{"type":"rich","version":"1.0","title":"befreeandopen [ARCHIVE] wrote","author_name":"befreeandopen [ARCHIVE] (npub18w…53c7a)","author_url":"https://yabu.me/npub18w62rfcdggkah7ql00r52pqtsfgdfygnc4h3hmwdq57d0f3szrzqr53c7a","provider_name":"njump","provider_url":"https://yabu.me","html":"📅 Original date posted:2021-06-01\n📝 Original message:Comments inline.\n\n\n\n\u003e \u003e Could you explain what am I missing here, because this actually does not seem better, but rather worse than some PoS schemes?\n\u003e\n\u003e Given your example, if !BTC is needed to burn, that's a $50k\n\u003e investment in an ASIC needed to mine a block. That's not anywhere\n\u003e near current levels. It's not even approaching the current PoW. A\n\u003e $50k investment to be a large amount of hash power is ... well,\n\u003e somewhere more than 10 years ago.\n\nThis is +- true with todays prices, that was not my point. We all know that today's total block revenue is nowhere near 1 BTC. If it is say 7 BTC, then we would expect that the miners spend roughly just about 7 BTC to produce the block - in long term, on average. Right? Today, this 7 BTC is supposed to be some average of investment into the mining rig, the building in which the rig exists (or its rent) and then some electricity. So when I said 1 BTC I meant that amount of BTC that is the sum of the block subsidy and fees at the time of this imagined switch to PoB. Use 7 BTC if you want to talk today. And yes, that seems very weak. But can you explain why it is not the case after switching to PoB that the cost of producing the block should roughly converge to to the revenue? Because I do not see why would miners spend more than what they can earn.\n\n\n\n\n\n\u003e My original proof-of-burn concept was designed to mimic ASICs as much\n\u003e as possible:\n\u003e\n\u003e 1.  large initial investment (burn to acquire power)\n\u003e 2.  continued investment (burn to activate power in each block, lost if\n\u003e     block is not found)\n\u003e\n\u003e     Ideally, the attacker would have to keep burning for each lottery\n\u003e     ticket, which can only be used once. Committing that burn to a\n\u003e     particular block for example.\n\u003e\n\u003e     Any attack you propose for a \"assumed well designed PoB\" can also attack PoW.\n\u003e     Any attack you propose for a \"assumed well designed PoB\" can also attack PoS.\n\u003e\n\u003e     But there are some things PoB can do that PoS can't... which is really\n\u003e     my original point.\n\nThis is the problem that I wanted to avoid. You refer to some \"my original PoB\", but I am strictly talking about the concept described in wiki because nothing else was provided to me. If we do not have a reference description of what you are talking about the debate will quickly turn into the classical debate with PoS supporters - I explain an attack and they \"patch it\", creating problem elsewhere. Then I explain an attack against that and they patch it there. And this goes infinitely.\n\nSo if there is some other version, better one than the one described in wiki, please let me know. If there is not, there is nothing to talk about really. You'd first need to define your model properly and describe very details of how it should work and then we can analyze it. It does not make much sense to me to analyze a ghost protocol that I always only see a tiny part of.\n\nFor example here above in the quoted text you mention some continual lost (if block is not found). If that is not the exponential decay as described in the wiki, then I have no idea what it is. I do not say that I can't imagine for myself what it could be, but it is up to you to define it, so we can be sure we are talking about the same thing.\n\nSame with those early unblinding of burns - nothing about that in the wiki, so that concept is alien to me and it can not be subject to a debate before it is precisely described.\n\n\n\n\n\u003e\n\u003e\n\u003e -   sunk costs/lost investment\n\u003e -   \"hashpower\" is \"offline\", and cannot be seized.\n\u003e\n\u003e     On Tue, Jun 1, 2021 at 4:21 AM befreeandopen\n\u003e     befreeandopen at protonmail.com wrote:\n\u003e\n\u003e\n\u003e \u003e Erik, thanks for the link. So referring to https://en.bitcoin.it/wiki/Proof_of_burn, I do not really understand how this is supposed to be that much better over many proof of stake proposals. If there is more research on PoB, please note I'm not commenting on that as I only read this wiki article and my comments are purely related to this only.\n\u003e \u003e I hope we can agree that the idea with manual insertion of entropy every week can be discarded, but at the same time I don't think it is a crucial point of the whole idea. So we can just focus on the rest of it.\n\u003e \u003e Then the whole idea seems just like certain proof of stake implementations with just small differences, which I try to summarize:\n\u003e \u003e\n\u003e \u003e -   in PoB, in order to use the coin for block production, you burn it in the past and wait some time -- in the certain PoS I'm talking about, in order to use the coin, you do not move the coin for some time - so in both there is the same idea - you somehow make the coin eligible for the block creation process by first doing some action followed by some inaction for some time; the difference here is that if later you use such coin in PoS, then after waiting more time, you can use the coin again (for whatever purpose), while in PoB the coin is gone forever (it is burned); this does not seem to be fundamentally different\n\u003e \u003e\n\u003e \u003e -   in PoB, the author suggests there is an exponential decay of the power of the coin to create a block; in some PoS schemas, there historically was an era of so called CoinAge mechanism, which was somewhat inverse to this exponential decay, it was that the coin gets more power the older it is untouched, some implementations were for linear increase in the power, some exponential. Usually there was a certain limit - i.e. a maximum power the coin may have reached. It turned out quite quickly that such property is making attacks easier. PoB reverses the idea, but I don't think that helps that much. In any case, there seems to be an optimal period of time for each used coin, in both PoS and PoB, where the coin is most suitable for block production. I admit PoB version is better, but the crucial property here is that some coins are more powerful than other.\n\u003e \u003e\n\u003e \u003e -   in both PoB and PoS it seems there is linear increase of the ability of the coin to produce blocks with the size of the coin (more BTC you burn/stake, the better your chance)\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e This characteristic of PoB does not suggest that it would have that much different properties than PoS. So it should suffer from same problems as PoS. Namely, the problems I see now, with the given proposal from wiki, are:\n\u003e \u003e\n\u003e \u003e -   there seems to be lack of definition of the heaviest chain and difficulty adjustment - this seems crucial, but likely solvable, I'm just saying it is importantly missing in the description\n\u003e \u003e\n\u003e \u003e -   there seems to be a problem with nothing at stake (nothing at burn maybe?) - How that can be? Again, it seems that every burned coin can be used for free checks at any time after the initial waiting period. These free checks are indeed free and are the core of the nothing at stake problem in PoS. You seem to make those checks for free and you seem to be able to use those burned coins to create arbitrary number of forks build on any parent blocks of your choice, not just the last block of the heaviest chain. I can't see at the moment how is this different from PoS nothing at stake problem. Maybe you can explain?