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Israeli researchers discovered the first consensus-level attack on Ethereum
- cryptoisthekey 4y agoThe attack is called "Uncle Maker", as it allows attackers to displace main-chain blocks with their own blocks, thus making these displaced blocks become uncles. By analyzing the timestamps of the last 3 million blocks, it becomes apparent that F2Pool has performed the attack in the wild.
- aaaaaaaaata 4y agoWhat is the implication of the findings?
- sschueller 4y agoETH 2.0 delayed by another year...
- quickthrower2 4y agoETH 2.0 sounds like commercial fusion power.
- pelagicAustral 4y agoHalf-Life 3 much?
- api 4y agoThere's steady but slow progress in fusion in energy density and power output, so no.
- inphovore 4y agoThe issue with fusion has been the same for the last 50 years. Harvesting the gamma’s full electron volt right out of the reaction. We’re still 50+ years away. Nothing in modern technology suggests otherwise. Science media has to explain why billions are dumped into these programs each year (as though edge science isn’t enough.) In the meantime, everyone will be happy if we can harvest just enough to make the cost of the exchange worth while. most optimistically through harvesting the heat from a sustained reaction (which is 1000 x less potential).
- shakezula 4y agoWhy would this have anything to do with Eth2 when it’s explicitly a vulnerability in Proof of Work systems?
- oneoff786 4y agoGood for crypto
- dang 4y agoCould you please stop posting unsubstantive and/or flamebait comments? You've been doing it a lot, unfortunately, and it's not what this site is for. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- xbar 4y agoProbably that if you weren't mining on f2pool for the last few years you were severely disadvantaged, and that if every other pool doesn't start executing this "attack", they are not playing the ETH game correctly.
- mistrial9 4y agoexaggeration does not lend clarity .. an advantage is short-lived, like so many opportunistic moves in real life? the math says that the "severity" of the disadvantage is related to the change in difficulty at that juncture
- deleted 4y ago[deleted]
- NickRandom 4y agoSee also - Uncle Maker: (Time)Stamping Out The Competition in Ethereum ( https://www.researchgate.net/publication/362482526_Uncle_Maker_TimeStamping_Out_The_Competition_in_Ethereum https://www.researchgate.net/publication/362482526_Uncle_Mak... )
- mjburgess 4y ago> Although most mining pools produce relatively inconspicuous-looking blocks, F2Pool blatantly disregards the rules and uses false timestamps for its blocks. Specifically, whenever a block should have a timestamp difference from its parent which is divisible by 9 (precisely the time at which mining difficulty decreases), F2Pool hangs at the preceding second a while longer, thereby increasing mining difficulty and profits. Thus, in the past two years, F2Pool didn’t have even a single block with a timestamp which is divisible by 9. from the medium post
- __s 4y agoWhat's the implication if everyone does this? Does it eventually converge on a working consensus?
- quickthrower2 4y agoHaving read bits of the paper and the article I don't get why divisibility by 9 matters. Can anyone ELI-9 this?
- horsawlarway 4y agoI haven't done the math, but I believe it's because of two points: 1 - The "difficulty" of mining a block is based on how long it's been since the last block was mined, with a drop off in difficulty at 9 seconds 2 - If two blocks "tie", the the block that was more difficult to mine is the winner, and takes the rewards. --- So essentially, it's a way of breaking ties in their favor - reliably - by cheating a smidge on the timestamps they send for their blocks.
- tromp 4y agoIt matters according to equation (48) on page 7 in the Ethereum design specification [1]. This section specifies how to adjust the difficulty target for each new block. The optimization (I hesitate to call it an attack) identified in the paper could have been rendered ineffective if rounding down (for division by 2048 and by 9) was delayed until after the multiplication in equation (45), resulting in a much smoother adjustment. The so-called "yellow paper" sadly lacks a motivation of all the seemingly arbitrary numbers involved. [1] https://ethereum.github.io/yellowpaper/paper.pdf https://ethereum.github.io/yellowpaper/paper.pdf
- yuan43 4y ago> Whenever F2Pool's block timestamps reach the point where mining difficulty is supposed to decrease, they artificially set them to be one second earlier. F2Pool has been executing this attack over the past two years, and the evidence has been hiding in plain sight! ... This has the effect of making it harder for the rest of the network to compete against F2Pool's blocks. In this way, F2Pool can, or so it appears, give itself an advantage while taking zero risk. It would be irrational not to adopt this strategy. The thread doesn't say what happens if the entire network adopts this strategy - maybe it's in the paper...
- mw888 4y agoThis issue actually seems less severe than selfish meaning exactly for the reason that all miners can enact it to the same proportional benefit.
- arisAlexis 4y agodoesn't matter, ETH turns to PoS very soon
- bombcar 4y ago
- chpatrick 4y agoSeems like it's been a PoS for a few years.
- foepys 4y agoThis has the same energy as fusion power is only 30 years away. I have been hearing this since at least 2019.
- affinepplan 4y agook but---it's literally set to merge in like a month. It did get delayed for quite a while yes, but it's happening now for realsies
- ogogmad 4y agoETH price unaffected by the news, it seems.
- spookthesunset 4y agoCryptocurrency never seems to track against real world events. Kinda makes you wonder how much of its volume is legit.
- spamizbad 4y agoAh but it does get impacted by things like interest rates and tech stocks.
- spookthesunset 4y agoVery true. And arguably government stimulus checks too. But bad news? Your crypto coin has a documented flaw that allows it to be manipulated? Good news for your coin!
