A 50 page quantum computing crypto risk assessment published Tuesday by Coinbase’s independent advisory board concludes that while today’s blockchains remain secure, a fault-tolerant quantum computer capable of breaking widely used encryption is increasingly plausible and that preparation must begin now, warning that “waiting for it to be urgent is not a good idea.”
Summary
- The 50 page paper, authored by an independent board including Stanford cryptographer Dan Boneh, Ethereum Foundation researcher Justin Drake, and EigenLayer founder Sreeram Kannan.
- Replacing today’s signatures with quantum-resistant alternatives could expand blockchain data sizes by up to 38 times, according to one estimate in the report, meaning the transition carries significant engineering costs and performance tradeoffs.
- Bitcoin wallets that have already revealed their public keys are identified as the most immediately vulnerable category of holdings in any future quantum attack scenario.
Quantum computing crypto risk has its most authoritative industry assessment yet. The Coinbase advisory board, a group of world-class cryptographers and blockchain researchers convened by Coinbase in January 2026, released its first major position paper Tuesday: a 50 page analysis of how future quantum computers could affect blockchain security and what the industry must do before that threat becomes real.
“Waiting for it to be urgent is not a good idea,” the paper states, emphasizing that transitions across blockchains, wallets, and exchanges could take years to execute safely even after all the technical standards are in place.
The board members who authored the paper include Dan Boneh, the director of the Stanford Center for Blockchain Research; Justin Drake of the Ethereum Foundation; Sreeram Kannan, the founder of EigenLayer; Yehuda Lindell, Coinbase’s head of cryptography; and Dahlia Malkhi, an expert in resilient distributed systems. Their institutional breadth gives the paper a credibility that no single-company security assessment would carry.
What the Report Found and What Makes It Credible
The paper’s core conclusion is carefully calibrated: quantum computers today cannot crack the cryptography underpinning Bitcoin, Ethereum, or any major blockchain. Breaking standard encryption would require fault-tolerant quantum machines with vastly more error-corrected qubits than current hardware provides, and achieving that is still considered a major engineering challenge. The report does not predict when that will happen. It argues that the timeline uncertainty itself is the problem.
The threat the paper focuses on most is the harvest now, decrypt later attack: adversaries can collect encrypted blockchain data today and store it, waiting for quantum hardware to mature enough to crack it retroactively. For long-held assets, this is a material risk that begins now rather than when the quantum threat becomes practical. Bitcoin addresses that have already revealed their public keys on-chain are specifically identified as the most immediately exposed category of holdings.
Why the Transition Will Be Harder Than It Sounds
The technical solution to quantum vulnerability already exists: NIST has standardized post-quantum cryptographic algorithms that are mathematically resistant to quantum attacks. The problem is implementation at blockchain scale. Post-quantum digital signatures can be tens to hundreds of times larger than the signatures in use today. One estimate in the Coinbase report suggests that replacing current signatures with quantum-proof alternatives could expand block sizes by up to 38 times.
For a network like Bitcoin, which processes blocks under a strict size limit and where any upgrade requires consensus among a decentralized set of stakeholders with no central authority, a 38-times expansion of signature data is not a parameter adjustment. It is a fundamental architectural change that touches every node, wallet, exchange, and application in the ecosystem. The debate among Bitcoin developers, already underway, reflects exactly this tension between urgency and the cost of change.
What Crypto Networks Are Already Doing
The Coinbase report arrives alongside parallel actions across the ecosystem. Ripple published a four phase XRPL post-quantum roadmap targeting completion by 2028. The Ethereum Foundation has elevated post-quantum security to a top strategic priority with a dedicated research team. Bitcoin developers are actively debating BIP 361, a proposal for a structured migration away from legacy address types that expose public keys.
For the Bitcoin quantum risk assessment specifically, researchers estimate approximately 4.5 million Bitcoin held in early or reused addresses may be exposed to future quantum attacks. The quantum threat debate in Bitcoin has become one of the most contested governance questions in the community, precisely because the solutions require either forcing coin migration or accepting that some portion of the supply may eventually be at risk.
