Researcher wins 1 bitcoin bounty for 'largest quantum attack' on underlying tech

Independent researcher Giancarlo Lelli broke a 15-bit elliptic curve key on publicly accessible quantum hardware, 512 times larger than the previous public demonstration in September 2025. What to know : An independent researcher used publicly accessible quantum hardware to break a 15-bit elliptic curve key, winning Project Eleven’s one bitcoin Q-Day Prize in the largest public demonstration yet of a quantum attack relevant to cryptocurrencies. While the feat is far from threatening bitcoin’s 256-bit elliptic curve security, it shows that practical quantum attacks on real cryptographic systems are progressing rapidly, with resource estimates for a full 256-bit break falling below 500,000 physical qubits. The advance is intensifying concern over the roughly 6.9 million bitcoin in addresses with exposed public keys and is adding urgency to post-quantum migration plans such as Bitcoin’s proposed BIP-360 and similar efforts by Ethereum, Tron, StarkWare and Ripple.