- shakezula 4y agoweird time to make this argument in the wake of the latest cryptocurrency downturn which tracked almost lockstep with the stock market.
- timbit42 4y agoAs Eth is moving to PoS soon, I'd expect it have to affect Bitcoin's price more.
- doomroot 4y agoThis does not work on bitcoin. Bitcoin’s difficulty targeting algorithm only retargets every 2016 blocks. This attack is only possible for diff target algos that retarget within a single block slot.
- mw888 4y agoThis news is not as bad as known advantages which can be exploited in PoW for several years now, namely selfish mining, which only benefits the largest or most coordinated miners. This attack is open for all, which effectively cancels out the advantage it offers (assuming everyone does it); the externalization is consistent, minor inaccuracies of time stamps on blocks.
- TacticalCoder 4y agoIs this an attack on PoW or PoS? For Ethereum, since quite a while, is already mining blocks on both the PoW and the PoS chain.
- vivegi 4y agoFrom the paper: > We introduce a novel attack vector on proof-of-work (PoW) cryptocurrencies which relieson timestamp manipulations, instead of traditional ones such as block withholding
- ironSkillet 4y agoMaybe it's just that hindsight is 20/20, but given how simple this trick is, I'm surprised this wasn't obvious to someone when declaring the policy.
- Majromax 4y agoIt seems to me that there's a delicate, probably impossible balance: the difficulty decreases at the critical times, but not fast enough to compensate for the tiebreak. Suppose the difficulty decreased by a lot: at 0:59 it is effectively impossible to mine a block but at 1:00 it is so easy that a speak-and-spell could do it. In that case, it seems like the optimum strategy for a selfish miner would be to try to post-date the timestamp and mine an "easy" block. It would still lose to a legitimately-mined "hard" block, but it would profit in expectation by being the first "easy" block to reach the network. On the other hand, setting a difficulty schedule such that there is no single optimum timestamp might impose a too-fast decay on difficulty.
- ogogmad 4y agoThis might not even be news to the people in the knows. @foldfinance says We have known this to be the case with F2Pool for awhile but flashbots refuses to do anything See https://nitter.42l.fr/foldfinance/status/1555477252736897024#m https://nitter.42l.fr/foldfinance/status/1555477252736897024... @railgun_project says This is a well known drawback of proof-of-work systems that was talked about even before Ethereum was launched. It is inaccurate to say that this is a recent "disclosure" See https://nitter.42l.fr/railgun_project/status/1555560277290192896#m https://nitter.42l.fr/railgun_project/status/155556027729019... @mesquka says Not as big of a discovery as it's made to seem IMO. Essentially just intentionally caused temporary chain forks to gain a competitive mining advantage. Known as an issue in PoW since Bitcoin launch (see any discussion about 'Longest Chain Rule' and things like 'Selfish Mining') See https://nitter.42l.fr/mesquka/status/1555562671575023618#m https://nitter.42l.fr/mesquka/status/1555562671575023618#m
- Ar-Curunir 4y agoAll the tweets about it being a well known drawback are missing the point: yes, we knew that there's a general class of attacks affecting PoW this way, but it's the first time AFAIK that there's been public evidence of this attack actually occurring.
- shmoneforeight 4y agoTo reaffirm Ar-Curunir, even the author of the original selfish mining paper thinks this is a big deal: https://twitter.com/ittayeyal/status/1555665714178101249 https://twitter.com/ittayeyal/status/1555665714178101249
- shmoneforeight 4y agoAnd now, the second author of the selfish mining paper joins in: https://twitter.com/el33th4xor/status/1555926860067921920 https://twitter.com/el33th4xor/status/1555926860067921920
- 4y ago
- mypastself 4y agoEven for someone with a reasonable amount of knowledge in the area, this was a difficult read. “…the attack does not entail any behavior which has a non-zero probability of earning less than mining honestly…”
- cwmma 4y agoYeah I had to read that a few times due to to a triple negative and a comparison, I think it's trying to say that the strategy has no parts that have any chance of earning you less money then normal.
- creeble 4y agoHas this strategy been used successfully in Bitcoin, or why not?
- Synaesthesia 4y agoAs the 2nd tweet explains, the difficulty of Ethereum changes dynamically amd can decrease the longer that a block hasnt been mined, this is not the case in Bitcoin.
- infthi 4y agoBitcoin also adjust difficulty - but does that every two weeks or so. would it make sense to mine for a sibling for the last block before the difficulty increase while everyone else mines for a child block with increased difficulty? thus having twice the relative hashrate for 10 min every time difficulty increases.
- game-of-throws 4y agoNo, this attack wouldn't work on bitcoin. Bitcoin chooses the chain with the most total work (which is blocks x difficulty), not the most blocks. Else someone could fork the chain from a block sometime in 2009 when difficulty was very low and outpace the rest of the network.
- shakezula 4y agoThis is not true. Bitcoin has a difficulty adjustment. https://www.blockchain.com/charts/difficulty https://www.blockchain.com/charts/difficulty https://www.coindesk.com/learn/bitcoin-mining-difficulty-everything-you-need-to-know/ https://www.coindesk.com/learn/bitcoin-mining-difficulty-eve...
- mw888 4y agoIt was true, but they didn’t specify that Bitcoin adjusts difficulty when the new block is published, not ever while waiting for a block.
- delaaxe 4y agoGuess what? Ethereum is switching from proof of work to proof of stake in about a month, so all of this is irrelevant