买比特币NFT被「抢单」？你被「RBF」了

In the past week, more and more friends have asked me this question——

Obviously the Bitcoin NFT trading market like Magic Eden is order locked, so why didnt the purchased NFT arrive in the end? Checking the purchase transaction shows that the transaction has been replaced and the item has been snatched.

The answer is: you were RBF.

In fact, this is no longer an old problem. At the end of November last year, the OrdiBot series released on Magic Eden Launchpad became the first famous victim. @mulan_arts Unigraphs series was also immediately delayed from being released on Magic Eden Launchpad. The reason was precisely because of the RBF at that time Any user who is not a whitelist can be allowed to bypass the whitelist mechanism to jump in. Magic Eden later fixed this problem with its Launchpad. Now, Magic Eden Launchpad whitelist casting no longer needs to worry about being RBF. (Related Reading:White single user Mint was robbed halfway by a sniper, Ordibots will reissue airdrops to make up for the loss）

The solution is to mint and trade Unigraphs

At the end of last year, someone used 0.0334 Bitcoin to front-run a transaction of 50 million BRC-20 Token $RATS.

Last month, the first buyer to submit a transaction for “Quantum Cat” cat 0673, who owns a “Golden Cloak” (you can get a Taproot Wizards for free in the future), was also paid an additional $180 in mining fees by another buyer. Got a jump. The buyer who finally made the transaction changed hands and sold 1.9 Bitcoins.

Quantum Cat cat 0673

The recent popularity of the Bitcoin ecosystem has caused more and more friends to encounter this problem, and there have been more and more discussions. In the early hours of this morning, the editor has been wondering why the rate of the Bitcoin network remains so high. Although last night to early this morning was a day when projects were released together, looking at the inscriptions on the chain, there was not enough BRC to clog the network- 20 or a small picture item appears. Now the editor finally knows why - more than 30% of the mining fees in many blocks are caused by RBF sniping...

At this point, you may be wondering: as long as you purchase Magic Eden, no second person can click the purchase button on the web page. How are these front-running achieved?

RBF front-running caused by PSBT trading mechanism

First of all, we need to understand that Bitcoin NFT trading markets like Magic Eden use PSBT, which is Partially Signed Bitcoin Transactions. Simply put, both buyers and sellers sign according to the template containing transaction information provided by the NFT trading market. The sellers signature is completed when it is put on the shelf, while the buyers signature is completed when submitting the purchase. The market then combines the two-part signature of the buyer and seller and broadcasts it. (Related Reading:Ordinals founder angrily refutes Yuga Labs auction, why is PSBT the correct solution for Bitcoin NFT transactions?）

But the problem comes after the transaction enters the mempool. When the combined transaction is broadcast, the sellers signature becomes visible to everyone because the transaction enters the mempool. After the sellers signature content is exposed, it means that everyone can conduct signature transactions as a buyer.

In this way, mempool actually changes from a memory pool to a PVP pool - since the time interval between two adjacent Bitcoin blocks is often relatively long, after the initial transaction is broadcast, Sniper If you feel that front-running is profitable, you can use the exposed sellers signature to re-sign a buyer for your transaction, and then use RBF to drive up your transaction rate. The miners will naturally give priority to the miners. Transactions with higher fees. (To put it simply, RBF is Replace by Fee, which achieves faster transaction confirmation by paying higher transaction fees)

Of course, snipers sometimes overturn. for example@robertjfclarkeIn the RBF attack mentioned by NodeMonkes in March this year, because the F2 Pool that mined the block did not allow full RBF, the front-running transaction was not packaged. The final result was that the original buyer We successfully obtained this NodeMonkes, which was about 60% lower than the floor price at the time, and successfully flipped it half an hour later to reap a profit of 0.2629 Bitcoins.

Bitcoin “MEV” Makes Rate Estimates Miscalculated?

In fact, the RBF front-running caused by PSBT is the same as the gas pull-up of Ethereum. The only difference is that the block confirmation time of Bitcoin is longer. On Ethereum, the next block is often produced in 10 seconds. Everyone knows clearly that the block confirmation time is longer. roll. The various concepts on Bitcoin may be a little unfamiliar to everyone for a while. In fact, the final effects of RBF front-running and MEV on Ethereum are somewhat similar.

If the Bitcoin ecosystem continues to be popular, more and more people will come in to compete for this arbitrage space for assets with good liquidity and good market performance. The editor has seen the emergence of projects that specifically provide sniper tools, such as@goldmine_tools. Assuming that this situation really happens, then for the assets that are sought after by everyone, the estimated block rate will actually fail to a certain extent. In essence, the transaction becomes an auction with a fixed price but a bid for mining fees. ”, the miners were delighted.

RBF History The higher the rate, the better it is for the miners.

As for a trading market like Magic Eden, I think we just need to better let users understand what the process of purchasing NFT is actually like, and on this basis, we can optimize the NFT purchasing process. For example, it would be nice to provide everyone with an RBF tool to change the current front-end page lock order to This NFT has TX Pending, and then allow everyone to pay a higher rate. The NFT aggregator on ETH is like this. There will be a Pending prompt, but it doesnt matter if you are willing to raise the gas to grab it.

Conclusion

At the end of writing, I thought of a question that everyone may be concerned about - if I am RBF, will I lose mining fees and money for shopping?

Wont.