Finishing: Sherry, Jin Xiaojia: Xiao Jie; calibration
From the beginning of the birth of digital currency, 51% attack is a hot topic in the discussion, the proof of work for the digital currency consensus mechanism, the biggest security risk is there may be 51% attack. If someone holds more than 51% of the whole network, then he can launch an attack. This attack can let the money be spent two times, or to change the state has reached a consensus.
The bitcoin network has been running for more than ten years, most of the time you will feel that the 51% attack just stays at the theoretical level, it actually happened rarely heard. But this time, it really happened, is the ETC of the 51% attack.
In this period, Fork It anchors (Terry, Daniel, Kevin) and you can talk to a ETC 51% attack sequence of events.
ETC 51% attack sequence of events
The 51% Daniel:ETC attack as an organized, premeditated, masterminded the attack. In January 6, 2019, a company called Bittrue exchange, issued notice that they found a $13000 ETC abnormal withdrawals. Is the transaction is rolled back in charge, but the transaction balance in exchange was found, was blocked off.
Further tracing, Coinbase officials found more large-scale recombinant ETC network.
Knowledge points: the so-called network (Block Reorganization) is the reorganization of the network six to eight blocks or more blocks have been miners dug up, but suddenly all these blocks are removed, produced some new pieces to replace these have been confirmed by block.
Coinbase official blog for the first time released a suspected problem of three large-scale network reorganization. After a comparison of the famous gate.io exchange was exposed suffered 51% attacks, hackers in this transaction all two large amount of recharge, recharge the two through the network reconfiguration is removed, hackers on the Internet through selling them in the exchange of currency, or to recharge into exchange currency into other currencies, finally to cash. Gate.io subsequently issued a notice that the attack caused about $200 thousand worth of losses.
This incident was exposed, some technology enthusiasts, especially domestic slow fog, PeckShield and other security organizations began to investigate the attack, they found a 51% attack from a site called NiceHash, hackers can at this site rent to a certain size of work force, and then to attack the ETC network.
At that time, more than 112% ETC network operator can be rent, and rent to the operator can engage in ETC mining, as well as any of the things you want to do. The hacker is to use the NiceHash website to rent is to attack.
Why ETC is vulnerable, is actually two features based on ETC.
The first feature is The attack cost . The main network we assume that ETC is 100, and now want to rent 101 of the calculated force to attack the ETC network, hacker attacks by leading to an exchange loss of about $200 thousand, is also the hackers earn $200 thousand. We feel the need to spend much money to rent a over ETC network is main attack force can earn 200 thousand dollars?
The answer is hackers as long as the cost of $5000 per hour. From that day to attack now, ETC network is also the main market value decline further, now go to rent is cheaper than the ETC network to attack before the attack.
Before the Fork It 2, we know that ETC is the 2016 THE DAO event branched chain. In a very long period of time, ETC is probably the total network capacity is Ethernet Fang 1/20, its currency price is about 1/20 square Ethernet network, but with the passage of time, the ETC network is less and less, the value is also more and more low, now just reached especially vulnerable to attack state.
ETC another feature is its fluidity is very good . Ethernet workshop is the mainstream digital currency is most exchanges worldwide support, ETC and Ethernet square root, so the exchange support for ETC is very good. Although its price is low, too low, but in view of its liquidity, hackers do a 51% attack in at least two ways to make money.
The first way is to exchange Shuanghua attack: turn a bill, and then through an attack on the chain get rid of this transfer in this consensus, also retains the exchange transfer records, so in the exchange will have a nonexistent money to cash. Another way is to achieve a 51% successful hacker attacks, is a very large negative news, it can affect the futures market, hackers can make money through early implementation in the futures market short arbitrage.
The PoW consensus has shaken the cornerstone?
Terry: in fact, this is not the first time the 51% PoW attacks, there are a lot of small coins just on the line is “destroyed”, the so-called “destroyed”, is the use of force is to attack. Whether the new currency or small currency, when they count force, market value is not high enough, hackers can use relatively low cost, to attack a chain, this is particularly unsafe.
Then I’ll have a doubt: this incident, there has been a lot of news about PoW, more representative is: “ ETC PoW suffered 51% attacks, the cornerstone of consensus thus shaken? ” (a title party) I want to ask is, you lose faith on the PoW consensus algorithm? Or that it is really a problem?
Kevin: first PoW is a witch attack, the consensus algorithm is very simple, is to choose a random number of natural, can be completely fair.
Knowledge points: Witch attacks (Sybil Attack): in a peer-to-peer network, a single node usually has multiple identity, through most of the nodes of the control system to reduce redundant backup function.
If there is a malicious node in the network, so a malicious node can have multiple identities, the original need to backup data to multiple nodes is cheating and backup to the same malicious nodes (the malicious nodes disguised as multiple identities), so it is possible to node evil control network.
