can't replace multiple transactions with one, you can't replace a transaction whose outputs have already been spent, you can't replace a transaction with one that spends additional unconfirmed inputs, etc. These restrictions aren't set in stone, but they do make the code simpler and less likely to have bugs. In comparison my previous standard RBF patch can replace multiple transactions with one, can replace long chains of transactions, etc. It's willing to do more computation before deciding if a transaction should be replaced, with more complex logic; it probably has a higher chance of having a bug or DoS attack. You've probably seen the huge controversy around zeroconf with regard to standard replace-by-fee. While FSS RBF doesn't make zeroconf any safer, it also doesn't make it any more dangerous, so politically with regard to zeroconf it makes no difference. You *can* still use it doublespend by taking advantage of how different transactions are accepted differently, but that's true of *every* change we've ever made to Bitcoin Core - by upgrading to v0.10 from v0.9 you've also broken zeroconf in the same way. Having said that... honestly, zeroconf is pretty broken already. Only with pretty heroic measures like connecting to a significant fraction of the Bitcoin network at once, as well as connecting to getblocktemplate supporting miners to figure out what transactions are being mined, are services having any hope of avoiding getting ripped off. For the average user their wallets do a terrible job of showing whether or not an unconfirmed transaction will go through. For example, Schildbach's Bitcoin wallet for Android has no code at all to detect double-spends until they get mined, and I've been able to trick it into showing completely invalid transactions. In fact, currently Bitcoin XT will relay invalid transactions that are doublepsends, and Schildbach's wallet displays them as valid, unconfirmed, payments. It's really no surprise to me that nearly no-one in the Bitcoin ecosystem accepts unconfirmed transactions without some kind of protection that doesn't rely on first-seen-safe mempool behavior. For instance, many ATM's these days know who their customers are due to AML requirements, so while you can deposit Bitcoins and get your funds instantly, the protection for the ATM operator is that they can go to the police if you rip them off; I've spoken to ATM operators who didn't do this who've lost hundreds or even thousands of dollars before giving up on zeroconf. My big worry with zeroconf is a service like Coinbase or Shapeshift coming to rely on it, and then attempting to secure it by gaining control of a majority of hashing power. For instance, if Coinbase had contracts with 80% of the Bitcoin hashing power to guarantee their transactions would get mined, but 20% of the hashing power didn't sign up, then the only way to guarantee their transactions could be for the 80% to not build on blocks containing doublespends by the 20%. There's no way in a decentralized network to come to consensus about what transactions are or are
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
For instance, if Coinbase had contracts with 80% of the Bitcoin hashing power to guarantee their transactions would get mined, but 20% of the hashing power didn't sign up, then the only way to guarantee their transactions could be for the 80% to not build on blocks containing doublespends by the 20%. This seems to be more of a problem with centralized mining than zeroconf transactions. Speaking of, could we get a confirmation that Coinbase is, or is not, one of the merchant service providers trying to get hashing power contracts with mining pools for guaranteed transaction acceptance? IIRC you are still an advisor to them. This is a serious concern for the reasons I outlined in my post. We have no contracts in place or plans to do this that I am aware of. However, we do rely pretty heavily on zeroconf transactions for merchant processing, so if any significant portion of the mining pools started running your unsafe RBF patch, then we would probably need to look into this as a way to prevent fraud. In the long term, I would love to see a safe, decentralized solution for accepting zeroconf transactions. However, right now there is no such solution supported by any wallets in use, and I don't think breaking the current bitcoin behavior for everyone is the best way to achieve this. Adrian -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 09:33:05AM -0400, Stephen Morse wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Specifically the following is what I told them: We are interested in the replace-by-fee patch, but I am not following the development closely, more background info is needed, like what the difference between standard and zeroconf versions? Thanks. Great! Basically both let you replace one transaction with another that pays a higher fee. First-seen-safe replace-by-fee adds the additional criteria that all outputs of the old transaction still need to be paid by the new transaction, with = as many Bitcoins. Basically, it makes sure that if someone was paid by tx1, then tx2 will still pay them. I've written about how wallets can use RBF and FSS-RBF to more efficiently use the blockchain on the bitcoin-development mailing list: http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07813.html http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07829.html Basically, for the purpose of increasing fees, RBF is something like %50 cheaper than CPFP, and FSS-RBF is something like %25 cheaper. In addition, for ease of implementation, my new FSS-RBF has a number of other restrictions. For instance, you can't replace multiple transactions with one, you can't replace a transaction whose outputs have already been spent, you can't replace a transaction with one that spends additional unconfirmed inputs, etc. These restrictions aren't set in stone, but they do make the code simpler and less likely to have bugs. In comparison my previous standard RBF patch can replace multiple transactions with one, can replace long chains of transactions, etc. It's willing to do more computation before deciding if a transaction should be replaced, with more complex logic; it probably has a higher chance of having a bug or DoS attack. You've probably seen the huge controversy around zeroconf with regard to standard replace-by-fee. While FSS RBF doesn't make zeroconf any safer, it also doesn't make it any more dangerous, so politically with regard to zeroconf it makes no difference. You *can* still use it doublespend by taking advantage of how different transactions are accepted differently, but that's true of *every* change we've ever made to Bitcoin Core - by upgrading to v0.10 from v0.9 you've also broken zeroconf in the same way. Having said that... honestly, zeroconf is pretty broken already. Only with pretty heroic measures like connecting to a significant fraction of the Bitcoin network at once, as well as connecting to getblocktemplate supporting miners to figure out what transactions are being mined, are services having any hope of avoiding getting ripped off. For the average user their wallets do a terrible job of showing whether or not an unconfirmed transaction will go through. For example, Schildbach's Bitcoin wallet for Android has no code at all to detect double-spends until they get mined, and I've been able to trick it into showing completely invalid transactions. In fact, currently Bitcoin XT will relay invalid transactions that are doublepsends, and Schildbach's wallet displays them as valid, unconfirmed, payments. It's really no surprise to me that nearly no-one in the Bitcoin ecosystem accepts unconfirmed transactions without some kind of protection that doesn't rely on first-seen-safe mempool behavior. For instance, many ATM's these days know who their customers are due to AML requirements, so while you can deposit Bitcoins and get your funds instantly, the protection for the ATM operator is that they can go to the police if you rip them off; I've spoken to ATM operators who didn't do this who've lost hundreds or even thousands of dollars before giving up on zeroconf. My big worry with zeroconf is a service like Coinbase or Shapeshift coming to rely on it, and then attempting to secure it by gaining control of a majority of hashing power. For instance, if Coinbase had contracts with 80% of the Bitcoin hashing power to guarantee their transactions would get mined, but 20% of the hashing power didn't sign up, then the only way to guarantee their transactions could be for the 80% to not build on blocks containing doublespends by the 20%. There's no way in a decentralized network to come to consensus about what transactions are or are not valid without mining itself, so you could end up in a situation where unless you're part of one of the big pools you can't reliably mine at all because your blocks may get rejected for containing doublespends. One of my goal with standard replace-by-fee is to prevent this scenario by forcing merchants and others to implement ways of accepting zeroconf transactions safely that work in a decentralized
