[Bitcoin-development] soft-fork block size increase (extension blocks)
Hi Gavin Sorry for slow response broken threading - mailbox filled up only saw your response on archive. I do earnestly think opt-in block-size increases are politically cleaner (gives different people different sized blocks by their own volition without forcing a compromise) and less risky than hard forks. Particularly if a hard-fork were really provoked without clear and wide consensus - dragons lay there. Then ask the various wallet developer how long it would take them to update their software to support something like this, I don't think thats any particular concern, extension block payments are forwards and backwards compatible. Businesses who are keen to have more transactions, would make it their problem to implement in their wallet, or ask the wallet vendor/maintainer they're working with to do it. Nothing breaks if they dont use it. The people that have the need for it will work on it. Market at work. If it turns out they dont really have a need for it, just projected huge numbers for their business plan that say dont materialise, well no foul. and do some UI mockups of what the experience would look like for users. I am not a UX guy, but for example it might be appropriate for tipping services or other micropayments to use an extension block. Or small retail payments. They can choose what address they use. Merchants, integrators etc can do likewise. It gives plenty enough scope that people can work with useful trade-offs while others work on lightning. If there are two engineering solutions to a problem, one really simple, and one complex, why would you pick the complex one? Because the more complex one is safer, more flexible, more future proof and better for decentralisation (and so as a bonus and might actually get done without more months of argument as its less contentious because it gives users choice to opt-in). Bitcoin itself is complex, a central ledger is simpler but as we know uninteresting which is to say this is a security tradeoff. Obviously I do appreciate KISS as a design principle, and utility of incremental improvements, but this is a security trade-off we're discussing here. I am proposing a way to not weaken security, while getting what you think is important - access to more TPS with a higher centralisation tradeoff (for those who opt-in to it, rather than for everyone whether that tradeoff is strongly against their interests or not). The decentralisation metrics are getting worse, not better, see Greg Maxwell's comments http://www.reddit.com/r/Bitcoin/comments/37vg8y/is_the_blockstream_company_the_reason_why_4_core/crqg381 This would not by those metrics be a good moment in history to make the situation worse. Especially if the complex solution has all of the problems of the simple one (20MB extension blocks are just as dangerous as 20MB main blocks, yes? If not, why not?) Not at all, thats the point. Bitcoin has a one-size fits all blocksize. People can pool mine the 8MB extension block, while solo or GBT mining the 1MB block. Thats more centralising than staying at 1MB (because to get the fees from the extension block some people without that kind of bandwidth are pool mining 8/9th of the lower security/decentralisation transactions. But its less centralising than a fixed blocksize of 9MB (1+8 for apples/apples) because realistically if those transactions are not spam, they would've happened offchain, and offchain until we get lightning like systems up, means central systems which are worse than the slight centralisation of 8MB blocks being single servers and prone to custody security failure. I think you made that point yourself in a recent post also. Sound good? ;) Seriously I think its the least bad idea I've heard on this topic. As an aside, a risk with using companies as a sounding board, is that you can get a misleading sense of consensus. Did they understand the tradeoff between security (decentralisation) and blocksize. Did they care? Do they represent users interests? Would they have voted instead for extension blocks if it was presented in similar terms? (I have to imagine they might have preferred extension blocks given the better story if you gloss over complexity and tradeoffs). Adam -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] soft-fork block size increase (extension blocks)
Mike wrote: Businesses who are keen to have more transactions, would make it their problem to implement in their wallet, or ask the wallet vendor/maintainer they're working with to do it. Nothing breaks if they dont use it. I don't see how this is the case. If an exchange supports extension blocks and I withdraw from that to a wallet that doesn't, the money will never arrive from my perspective. Yet the exchange will claim they sent it and they will wash their hands of the matter. Disaster. To be clear in case you are missing part of the mechanism.: it is forward and backwards compatible meaning a 1MB address can receive payments from an 8MB address (at reduced security if it has software that doesnt understand it) and a 1MB address can pay an 8MB address by paying to an OP_TRUE that has meaning to the extension block nodes. A 1MB client wont even understand the difference