Quantum computers can crack 15-bit ECC keys, and there is currently no threat to 256-bit Bitcoin security, but the countdown for migration is accelerating

Project Eleven today awarded the Q-Day prize to researcher Giancarlo Lelli, who successfully derived a 15-digit elliptic curve private key from a public key using publicly accessible quantum hardware, marking the largest scale demonstration of its kind to date, a 512-fold increase from the 6-digit demonstration in September 2025.

Lelli used a variant of Shor's algorithm for the elliptic curve discrete logarithm problem, which is the mathematical foundation of the Bitcoin signature scheme, with the awarded hardware featuring approximately 70 qubits. Currently, no known quantum computer can crack real Bitcoin wallets, and the security of Bitcoin's 256-bit elliptic curve remains far beyond current quantum capabilities. Notably, Google lowered its resource estimates for ECDLP-256 on March 31 and set a target for the migration to quantum cryptography after 2029, followed by Cloudflare, and the UK's NCSC also set migration milestones from 2028 to 2035.

On-chain data shows that approximately 6.93 million BTC are at potential quantum risk due to exposed public keys. The Bitcoin community has proposed BIP 360 and BIP 361 to promote the migration to quantum-resistant output types, but the coordination challenges of a decentralized network remain the biggest hurdle.