The other one is open, any node can participate in the consensus, the miners only need to buy a machine plug, can directly. If the network itself is very high, PoW’s advantage is very obvious. While the PoS constraints more, may need to stay online, buy Token, this process may have some personal information containing IP address will be exposed. The PoW system ensures each miner must submit block in the long chain, which makes each of the miners dug into a block, there is power as soon as possible to broadcast. These are the attributes of bitcoin Nakamoto Consensus very good.
But any consensus mechanism has its security model, there will be the possibility of being attacked . Only people understand the attack model of PoW, know how it can resist the attack. Other people do not fully understand the consensus, especially for new companies, including many in the PoS project, the foundation or other relevant organizations to hold 50% of Token, to ensure not to be attacked. The real growth in the “wild” in PoS, the operation time is very short, people are still groping in the process, but it is a very valuable research direction.
Daniel: Yes, the consensus mechanism do not understand, we are more worried about the unknown attacks, as well as for these attacks, we have no mature solutions. PoW, we know very well how the hacker attack.
Terry:Vitalik Twitter said that he had sent to PoS ETH, from the philosophy point of view is correct. Of course, there are a lot of opposition. A conversation about the founder of science and technology is the fog slowly, no matter what the algorithm, as long as it is to solve the Byzantine Generals Problem, it has its own security model. Like Kevin said, security assumption is not the same, will have their own problems , there are also many PoS did not solve the problem. In fact, our consensus algorithm for PoS also has pretty much understanding and awareness, we can in the future show special chat PoS.
But now I want to express is to replace PoW PoS, this is not a solution to the problem, or is that it may lead to many new problems. From the perspective of solving practical problems, people have put forward some real solutions, such as restructuring chain, BCH launched a reorganization of community protection (in BCH, ABC 0.18.5 version adds recombinant protection, can remove more than 10 pieces of recombinant).
Now the PoW mining methods can be divided into two kinds, one is to dig through the ASIC machine, such as bitcoin, the other one is to dig through the GPU machine (hereinafter referred to as the graphics, such as ETC mining). Have to admit is that graphics mining considered higher liquidity, because it can dig the currency more easily to rent is to attack a particular currency, after the end of a currency attack, even if the currency collapsed, miners can still dig through additional money to gain income. So the question is, is liquidity card mining so high, will to some extent affect the graphics mining chain security?
Daniel: Based on the fact that the entire computing power market is a stock market , in the current market environment, few people will invest in the market to buy the graphics card, increased computing power. On the contrary, more miners will choose to stop the machine, because now all currency prices are very low, mining uneconomical.
All the miners are free to choose which one to dig coins, usually rational miners will choose those profitable, profitable currency. The result is that all the currency will return to a relative breakeven point, each kind of currency or dig the profit may be almost. So now behind every currency support is maintained in a stable state.
In this steady state, some currency value is higher, it is more big, want to rent more than the main network is very difficult to attack. And those who because of high enough value, or mining economy, resulting in few miners to dig the currency is not very safe, very easy to rent an attacker to force attack.
Any one project, especially PoW is selected as the consensus protocol project, operator force growth phase in line early, will experience an unsafe stage, so how to from a dangerous state to a safe transition to mature stage is especially key.
ASIC Friendly or Not?
Terry: we have seen many projects, they have different attitudes to mining whether using ASIC machine, some are inconsistent, some are neutral, but some are friendly. If a small currency ASIC to dig, then it is more secure?
Kevin: it depends on how you define the safety. Small ASIC Friendly criticized the attitude of the currency two . One is the assumption that in a very short period of development can put a new project ASIC machine to do it, but we are optimistic about this project. Maybe there will be such a problem:
In general a project in the early stage of loose money is the fastest, and the fastest period to have a dividend of ASIC miners, so these miners may be the center of the. There may even be ASIC manufacturers themselves after the development of machine, and not to sell, but to dig their own currency, which would cause the Token itself is very concentrated. If the Token is too concentrated, the community will be very concentrated, then if there is need to vote by Token or by an online control force, are likely to have problems. Even if, as a monopoly situation like bitcoin ASIC machine manufacturers, manufacturers can produce the machine, dug up to Token, after selling Token, put the money back into the production and development, it will lead others to a body. So this is everyone on the ASIC Friendly criticized local.
Another is the number of projects with other projects (such as digging bitcoin mining machine) ASIC mining algorithm, so the market has a large number of ASIC mill digging in the bitcoin, this is not very safe for the project. Because once the project launched, bitcoin miners can direct the project for dimensionality reduction attack. As long as these bitcoin miners themselves have enough computing power, it is easy for the project is launched 51% attacks.