\n\u003e \u003e\n\u003e \u003e -   it seems to me that there is a trivial attack against the scheme by a wealthy attacker. Suppose a common size of the burn is 1 BTC per block, suppose you define the heaviest chain rule somehow in relation to total number of burned coins or the cumulative \"strength\" of the \"lowest\" hashes, then you can just burn 20 UTXOs, each being 10 BTC in value, so you spent 200 BTC on this attack, but you are in very strong position because after you wait the needed time, you should be able to do pretty nasty reorg. Suppose that the main chain is A-B-C-D-E-F, so what you do at that point is that you just \"try for free\" all your 20 UTXOs, whether or not they can build on top of block A (which has 5 confs on top, F is the tip of the main chain). Since you have big UTXOs, your chances should be good, of course you can always try many times because you have a \"lottery ticket\" for every timestampt t. So with this you should be able, with good chance, to find such B' and then you have 19 UTXOs remaining to try to build on B' in the same way. I can't see what prevents this attack in the described scheme.\n\u003e \u003e\n\u003e \u003e -   the ability to retroactively try all different kids of timestamp t seems devastating - you again get super easy and somewhat cheap attack (due to nothing at burn problem) that allows you to rewrite even long chains at will.\n\u003e \u003e\n\u003e \u003e\n\u003e \u003e Could you explain what am I missing here, because this actually does not seem better, but rather worse than some PoS schemes?\n\u003e \u003e Sent with ProtonMail Secure Email.\n\u003e \u003e ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐\n\u003e \u003e On Friday, May 28, 2021 9:06 PM, Erik Aronesty erik at q32.com wrote:\n\u003e \u003e\n\u003e \u003e \u003e best writeup i know of is here:\n\u003e \u003e \u003e https://en.bitcoin.it/wiki/Proof_of_burn\n\u003e \u003e \u003e no formal proposals or proofs that i know of.\n\u003e \u003e \u003e On Fri, May 28, 2021 at 10:40 AM befreeandopen\n\u003e \u003e \u003e befreeandopen at protonmail.com wrote:\n\u003e \u003e \u003e\n\u003e \u003e \u003e \u003e Erik, I am sorry, I have little knowledge about proof-of-burn, I never found it interesting up until now. Some of your recent claims seem quite strong to me and I'd like to read more.\n\u003e \u003e \u003e \u003e Forgive me if this has been mentioned recently, but is there a full specification of the concept you are referring to? I don't mean just the basic idea description (that much is clear to me), I mean a fully detailed proposal or technical documentation that would give me a precise information about what exactly it is that you are talking about.\n\u003e \u003e \u003e \u003e Sent with ProtonMail Secure Email.\n\u003e \u003e \u003e \u003e ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐\n\u003e \u003e \u003e \u003e On Wednesday, May 26, 2021 11:07 PM, Erik Aronesty erik at q32.com wrote:\n\u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e note: the \"nothing at stake\" problem you propose is not broken for\n\u003e \u003e \u003e \u003e \u003e proof-of-burn, because the attacker\n\u003e \u003e \u003e \u003e \u003e a) has no idea which past transactions are burns\n\u003e \u003e \u003e \u003e \u003e b) has no way to use his mining power, even 5%, to maliciously improve\n\u003e \u003e \u003e \u003e \u003e his odds of being selected\n\u003e \u003e \u003e \u003e \u003e On Wed, May 26, 2021 at 9:12 AM befreeandopen\n\u003e \u003e \u003e \u003e \u003e befreeandopen at protonmail.com wrote:\n\u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e @befreeandopen I guess I misunderstood your selfish minting attack. Let me make sure I understand it. You're saying it would go as follows?:\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e 1.  The malicious actor comes across an opportunity to mint the next 3 blocks. But they hold off and don't release their blocks just yet.\n\u003e \u003e \u003e \u003e \u003e \u003e 2.  They receive a new block minted by someone else.\n\u003e \u003e \u003e \u003e \u003e \u003e 3.  The malicious actor then chooses to release their other 2 blocks on on the second from the top block if it gives them more blocks in the future than minting on the top block. And instead lets the top block proceed if it gives them more blocks in the future (also figuring in the 3 blocks they're missing out on minting).\n\u003e \u003e \u003e \u003e \u003e \u003e 4.  Profit!\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e The problem with this attack is that any self respecting PoS system wouldn't have the information available for minters to know how blocks will affect their future prospects of minting. Otherwise this would introduce the problem of stake grinding. This can be done using collaborative randomness (where numbers from many parties are combined to create a random number that no individual party could predict). In fact, that's what the Casper protocol does to decide quorums. In a non quorum case, you can do something like record a hash of a number in the block header, and then have a second step to release that number later. Rewards can be given can be used to ensure minters act honestly here by minting messages that release these numbers and not releasing their secret numbers too early.\n\u003e \u003e \u003e \u003e \u003e \u003e Yes, you misunderstood it. First, let me say that the above thoughts of yours are incorrect, at least for non-quorum case. Since the transition in the blockchain system from S1 to S2 is only by adding new block, and since stakers always need to be able to decide whether or not they can add the next block, it follows that if a staker creates a new block locally, she can decide whether the new state allows her to add another block on top. As you mentioned, this COULD introduce problem of staking, that you are incorrect in that it is a necessity. Usual prevention of the grinding problem in this case is that an \"old enough\" source of randomness applies for the current block production process. Of course this, as it is typical for PoS, introduces other problems, but let's discard those.\n\u003e \u003e \u003e \u003e \u003e \u003e I will try to explain in detail what you misunderstood before. You start with a chain ending with blocks A-B-C, C being the top, the common feature of PoS system (non-quorum), roughly speaking, is that if N is the total amount of coins that participate in the staking process to create a new block on top of C (let's call that D), then a participant having K*N amount of stake has chance K to be the one who will create the next stake. In other words, the power of stakers is supposed to be linear in the system - you own 10 coins gives you 10x the chance of finding block over someone who has 1 coin.