저자: AndreasM.Antonopoulos · 외국인
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결론: 이 영상은 특정 자산의 가격 방향을 예측하는 내용이 아니라 비트코인 보안(51% 공격, 지분증명 비교, 체인락)에 관한 기술 해설이다. 정부의 51% 공격 가능성: 무제한 자금이 있어도 채굴장비 확보가 어렵고(7nm 이하 ASIC 제조사 생산 능력 예약), 공격 성공 시 즉각적 대응과 비트코인 신뢰도 상승 역효과가 있어 비효율적이라고 설명. 채굴자 매수 비용: 정직한 채굴의 확률적 수익보다 공격 성공 위험을 보상할 만큼 뇌물이 비싸야 하므로 경제적으로 비현실적이라는 논리. 작업증명 vs 지분증명: 작업증명은 과거 기록 재작성 비용이 채굴 에너지 비용과 비슷하지만, 위임지분증명은 담합 시 재작성 비용이 사실상 0이라 보안성이 다르다고 주장. 체인락: 마스터노드 60% 투표로 체크포인트를 찍는 하이브리드 방식으로, 작은 체인의 51% 공격을 어렵게 하지만 비트코인에는 해시파워가 충분해 불필요하다는 평가. 비트코인 도입에는 Sybil 방지용 지분 시스템이 필요하다고 언급. 리스크/조건: 해시파워가 약한 신생 체인은 51% 공격에 취약하다는 점. 일부 기사의 51% 공격 관련 오해도 지적. 출연자 전망: 해당 없음(가격 전망 발언 없음).
다듬은 글
this is a question that comes up often and in fact there's a few questions today that all relate to the same kind of topic so I'm going to bundle them all together and answer them all together can government's launch a 51% network attack Vasilis asks governments have an unlimited supply of money they can print an unlimited amount and in theory they can purchase an almost unlimited amount of mining equipment since they also have access to free unlimited power why can they not acquire the majority of the network cash rates and launch a 51% attack to harm the Bitcoin network they could even bribe all the major pool mining players distr distributing all block rewards to them according to the hash rate percentage to discourage them from further mining so what do you thought - that if governments start to feel that bitcoin is a threat to them and make a collaborative decision let's say in a g20 summit without stopping them from succeeding what are your thoughts well first of all I don't believe in this general idea that governments have their together are organized enough and even enough to collaborate on a global basis to do anything meaningful other than press conferences you know if the g20 could get its act together and figure out how to collaborate maybe they could solve some more serious problems like I don't know climate change the global rise of fascism war and diplomacy you know things like that for example poverty hey but they can't very rarely do governments collaborates on a on a global scale now what if governments really got got it in for Bitcoin and decided they were going to spend a lot of money in order to launch some kind of 51% stack first of all you have to understand the what can be done with a 51% attack is limited effectively to a short term denial-of-service attack against Bitcoin which would lead to immediate countermeasures would cost an enormous amounts of money and ultimately would most likely prove that you can't disrupt Bitcoin that way only by spending a lot of money so governments don't want to spend a lot of money to prove you can't disrupt Bitcoin for very long that's the most counterproductive thing they could do it would actually produce enormous ly positive marketing for Bitcoin because if they failed in this 51% attack eventually failed in this 51% attack it would prove the Bitcoin is resilient so it's unlikely that anyone's going to try and attack some the Bitcoin chain in such an expensive way when there are cheaper more effective ways to attack his through long propaganda and various other things that we're seeing already so let's go and look at this question a bit more detailed governments have an unlimited supply of money yes but if they use an unlimited supply of money about money loses its value it's called inflation so not really and in theory they can purchase with fiat and almost unlimited amounts of mining equipment again in theory yes in practice no and part of the reason is that in practice that involves collaborate in which at manufacturers who already have all of their capacity booked they would have to kick out some other private buyer in order to replace their orders with government orders that gets noticed or build their own silicon fabrication plants which you know if they did maybe they would actually produce something valuable rather than just mining equipment to disrupt Bitcoin so first of all it's difficult to buy all of the mining equipment this is one of the hidden benefits of ASIC mining it's that you actually need equipment that equipment is manufactured in some of the more expensive fabrication facilities you know 7 nanometer and below facilities nowadays and those facilities are working 24 hours a day and booked months or sometimes even heroes in advance with orders because there aren't that many of them so it's difficult to acquire this hardware in secret you could bribe the miners but first you'd have to find them and you'd have to persuade them that your bra in order to do a very risky 51% attack is better than the alternative which is to simply continue mining honestly and earning fees and block rewards that way and that's always a challenge because just continuing to mine honestly and earning fees and rewards has a very high probabilistic ly determines level of success you know that with a certain amount of hash rate you're going to succeed in finding blocks at a certain percentage of the total and as a result you have a fairly regular income stream in the future if you already have the mining equipment whereas if you take this bribe from this government to do an attack on the network yes if the attack succeeds you get the mining rewards but who knows if it's gonna succeed so they need to bribe you a lot more let's think about it from a point of economics if you have guaranteed returns at a certain percentage of blocks simply by continuing to mine honestly and then you have risky returns by doing an attack