Safeguarding cryptocurrency by disclosing quantum vulnerabilities responsibly (opens in new tab)
Google Quantum AI argues that future cryptographically relevant quantum computers could break the elliptic-curve cryptography securing many cryptocurrencies sooner and with fewer resources than previously estimated. Its research presents circuits for attacking 256-bit elliptic-curve discrete logarithms using fewer than 1,200–1,450 logical qubits and 70–90 million Toffoli gates. Google urges cryptocurrency developers to migrate to post-quantum cryptography while disclosing the findings through verifiable zero-knowledge proofs rather than publishing exploitable attack details. ## Updated Quantum Resource Estimates - The relevant threat is Shor’s algorithm running on a large, fault-tolerant quantum computer. - Google developed two circuits for solving ECDLP-256: - Fewer than 1,200 logical qubits and 90 million Toffoli gates. - Fewer than 1,450 logical qubits and 70 million Toffoli gates. - Under assumptions aligned with some superconducting quantum hardware, the attack could require: - Fewer than 500,000 physical qubits. - Only a few minutes of computation. - This represents an estimated 20-fold reduction in physical-qubit requirements compared with earlier estimates. - Google connects the findings to its proposed 2029 timeline for beginning migration to post-quantum cryptography. ## Protecting Cryptocurrencies with PQC - Most blockchains and cryptocurrencies rely on elliptic-curve cryptography for essential security functions. - Post-quantum cryptography offers a practical, established direction for protecting blockchains against quantum attacks. - Migration will take significant time, creating urgency for networks to begin transitioning now. - Short- and long-term recommendations include: - Avoid exposing vulnerable wallet addresses. - Do not reuse vulnerable addresses. - Consider policy responses for abandoned or inaccessible coins. - The post points to existing post-quantum blockchain projects and experimental deployments as evidence that migration is feasible. ## Responsible Disclosure Through Zero-Knowledge Proofs - Public vulnerability disclosure must balance two risks: - Revealing enough information for defenders to respond. - Giving attackers a usable blueprint. - Cryptocurrency disclosure is especially sensitive because fear and unsupported claims can damage public confidence even before a technical attack is possible. - Google says it reduced this risk by clarifying which blockchain components are not vulnerable and emphasizing existing post-quantum progress. - It also published a zero-knowledge proof that allows independent parties to verify the resource estimates without accessing the underlying quantum circuits. - Google encourages other research groups to adopt similarly responsible disclosure practices. ## Outlook for the Cryptocurrency Ecosystem - Google hopes the work will encourage coordinated discussion among quantum researchers, security experts, cryptocurrency developers, and policymakers. - The broader goal is to preserve confidence in blockchain systems while giving them enough time to complete a post-quantum transition. Cryptocurrency projects should begin planning and testing PQC migration now, while avoiding address exposure and reuse in the interim. At the same time, quantum researchers should disclose attack estimates in ways that support verification and defense without unnecessarily enabling exploitation.
