Bitcoin Core developer Luke Dashjr has expressed concerns about the finality of Bitcoin transactions, suggesting that the widely accepted six-block confirmation rule is no longer valid. According to Dashjr, it now takes over a week for transactions to be finalized, raising doubts about Bitcoin’s resistance to censorship.
Finality refers to the point at which reversing a transaction becomes practically impossible due to the immense computational power required. Traditionally, this threshold was reached once six blocks were added after the original transaction.
Dashjr argues that the traditional standard no longer applies due to the increasing centralization of Bitcoin mining pools. In a recent post, he explained that he attempted to update the six-block confirmation target in Bitcoin Knots, a Bitcoin Core alternative. However, his calculations revealed that achieving 95% security now requires over 800 blocks, which is equivalent to approximately 5.5 days, due to Antpool’s significant share of the network hashrate.
Data from the HashRate Index shows that Antpool controls about 16.67% of Bitcoin’s total hash power, trailing Foundry USA at 33.12%. Other major pools include F2Pool, MARA Pool, and SecPool. However, Dashjr disputes these figures, asserting that several pools, such as Braiins and possibly ViaBTC, act as proxies for Antpool, amplifying its influence. He also noted that many miners unknowingly contribute to potential network reorganizations by operating under centralized pools.
Industry experts have echoed these concerns, warning that the increasing dominance of a few mining pools exposes Bitcoin to potential censorship and even a 51% attack. Bob Burnett, CEO of Barefoot Mining, highlighted the threat and its implications for Bitcoin’s censorship resistance and immutability. He proposed that retail investors play a role in restoring decentralization by pressuring publicly traded mining firms to spread their hash power across smaller pools, ensuring no single entity controls over 15% of Bitcoin’s network.
While some experts downplay the severity of the issue, suggesting that Bitcoin’s design allows it to self-regulate over time, the concerns raised by Dashjr and others highlight the need for ongoing improvements and efforts to maintain Bitcoin’s decentralized nature.