\n\u003e \u003e \u003e \u003e \u003e \u003e What i was claiming is that using the technique I have described, this linearity is violated. Why? Well, it works for honest stakers among the competition of honest stakers - they really do have the chance of K to find the next block. However, the attacker, using nothing at stake, checks her ability to build block D (at some timestamp). If she is successful, she does not propagate D immediately, but instead she also checks whether she can build on top of B and on top of A. Since with every new timestamp, usually, there is a new chance to build the block, it is not uncommon that she finds she is indeed able to build such block C' on top of B. Here it is likely t(C') \u003e t(C) as the attacker has relatively low stake. Note that in order to produce such C', she not only could have tried the current timestamp t(D), but also all previous timestamps up to t(B) (usually that's the consensus rule, but it may depend on a specific consensus). So her chance to produce such C' is greater than her previous chance of producing C (which chance was limited by other stakers in the system and the discovery of block C by one of them). Now suppose that she found such C' and now she continues by trying to prolong this chain by finding D'. And again here, it is quite likely that her chance to find such D' is greater than was her chance of finding D because again there are likely multiple timestamps she could try. This all was possible just because nothing at stake allows you to just try if you can produce a block in certain state of block chain or not. Now if she actually was able to find D', she discards D and only publishes chain A-B-C'-D', which can not be punished despite the fact that she indeed produced two different forks. She can not be punished because this production was local and only the final result of A-B-C'-D' was published, in which case she gained an extra block over the honest strategy which would only give her block D.\n\u003e \u003e \u003e \u003e \u003e \u003e Fun fact tho: there is an attack called the \"selfish mining attack\" for proof of work, and it reduces the security of PoW by at least 1/3rd.\n\u003e \u003e \u003e \u003e \u003e \u003e How is that relevant to our discussion? This is known research that has nothing to do with PoS except that it is often worse on PoS.\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e the problem is not as hard as you think\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e I don't claim to know just how hard finding the IP address associated with a bitcoin address is. However, the DOS risk can be solved more completely by only allowing the owner of coins themselves to know whether they can mint a block. Eg by determining whether someone can mint a block based on their public key hidden behind hashes (as normal in addresses). Only when someone does in fact mint a block do they reveal their hidden public key in order to prove they are allowed to mint the block.\n\u003e \u003e \u003e \u003e \u003e \u003e This is true, but you are mixing quorum and non-quorum systems. My objection here was towards such system where I specifically said that the list of producers for next epoch is known up front and you confirmed that this is what you meant with \"quorum\" system. So in such system, I claimed, the known producer is the only target at any given point of time. This of course does not apply to any other type of system where future producers are not known. No need to dispute, again, something that was not claimed.\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e I agree that introduction of punishment itself does not imply introducing a problem elsewhere (which I did not claim if you reread my previous message)\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e I'm glad we agree there. Perhaps I misunderstood what you meant by \"you should not omit to mention that by doing so, typically, you have introduced another problem elsewhere.\"\n\u003e \u003e \u003e \u003e \u003e \u003e Perhaps you should quote the full sentence and not just a part of it:\n\u003e \u003e \u003e \u003e \u003e \u003e \"Of course you can always change the rules in a way that a certain specific attack is not doable, but you should not omit to mention that by doing so, typically, you have introduced another problem elsewhere, or you have not solved it completely.\"\n\u003e \u003e \u003e \u003e \u003e \u003e You can parse this as: (CREATE PROBLEM ELSEWHERE) OR (NOT SOLVE IT COMPLETELY)\n\u003e \u003e \u003e \u003e \u003e \u003e In case of the punishment it was meant to be the not solve it completely part.\n\u003e \u003e \u003e \u003e \u003e \u003e Also \"typically\" does not imply always.\n\u003e \u003e \u003e \u003e \u003e \u003e But this parsing of English sentences for you seems very off topic here. My point is, in context of Bitcoin, reject such unsupported claims that PoS is a reasonable alternative to PoW, let's stick to that.\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e As long as the staker makes sure (which is not that hard) that she does not miss a chance to create a block, her significance in the system will always increase in time. It will increase relative to all normal users who do not stake\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e Well, if you're in the closed system of the cryptocurrency, sure. But we don't live in that closed system. Minters will earn some ROI from minting just like any other financial activity. Others may find more success spending their time doing things other than figuring out how to mint coins. In that case, they'll be able to earn more coin that they could later decide to use to mint blocks if they decide to.\n\u003e \u003e \u003e \u003e \u003e \u003e This only supports the point I was making. Since the optimal scenario with all existing coins participating is just theoretical, the attacker's position will ever so improve. It seems we are in agreement here, great.\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Just because of the above we must reject PoS as being critically insecure\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e I think the only thing we can conclude from this is that you have come up with an insecure proof of stake protocol. I don't see how anything you've brought up amounts to substantial evidence that all possible PoS protocols are insecure.\n\u003e \u003e \u003e \u003e \u003e \u003e I have not come up with anything. I'm afraid you've not realized the burden of proof is on your side if you vouch for a design that is not believed and trusted to be secure. It is up to you to show that you know how to solve every problem that people throw at you. So far we have just demonstrated that your claim that nothing at stake is solved was unjustified. You have not described a system that would solve it (and not introduce critical DDOS attack vector as it is in quorum based systems - per the prior definition of such systems).\n\u003e \u003e \u003e \u003e \u003e \u003e Of course the list of problems of PoS systems do not end with just nothing at stake, but it is good enough example that by itself prevents its adoption in decentralized consensus. No need to go to other hard problems without solving nothing at stake.\n\u003e \u003e \u003e \u003e \u003e \u003e On Tue, May 25, 2021 at 11:10 AM befreeandopen befreeandopen at protonmail.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e @befreeandopen \" An attacker can calculate whether or not she can prolong this chain or not and if so with what timestamp.\"\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e The scenario you describe would only be likely to happen at all if the malicious actor has a very large fraction of the stake - probably quite close to 50%. At that point, you're talking about a 51% attack, not the nothing at stake problem. The nothing at stake problem is the problem where anyone will mint on any chain. Its clear that if there's a substantial punishment for minting on chains other than the one that eventually wins, every minter without a significant fraction of the stake will be honest and not attempt to mint on old blocks or support someone else's attempt to mint on old blocks (until and if it becomes the heaviest chain). Because the attacker would need probably \u003e45% of the active stake (take a look at the reasoning here for a deeper analysis of that statement), I don't agree that punishment is not a sufficient mitigation of the nothing at stake problem. To exploit the nothing at stake problem, you basically need to 51% attack, at which point you've exceeded the operating conditions of the system, so of course its gonna have problems, just like a 51% attack would cause with PoW.