The whole story of Filecoin’s “double spending”: Did Shuai Chu’s long-planned attack succeed?

At midnight on the 19th, several Chinese media outlets published articles stating that Binance, Matcha, and EURUSD have closed the recharge function for Filecoin mainnet token FIL. Some users in the community reported that there is a risk of double spending on the Filecoin mainnet, but the official has not yet responded.

The article states that according to the joint analysis of the Filecoin Feihu browser Filfox and FileStar developers, it was found that the deposit process of the exchange recommended by Filecoin officially has the risk of double spending. The team suggested that the exchange can temporarily postpone the deposit of Filecoin. The team stated that the double spending risk has affected the deposit of a certain exchange and has been verified by double spending. At present, the developers of Filfox and Filestar have assisted some exchanges to improve the recharge process and notified the Filecoin official.

The English explanation of double spending is actually easier to understand, namely Double Spend Attack: Double-spending is a transaction that uses the same input as another transaction that has already been validated on the network, that is, using the tokens of the previous transaction to conduct a transaction again, which results in a false transaction.

The most famous double-spending attack was the attack on Bitcoin Gold (BTG) in 2018. A malicious miner temporarily controlled the BTG blockchain, quickly withdrew the coins after recharging the exchange, and then reversed the block, successfully carrying out the double-spending attack. Liao Xiang, the founder of Bitcoin Gold (BTG), responded: "We have worked closely with various exchanges, and have made the attack ineffective by temporarily confirming the number of times to more than 20 times, and are collecting evidence to report the case to the FBI (Federal Bureau of Investigation)." In this attack, the attacker stole more than 388,200 BTG, worth up to $18.6 million, and BTG has basically "failed" since then.

So did Filecoin have a double-spending problem? Both sides have their own opinions.

Filecoin officials and Protocol Labs, who have always been indifferent, responded very quickly this time. They responded to Wu Blockchain immediately, saying that after confirmation by the Filecoin development team, there is no double-spending problem with Filecoin. The possible reason is the browser front-end reality problem, which makes some users think that double-spending is possible during the recharge of Filecoin on the exchange. Protocol Labs also provided pictures as evidence:

Subsequently, Filfox and FileStar published articles again through a large number of Chinese media, saying that after careful and detailed analysis, it can be confirmed that the recharge process recommended by the Filecoin official website to the exchange has serious problems. Special transactions can be constructed to deceive the exchange's recharge detection, thereby realizing double spending of a transaction. Through this method of constructing special transactions, a certain exchange currently has about 5 million US dollars worth of Filecoin fake recharges. FilFox and FileStar developers have contacted the mainstream exchange as soon as possible and notified Filecoin officials as soon as possible. Therefore, there are serious loopholes in the recharge process recommended by Filecoin officials, which has nothing to do with the FilFox front-end display. After confirmation by Filfox developers, the FilFox browser front-end display is normal, and even if there are any problems, it will not affect the exchange's deposit problem. The exchange deposit is carried out according to the process recommended by Filecoin officials and has nothing to do with the browser display. FilFox and FileStar developers will disclose the technical details of false recharges and double spending after the protocol labs modify the problem.

Protocol Labs responded again, saying that the Lotus team checked the relevant issues and confirmed that the network was normal and there was no risk of double spending. We learned that the relevant exchange is reviewing its withdrawal and recharge processing logic. The team is assisting the exchange and other exchanges to connect the correct withdrawal and recharge processing logic to avoid subsequent problems.

Community KOL Xie Dapao believes that it is the exchange's own responsibility. He said in the Wu Blockchain Community that there is a small bug in the exchange's recharge logic, and it is estimated that there is no distinction between the status of canceled recharge messages.

Filecoin prices also experienced minor fluctuations in a short period of time, falling below $75 when the news was released, and returning to over $80 after the clarification. Recently, due to the linear release of all 6-month Fil tokens of SAFT investors on April 15, as well as the continuous growth of China's network computing power and the addition of FIL fund products by Grayscale in the United States, Filecoin prices have reached a new high, with a seven-day increase of 80%, and the market value has entered the top 15.

This public relations war is undoubtedly an overt conspiracy created by the "Shuai Chu faction". Both Filecoin Feihu Browser and forked coin Filestar are allies of the Shuai Chu faction's Pomegranate Mining Pool. At present, due to the timely clarification of Protocol Labs, the recent surge in coin prices, and community unity, this surprise attack does not seem to have a particularly big effect on Filecoin. But the purpose of this attack may not be to hit Filecoin. The forked coin Filestar, which is promoted by the Shuai Chu faction, has risen by as much as 300% in the past 7 days. The main purpose may be to use this to promote the popularity of its own forked coin. Reference depth: Analysis of Filecoin's three major "fork" projects: Are they worth investing in?

Filestar received investment from HashKey in early 2021. On March 17, Filestar released a POS roadmap, and the POS function is expected to be launched in May. Looking back at history, there are very few successful fork projects, which has increased the popularity of the projects. The only successful fork project at present may be the community-based Sushiswap.

Shuai Chu is the founder of Quantum Chain and a key figure of the "Shanghai School" in the domestic currency circle. He is very interested in mining and has focused on GRIN, HNS, Filecoin and other fields. The Quantum Chain team has excellent code and marketing capabilities, and can often produce relatively high-level projects, but it seems that the "struggle mentality", the idea of ​​making imitations and making quick money are heavy. ZKS, which has recently become famous at home and abroad, also comes from his team. ZKS has good code and marketing capabilities, but it has been questioned by many people at home and abroad. Domestic opinion leaders such as Shenyu criticized its L2 design as "very stupid", and the original team of ZKC, the pearl of Ethereum, angrily accused it of plagiarizing the code. In this way, a similar plot seems to be repeated in the Filecoin field.

Wu said blockchain analyst Zhong Xuewen believes that the truth becomes clearer through debate, and we look forward to Filestar and Filecoin presenting evidence and detailed argumentation articles in the future. For example, Filestar can present the "technical details of false recharge and double spending" as soon as possible, and Protocol Labs should also respond frankly and correct any mistakes. From the perspective of operation, it is a double-edged sword. Such operation does increase Filestar's popularity, but it may also cause disgust in the mainstream community and lead to more attacks.