against network consensus that may fail then that risk has to be incorporated into the bribe is that they will pay you which means that the bribe has to be more expensive than the block rewards that you would otherwise earn by a certain percentage that represents the risk of the attack failing and you're not actually getting paid the pride oh well that makes it more expensive for someone to bribe is then to simply use that money to buy equipment to mind honestly and again these are the profits incentives that exist in every case so could the government launch a 51% network attack theoretically yes in practice it's a very very expensive effort with a very low probability of success that may backfire incredibly badly and is far too expensive compared to all of the other ways you could attack the network which includes for example making the capital gains reporting so onerous that no one's going to do retail transactions as has happened in the United States send threatening letters from the IRS as this happened in the United States making criminals out of anyone who purchases Bitcoin or persuading the banks to shut down the bank accounts as this happens in India etc etc etc so the reason governments haven't tried a 51% attack is not because they can't afford it not because they can't try to pull it off it's because they understand that it's the least likely to succeed of all of the other strategies and they're trying all of the other strategies instead question format if all it takes is electricity to attack a proof-of-work Network then isn't then isn't delegated proof of state a more secure way of reaching consensus if delegated proof of stake is about game theory and using eos as an example you wouldn't need to bribe 15 out of 21 elected block producers those block producers would then lose their reputation and position as wok producers not going to happen in my opinion what is your opinion my opinion is that there's a fundamental difference between bribing miners and bribing block producers is in the beginning of your question where you say if all it takes is electricity to attack proof of work it's not all it takes all it takes is electricity and hardware brought together at the right time in the right place with the rights and senses and that is an incredibly difficult thing to do and the delegated proof of state system all it takes is money to bribe the producers and the risk of pulling off an attack is their reputation only but not monetary risk in a proof-of-work system it takes a lot of money to bribe the existing miners or by electricity and mining equipment but the risk is not limited to reputation it's also the risk of losing the money you spend on energy because no matter what you do in a proof-of-work system if you attack the system you will have to spend the energy again to at least the same extents that you spent the energy the first time you mind blocks in order to rewrite history the cost of rewriting is the past in a proof-of-work system is the same as the cost it took to write it in the first place a bit less because you have more efficient equipments but that's marginal whereas the cost of rewriting history in a delegated proof of stake system is zero as long as you collude then you can the cost of the producers colluding is zero they can rewrite the history all the way back to the beginning and they don't lose anything so the proof of work you still have to provide work and that work is validated by all the producers now you can change these parameters a bit you can use checkpointing and other techniques to limit what the block producers can do in a network like this you can punish them in a more severe way for trying to rewrite history further back but the bottom line is that proof of work produces a different quality of immutability than proof of stake systems that doesn't mean the proof of stakes systems are not useful but in fact if you look at the game theory EOS block producers have been attacked with their reputation and their lobbying and various other techniques and a lot of proof of stakes systems use what they call proof of proof one example of that is very block where essentially what they do is they checkpoint their proof of stake system into Bitcoin in order to protect against essentially rewriting attacks and consensus attacks against weaker chains so proof of work and proof of stake are not entirely equivalent you can argue that one is better for one type of application and then the other sure go ahead but they're not equivalent and you can't just simply substitute one for the other I think there's a good place for both of them and they can solve different problems and I actually in fact I think they work best when used together so you can check point to prove mistake system and a proof-of-work you can use a proof-of-work system to underpin the security of many other chains as is done today was proof of proof systems and very block Tim Wright asks our chain locks just hype or something interesting today an out coin called - activated chain locks which they claim makes 51% attacks virtually impossible and makes their block chain arguably as secure or more secure than the Bitcoin blockchain Zhi coin have already announced that they will be copying chain locks - do you think there's anything worthwhile in this tech and how does it differ from checkpoints could Bitcoin adopt chain locks there's a follow-up comment from Jax saying it sounds like a bit check points based on master node voting yeah that's exactly what it is so let's explain the technology a bit in a system like - there are essentially two