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e This is not at all the case. The attacker benefits using the described technique at any size of the stake and significantly so with just 5% of the stake. By significantly, I do not mean that the attacker is able to completely take control the network (in short term), but rather that the attacker has significant advantage in the number of blocks she creates compared to what she \"should be able to create\". This means the attacker's stake increases significantly faster than of the honest nodes, which in long term is very serious in PoS system. If you believe close to 50% is needed for that, you need to redo your math. So no, you are wrong stating that \"to exploit nothing at stake problem you basically need to 51% attack\". It is rather the opposite - eventually, nothing at stake attack leads to ability to perform 51% attack.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I am not sure if this is what you call quorum-based PoS\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Yes, pre-selected minters is exactly what I mean by that.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e it allows the attacker to know who to attack at which point with powerful DDOS in order to hurt liveness of such system\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Just like in bitcoin, associating keys with IP addresses isn't generally an easy thing to do on the fly like that. If you know someone's IP address, you can target them. But if you only know their address or public key, the reverse isn't as easy. With a quorum-based PoS system, you can see their public key and address, but finding out their IP to DOS would be a huge challenge I think.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e I do not dispute that the problem is not trivial, but the problem is not as hard as you think. The network graph analysis is a known technique and it is not trivial, but not very hard either. Introducing a large number of nodes to the system to achieve very good success rate of analysis of area of origin of blocks is doable and has been done in past. So again, I very much disagree with your conclusion that this is somehow secure. It is absolutely insecure.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Note, tho, that quorum-based PoS generally also have punishments as part of the protocol. The introduction of punishments do indeed handily solve the nothing at stake problem. And you didn't mention a single problem that the punishments introduce that weren't already there before punishments. There are tradeoffs with introducing punishments (eg in some cases you might punish honest actors), but they are minor in comparison to solving the nothing at stake problem.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e While I agree that introduction of punishment itself does not imply introducing a problem elsewhere (which I did not claim if you reread my previous message), it does introduce additional complexity which may introduce problem, but more importantly, while it slightly improves resistance against the nothing at stake attack, it solves absolutely nothing. Your claim is based on wrong claim of needed close to 50% stake, but that could not be farther from the truth. It is not true even in optimal conditions when all participants of the network stake or delegate their stake. These optimal conditions rarely, if ever, occur. And that's another thing that we have not mention in our debate, so please allow me to introduce another problem to PoS.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Consider what is needed for such optimal conditions to occur - all coins are always part of the stake, which means that they need to somehow automatically part of the staking process even when they are moved. But in many PoS systems you usually require some age (in terms of confirmations) of the coin before you allow it to be used for participation in staking process and that is for a good reason - to prevent various grinding attacks. In some systems the coin must be specifically registered before it can be staked, in others, simply waiting for enough confirmations enables you to stake with the coin. I am not sure if there is a system which does not have this cooling period for a coin that has been moved. Maybe it is possible though, but AFAIK it is not common and not battle tested feature.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Then if we admit that achieving the optimal condition is rather theoretical. Then if we do not have the optimal condition, it means that a staker with K% of the total available supply increases it's percentage over time to some amounts \u003eK%. As long as the staker makes sure (which is not that hard) that she does not miss a chance to create a block, her significance in the system will always increase in time. It will increase relative to all normal users who do not stake (if there are any) and relative to all other stakers who make mistakes or who are not wealthy enough to afford not selling any position ever. But powerful attacker is exactly in such position and thus she will gain significance in such a system. The technique I have described, and that you mistakenly think is viable only with huge amounts of stake, only puts the attacker to even greater advantage. But even without the described attack (which exploits nothing at stake), the PoS system converges to a system more and more controlled by powerful entity, which we can assume is the attacker.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e So I don't think it is at all misleading to claim that \"nothing at stake\" is a solved problem. I do in fact mean that the solutions to that problem don't introduce any other problems with anywhere near the same level of significance.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e It still stands as truly misleading claim. I disagree that introducing DDOS opportunity with medium level of difficulty for the attacker to implement it, in case of \"quorum-based PoS\" is not a problem anywhere near the same level of significance. Such an attack vector allows you to turn off the network if you spend some time and money. That is hardly acceptable.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e Just because of the above we must reject PoS as being critically insecure until someone invents and demonstrates an actual way of solving these issues.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e On Tue, May 25, 2021 at 3:00 AM Erik Aronesty erik at q32.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e you burn them to be used at a future particular block height\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e This sounds exploitable. It seems like an attacker could simply focus all their burns on a particular set of 6 blocks to double spend, minimizing their cost of attack.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e could be right. the original idea was to have burns decay over time,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e like ASIC's.