So the best way is to adopt a new algorithm , whether using graphics mining, ASIC or Friendly.
But for the adoption of a new algorithm of the project, there are also some problems. If it is used in graphics mining, because the card is the same, then the hacker can be loaded by mining software attacks on its. If it is used in ASIC ore mining, so the existing ASIC machine in the first stage it is difficult to directly attack, but this may cause some other problems, such as mining center.
We take Grin as an example. Grin mining design is very interesting, it has two Cuckoo based on Cycle (a type of graph workload invented by John Tromp certification, we will introduce in the next Fork It) algorithm, an anti ASIC (ASIC Resistant, graphics by mining, it is difficult to dig the ore with ASIC). Called Cuckaroo29; the other algorithm is called Cuckatoo31+ ASIC Friendly.
Beginning with Grin through massive video mining, and put out the money to the miners. Because Grin uses a new algorithm, so before the stock card can switch is in the past, but also a certain degree of difficulty. At the same time, Grin does not exclude ASIC, there is a certain amount of money from the ASIC machine dug up, with the passage of time, different mining algorithm to dig out the currency ratio will gradually change.
If the card to mercenaries, then ASIC mills as Praetorian guard. Optimization of the ASIC machine, it will be impossible to dig for other Token projects, these devices can only dig a project. If the other miners want to join, can only be purchased through its way into. From this perspective, Grin is a good project, although ASIC miners may have the center of some, but as long as the miners digging in the Grin Token, so they have the power to protect the project (because in addition to their chips or other functions).
Terry: the new ASIC algorithm, assuming a new project was created, and a lot of people are digging in the currency, the miners are not necessarily willing to hire is to attack it by force. Although the short-term may be profitable, but in the long term, if the money has no value, all of mine just scrap it, the loss will be greater. But the use of graphics mining miners will not consider the currency of this kind of situation, because even if the coin is attacked, or other miners can dig coins. It also reflects the loyalty of ASIC mining, it is a bit different from the graphics mining.
We have also mentioned the Grin mining, a very interesting design, at the beginning of the 90% Grin mining is used in Cuckaroo29 (anti ASIC), 10% Cuckatoo31+ (ASIC Friendly). The ratio will change, part of the ASIC mining will become increasingly large, the graphics part will be more and more small. This shows that Grin transform is neutral for ASIC, this point is very consistent with our views.
I heard a senior machine manufacturers point of view, he believes that as long as the project is good enough, ASIC is inevitable. To avoid the only two things, one is threatening a project, as long as you dare to make ASIC, I dare to change the algorithm of bifurcation. There is a “cheat”, as has been said to PoS that ETH. I do not agree to “cheat” argument, but I think that since people have to humor to say this sentence, the expression of the focus should be, as long as the interest is large enough, can do ASIC, whether it is friendly or unfriendly.
Although technically I cannot judge is not all algorithm can do ASIC, but if the interests of large enough, I believe that the study will have people to do this project ASIC. According to some hearsay I know, like Zcash and Monroe actually have ASIC mill, mill just for ASIC in different community attitudes.
Daniel: Yes, after the Monroe community ASIC mill, quickly reached a consensus, the switching algorithm, before ASIC machine turned into scrap metal.
Terry:OK, a statement about the need here, we do not recommend Grin for this project, our program is recommended even recommend it, but behind this project Grin MimbleWimble protocol does have a very strong legendary color. In addition to Grin, the MimbleWimble protocol is another implementation of Beam project, but it is on the basis of the original agreement to do some so-called “improved”, the “improved” is good or bad, may need to give time to judge. In contrast, I think Grin more fundamentalist realizes MimbleWimble. In addition, I heard that some domestic team also plans to achieve MimbleWimble, which may cause a small wave.
Daniel: finally, it’s our most love Pick Time. I recommend to you a movie: “ignition”. I just took the Department colleagues to see, our team has some people have had business experience, we are now in the entrepreneur’s identity in the movie to see the entrepreneurial story, or there will be a lot of feelings and sympathy. You can take it as a small group to build, and their colleagues tell your own story in business, it may be more interesting than the film itself.
Kevin: and I recommend a shop full of red net “Etam”. My wife has been very concerned about the delicacy, she bought some dried in the red net store, especially delicious. This net red shop full of “public” Etam howl. (of course, we are not sponsored)
Terry: I recommend a phone card, called Google Fi, but this phone card is only available in the United States to. This card is characterized by its traffic charges, after no 6G charges. The cost is about ten /G in China knife, this is not cheap. But for the friends who often go abroad, this card is very convenient, because it can be used in all parts of the world, including Chinese. He is the only drawback (good sense, is like ~) in China can not through the scientific way of the Internet, you can access to some foreign websites “evil” (evil laugh), we must pay attention to.