between a 1MB and 8MB out payment. An 8MB client will understand and pay 1MB addresses in a different way (moving the coin back to the 1MB chain). So its opt-in and incrementally deployable. Exchanges could encourage their users to use wallets that support 8MB blocks, eg by charging a fee for 1MB transactions. If 1MB blocks experience significant fee pressure, this will be persuasive. Or they could chose not to and eat the cost. This is all normal market adoption of a new cheaper technical option (in this case with a tradeoff of reduced security/more centralisation for those opting in to it). Because the more complex one is safer, more flexible, more future proof and better for decentralisation I disagree with all of those points. I find Lightning/Stroem etc to be more dangerous, less flexible, and worse for decentralisation. I explain why here: Extension blocks lightning are unrelated things. While I understand the need for being practical, there is IMO, amongst engineering maxims something as far as being too pragmatic, dangerously pragmatic even. We cant do stuff in bitcoin that has bad carry costs, nor throw out the baby with the bathwater. The situation is just that we are facing a security vs volume tradeoff and different people will have different requirements and comfort zones. If I am not misremembering, I think you've sided typically with the huge block, big data center only end of the spectrum. What I am proposing empowers you to do experiments in that direction without getting into a requirements conflict with people who value more strongly the bitcoin properties arising from it being robustly decentralised. I am not sure personally where the blocksize discussion comes out - if it stays as is for a year, in a wait and see, reduce spam, see fee-pressure take effect as it has before, work on improving improve decentralisation metrics, relay latency, and do a blocksize increment to kick the can if-and-when it becomes necessary and in the mean-time try to do something more long-term ambitious about scale rather than volume. Bitcoin without scale improvements probably wont get the volume people would like. So scale is more important than volume; and security (decentralisation) is important too. To the extreme analogy we could fix scale tomorrow by throwing up a single high perf database, but then we'd break the security properties arising from decentralisation. We should improve both within an approximately safe envelope IMO. Adam -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] soft-fork block size increase (extension blocks)
(at reduced security if it has software that doesnt understand it) Well, yes. Isn't that rather key to the issue? Whereas by simply increasing the block size, SPV wallets don't care (same security and protocol as before) and fully validating wallets can be updated with a very small code change. A 1MB client wont even understand the difference between a 1MB and 8MB out payment. Let's say an old client makes a payment that only gets confirmed in an extension block. The wallet will think the payment is unconfirmed and show that to the user forever, no? Can you walk through the UX for each case? If I am not misremembering, I think you've sided typically with the huge block, big data center only end of the spectrum. It would be Satoshi, that argued that. I think there must be a communication issue here somewhere. I'm not sure how this meme has taken hold amongst you guys, as I am the guy who wrote the scalability page back in 2011: https://en.bitcoin.it/wiki/Scalability It says: *The core Bitcoin network can scale to much higher transaction rates than are seen today, assuming that nodes in the network are primarily running on high end servers rather than desktops. * By much higher rates I meant VISA scale and by high end server I meant high end by today's standards not tomorrows. There's a big difference between a datacenter and a single server! By definition a single server is not a datacenter, although it would be conventional to place it in one. But even with the most wildly optimistic growth imaginable, I couldn't foresee a time when you needed more than a single machine to keep up with the transaction stream. And we're not going to get to VISA scale any time soon: I don't think I've ever argued we will. If it does happen it would presumably be decades away. Again, short of some currently unimagined killer app. So I don't believe I've ever argued this, and honestly I kinda feel people are putting words in my mouth. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] soft-fork block size increase (extension blocks)
On 6/1/2015 10:21 AM, Adam Back wrote: if it stays as is for a year, in a wait and see, reduce spam, see fee-pressure take effect as it has before, work on improving improve decentralisation metrics, relay latency, and do a blocksize increment to kick the can if-and-when it becomes necessary and in the mean-time try to do something more long-term ambitious about scale rather than volume. What's your estimate of the lead time required to kick the can, if-and-when it becomes necessary? The other time-series I've seen all plot an average block size. That's misleading, because there's a distribution of block sizes. If you bin by retarget interval and plot every single block, you get this http://i.imgur.com/5Gfh9CW.png The max block size has clearly been in play for 8 months already. -- ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