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e anyway the point was not that \"i had a magic formula\"\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e the point was that proof of burn is almost always better than proof of\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e stake - simply because the \"proof\" is on-chain, not sitting on a node\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e somewhere waiting to be stolen.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Mon, May 24, 2021 at 9:53 PM Billy Tetrud billy.tetrud at gmail.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Is this the kind of proof of burn you're talking about?\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e if i have a choice between two chains, one longer and one shorter, i can only choose one... deterministically\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e What prevents you from attempting to mine block 553 on both chains?\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e miners have a very strong, long-term, investment in the stability of the chain.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Yes, but the same can be said of any coin, even ones that do have the nothing at stake problem. This isn't sufficient tho because the chain is a common good, and the tragedy of the commons holds for it.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e you burn them to be used at a future particular block height\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e This sounds exploitable. It seems like an attacker could simply focus all their burns on a particular set of 6 blocks to double spend, minimizing their cost of attack.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e i can imagine scenarios where large stakeholders can collude to punish smaller stakeholders simply to drive them out of business, for example\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Are you talking about a 51% attack? This is possible in any decentralized cryptocurrency.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Mon, May 24, 2021 at 11:49 AM Erik Aronesty erik at q32.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e your burn investment is always \"at stake\", any redaction can result in a loss-of-burn, because burns can be tied, precisely, to block-heights\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I'm fuzzy on how proof of burn works.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e when you burn coins, you burn them to be used at a future particular\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e block height: so if i'm burning for block 553, i can only use them to\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e mine block 553. if i have a choice between two chains, one longer\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e and one shorter, i can only choose one... deterministically, for that\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e burn: the chain with the height 553. if we fix the \"lead time\" for\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e burned coins to be weeks or even months in advance, miners have a very\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e strong, long-term, investment in the stability of the chain.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e therefore there is no \"nothing at stake\" problem. it's\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e deterministic, so miners have no choice. they can only choose the\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e transactions that go into the block. they cannot choose which chain\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e to mine, and it's time-locked, so rollbacks and instability always\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e hurt miners the most.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e the \"punishment\" systems of PoS are \"weird at best\", certainly\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e unproven. i can imagine scenarios where large stakeholders can\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e collude to punish smaller stakeholders simply to drive them out of\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e business, for example. and then you have to put checks in place to\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e prevent that, and more checks for those prevention system...\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e in PoB, there is no complexity. simpler systems like this are\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e typically more secure.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e PoB also solves problems caused by \"energy dependence\", which could\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e lead to state monopolies on mining (like the new Bitcoin Mining\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Council). these consortiums, if state sanctioned, could become a\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e source of censorship, for example. Since PoB doesn't require you to\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e have a live, well-connected node, it's harder to censor \u0026 harder to\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e trace.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Eliminating this weakness seems to be in the best interests of\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e existing stakeholders\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Mon, May 24, 2021 at 4:44 PM Billy Tetrud billy.tetrud at gmail.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e proof of burn clearly solves this, since nothing is held online\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Well.. the coins to be burned need to be online when they're burned. But yes, only a small fraction of the total coins need to be online.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e your burn investment is always \"at stake\", any redaction can result in a loss-of-burn, because burns can be tied, precisely, to block-heights\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e So you're saying that if say someone tries to mine a block on a shorter chain, that requires them to send a transaction burning their coins, and that transaction could also be spent on the longest chain, which means their coins are burned even if the chain they tried to mine on doesn't win? I'm fuzzy on how proof of burn works.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e proof of burn can be more secure than proof-of-stake\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e FYI, proof of stake can be done without the \"nothing at stake\" problem. You can simply punish people who mint on shorter chains (by rewarding people who publish proofs of this happening on the main chain). In quorum-based PoS, you can punish people in the quorum that propose or sign multiple blocks for the same height. The \"nothing at stake\" problem is a solved problem at this point for PoS.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Mon, May 24, 2021 at 3:47 AM Erik Aronesty erik at q32.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I don't see a way to get around the conflicting requirement that the keys for large amounts of coins should be kept offline but those are exactly the coins we need online to make the scheme secure.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e proof of burn clearly solves this, since nothing is held online\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e how does proof of burn solve the \"nothing at stake\" problem in your view?