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Extremely disappointed to hear this. This change turns double spending from a calculable (and affordable) risk for merchant payment processors into certain profit for scammers, and provides no useful benefit for consumers. I sincerely hope that F2Pool reconsider, given that RBF will decrease the overall utility of bitcoin and reduce the number of people using it for online purchases. Adrian On Fri, Jun 19, 2015 at 6:33 AM, Stephen Morse stephencalebmo...@gmail.com wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Best, Stephen On Fri, Jun 19, 2015 at 6:39 AM, Peter Todd p...@petertodd.org wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. I'm a user. What does this mean for me? --- In the short term, very little. Wallet software aimed at average users has no ability to reliably detect conditions where an unconfirmed transaction may be double-spent by the sender. For example, Schildbach's Bitcoin Wallet for Android doesn't even detect double-spends of unconfirmed transactions when connected to a RBF or Bitcoin XT nodes that propagate them. The least sophisticated double-spend attack possibly - simply broadcasting two conflicting transactions at the same time - has about 50% probability of success against these wallets. Additionally, SPV wallets based on bitcoinj can't even detect invalid transactions reliably, instead trusting the full node(s) it is connected too over the unauthenticated, unencrypted, P2P protocol to do validation for them. For instance due to a unfixed bug¹ Bitcoin XT nodes will relay double-spends that spend the output of the conflicting transaction. I've personally tested this with Schildbach's Bitcoin Wallet for Android, which shows such invalid transactions as standard, unconfirmed, transactions. Users should continue to assume that unconfirmed transactions could be trivially reversed by the sender until the first confirmation. In general, only the sender can reverse a transaction, so if you do trust the sender feel free to assume an unconfirmed transaction will eventually confirm. However, if you do not trust the sender and/or have no other recourse if they double-spend you, wait until at least the first confirmation before assuming the transaction will go through. In the long term, miner support of full RBF has a number of advantages to users, allowing you to more efficiently make transactions, paying lower fees. However you'll need a wallet supporting these features; none exist yet. I'm a business. What does this mean for me? --- If you use your own node to verify transactions, you probably are in a similar situation as average users, so again, this means very little to you. If you use a payment processor/transaction API such as BitPay, Coinbase, BlockCypher, etc. you may or may not be accepting unconfirmed transactions, and they may or may not be guaranteed by your payment processor even if double-spent. If like most merchants you're using the API such that confirmations are required prior to accepting orders (e.g. taking a meaningful loss such as shipping a product if the tx is reversed) nothing changes for you. If not I recommend you contact your payment processor. I'm a miner. Why should I support replace-by-fee? - Whether full or first-seen-safe⁵ RBF support (along with child-pays-for-parent) is an important step towards a fully functioning transaction fee market that doesn't lead to users' transactions getting mysteriously stuck, particularly during network flooding events/attacks. A better functioning fee market will help reduce pressure to increase the blocksize, particularly from the users creating the most valuable transactions. Full RBF also helps make use of the limited blockchain space more efficiently, with up to 90%+ transaction size savings possible in some transaction patterns. (e.g. long payment chains⁶) More users in less blockchain space will lead to higher overall fees per block. Finally as we'll discuss below full RBF prevents a number of serious threats to the existing level playing field that miners operate in. Why can't we make accepting unconfirmed txs from untrusted people safe? --- For a decentralized wallet, the situation
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Hello. We recognize the problem. We will switch to FSS RBF soon. Thanks. On Fri, Jun 19, 2015 at 9:33 PM, Stephen Morse stephencalebmo...@gmail.com wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Best, Stephen On Fri, Jun 19, 2015 at 6:39 AM, Peter Todd p...@petertodd.org wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. I'm a user. What does this mean for me? --- In the short term, very little. Wallet software aimed at average users has no ability to reliably detect conditions where an unconfirmed transaction may be double-spent by the sender. For example, Schildbach's Bitcoin Wallet for Android doesn't even detect double-spends of unconfirmed transactions when connected to a RBF or Bitcoin XT nodes that propagate them. The least sophisticated double-spend attack possibly - simply broadcasting two conflicting transactions at the same time - has about 50% probability of success against these wallets. Additionally, SPV wallets based on bitcoinj can't even detect invalid transactions reliably, instead trusting the full node(s) it is connected too over the unauthenticated, unencrypted, P2P protocol to do validation for them. For instance due to a unfixed bug¹ Bitcoin XT nodes will relay double-spends that spend the output of the conflicting transaction. I've personally tested this with Schildbach's Bitcoin Wallet for Android, which shows such invalid transactions as standard, unconfirmed, transactions. Users should continue to assume that unconfirmed transactions could be trivially reversed by the sender until the first confirmation. In general, only the sender can reverse a transaction, so if you do trust the sender feel free to assume an unconfirmed transaction will eventually confirm. However, if you do not trust the sender and/or have no other recourse if they double-spend you, wait until at least the first confirmation before assuming the transaction will go through. In the long term, miner support of full RBF has a number of advantages to users, allowing you to more efficiently make transactions, paying lower fees. However you'll need a wallet supporting these features; none exist yet. I'm a business. What does this mean for me? --- If you use your own node to verify transactions, you probably are in a similar situation as average users, so again, this means very little to you. If you use a payment processor/transaction API such as BitPay, Coinbase, BlockCypher, etc. you may or may not be accepting unconfirmed transactions, and they may or may not be guaranteed by your payment processor even if double-spent. If like most merchants you're using the API such that confirmations are required prior to accepting orders (e.g. taking a meaningful loss such as shipping a product if the tx is reversed) nothing changes for you. If not I recommend you contact your payment processor. I'm a miner. Why should I support replace-by-fee? - Whether full or first-seen-safe⁵ RBF support (along with child-pays-for-parent) is an important step towards a fully functioning transaction fee market that doesn't lead to users' transactions getting mysteriously stuck, particularly during network flooding events/attacks. A better functioning fee market will help reduce pressure to increase the blocksize, particularly from the users creating the most valuable transactions. Full RBF also helps make use of the limited blockchain space more efficiently, with up to 90%+ transaction size savings possible in some transaction patterns. (e.g. long payment chains⁶) More users in less blockchain space will lead to higher overall fees per block. Finally as we'll discuss below full RBF prevents a number of serious threats to the existing level playing field that miners operate in. Why can't we make accepting unconfirmed txs from untrusted people safe? --- For a decentralized wallet, the situation is pretty bleak. These wallets only have a handful of connections to the network, with no way of knowing if those connections give an accurate view of what transactions miners actually know about. The only serious attempt to fix this problem for decentralized wallets that has been actually deployed is
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Best, Stephen On Fri, Jun 19, 2015 at 6:39 AM, Peter Todd p...@petertodd.org wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. I'm a user. What does this mean for me? --- In the short term, very little. Wallet software aimed at average users has no ability to reliably detect conditions where an unconfirmed transaction may be double-spent by the sender. For example, Schildbach's Bitcoin Wallet for Android doesn't even detect double-spends of unconfirmed transactions when connected to a RBF or Bitcoin XT nodes that propagate them. The least sophisticated double-spend attack possibly - simply broadcasting two conflicting transactions at the same time - has about 50% probability of success against these wallets. Additionally, SPV wallets based on bitcoinj can't even detect invalid transactions reliably, instead trusting the full node(s) it is connected too over the unauthenticated, unencrypted, P2P protocol to do validation for them. For instance due to a unfixed bug¹ Bitcoin XT nodes will relay double-spends that spend the output of the conflicting transaction. I've personally tested this with Schildbach's Bitcoin Wallet for Android, which shows such invalid transactions as standard, unconfirmed, transactions. Users should continue to assume that unconfirmed transactions could be trivially reversed by the sender until the first confirmation. In general, only the sender can reverse a transaction, so if you do trust the sender feel free to assume an unconfirmed transaction will eventually confirm. However, if you do not trust the sender and/or have no other recourse if they double-spend you, wait until at least the first confirmation before assuming the transaction will go through. In the long term, miner support of full RBF has a number of advantages to users, allowing you to more efficiently make transactions, paying lower fees. However you'll need a wallet supporting these features; none exist yet. I'm a business. What does this mean for me? --- If you use your own node to verify transactions, you probably are in a similar situation as average users, so again, this means very little to you. If you use a payment processor/transaction API such as BitPay, Coinbase, BlockCypher, etc. you may or may not be accepting unconfirmed transactions, and they may or may not be guaranteed by your payment processor even if double-spent. If like most merchants you're using the