[Bitcoin-development] soft-fork block size increase (extension blocks) Re: Proposed alternatives to the 20MB stepfunction
I discussed the extension block idea on wizards a while back and it is a way to soft-fork an opt-in block-size increase. Like everything here there are pros and cons. The security is better than Raylstonn inferred from Tier's explanation I think.. It works as Tier described - there is an extension block (say 10MB) and the existing 1MB block. The extension block is committed to in the 1MB chain. Users can transfer bitcoin into the extension block, and they can transfer them out. The interesting thing is this makes block sizes changes opt-in and gives users choice. Choice is good. Bitcoin has a one-size-fits-all blocksize at present hence the block size debate. If a bigger block-size were an opt-in choice, and some people wanted 10MB or even 100MB blocks for low value transactions I expect it would be far easier a discussion - people who think 100MB blocks are dangerously centralising, would not opt to use them (or would put only small values they can afford to lose in them). There are some security implications though, so this also is nuanced, and more on that in a bit. Fee pressure still exists for blocks of difference size as the security assurances are not the same. It is plausible that some people would pay more for transactions in the 1MB block. Now there are three choices of validation level, rather than the normal 2-levels of SPV or full-node, with extension blocks we get a choice: A) a user could run a full node for both 1MB and 10MB blocks, and get full security for both 1MB and 10MB block transactions (but at higher bandwidth cost), or B) a user could run a full node on the 1MB block, but operate as an SPV node for the 10MB block, or C) run in SPV mode for both 1MB and 10MB blocks. Similarly for mining - miners could validate 1MB and 10MB transactions (solo mine or GBT-style), or they could self-validate 1MB transactions and pool mine 10MB transactions (have a pool validate those). 1MB full node users who do not upgrade to software that understands extension blocks, could run in SPV mode with respect to 10MB blocks. Here lies the risk - this imposes a security downgrade on the 1MB non-upgraded users, and also on users who upgrade but dont have the bandwidth to validate 10MB blocks. We could defend non-upgrade users by making receiving funds that came via the extension block opt-in also, eg an optional to use new address version and construct the extension block so that payments out of it can only go to new version addresses. We could harden 1MB block SPV security (when receiving weaker extension block transactions) in a number of ways: UTXO commitments, fraud proofs (and fraud bounties) for moving from the extension block to the 1MB block. We could optionally require coins moving via the extension block to the 1MB block to be matured (eg 100 blocks delay) Anyway something else to evaluate. Not as simple to code as a hard-fork, but way safer transition than a hard-fork, and opt-in - if you prefer the higher decentralisation of 1MB blocks, keep using them; if you prefer 10MB blocks you can opt-in to them. Adam On 29 May 2015 at 17:39, Raystonn . rayst...@hotmail.com wrote: Regarding Tier’s proposal: The lower security you mention for extended blocks would delay, possibly forever, the larger blocks maximum block size that we want for the entire network. That doesn’t sound like an optimal solution. Regarding consensus for larger maximum block size, what we are seeing on this list is typical of what we see in the U.S. Congress. Support for changes by the stakeholders (support for bills by the citizens as a whole) has become irrelevant to the probability of these changes being adopted. Lobbyists have all the sway in getting their policies enacted. In our case, I would bet on some lobbying of core developers by wealthy miners. Someone recently proposed that secret ballots could help eliminate the power of lobbyists in Congress. Nobody invests in that which cannot be confirmed. Secret ballots mean the vote you are buying cannot be confirmed. Perhaps this will work for Bitcoin Core as well. From: Tier Nolan Sent: Friday, May 29, 2015 7:22 AM Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] Proposed alternatives to the 20MB stepfunction On Fri, May 29, 2015 at 3:09 PM, Tier Nolan tier.no...@gmail.com wrote: On Fri, May 29, 2015 at 1:39 PM, Gavin Andresen gavinandre...@gmail.com wrote: But if there is still no consensus among developers but the bigger blocks now movement is successful, I'll ask for help getting big miners to do the same, and use the soft-fork block version voting mechanism to (hopefully) get a majority and then a super-majority willing to produce bigger blocks. The purpose of that process is to prove to any doubters that they'd better start supporting bigger blocks or they'll be left behind, and to give them a chance to upgrade before that happens. How do you define that the movement is successful? Sorry again, I