\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e definition of nothing at stake: in the event of a fork, whether the\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e fork is accidental or a malicious, the optimal strategy for any miner\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e is to mine on every chain, so that the miner gets their reward no\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e matter which fork wins. indeed in proof-of-stake, the proofs are\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e published on the very chains mines, so the incentive is magnified.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e in proof-of-burn, your burn investment is always \"at stake\", any\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e redaction can result in a loss-of-burn, because burns can be tied,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e precisely, to block-heights\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e as a result, miners no longer have an incentive to mine all chains\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e in this way proof of burn can be more secure than proof-of-stake, and\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e even more secure than proof of work\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Sun, May 23, 2021 at 3:52 AM Lloyd Fournier via bitcoin-dev\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev at lists.linuxfoundation.org wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Hi Billy,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I was going to write a post which started by dismissing many of the weak arguments that are made against PoS made in this thread and elsewhere.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Although I don't agree with all your points you have done a decent job here so I'll focus on the second part: why I think Proof-of-Stake is inappropriate for a Bitcoin-like system.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Proof of stake is not fit for purpose for a global settlement layer in a pure digital asset (i.e. \"digital gold\") which is what Bitcoin is trying to be.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e PoS necessarily gives responsibilities to the holders of coins that they do not want and cannot handle.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e In Bitcoin, large unsophisticated coin holders can put their coins in cold storage without a second thought given to the health of the underlying ledger.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e As much as hardcore Bitcoiners try to convince them to run their own node, most don't, and that's perfectly acceptable.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e At no point do their personal decisions affect the underlying consensus -- it only affects their personal security assurance (not that of the system itself).\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e In PoS systems this clean separation of responsibilities does not exist.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I think that the more rigorously studied PoS protocols will work fine within the security claims made in their papers.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e People who believe that these protocols are destined for catastrophic consensus failure are certainly in for a surprise.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e But the devil is in the detail.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Let's look at what the implications of using the leading proof of stake protocols would have on Bitcoin:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e ### Proof of SquareSpace (Cardano, Polkdadot)\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Cardano is a UTXO based PoS coin based on Ouroboros Praos3 with an inbuilt on-chain delegation system5.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e In these protocols, coin holders who do not want to run their node with their hot keys in it delegate it to a \"Stake Pool\".\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I call the resulting system Proof-of-SquareSpace since most will choose a pool by looking around for one with a nice website and offering the largest share of the block reward.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On the surface this might sound no different than someone with an mining rig shopping around for a good mining pool but there are crucial differences:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 1.  The person making the decision is forced into it just because they own the currency -- someone with a mining rig has purchased it with the intent to make profit by participating in consensus.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 2.  When you join a mining pool your systems are very much still online. You are just partaking in a pool to reduce your profit variance. You still see every block that you help create and you never help create a block without seeing it first.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 3.  If by SquareSpace sybil attack you gain a dishonest majority and start censoring transactions how are the users meant to redelegate their stake to honest pools?\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     I guess they can just send a transaction delegating to another pool...oh wait I guess that might be censored too! This seems really really bad.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     In Bitcoin, miners can just join a different pool at a whim. There is nothing the attacker can do to stop them. A temporary dishonest majority heals relatively well.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e There is another severe disadvantage to this on-chain delegation system: every UTXO must indicate which staking account this UTXO belongs to so the appropriate share of block rewards can be transferred there.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Being able to associate every UTXO to an account ruins one of the main privacy advantages of the UTXO model.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e It also grows the size of the blockchain significantly.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e ### \"Pure\" proof of stake (Algorand)\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Algorand's4 approach is to only allow online stake to participate in the protocol.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Theoretically, This means that keys holding funds have to be online in order for them to author blocks when they are chosen.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Of course in reality no one wants to keep their coin holding keys online so in Alogorand you can authorize a set of \"participation keys\"1 that will be used to create blocks on your coin holding key's behalf.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Hopefully you've spotted the problem.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e You can send your participation keys to any malicious party with a nice website (see random example 2) offering you a good return.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Damn it's still Proof-of-SquareSpace!\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e The minor advantage is that at least the participation keys expire after a certain amount of time so eventually the SquareSpace attacker will lose their hold on consensus.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Importantly there is also less junk on the blockchain because the participation keys are delegated off-chain and so are not making as much of a mess.