Quantum Computers Crack 15-bit ECC Keys; Bitcoin’s 256-bit Security Remains Unthreatened—But Migration Countdown Accelerates

According to CryptoSlate, Project Eleven awarded the Q-Day Prize to researcher Giancarlo Lelli on April 24 for successfully deriving a 15-bit elliptic curve private key from its public key using publicly accessible quantum hardware—the largest publicly demonstrated instance of its kind to date, representing a 512-fold improvement over the prior 6-bit demonstration in September 2025. Lelli employed a variant of Shor’s algorithm tailored to the Elliptic Curve Discrete Logarithm Problem (ECDLP), the mathematical foundation of Bitcoin’s signature scheme; the award-winning hardware comprised approximately 70 qubits. Currently, no known quantum computer can break real Bitcoin wallets, and Bitcoin’s 256-bit elliptic curve security remains far beyond the capabilities of existing quantum systems. Notably, Google revised downward its resource estimates for ECDLP-256 on March 31 and set a post-2029 target for migration to quantum-resistant cryptography; Cloudflare promptly followed suit, and the UK’s National Cyber Security Centre (NCSC) established migration milestones between 2028 and 2035. On-chain data indicates that roughly 6.93 million BTC are currently exposed to potential quantum risk due to publicly revealed public keys. The Bitcoin community has proposed BIP 360 and BIP 361 to facilitate migration toward quantum-resistant output types; however, coordination across the decentralized network remains the greatest challenge.