API such that confirmations are required prior to accepting orders (e.g. taking a meaningful loss such as shipping a product if the tx is reversed) nothing changes for you. If not I recommend you contact your payment processor. I'm a miner. Why should I support replace-by-fee? - Whether full or first-seen-safe⁵ RBF support (along with child-pays-for-parent) is an important step towards a fully functioning transaction fee market that doesn't lead to users' transactions getting mysteriously stuck, particularly during network flooding events/attacks. A better functioning fee market will help reduce pressure to increase the blocksize, particularly from the users creating the most valuable transactions. Full RBF also helps make use of the limited blockchain space more efficiently, with up to 90%+ transaction size savings possible in some transaction patterns. (e.g. long payment chains⁶) More users in less blockchain space will lead to higher overall fees per block. Finally as we'll discuss below full RBF prevents a number of serious threats to the existing level playing field that miners operate in. Why can't we make accepting unconfirmed txs from untrusted people safe? --- For a decentralized wallet, the situation is pretty bleak. These wallets only have a handful of connections to the network, with no way of knowing if those connections give an accurate view of what transactions miners actually know about. The only serious attempt to fix this problem for decentralized wallets that has been actually deployed is Andresen/Harding's double-spend relaying, implemented in Bitcoin XT. It relays up to one double-spend transaction per double-spent txout, with the intended effect to warn
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 07:00:56AM -0700, Adrian Macneil wrote: For instance, if Coinbase had contracts with 80% of the Bitcoin hashing power to guarantee their transactions would get mined, but 20% of the hashing power didn't sign up, then the only way to guarantee their transactions could be for the 80% to not build on blocks containing doublespends by the 20%. This seems to be more of a problem with centralized mining than zeroconf transactions. You're mistaking cause and effect: the contracts will drive centralization of mining, as only the larger, non-anonymous, players have the ability to enter into such contracts. Speaking of, could we get a confirmation that Coinbase is, or is not, one of the merchant service providers trying to get hashing power contracts with mining pools for guaranteed transaction acceptance? IIRC you are still an advisor to them. This is a serious concern for the reasons I outlined in my post. We have no contracts in place or plans to do this that I am aware of. However, we do rely pretty heavily on zeroconf transactions for merchant processing, so if any significant portion of the mining pools started running your unsafe RBF patch, then we would probably need to look into this as a way to prevent fraud. What happens if the mining pools who are mining double-spends aren't doing it delibrately? Sybil attacking pools appears to have been done before to get double-spends though, equally there are many other changes the reduce the reliability of transaction confirmations. For instance the higher demands on bandwidth of a higher blocksize will inevitably reduce the syncronicity of mempools, resulting in double-spend opportunities. Similarly many proposals to limit mempool size allow zeroconf double-spends. In that case would you enter into such contracts? -- 'peter'[:-1]@petertodd.org 05a4c76d0bf088ef3e059914d6fc0335683a92b5be01b7dc signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Chun Wang 1240902 at gmail.com writes: Hello. We recognize the problem. We will switch to FSS RBF soon. Thanks. FSS RBF is better than no RBF but we think it is better to use full RBF. We think Full RBF is better for a number of reasons: -user experience -efficiency -cost -code complexity We think FSS RBF is great progress but ultimately less efficient and more complicated to keep alive something that never worked properly. And why would miner pick the option paying less when other miners run the option paying more? It may be soon more than 1-5% of block reward. A lot of users don't have multiple UTXO handy. Full RBF is the best, second FSS RBF and we'd be looking into supporting them both separately so that miners and users can pick whichever they prefer. If users only had one UTXO it makes sense to use Full RBF since there are no other options. Disclosure: GreenAddress always believed zero conf transactions are not secure and that miners have the incentive to run FBF; this bias doesn't make the above less true -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
[Bitcoin-development] F2Pool has enabled full replace-by-fee
Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. I'm a user. What does this mean for me? --- In the short term, very little. Wallet software aimed at average users has no ability to reliably detect conditions where an unconfirmed transaction may be double-spent by the sender. For example, Schildbach's Bitcoin Wallet for Android doesn't even detect double-spends of unconfirmed transactions when connected to a RBF or Bitcoin XT nodes that propagate them. The least sophisticated double-spend attack possibly - simply broadcasting two conflicting transactions at the same time - has about 50% probability of success against these wallets. Additionally, SPV wallets based on bitcoinj can't even detect invalid transactions reliably, instead trusting the full node(s) it is connected too over the unauthenticated, unencrypted, P2P protocol to do validation for them. For instance due to a unfixed bug¹ Bitcoin XT nodes will relay double-spends that spend the output of the conflicting transaction. I've personally tested this with Schildbach's Bitcoin Wallet for Android, which shows such invalid transactions as standard, unconfirmed, transactions. Users should continue to assume that unconfirmed transactions could be trivially reversed by the sender until the first confirmation. In general, only the sender can reverse a transaction, so if you do trust the sender feel free to assume an unconfirmed transaction will eventually confirm. However, if you do not trust the sender and/or have no other recourse if they double-spend you, wait until at least the first confirmation before assuming the transaction will go through. In the long term, miner support of full RBF has a number of advantages to users, allowing you to more efficiently make transactions, paying lower fees. However you'll need a wallet supporting these features; none exist yet. I'm a business. What does this mean for me? --- If you use your own node to verify transactions, you probably are in a similar situation as average users, so again, this means very little to you. If you use a payment processor/transaction API such as BitPay, Coinbase, BlockCypher, etc. you may or may not be accepting unconfirmed transactions, and they may or may not be guaranteed by your payment processor even if double-spent. If like most merchants you're using the API such that confirmations are required prior to accepting orders (e.g. taking a meaningful loss such as shipping a product if the tx is reversed) nothing changes for you. If not I recommend you contact your payment processor. I'm a miner. Why should I support replace-by-fee? - Whether full or first-seen-safe⁵ RBF support (along with child-pays-for-parent) is an important step towards a fully functioning transaction fee market that doesn't lead to users' transactions getting mysteriously stuck, particularly during network flooding events/attacks. A better functioning fee market will help reduce pressure to increase the blocksize, particularly from the users creating the most valuable transactions. Full RBF also helps make use of the limited blockchain space more efficiently, with up to 90%+ transaction size savings possible in some transaction patterns. (e.g. long payment chains⁶) More users in less blockchain space will lead to higher overall fees per block. Finally as we'll discuss below full RBF prevents a number of serious threats to the existing level playing field that miners operate in. Why can't we make accepting unconfirmed txs from untrusted people safe? --- For a decentralized wallet, the situation is pretty bleak. These wallets only have a handful of connections to the network, with no way of knowing if those connections give an accurate view of what transactions miners actually know about. The only serious attempt to fix this problem for decentralized wallets that has been actually deployed is Andresen/Harding's double-spend relaying, implemented in Bitcoin XT. It relays up to one double-spend transaction per double-spent txout, with the intended effect to warn recipients. In practice however this functionality makes it easier to double-spend rather than harder, by giving an efficient and easy way to get double-spends to miners after the fact. Notably my RBF implementation even connects to Bitcoin XT nodes, reserving a % of all incoming and outgoing connection slots for them. Additionally Bitcoin XT's double-spend relaying is subject to attacks include bandwidth exhaustion, sybil
