Bitcoin developers have made significant strides in fortifying the cryptocurrency against potential threats from quantum computing. Recently, they integrated BIP 360 into the Bitcoin Improvement Proposals (BIP) repository on GitHub. This milestone advances the development of a post-quantum architecture aimed at safeguarding Bitcoin in a future when quantum computers could pose risks to existing cryptographic protocols.
BIP 360 introduces an innovative output type known as Pay-to-Merkle-Root (P2MR). This design eliminates a feature referred to as key-path spending, which may expose public keys when transactions are executed. By doing so, BIP 360 establishes a framework for incorporating post-quantum signature schemes in subsequent soft forks of the Bitcoin network. Although the merge does not immediately activate these changes, it serves to formalize the proposal for review.
Ethan Heilman, a cryptographic researcher and co-author of BIP 360, emphasized its significance in addressing vulnerabilities in the Taproot upgrade introduced in 2021. He noted that the key spend remains susceptible to quantum attacks due to the exposure of public keys. “A quantum attacker could exploit the key spend and steal your funds,” Heilman explained, highlighting the importance of removing this vulnerability from the upgrade while maintaining the ability to further enhance Bitcoin’s security.
The urgency behind the proposal stems from concerns about Shor’s algorithm, which, if executed on a sufficiently advanced quantum computer, could derive private keys from public keys. In a recent discussion, Thomas Rosenbaum, President of the California Institute of Technology (Caltech), expressed confidence that fault-tolerant quantum systems could be realized in five to seven years. “We will, I believe, create a functioning, fault-tolerant quantum computer in five to seven years,” he stated, urging the United States to reassess its strategies for protecting sensitive data.
Recent advancements in quantum computing lend credibility to Rosenbaum’s timeline. Caltech researchers recently achieved coherence in over 6,000 qubits with an impressive 99.98% accuracy, while IBM demonstrated an entangled state of 120 qubits—the largest and most stable of its kind.
However, Heilman cautioned against making precise forecasts about the timeline of quantum computing advancements. “There’s no good, concrete way of actually predicting it on a timescale of more than one or two or three years,” he stated, suggesting a more cautious outlook for quantum milestones. The U.S. National Institute of Standards and Technology has established targets for post-quantum migration that extend into the mid-2030s. Meanwhile, Jameson Lopp, co-founder and Chief Security Officer of Bitcoin wallet developer Casa, indicated that it might be decades before quantum computers can effectively threaten modern cryptography.
“As far as we know, we are several orders of magnitude away from achieving a cryptographically relevant quantum computer,” said Lopp. He attributed the potential slow progress to the tendency of decentralized networks like Bitcoin’s to become less adaptable over time, making consensus increasingly challenging.
Heilman elaborated on the consensus required to activate a proposal, which necessitates broad support among miners, node operators, businesses, and users. The process typically demands a 95% approval rate over a sustained period for any change to be solidified.
Notably, some in the blockchain community perceive quantum risks as speculative or exaggerated, suggesting that, should large-scale quantum systems become a reality, they would more likely target centralized infrastructures rather than individual wallets. While Heilman acknowledged the possibility that physical constraints could impede the development of massively capable quantum computers, he stressed the importance of addressing existential risks to ensure Bitcoin’s long-term viability. “It is vital for Bitcoin to be valuable and useful, and to take existential risks seriously, even amid uncertainties about their potential impact,” he concluded.