layers of consensus there's proof of work so sorry there's a proof of stake system that operates through the master nodes and in a proof of stake system that operates through the master nodes in order to operate a master node you need to have I believe it's a thousands - in order to operate one of these master nodes so there's many of these and these master nodes have a special status within the system chain locks are checkpoints essentially what they do is they vote on a specific block being the head of the current chain and as long as the master knows all see that block as the head of the chain a certain percentage of them can vote and once it's received sixty percent of the votes I think then that's check pointed meaning that all of the nodes in the system will reject any blocks that are not children of that block so they will refuse to reorganize the chain now essentially what that does is it creates a hybrid proof of work proof of state system you can't attack the proof of work with a 51% attack because the masternodes are checkpointing with a with a vote using threshold signatures and 160 percent of them agree on the current state of the chain that locks in that chain with a checkpoint so it's a it's a novel and interesting way to do a hybrid proof of work proof of stake system and Jess it will make 51% attacks much harder on that particular chain in fact if you want to do a 51% attack you actually have to do a 60% attack where you either compromise the code running on the masternodes or you put enough snake which probably wouldn't be possible to run 60% of the masternodes yourself I think at the current rates that would be like 300 million dollars so that's not feasible so why is - doing it and the primary reason - NZ coin are doing it is because we've seen again and again and again that systems that have proof of work that has enormous hash rates and uses Asics like Bitcoin are very difficult and expensive to attack with a 51% attack so they're not attacked but systems that have lower hash rates or that have hash rates that depends on GPUs not ASIC based mining then people can switch GPU mining from other chains and attack a chain that's a bit weaker in its hashing power quite effectively we've seen 51 percent attacks against if they're in classic we've seen I believe Z coin had a 51% attack at some point when we've seen attacks against a number of other chains and this isn't you know I'm not attacking these chains by saying this is it just means that proof-of-work systems are indeed vulnerable when the chains are brand new and they don't have enough hashing power to make it prohibitively expensive so change enormous acure with proof-of-work it's the cost of attacking it far far exceeds the potential benefits of attacking it it's a gain serious system so if the cost of attacking it doesn't exceed the potential gains then it will and does get attacked and we've seen this happen again and again on weaker chains we haven't seen it happen in Bitcoin so in that case if you have a chain that doesn't have enough hashing power to really make it completely cost and effective to attack then you need something else to buttress that and and that's essentially what chain locks is doing here it's a hybrid proof of work proof of stake system it's a smart way of doing it because instead of having a proof of way proof of stake system on its own which is vulnerable to historical immutability attacks or proof of work system that without enough hash powers vulnerable to 51% attacks by combining them you have a system that defends better against 51% attacks that improve of work and defense better against historical immutability attacks than proof of stake a good solution for a system like - could Bitcoin adopt chain locks no and the reason at least not on is conjured iteration the reason is that chain locks basically require some kind of Sybil proof system of nodes simple proof meaning that they cannot be Sybil attack they cannot be faked and the only way to prevent Sybil attacks the only two ways we know today are proof of work meanings that you put work behind each node that's participating consensus or proof of stake which means you have to put money up behind each notice participating in consensus so in order for Bitcoin to adopt chain locks it would have to have some kind of proof of stake system interestingly enough because lightning nodes deposit of money in in payment channels and use that money which is locked into it to transactions to earn fees and things like that this is the kind of things that could cause the emergence eventually of a proof of stake system but that's a much longer conversation so what a chain locks are they just hype or something interesting there's something interesting for change that don't have enough hash rate to defend against proof of sorry to defend against 51 percent attacks they're not really that interesting for Bitcoin primarily because Bitcoin doesn't need them it has enough hash rate to defend against 51 percent attacks some of the articles I read about this were very very wofully and they claimed that 51 percent attacks are a kind of fatal weakness of proof of work chains and that in fact once miners get 51 percent they can do anything they want including validate invalid transactions and invalidate valid transactions not true there's a lot of misconceptions about how powerful work actually works in these articles so be careful when you read that don't always take it for granted some of the facts are wrong but an interesting solution from - nevertheless you
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