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 10:00 PM, Adrian Macneil adr...@coinbase.com wrote: However, we do rely pretty heavily on zeroconf transactions for merchant processing, so if any significant portion of the mining pools started running your unsafe RBF patch, then we would probably need to look into this as a way to prevent fraud. This might be useful to you: https://www.f2pool.com/api/mempool -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015-06-19 15:11, Peter Todd wrote: If you ask me to pay you 1BTC at address A and I create tx1 that pays 1BTC to A1 and 2BTC of chain to C, what's wrong with me creating tx2 that still pays 1BTC to A, but now only pays 1.999BTC to C? I'm not defrauding you, I'm just reducing the value of my change address to pay a higher fee. Similarly if I now need to pay Bob 0.5BTC, I can create tx3 paying 1BTC to A, 0.5BTC to B, and 1.498BTC to C. Yet from the point of view of an external observer they have no idea why the transaction outputs reduced in size, nor any way of knowing if fraud did or did not occur. If there are two transactions which spend the same inputs, and each transaction has completely different output scripts, then this is prima facie fraudulent. https://en.wikipedia.org/wiki/Prima_facie If the two transactions have identical output scripts, and one output is reduced in value to increase the transaction fee, that has the appearance of honest dealing. There is a possibility that the payer has chose to under-pay their payee in order to over-pay the miner, but that's not what a reasonable observer would assume at first glance. Adding outputs to a transaction, while keeping all the existing outputs exactly how they are is another way of increasing the transaction fee of a transaction and is prima facie non-fraudulent. Note that child-pays-for-parent has none of this ambiguity. What do you think of Bitcoin XT then? It relays double-spends, which makes it much easier to get double-spends to miners than before. In particular you see a lot of zero-fee transactions being replaced by fee-paying transactions, relayed through Bitcoin XT nodes and then mined. Is that encouraging fraud? I haven't closely looked into the features of Bitcoin XT because I'm hoping that it never becomes relevant. I do want to see a heterogenous implementation network develop, but Bitcoin XT doesn't really count since it's a derivative of the Bitcoin Core codebase. In general, I think every signed Bitcoin transaction sent between different parties is part of a valid, enforceable contract (using common law definitions which predate any particular legal jurisdiction). Handling contracts and money is Serious Business and so the decision of how software should respond to double spends should not be made frivolously. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iQIcBAEBCgAGBQJVhDcpAAoJECpf2nDq2eYj23gP/ja9zqWZBoI/EfTJM0ZDVVY1 7lNwPJrAhO7oKQOKDrqhimA0TPRkoU0rCoYXSUEWn5X8ZIFlz9SQnGwXjIxt7PfG yZTxF+vJbFCDifNcUlF7DRs07cavEFM9AOutYi8PyVg0LoV5+0VMhhWT4Kc5vnlZ 4Tw91r1lvtI9MCif+KFpida/PnPlhvIfjASEuaK+vYx3ro1ovSUesh558xZmCZ9A Jfs+EwXBrxDO0zC0fatnaoRMkYQN7i/Dq1PFis7OHcZYBaQwgQTUoF8/wASvr8fQ dPXJNzhgpYYXeu4IsYH/Of9HkEw+N+/0DEW07asJJ5OIgQmcyoGn+ph8QzrPqG5m Rgb9BAmpqfCX+KrG6VDxU7xHLebwPhrPoYMIppvf77xhB2mV8c7Xky16Y/1tmxcH NLOL/WQelNBqCvx2+6c9yDJsJoY12Z0n1tdbIfp3m65xcFzqHPFPtTpsNl0p/gX7 xOMSEUdSVyjvsJjXxWOG3B06+dVRqjS0Pr9ERjjviqx40XVpg4Q0b6y+LL0ZVweE vs8ECN4y3vB7Qg2swYryVA7kNBh6GwCs7pMCh0DFw1mynGKndCKD+cPh8r3taP1u 8SlrKaD33schk4x70kxbtUzU+C7Yb5187Ct4U5kmsXhz1sypu4ebFPuWbJYG/Sjl uEW4Vcn+HxlNI/rhxBw4 =odRL -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Yes, FSS RBF is far better. On Fri, Jun 19, 2015 at 6:52 AM, Chun Wang 1240...@gmail.com wrote: Before F2Pool's launch, I performed probably the only successful bitcoin double spend in the March 2013 fork without any mining power. [ https://bitcointalk.org/index.php?topic=152348.0 ] I know how bad the full RBF is. We are going to switch to FSS RBF in a few hours. Sorry. On Fri, Jun 19, 2015 at 9:44 PM, Peter Todd p...@petertodd.org wrote: On Fri, Jun 19, 2015 at 09:33:05AM -0400, Stephen Morse wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Specifically the following is what I told them: We are interested in the replace-by-fee patch, but I am not following the development closely, more background info is needed, like what the difference between standard and zeroconf versions? Thanks. Great! Basically both let you replace one transaction with another that pays a higher fee. First-seen-safe replace-by-fee adds the additional criteria that all outputs of the old transaction still need to be paid by the new transaction, with = as many Bitcoins. Basically, it makes sure that if someone was paid by tx1, then tx2 will still pay them. I've written about how wallets can use RBF and FSS-RBF to more efficiently use the blockchain on the bitcoin-development mailing list: http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07813.html http://www.mail-archive.com/bitcoin-development@lists.sourceforge.net/msg07829.html Basically, for the purpose of increasing fees, RBF is something like %50 cheaper than CPFP, and FSS-RBF is something like %25 cheaper. In addition, for ease of implementation, my new FSS-RBF has a number of other restrictions. For instance, you can't replace multiple transactions with one, you can't replace a transaction whose outputs have already been spent, you can't replace a transaction with one that spends additional unconfirmed inputs, etc. These restrictions aren't set in stone, but they do make the code simpler and less likely to have bugs. In comparison my previous standard RBF patch can replace multiple transactions with one, can replace long chains of transactions, etc. It's willing to do more computation before deciding if a transaction should be replaced, with more complex logic; it probably has a higher chance of having a bug or DoS attack. You've probably seen the huge controversy around zeroconf with regard to standard replace-by-fee. While FSS RBF doesn't make zeroconf any safer, it also doesn't make it any more dangerous, so politically with regard to zeroconf it makes no difference. You *can* still use it doublespend by taking advantage of how different transactions are accepted differently, but that's true of *every* change we've ever made to Bitcoin Core - by upgrading to v0.10 from v0.9 you've also broken zeroconf in the same way. Having said that... honestly, zeroconf is pretty broken already. Only with pretty heroic measures like connecting to a significant fraction of the Bitcoin network at once, as well as connecting to getblocktemplate supporting miners to figure out what transactions are being mined, are services having any hope of avoiding getting ripped off. For the average user their wallets do a terrible job of showing whether or not an unconfirmed transaction will go through. For example, Schildbach's Bitcoin wallet for Android has no code at all to detect double-spends until they get mined, and I've been able to trick it into showing completely invalid transactions. In fact, currently Bitcoin XT will relay invalid transactions that are doublepsends, and Schildbach's wallet displays them as valid, unconfirmed, payments. It's really no surprise to me that nearly no-one in the Bitcoin ecosystem accepts unconfirmed transactions without some kind of protection that doesn't rely on first-seen-safe mempool behavior. For instance, many ATM's these days know who their customers are due to AML requirements, so while you can deposit Bitcoins and get your funds instantly, the protection for the ATM operator is that they can go to the police if you rip them off; I've spoken to ATM operators who didn't do this who've lost hundreds or even thousands of dollars before giving up on zeroconf. My big worry with zeroconf is a service like Coinbase or Shapeshift coming to rely on it, and then attempting to secure it by gaining control of a majority of hashing power. For instance, if Coinbase had contracts with 80% of the Bitcoin hashing power to guarantee their transactions would get mined, but 20% of the hashing power didn't sign up, then the only way to guarantee their
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
OK, a few things here: The Bitcoin network was designed (or should be designed) with the requirement that it can withstand deliberate double-spend attacks that can come from anywhere at any time…and relaxing this assumption without adequately assessing the risk (i.e. I’ve never been hacked before so I can assume it’s safe) is extremely dangerous at best and just horrid security practice at worst. Your users might not thank you for not getting hacked - but they surely will not like it when you DO get hacked…and lack a proper recovery plan. Furthermore, the protocol itself makes no assumptions regarding the intentions behind someone signing two conflicting transactions. There are many potential use cases where doing so could make a lot of sense. Had the protocol been designed along the lines of, say, tendermint…where signing multiple conflicting blocks results in loss of one’s funds…then the protocol itself disincentivizes the behavior without requiring any sort of altruistic, moralistic assumptions. That would also mean we’d need a different mechanism for the use cases that things like RBF address. Thirdly, taken to the extreme, the viewpoint of “signing a conflicting transaction is fraud and vandalism” means that if for whatever reason you attempt to propagate a transaction and nobody mines it for a very long time, you’re not entitled to immediately reclaim those funds…they must remain in limbo forever. - Eric Lombrozo On Jun 19, 2015, at 8:11 AM, Peter Todd p...@petertodd.org wrote: On Fri, Jun 19, 2015 at 03:00:57PM +, justusranv...