Bitcoin Core developer Luke Dashjr has raised concerns about the finality of Bitcoin transactions, stating that the widely accepted six-block confirmation rule no longer holds.
According to him, transaction finalization now takes over a week, casting doubt on Bitcoin’s resistance to censorship.
Finality refers to the point where 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.
Why Bitcoin transactions are taking longer to finalize
Dashjr argues that the traditional standard no longer applies due to the increasing centralization of Bitcoin mining pools. In a Feb. 8 X post, he explained that he attempted to update the six-block confirmation target in Bitcoin Knots, a Bitcoin Core alternative.
However, his calculations indicated that due to Antpool’s significant share of the network hashrate, achieving 95% security now requires over 800 blocks—equivalent to approximately 5.5 days.
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 (8.87%), MARA Pool (6.06%), and SecPool (5.19%).
However, Dashjr disputes these figures, asserting that several pools, such as Braiins and possibly ViaBTC, act as proxies for Antpool, making its influence far greater. He also noted that many miners unknowingly contribute to potential network reorganizations by operating under centralized pools.
Industry concerns
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, said that if a single entity controls a significant portion of the network’s hash power, it could manipulate the blockchain by reorganizing transactions.
He noted:
“At a minimum, [the threat] is existential to Bitcoin being censorship resistant and it also means immutability takes a very long time to achieve.”
Considering this, Burnett proposed that retail investors play a role in restoring decentralization.
He suggested pressuring publicly traded mining firms to spread their hash power across smaller pools, ensuring no single entity controls over 15% of Bitcoin’s network. If miners refuse, he believes investors should divest their stocks and publicly call out non-compliant firms to maintain Bitcoin’s decentralized nature.
Meanwhile, not everyone agrees that this issue is as severe as Dashjr claims. Daniel Roberts, the co-founder of Iris Energy Ltd, downplayed these concerns, suggesting that Bitcoin’s design allows it to self-regulate over time.
Roberts added:
“Bitcoin may not perfect, and we should continue to try and improve it, but these types of issues are generally either self-correcting or built into the design intentionally.”