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e ### Conclusion\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I don't see a way to get around the conflicting requirement that the keys for large amounts of coins should be kept offline but those are exactly the coins we need online to make the scheme secure.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e If we allow delegation then we open up a new social attack surface and it degenerates to Proof-of-SquareSpace.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e For a \"digital gold\" like system like Bitcoin we optimize for simplicity and desperately want to avoid extraneous responsibilities for the holder of the coin.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e After all, gold is an inert element on the periodic table that doesn't confer responsibilities on the holder to maintain the quality of all the other bars of gold out there.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Bitcoin feels like this too and in many ways is more inert and beautifully boring than gold.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e For Bitcoin to succeed I think we need to keep it that way and Proof-of-Stake makes everything a bit too exciting.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I suppose in the end the market will decide what is real digital gold and whether these bad technical trade offs are worth being able to say it uses less electricity. It goes without saying that making bad technical decisions to appease the current political climate is an anathema to Bitcoin.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Would be interested to know if you or others think differently on these points.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Cheers,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e LL\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Fri, 21 May 2021 at 19:21, Billy Tetrud via bitcoin-dev bitcoin-dev at lists.linuxfoundation.org wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I think there is a lot of misinformation and bias against Proof of Stake. Yes there have been lots of shady coins that use insecure PoS mechanisms. Yes there have been massive issues with distribution of PoS coins (of course there have also been massive issues with PoW coins as well). However, I want to remind everyone that there is a difference between \"proved to be impossible\" and \"have not achieved recognized success yet\". Most of the arguments levied against PoS are out of date or rely on unproven assumptions or extrapolation from the analysis of a particular PoS system. I certainly don't think we should experiment with bitcoin by switching to PoS, but from my research, it seems very likely that there is a proof of stake consensus protocol we could build that has substantially higher security (cost / capital required to execute an attack) while at the same time costing far less resources (which do translate to fees on the network) without compromising any of the critical security properties bitcoin relies on. I think the critical piece of this is the disagreements around hardcoded checkpoints, which is a critical piece solving attacks that could be levied on a PoS chain, and how that does (or doesn't) affect the security model.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e @Eric Your proof of stake fallacy seems to be saying that PoS is worse when a 51% attack happens. While I agree, I think that line of thinking omits important facts:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   The capital required to 51% attack a PoS chain can be made substantially greater than on a PoS chain.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   The capital the attacker stands to lose can be substantially greater as well if the attack is successful.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   The effectiveness of paying miners to raise the honest fraction of miners above 50% may be quite bad.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   Allowing a 51% attack is already unacceptable. It should be considered whether what happens in the case of a 51% may not be significantly different. The currency would likely be critically damaged in a 51% attack regardless of consensus mechanism.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Proof-of-stake tends towards oligopolistic control\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e People repeat this often, but the facts support this. There is no centralization pressure in any proof of stake mechanism that I'm aware of. IE if you have 10 times as much coin that you use to mint blocks, you should expect to earn 10x as much minting revenue - not more than 10x. By contrast, proof of work does in fact have clear centralization pressure - this is not disputed. Our goal in relation to that is to ensure that the centralization pressure remains insignifiant. Proof of work also clearly has a lot more barriers to entry than any proof of stake system does. Both of these mean the tendency towards oligopolistic control is worse for PoW.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Energy usage, in-and-of-itself, is nothing to be ashamed of!!\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I certainly agree. Bitcoin's energy usage at the moment is I think quite warranted. However, the question is: can we do substantially better. I think if we can, we probably should... eventually.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Proof of Stake is only resilient to ⅓ of the network demonstrating a Byzantine Fault, whilst Proof of Work is resilient up to the ½ threshold\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e I see no mention of this in the pos.pdf you linked to. I'm not aware of any proof that all PoS systems have a failure threshold of 1/3. I know that staking systems like Casper do in fact have that 1/3 requirement. However there are PoS designs that should exceed that up to nearly 50% as far as I'm aware. Proof of work is not in fact resilient up to the 1/2 threshold in the way you would think. IE, if 100% of miners are currently honest and have a collective 100 exahashes/s hashpower, an attacker does not need to obtain 100 exahashes/s, but actually only needs to accumulate 50 exahashes/s. This is because as the attacker accumulates hashpower, it drives honest miners out of the market as the difficulty increases to beyond what is economically sustainable. Also, its been shown that the best proof of work can do is require an attacker to obtain 33% of the hashpower because of the selfish mining attack discussed in depth in this paper: https://arxiv.org/abs/1311.0243. Together, both of these things reduce PoW's security by a factor of about 83% (1 - 50%*33%).\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Proof of Stake requires other trade-offs which are incompatible with Bitcoin's objective (to be a trustless digital cash) — specifically the famous \"security vs. liveness\" guarantee\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Do you have a good source that talks about why you think proof of stake cannot be used for a trustless digital cash?\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e You cannot gain tokens without someone choosing to give up those coins - a form of permission.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e This is not a practical constraint. Just like in mining, some nodes may reject you, but there will likely be more that will accept you, some sellers may reject you, but most would accept your money as payment for bitcoins. I don't think requiring the \"permission\" of one of millions of people in the market can be reasonably considered a \"permissioned currency\".