@riseup.net wrote: On 2015-06-19 10:39, Peter Todd wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. Intentional fraud is a bad thing to add to a financial protocol. A user who creates conflicting transactions, one that pays someone else and another which does not pay them, and broadcasts both of them, has just self-incriminated themselves by producing prima facie evidence of fraud. Depends. If you ask me to pay you 1BTC at address A and I create tx1 that pays 1BTC to A1 and 2BTC of chain to C, what's wrong with me creating tx2 that still pays 1BTC to A, but now only pays 1.999BTC to C? I'm not defrauding you, I'm just reducing the value of my change address to pay a higher fee. Similarly if I now need to pay Bob 0.5BTC, I can create tx3 paying 1BTC to A, 0.5BTC to B, and 1.498BTC to C. Yet from the point of view of an external observer they have no idea why the transaction outputs reduced in size, nor any way of knowing if fraud did or did not occur. Equally, maybe you tell me Actually, just give me 0.5BTC to cancel out that debt, in which case I'm not breaking any contract at all by giving you less money than I first promised - the contract has changed. Again, none of this can or should be observable to anyone other than the parties directly involved. It may be the case that since Bitcoin spans multiple legal jurisdictions and can be use anonymously that the victims of such fraud can not rely on legal recourse, and it may also be the case that proof of work is how Bitcoin deals with the aforementioned factors, but regardless un-prosecutable fraud is still fraud and anyone who encourages it should be recognied as a bad actors. Committing vandalism and encouraging fraud to prove a point may be something the network can't stop on a technical level, but there's no reason not to call it out for what it is. What do you think of Bitcoin XT then? It relays double-spends, which makes it much easier to get double-spends to miners than before. In particular you see a lot of zero-fee transactions being replaced by fee-paying transactions, relayed through Bitcoin XT nodes and then mined. Is that encouraging fraud? -- 'peter'[:-1]@petertodd.org 03932458055c68d4ee2b6d68441c4764efbdf6b0b1683717 -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development signature.asc Description: Message signed with OpenPGP using GPGMail -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 03:00:57PM +, justusranv...@riseup.net wrote: On 2015-06-19 10:39, Peter Todd wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. Intentional fraud is a bad thing to add to a financial protocol. A user who creates conflicting transactions, one that pays someone else and another which does not pay them, and broadcasts both of them, has just self-incriminated themselves by producing prima facie evidence of fraud. Depends. If you ask me to pay you 1BTC at address A and I create tx1 that pays 1BTC to A1 and 2BTC of chain to C, what's wrong with me creating tx2 that still pays 1BTC to A, but now only pays 1.999BTC to C? I'm not defrauding you, I'm just reducing the value of my change address to pay a higher fee. Similarly if I now need to pay Bob 0.5BTC, I can create tx3 paying 1BTC to A, 0.5BTC to B, and 1.498BTC to C. Yet from the point of view of an external observer they have no idea why the transaction outputs reduced in size, nor any way of knowing if fraud did or did not occur. Equally, maybe you tell me Actually, just give me 0.5BTC to cancel out that debt, in which case I'm not breaking any contract at all by giving you less money than I first promised - the contract has changed. Again, none of this can or should be observable to anyone other than the parties directly involved. It may be the case that since Bitcoin spans multiple legal jurisdictions and can be use anonymously that the victims of such fraud can not rely on legal recourse, and it may also be the case that proof of work is how Bitcoin deals with the aforementioned factors, but regardless un-prosecutable fraud is still fraud and anyone who encourages it should be recognied as a bad actors. Committing vandalism and encouraging fraud to prove a point may be something the network can't stop on a technical level, but there's no reason not to call it out for what it is. What do you think of Bitcoin XT then? It relays double-spends, which makes it much easier to get double-spends to miners than before. In particular you see a lot of zero-fee transactions being replaced by fee-paying transactions, relayed through Bitcoin XT nodes and then mined. Is that encouraging fraud? -- 'peter'[:-1]@petertodd.org 03932458055c68d4ee2b6d68441c4764efbdf6b0b1683717 signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Unless you're sybil attacking the network and miners, consuming valuable resources and creating systemic risks of failure like we saw with Chainalysis, I don't see how you're getting very small double-spend probabilities. So connecting to many nodes just because we can and it's not technically prevented is bad for the network and creating systemic risks of failure, but relaying harmful double spend transactions just because you can and it's not technically prevented, is good for everyone? You know, you're creating an interesting bit of game theory here: if I'm a miner who doesn't already have a mining contract, why not implement full-RBF to force Coinbase to offer me one? One reason might be because other miners with such a contract - a majority - are going to be asked by Coinbase to reorg you out of the blockchain, but then we have a situation where a single entity has control of the blockchain. If someone did enter into contracts with miners to mine certain transactions, and had a guarantee that the miners would not build on previous blocks which included double spends, then they would only need contracts with 51% of the network anyway. So it wouldn't really matter if you were a small time miner and wanted to run full-RBF. For the good of Bitcoin, and your own company, you'd do well to firmly state that under no condition will Coinbase ever enter into mining contracts. I don't personally see what good this does for bitcoin. Now you are suggesting that we should prevent a 51% attack by using policy and promises, rather than a technical solution. How is this any better than us relying on existing double spend rules which are based on policy and promises? -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 6:44 AM, Peter Todd p...@petertodd.org wrote: Having said that... honestly, zeroconf is pretty broken already. Only with pretty heroic measures like connecting to a significant fraction of the Bitcoin network at once, as well as connecting to getblocktemplate supporting miners to figure out what transactions are being mined, are services having any hope of avoiding getting ripped off. For the average user their wallets do a terrible job of showing whether or not an This is no excuse for further degrading the overall network security. There are many issues to address in the bitcoin ecosystem. It negatively impacts users to roll out scorched earth replace-by-fee given today's ecosystem. Yes, zero conf security is poor. An outright attack on zero conf degrades user security even more. -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/ -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015-06-19 10:39, Peter Todd wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. Intentional fraud is a bad thing to add to a financial protocol. A user who creates conflicting transactions, one that pays someone else and another which does not pay them, and broadcasts both of them, has just self-incriminated themselves by producing prima facie evidence of fraud. It may be the case that since Bitcoin spans multiple legal jurisdictions and can be use anonymously that the victims of such fraud can not rely on legal recourse, and it may also be the case that proof of work is how Bitcoin deals with the aforementioned factors, but regardless un-prosecutable fraud is still fraud and anyone who encourages it should be recognied as a bad actors. Committing vandalism and encouraging fraud to prove a point may be something the network can't stop on a technical level, but there's no reason not to call it out for what it is. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iQIcBAEBCgAGBQJVhCsXAAoJECpf2nDq2eYjA08P/ApDFcIGws55TsgDFxPhDpN+ Iq9a06mPbXVjUfRxP5ZwmJuiM+XzHQ4QL3C2BH0OETatIV+bh7GP2mGHPcUAISYt 1j4TKhurnC+mqN+YAsiI5hQsws8DvPYXBTYYn0savaJTbq6/Q77+xvfRgNxofcPW EHpnl/5wcmYGgp3mVyStGJ+qIP17yywzCLnSA3WEPaZG/9/FPrIq3Ptw2+RHod79 nzDiFBiKLK8E5NPbdbXS+gkjkkBA/QeCzZObpMOeWMriu/PIifVi8KssLSznnEwx r7hiv6ISW47BTzkRbjxmXmGep3wfl8MjH7BZq3g0uyiApMdmjohIJ2lyuvOXdh7s 47+4r2xA8gG+z0aQTmCx5TS75T0Hnj3I78ZtCVr31Ip2OLbNI1mQ2gPR2zaoZkUZ atp2XCssHDlY2s30k5hAnIHxuN6CkyGkZCECSuv46Z3ok6ll/nIP80qB7BBzVlP1 xfSOPZh57J31U8PxZBZcwgdRg+HBiExvg484grE+h18izxcrjNfPRSWP4+7nEZtK LN7JL7YcmhVfhqKTSd6+C4bD2LsKsrcMiUhH1xHkD/hzAxc7egL6lgYTHJjU+yPu BTIh0VHJxBgroHB45Vq6loa4B3l4ZCl4Ykw8Opm7NJIfueJ0l0ySyJXi6ix4bjVf ZRF0Ot9RP0M0fHEwOpT6 =s0w/ -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 07:30:17AM -0700, Adrian Macneil wrote: In that case would you enter into such contracts? We take it as it comes. Currently, it's perfectly possible to accept zeroconf transactions with only a very small chance of double spend. As long as it's only possible to double spend a small fraction of the time, it's an acceptable cost to us in exchange for being able to provide a fast checkout experience to customers and merchants. Unless you're sybil attacking the network and miners, consuming valuable resources and creating systemic risks of failure like we saw with Chainalysis, I don't see how you're getting very small double-spend probabilities. You realise how the fact that F2Pool is using full-RBF right now does strongly suggest that the chances of a double-spend are not only low, but more importantly, vary greatly? Any small change in relaying policy or even network conditions creates opportunities to double-spend. If the status quo changes, then we will need to investigate alternatives (which realistically would include mining contracts, or only accepting instant payments from other trusted hosted wallets, which would be a net loss for decentralization). You know, you're creating an interesting bit of game theory here: if I'm a miner who doesn't already have a mining contract, why not implement full-RBF to force Coinbase to offer me one? One reason might be because other miners with such a contract - a majority - are going to be asked by Coinbase to reorg you out of the blockchain, but then we have a situation where a single entity has control of the blockchain. For the good of Bitcoin, and your own company, you'd do well to firmly state that under no condition will Coinbase ever enter into mining contracts. -- 'peter'[:-1]@petertodd.org 0fe727215265d9ddacb2930ad2d45920b71920b7aed687f1 signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Great. Thank you for this! Adrian On Fri, Jun 19, 2015 at 7:40 AM, Chun Wang 1240...@gmail.com wrote: On Fri, Jun 19, 2015 at 10:00 PM, Adrian Macneil adr...@coinbase.com wrote: However, we do rely pretty heavily on zeroconf transactions for merchant processing, so if any significant portion of the mining pools started running your unsafe RBF patch, then we would probably need to look into this as a way to prevent fraud. This might be useful to you: https://www.f2pool.com/api/mempool -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
