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.

The quantum attack Bitcoin has spent years treating as tomorrow's problem just got a little less theoretical.

Quantum security startup Project Eleven said it awarded its 1 bitcoin BTC$76,796.16 Q-Day Prize to independent researcher Giancarlo Lelli on Friday after he broke a 15-bit elliptic curve key on publicly accessible quantum hardware, deriving a private encryption key from its public counterpart.