The threat of quantum computing has sent some of the most outspoken Bitcoin developers to very different places.
Blockstream CEO Adam Back told Paris Blockchain Week attendees on Wednesday that Bitcoin developers should start building optional quantum-resistant upgrades now, and that while current quantum computers are still “essentially lab experiments,” progress has been “incremental” in the 25 years he has tracked the field.
“Preparation is key. Making changes in a controlled way is much safer than reacting in the middle of a crisis,” the Blockstream CEO said.
He mentioned his company’s work testing quantum-resistant transaction signatures on Liquid, Bitcoin’s sister network. He believes that the 2021 Bitcoin upgrade called Taproot is designed to be flexible enough to accept new signing methods without disrupting anyone currently using the network.
The comments echo Back’s stance last week, when he told CoinDesk that users should have about ten years to migrate their keys to a quantum-resistant format.
What’s different now is their surroundings. BIP-361, a proposal released by Jameson Lopp and five other developers on Tuesday, would phase out quantum-fragile addresses over a fixed five-year period and freeze any tokens that fail to migrate.
This includes approximately 1 million Bitcoins owned by Bitcoin’s anonymous creator Satoshi Nakamoto, as well as Loppsays’ estimate of 5.6 million Bitcoins that have not moved in more than a decade.
Back’s framework is interpreted as an implicit alternative to BIP-361’s forced migration. He did not mention Loop’s proposal directly, but addressed the fundamental question of whether the Bitcoin developer community would be able to respond quickly to a sudden quantum breakthrough.
“Errors were identified and fixed within hours. When things became urgent, it focused attention and drove consensus,” he said, suggesting that Bitcoin’s rough consensus governance can handle emergencies without the need to pre-arrange freezes years in advance.
These two positions represent the core disagreements shaping the Bitcoin quantum debate.
Back believes developers can quickly coordinate if the threat intensifies. Lopp bets they can’t, and that a planned freeze is the only way to avoid disorderly migration under pressure.
Functional quantum computers capable of cracking Bitcoin’s password could emerge sooner than previously estimated, researchers at Google and Caltech said last month, shifting the debate from theoretical to active.