This is very disappointing. scorched earth replace-by-fee implemented first at a pool, without updating wallets and merchants, is very anti-social and increases the ability to perform Finney attacks and double-spends. The community is progressing more towards a safer replace-by-fee model, as indicated by the following code change: https://github.com/bitcoin/bitcoin/pull/6176 On Fri, Jun 19, 2015 at 3:39 AM, Peter Todd p...@petertodd.org wrote: Yesterday F2Pool, currently the largest pool with 21% of the hashing power, enabled full replace-by-fee (RBF) support after discussions with me. This means that transactions that F2Pool has will be replaced if a conflicting transaction pays a higher fee. There are no requirements for the replacement transaction to pay addresses that were paid by the previous transaction. I'm a user. What does this mean for me? --- In the short term, very little. Wallet software aimed at average users has no ability to reliably detect conditions where an unconfirmed transaction may be double-spent by the sender. For example, Schildbach's Bitcoin Wallet for Android doesn't even detect double-spends of unconfirmed transactions when connected to a RBF or Bitcoin XT nodes that propagate them. The least sophisticated double-spend attack possibly - simply broadcasting two conflicting transactions at the same time - has about 50% probability of success against these wallets. Additionally, SPV wallets based on bitcoinj can't even detect invalid transactions reliably, instead trusting the full node(s) it is connected too over the unauthenticated, unencrypted, P2P protocol to do validation for them. For instance due to a unfixed bug¹ Bitcoin XT nodes will relay double-spends that spend the output of the conflicting transaction. I've personally tested this with Schildbach's Bitcoin Wallet for Android, which shows such invalid transactions as standard, unconfirmed, transactions. Users should continue to assume that unconfirmed transactions could be trivially reversed by the sender until the first confirmation. In general, only the sender can reverse a transaction, so if you do trust the sender feel free to assume an unconfirmed transaction will eventually confirm. However, if you do not trust the sender and/or have no other recourse if they double-spend you, wait until at least the first confirmation before assuming the transaction will go through. In the long term, miner support of full RBF has a number of advantages to users, allowing you to more efficiently make transactions, paying lower fees. However you'll need a wallet supporting these features; none exist yet. I'm a business. What does this mean for me? --- If you use your own node to verify transactions, you probably are in a similar situation as average users, so again, this means very little to you. If you use a payment processor/transaction API such as BitPay, Coinbase, BlockCypher, etc. you may or may not be accepting unconfirmed transactions, and they may or may not be guaranteed by your payment processor even if double-spent. If like most merchants you're using the API such that confirmations are required prior to accepting orders (e.g. taking a meaningful loss such as shipping a product if the tx is reversed) nothing changes for you. If not I recommend you contact your payment processor. I'm a miner. Why should I support replace-by-fee? - Whether full or first-seen-safe⁵ RBF support (along with child-pays-for-parent) is an important step towards a fully functioning transaction fee market that doesn't lead to users' transactions getting mysteriously stuck, particularly during network flooding events/attacks. A better functioning fee market will help reduce pressure to increase the blocksize, particularly from the users creating the most valuable transactions. Full RBF also helps make use of the limited blockchain space more efficiently, with up to 90%+ transaction size savings possible in some transaction patterns. (e.g. long payment chains⁶) More users in less blockchain space will lead to higher overall fees per block. Finally as we'll discuss below full RBF prevents a number of serious threats to the existing level playing field that miners operate in. Why can't we make accepting unconfirmed txs from untrusted people safe? --- For a decentralized wallet, the situation is pretty bleak. These wallets only have a handful of connections to the network, with no way of knowing if those connections give an accurate view of what transactions miners actually know about. The only serious attempt to fix this problem for decentralized wallets that has been actually deployed is Andresen/Harding's double-spend relaying, implemented in Bitcoin XT. It relays up
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
We have no contracts in place or plans to do this that I am aware of. However, we do rely pretty heavily on zeroconf transactions for merchant processing, so if any significant portion of the mining pools started running your unsafe RBF patch, then we would probably need to look into this as a way to prevent fraud. What happens if the mining pools who are mining double-spends aren't doing it delibrately? Sybil attacking pools appears to have been done before to get double-spends though, equally there are many other changes the reduce the reliability of transaction confirmations. For instance the higher demands on bandwidth of a higher blocksize will inevitably reduce the syncronicity of mempools, resulting in double-spend opportunities. Similarly many proposals to limit mempool size allow zeroconf double-spends. In that case would you enter into such contracts? We take it as it comes. Currently, it's perfectly possible to accept zeroconf transactions with only a very small chance of double spend. As long as it's only possible to double spend a small fraction of the time, it's an acceptable cost to us in exchange for being able to provide a fast checkout experience to customers and merchants. If the status quo changes, then we will need to investigate alternatives (which realistically would include mining contracts, or only accepting instant payments from other trusted hosted wallets, which would be a net loss for decentralization). Long term we would prefer to see an open, decentralized solution, such as payment channels / green addresses / lightening networks. However, I think as a community we are a long way away from choosing a standard here and implementing it across all popular wallet software and merchant processors. Adrian -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 09:44:08AM -0400, Peter Todd wrote: On Fri, Jun 19, 2015 at 09:33:05AM -0400, Stephen Morse wrote: It is disappointing that F2Pool would enable full RBF when the safe alternative, first-seen-safe RBF, is also available, especially since the fees they would gain by supporting full RBF over FSS RBF would likely be negligible. Did they consider using FSS RBF instead? Specifically the following is what I told them: Incidentally, because someone asked that message was sent two weeks ago. Also, a shout-out to Marshal Long of FinalHash for his help with (FSS)-RBF deployment and for getting F2Pool and myself in touch, as well as his work in talking getting pools on board with BIP66. -- 'peter'[:-1]@petertodd.org 0bb4abd88c6b023e9f19a1c1deaac120467279c330a803cf signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015-06-19 16:36, Matt Whitlock wrote: On Friday, 19 June 2015, at 3:53 pm, justusranv...@riseup.net wrote: I'd also like to note that prima facie doesn't mean always, it means that the default assumption, unless proven otherwise. Why would you automatically assume fraud by default? Shouldn't the null hypothesis be the default? Without any information one way or another, you ought to make *no assumption* about the fraudulence or non-fraudulence of any given double-spend. If we have ECDSA proof that an entity intentionally made and publicly announced incompatible promises regarding the disposition of particular Bitcoins under their control, then why shouldn't that be assumed to be a fraud attempt unless shown otherwise? There are ways of achiving transaction fee adjustment after broadcast that do not present the appearance of, or opportunity for, fraud. If those options are available and the user chooses not to use them in favor of the option that does, that makes bad intentions even more probable. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iQIcBAEBCgAGBQJVhEasAAoJECpf2nDq2eYjcwIP/25yoRpNvZkkdFfYiBKaiL/g XRH8iFAyM5q3/75sA23vD/fzCNGIRRWYyp8PWk+23NF1gdsgVU6gFNNCUmDbjANv nWTt2Bd926St24jcU+OxMewSGlxpenDSFDNQVtxhNFKst6hoPatwK1Zfa0Eq7/Qw +r0H2Pse1ulrN4P1n5xnrYMq2w/GF3zinNZbrn2KOZCnsDa8lKlP8y9eNFHBJ//Z wDrOcfZ1WLhf5/5xlV1NiH0tdxzABilH0ITimm2LCKbj3JcSJayZlyu4n3NypE0E cVFeYpBaVZW9wuKUv/va5fzcyWDFPAo+OrR2B3siAb8nfY1jONXNhuV3yZ76pzMr j39lvuSpoTbLobnEWMCJQ5bI/ngbhatT57gqMfF92sO0YjMe/gi/iU6urR9fi5Gz 3Ov6QA78vxzy/YduFjkc/1FV2dNdbGJtq6b0stmz5TtM1uljeGUoj6JZ8kOJ0EXn 857KFAqEd3hG9eYtBdFQcYeV2ShndALBQE0k3cqQvV6XYdHwHuTY15i1nq+u91MZ VwsR1M69PrDX5Ps6qo1F6QYJA/fA4fyOZ9dwIvh+cgtu4wBptr/NOpL3XH0kE2+G b2FRGOwdb2KlejIXSL9p4mfJTX9lmk4twbZe2Spjiy4FinOUyzxEobNoUTMcFCU7 Zu2i5yjMlJzrDB8yXz/N =xtXD -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