\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 2.  Proof of stake must have a trusted means of timestamping to regulate overproduction of blocks\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Both PoW and PoS could mine/mint blocks twice as fast if everyone agreed to double their clock speeds. Both systems rely on an honest majority sticking to standard time.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Wed, May 19, 2021 at 5:32 AM Michael Dubrovsky via bitcoin-dev bitcoin-dev at lists.linuxfoundation.org wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Ah sorry, I didn't realize this was, in fact, a different thread! :)\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Wed, May 19, 2021 at 10:07 AM Michael Dubrovsky mike at powx.org wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Folks, I suggest we keep the discussion to PoW, oPoW, and the BIP itself. PoS, VDFs, and so on are interesting but I guess there are other threads going on these topics already where they would be relevant.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Also, it's important to distinguish between oPoW and these other \"alternatives\" to Hashcash. oPoW is a true Proof of Work that doesn't alter the core game theory or security assumptions of Hashcash and actually contains SHA (can be SHA3, SHA256, etc hash is interchangeable).\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Cheers,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Mike\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Tue, May 18, 2021 at 4:55 PM Erik Aronesty via bitcoin-dev bitcoin-dev at lists.linuxfoundation.org wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 1.  i never suggested vdf's to replace pow.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 2.  my suggestion was specifically in the context of a working\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     proof-of-burn protocol\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   vdfs used only for timing (not block height)\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   blind-burned coins of a specific age used to replace proof of work\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   the required \"work\" per block would simply be a competition to\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     acquire rewards, and so miners would have to burn coins, well in\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     advance, and hope that their burned coins got rewarded in some far\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     future\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   the point of burned coins is to mimic, in every meaningful way, the\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     value gained from proof of work... without some of the security\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     drawbacks\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   the miner risks losing all of his burned coins (like all miners risk\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     losing their work in each block)\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   new burns can't be used\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   old burns age out (like ASICs do)\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e -   other requirements on burns might be needed to properly mirror the\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     properties of PoW and the incentives Bitcoin uses to mine honestly.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 3.  i do believe it is possible that a \"burned coin + vdf system\"\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     might be more secure in the long run, and that if the entire space\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     agreed that such an endeavor was worthwhile, a test net could be spun\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     up, and a hard-fork could be initiated.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 4.  i would never suggest such a thing unless i believed it was\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     possible that consensus was possible. so no, this is not an \"alt\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e     coin\"\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Tue, May 18, 2021 at 10:02 AM Zac Greenwood zachgrw at gmail.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Hi ZmnSCPxj,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Please note that I am not suggesting VDFs as a means to save energy, but solely as a means to make the time between blocks more constant.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Zac\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e On Tue, 18 May 2021 at 12:42, ZmnSCPxj ZmnSCPxj at protonmail.com wrote:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Good morning Zac,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e VDFs might enable more constant block times, for instance by having a two-step PoW:\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 1.  Use a VDF that takes say 9 minutes to resolve (VDF being subject to difficulty adjustments similar to the as-is). As per the property of VDFs, miners are able show proof of work.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e 2.  Use current PoW mechanism with lower difficulty so finding a block takes 1 minute on average, again subject to as-is difficulty adjustments.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e As a result, variation in block times will be greatly reduced.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e As I understand it, another weakness of VDFs is that they are not inherently progress-free (their sequential nature prevents that; they are inherently progress-requiring).\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Thus, a miner which focuses on improving the amount of energy that it can pump into the VDF circuitry (by overclocking and freezing the circuitry), could potentially get into a winner-takes-all situation, possibly leading to even worse competition and even more energy consumption.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e After all, if you can start mining 0.1s faster than the competition, that is a 0.1s advantage where only you can mine in the entire world.\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Regards,\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e ZmnSCPxj\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev mailing list\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e --\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Michael Dubrovsky\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Founder; PoWx\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e www.PoWx.org\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e --\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Michael Dubrovsky\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e Founder; PoWx\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e www.PoWx.org\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev mailing list\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev mailing list\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev mailing list\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e \u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev"}