prima facie generally means that in a court case the burden of proof shifts from one party to another. For instance, if you have a federal trademark registration that is prima fascia evidence of those rights even though they could still be challenged. To say a prosecutor would have prima fascia evidence of a crime because double spend was detected is quite a stretch. On 6/19/2015 12:36 PM, Matt Whitlock wrote: On Friday, 19 June 2015, at 3:53 pm, justusranv...@riseup.net wrote: I'd also like to note that prima facie doesn't mean always, it means that the default assumption, unless proven otherwise. Why would you automatically assume fraud by default? Shouldn't the null hypothesis be the default? Without any information one way or another, you ought to make *no assumption* about the fraudulence or non-fraudulence of any given double-spend. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Friday, 19 June 2015, at 3:53 pm, justusranv...@riseup.net wrote: I'd also like to note that prima facie doesn't mean always, it means that the default assumption, unless proven otherwise. Why would you automatically assume fraud by default? Shouldn't the null hypothesis be the default? Without any information one way or another, you ought to make *no assumption* about the fraudulence or non-fraudulence of any given double-spend. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015-06-19 16:42, Eric Lombrozo wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… Again, I'm not talking about any changes to the protocol. The mining mechanism in the Bitcoin protocol is the fallback method of resolving fraud that isn't prevented or resolved via other mechanisms. There are plenty of other ways economic actors resolve their disagreements other than blockchain adjudication. Sometimes when both parties are identified and reside in the same legal jurisdiction, contract violations and fraud can be adjudicated in courts. In some situations, the parties involved may have access to private dispute resolution techniques. Sometimes the stakeholders in the network act to preserve the long term value of their investments, even if it means passing short-term profits. The more of those stakeholders there are in Bitcoin, the more effective it is to make the case for choices that are long-term beneficial. The degree to which anyone should rely on a signed transaction as assurance of future payment is not a question with a universal answer. It depends on the particular details of the situation, and the parties involved, and their own risk tolerances and time preferences. There's no right answer for everyone, which is why let's break zeroconf because *I* don't think it's safe enough is a kind of vandalism. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iQIcBAEBCgAGBQJVhEkhAAoJECpf2nDq2eYj8qAP/0qYP7FJDjke1qNARGkySjC5 8fSuefu8bus/O2fNYsvPf0OcHeqepLUtQ/hgTml5AHaF1Fa9iZopVr8nZv0NFMuF sv9RfkBKvnnrLWre3e/kQIdKzdMXompEsDwGfIeM3qvVV9AD3mKrz/YNmjs60+hU rEdLCX8xw3ZvF3CGOzE1KnOMbADEd7i3E/Pm1n7pLVdRAg2CIU+w6mjErgucSdvB kQ9SNAVQngjhMJyVbxsQh/+/xgecdqeZ07aaGsLhiw6zML2Tz8KMhrjJ9xw9+7h0 Gze+JdqxpgH4QrvD8KMDnlZjM+cWDUGyoVfsRvrVvPdW6kejU1r1B5Pf6dJg9TwZ kK48RJFdd2rpAkz/kAbvQtoNMxSxhm2gKKFLEMi7g8MZUiGa/Rxj0tWL7OL9SA1U VfpUzgAovoat9lBQM92T5vcS6kfhiNgAmF24ULGGYIhts77Ae6h8Fl3TECtnR0dM 1U1yio4Im1TfUDfjqNSK+ZjVpzkQli0R057y6XzI9HWkSYo94WyjNVoUlUozuAam /2+tUMTrMYPeApRv+1nv13InYO8RZiFqs0E4w4TmB5V4Xt6uGUz4Olioyuo0NqMO lBZwa1ZWKw4fLgHHDu9FhTEOXsOcX5W0gEgcoqMlzTzyoapekk9Esd0pAFLYxYMY YQyAWtWUA4JBbgLxlB8Y =x8eh -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015-06-19 15:37, Eric Lombrozo wrote: OK, a few things here: The Bitcoin network was designed (or should be designed) with the requirement that it can withstand deliberate double-spend attacks that can come from anywhere at any time…and relaxing this assumption without adequately assessing the risk (i.e. I’ve never been hacked before so I can assume it’s safe) is extremely dangerous at best and just horrid security practice at worst. Your users might not thank you for not getting hacked - but they surely will not like it when you DO get hacked…and lack a proper recovery plan. Furthermore, the protocol itself makes no assumptions regarding the intentions behind someone signing two conflicting transactions. There are many potential use cases where doing so could make a lot of sense. Had the protocol been designed along the lines of, say, tendermint…where signing multiple conflicting blocks results in loss of one’s funds…then the protocol itself disincentivizes the behavior without requiring any sort of altruistic, moralistic assumptions. That would also mean we’d need a different mechanism for the use cases that things like RBF address. Thirdly, taken to the extreme, the viewpoint of “signing a conflicting transaction is fraud and vandalism” means that if for whatever reason you attempt to propagate a transaction and nobody mines it for a very long time, you’re not entitled to immediately reclaim those funds…they must remain in limbo forever. I'm not talking about changing the protocol - I'm talking about the business relationships between users of Bitcoin. I would expect a payment processor to inform the merchants of relevant double spends that it observes on the network, even if the payment is actually successful, so that the merchant can decide for themselves whether or not to pursue it out of band. Mining is a kind of technical fallback that allows the network to resolve human misbehavior without human intervention. If nobody ever attempted to make a fraudulent payment, we wouldn't need mining at all because the signed transaction itself is proof of intention to pay. That it exists doesn't suddenly make fraud less fraudulent and mean that users who are in a position to pursue out of band recourse shouldn't do so. I agree that there are valid reasons for replacing transactions in the mempool, I just think they should be implemented in a way that doesn't facilitate fraud. I'd also like to note that prima facie doesn't mean always, it means that the default assumption, unless proven otherwise. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iQIcBAEBCgAGBQJVhDqcAAoJECpf2nDq2eYjX/UP/RlVIGqzwvdKftFW8kRW1+Dk 3befE2vEIEWFAShNt0pk7/Isqk7prRWQDKP+VNZSJfaoyE3akOe7s3OPWuevVRqM Y1N658hYnG6NPebkyp5zUQkjT3mXVxOo9Fw9k7JyHgkWaDcwx330z2n6yztleodq 7hlKdW6sZrgqHw+DoF0Zal3QPN0WYm0XAno3uy71RXOs5cAoUxViuVzWHY0oReTQ uggTggT1A5acmyOM7v65h9Cb2AKcLvHKfSEIwVQbHxYMOT+3GIJOXPKAluh8MjB3 oWg8ERy5dEEHu5kF/MLPQMg5yVQACuQmO2dlmtRoOs3mUQQj+q7dEil/dZMIp0f+ unDKIwLhXMa0sZ+63123UOgaKGZkF7afed3ueniJWQM80VS0WoZvZYhQadT/sCED Ntfxifi1ZqCiKFeshyN9z7jDC8QEJ3N176Kr/wX76h/vvnPYicMEcfRgSE8EGd10 +oRQQpYzb69WPSFRhhrR3yG9Dev1JfzNPEaIKKYerDk9Vo3OnQ3VaaqBNZwBDo46 4r3O5orFES/ZxMdzWE1cWp99n4T4L6KxdZXmfQSYHehUJBnt62vKuEk9X/Li2ZWo i3dr3yxx8xhKGGjsSjG03arz70bkXE7SvrICPOs9OEAdGlJI2liLrSWzYU9BbTle eWvElyVQJsJHgAU8ygvn =77NP -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 09:18:54AM -0700, Adrian Macneil wrote: So connecting to many nodes just because we can and it's not technically prevented is bad for the network and creating systemic risks of failure, Well it is actually; that's why myself, Wladimir van der Laan, and Gregory Maxwell all specifically¹ called Chainalysis's actions a sybil attack. The Bitcoin P2P network is resilliant to failure when the chance of any one node going down is uncorrelated with others. For instance if you accidentally introduced a bug in your nodes that failed to relay transactions/blocks properly, you'd simultaneously be disrupting a large portion of the network all at once. This is exactly what your RBF patch is doing. By your own logic, nodes on the network should be allowed to relay (or not relay) whatever they wish. Ah, seems you misunderstand the problem. By properly we're concerned that things do get relayed, not that they do not. In particularl with blocks a fairly to relay valid blocks will quickly lead to a loss of consensus. How many nodes is Coinbase connecting too? What software are they running? What subnets are they using? In particular, are they all on one subnet or multiple? We're running about a dozen nodes running regular Bitcoin Core in various subnets. We aren't doing anything particularly out of the ordinary here. Nothing that would fall under your definition of a sybil attack or harmful to the network. Right, so those dozen nodes, how many outgoing connections are they making? But of course, you'd never 51% the network right? After all it's not possible to guarantee that your miner won't mine double-spends, as there is no single consensus definition of which transaction came first, nor can there be. Or do you see things differently? If I'm a small miner should I be worried my blocks might be rejected by the majority with hashing power contracts because I'm unable to predict which transactions Coinbase believes should go in the blockchain? You seem so concerned that we are actively trying to harm or control the network. We're simply trying to drive bitcoin adoption by making it easy for people to spend their bitcoin with merchants online. The problems we face are no different from other merchant processors, or small independent merchants accepting online or point-of-sale payments. We've historically had relatively little interest in what miners were doing (until RBF came out) - for the most part it didn't affect our business. However, most large merchants would be simply uninterested in accepting bitcoin if we forced their customers to wait 10-60 minutes for their payments to confirm. Many have inventory management systems which can not even place items on hold that long. While your goals may be reasonable, again, the question is how are you going to achieve them? Do you accept that you may be in a position where you can't guarantee confirmations? Again, what's your plan to deal with this? For instance, I know Coinbase is contractually obliged to accept zeroconf payments with at least some of your customers - how strong are those agreements? What we're worried about is your plan appears to include nothing concrete beyond the possibility of getting contracts with hashing power, maybe even just a majority of hashing power. This is something that should concern everyone in the Bitcoin ecosystem, and it'd help if you clearly stated what your intentions are. -- 'peter'[:-1]@petertodd.org 1128683847671e0ca022f9c74df90a3dc718545379101b72 signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 09:42:33AM -0700, Eric Lombrozo wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… Indeed. For instance, one of the ideas behind my Proofchains work is that you could hind all details of a smartcontract-whatchamacallit protocol behind single-use-seals in a consensus blockchain. Closing those seals, that is spending the appropriate txouts, represents things in the protocol which are absolutely unobservable to anyone without the data behind those hashes, an extreme version of the above. Incidentally, some patent prior-art exposure: https://github.com/proofchains/python-proofchains :) -- 'peter'[:-1]@petertodd.org 0a203bd78c8536399f67275064107def6c7afea29c4e3a7b signature.asc Description: Digital signature -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
So connecting to many nodes just because we can and it's not technically prevented is bad for the network and creating systemic risks of failure, Well it is actually; that's why myself, Wladimir van der Laan, and Gregory Maxwell all specifically¹ called Chainalysis's actions a sybil attack. The Bitcoin P2P network is resilliant to failure when the chance of any one node going down is uncorrelated with others. For instance if you accidentally introduced a bug in your nodes that failed to relay transactions/blocks properly, you'd simultaneously be disrupting a large portion of the network all at once. This is exactly what your RBF patch is doing. By your own logic, nodes on the network should be allowed to relay (or not relay) whatever they wish. How many nodes is Coinbase connecting too? What software are they running? What subnets are they using? In particular, are they all on one subnet or multiple? We're running about a dozen nodes running regular Bitcoin Core in various subnets. We aren't doing anything particularly out of the ordinary here. Nothing that would fall under your definition of a sybil attack or harmful to the network. You know, you're creating an interesting bit of game theory here: if I'm a miner who doesn't already have a mining contract, why not implement full-RBF to force Coinbase to offer me one? One reason might be because other miners with such a contract - a majority - are going to be asked by Coinbase to reorg you out of the blockchain, but then we have a situation where a single entity has control of the blockchain. If someone did enter into contracts with miners to mine certain transactions, and had a guarantee that the miners would not build on previous blocks which included double spends, then they would only need contracts with 51% of the network anyway. So it wouldn't really matter if you were a small time miner and wanted to run full-RBF. But of course, you'd never 51% the network right? After all it's not possible to guarantee that your miner won't mine double-spends, as there is no single consensus definition of which transaction came first, nor can there be. Or do you see things differently? If I'm a small miner should I be worried my blocks might be rejected by the majority with hashing power contracts because I'm unable to predict which transactions Coinbase believes should go in the blockchain? You seem so concerned that we are actively trying to harm or control the network. We're simply trying to drive bitcoin adoption by making it easy for people to spend their bitcoin with merchants online. The problems we face are no different from other merchant processors, or small independent merchants accepting online or point-of-sale payments. We've historically had relatively little interest in what miners were doing (until RBF came out) - for the most part it didn't affect our business. However, most large merchants would be simply uninterested in accepting bitcoin if we forced their customers to wait 10-60 minutes for their payments to confirm. Many have inventory management systems which can not even place items on hold that long. If full-RBF sees any significant adoption by miners, then it will actively harm bitcoin adoption by reducing or removing the ability for online or POS merchants to accept bitcoin payments at all. I do not see a single benefit to running full-RBF. FWIW, I'm fine with the first-seen-safe RBF, that seems like a sensible addition and a good way to allow fees to be added or increased on existing transactions, without harming existing applications of bitcoin. Adrian -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… On Jun 19, 2015, at 9:36 AM, Matt Whitlock b...@mattwhitlock.name wrote: On Friday, 19 June 2015, at 3:53 pm, justusranv...@riseup.net wrote: I'd also like to note that prima facie doesn't mean always, it means that the default assumption, unless proven otherwise. Why would you automatically assume fraud by default? Shouldn't the null hypothesis be the default? Without any information one way or another, you ought to make *no assumption* about the fraudulence or non-fraudulence of any given double-spend. signature.asc Description: Message signed with OpenPGP using GPGMail -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
Even if you could prove intent to pay, this would be almost useless. I can sincerely intend to do a lot of things, but this doesn't mean I'll ever actually do them. I am in favor of more zero-confirmation transactions being reversed / double-spent. Bitcoin users largely still believe that accepting zero-conf transactions is safe, and evidently it's going to take some harsh lessons in reality to correct this belief. On Friday, 19 June 2015, at 9:42 am, Eric Lombrozo wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… On Jun 19, 2015, at 9:36 AM, Matt Whitlock b...@mattwhitlock.name wrote: On Friday, 19 June 2015, at 3:53 pm, justusranv...@riseup.net wrote: I'd also like to note that prima facie doesn't mean always, it means that the default assumption, unless proven otherwise. Why would you automatically assume fraud by default? Shouldn't the null hypothesis be the default? Without any information one way or another, you ought to make *no assumption* about the fraudulence or non-fraudulence of any given double-spend. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 5:42 PM, Eric Lombrozo elombr...@gmail.com wrote: If we want a non-repudiation mechanism in the protocol, we should explicitly define one rather than relying on “prima facie” assumptions. Otherwise, I would recommend not relying on the existence of a signed transaction as proof of intent to pay… Outputs could be marked as locked. If you are performing a zero confirmation spend, then the recipient could insist that you flag the output for them as non-reducible. This reduces privacy since it would be obvious which output was change. If both are locked, then the fee can't be increased. This would be information that miners could ignore though. Creating the right incentives is hard though. Blocks could be discouraged if they have a double spend that is known about for a while which reduces payment for a locked output. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 2015-06-19 17:50, Jeff Garzik wrote: No. You cannot know which is the 'right' or wrong transaction. One tx has obvious nSequence adjustments, the other - the refund transaction - may not. I'm still not seeing a case where a node could see conflicting transactions on the network as part of a micropayment channel, and not know it was observing the resolution of a channel rather than a likely retail double spend. If both transactions have been broadcast, then one of the conflicting members of the set will have nSequence adjustments. Maybe a clever griefer could try to make their retail double spend look like a micropayment channel, but it seems like they'd be missing the other identifiable markers of that protocol. -BEGIN PGP SIGNATURE- Version: GnuPG v2 iQIcBAEBCgAGBQJVhFhqAAoJECpf2nDq2eYjWtgP/2ir11TUfxoIIzK9t0groKY3 yMR32HP3caDLKdc5ML41jf0l0cp7a54sFPuRE+Am8rkg9ogcf6fho/hCwLnhhNb4 YYBqJ2pzqCU1uN8jwPYSwSw3AO+F+hPE8gcm7lKD297a1k9xpYayAFjChJowoyNT Wuq9YDkakQeSjV1aCiRHuXNxqnnbymf9xHEiB0buVnSgnyXrgZNCnefAo8DeXYqi FTSceakNwdkklddK5ObNNK9ZoLpjHhX6hZwRiXsOoG+WUzXhLQ+BsyIFzsCKxQk1 cXjTvLn+Ub9FasRCK5KXMBkkPa1U5JLs1nTn6eTbPyroTs10WLkXWjIpZHrkf7ZW 9RsxoKIRaJur8gbYd6BMvV5rgkfGdb6j24pVNxFF2t89SLo44H0NvqE6koNzgubG 4DyXZ+UlzxzwRVBNDeF4pdlKZGsz2ycvQPuNHRoaZY2IsieMBN/5HEqGNOmXsvKf tCg1SInO/FkE4njCxSW0R31s2KXCpgVCuq3qmoIKZobDdx7AC8GnpY1rdxUGpVoy USJwZ2IOgtNfl/rBtOpkp/BaUCmCYOiUj13/ycDrqWvnM4TmiDdzJNEZNfez5UQp Uvgvstoo88sewv9hGsuBWX0nC+ze/m43ZRReFhQDsypEaOw6pL2LSG9dD3tzulax TrbPXPlN55NarQ3nmPIW =Hj0x -END PGP SIGNATURE- -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 9:44 AM, justusranv...@riseup.net wrote: If we have ECDSA proof that an entity intentionally made and publicly announced incompatible promises regarding the disposition of particular Bitcoins under their control, then why shouldn't that be assumed to be a fraud attempt unless shown otherwise? Making multiple incompatible versions of a spend is a -requirement- of various refund contract protocols. -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/ -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee
On Fri, Jun 19, 2015 at 10:48 AM, justusranv...@riseup.net wrote: On 2015-06-19 17:40, Jeff Garzik wrote: Making multiple incompatible versions of a spend is a -requirement- of various refund contract protocols. Is there not a dedicated field in a transaction (nSequence) for express purpose of indicating when a protocol like this is in use? No. You cannot know which is the 'right' or wrong transaction. One tx has obvious nSequence adjustments, the other - the refund transaction - may not. -- Jeff Garzik Bitcoin core developer and open source evangelist BitPay, Inc. https://bitpay.com/ -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
