Researcher Earns 1 BTC for Cracking 15-Bit ECC Key on a Quantum Computer

Record-Breaking Quantum Attack on Elliptic Curve Cryptography

Independent researcher Giancarlo Lelli has successfully computed a 15-bit elliptic curve cryptography (ECC) key using publicly accessible quantum hardware. Project Eleven, the startup behind the Q-Day Prize competition, confirmed the breakthrough and awarded Lelli 1 BTC.

"Project Eleven Awards 1 BTC Q-Day Prize for Largest Quantum Attack on Elliptic Curve Cryptography to Date. Researcher breaks 15-bit ECC key on publicly accessible quantum hardware in a 512x jump from the previous public demonstration." — Project Eleven (@projecteleven), original post

Lelli employed a modified version of Shor's algorithm, navigating a search space of 32,767 possible combinations. The method targets the elliptic curve discrete logarithm problem — the mathematical foundation underpinning digital signatures used by the vast majority of blockchains.

Why This Matters

The Q-Day Prize program launched in 2025 with the goal of breaking ECC keys ranging from 1 to 25 bits. In September, engineer Steve Tippeconnic extracted a six-bit ECC key on IBM's 133-qubit quantum computer, which at the time represented the first known public quantum attack of this kind. Lelli's achievement surpasses that benchmark by a factor of 512, and the Project Eleven team has called it the largest quantum-powered break of elliptic curve cryptography to date.

The gap between this demonstration and a real-world threat remains enormous. Bitcoin relies on 256-bit ECC to secure wallets — orders of magnitude beyond what Lelli cracked. However, Project Eleven's developers view closing that gap as an engineering challenge rather than a fundamental physical barrier.

Growing Risks and the Push for Post-Quantum Cryptography

Project Eleven CEO Alex Pruden stated that the resource requirements for carrying out such attacks are declining, with the practical barrier to execution steadily lowering. He argued that this trend reinforces the urgency of transitioning to post-quantum cryptography.

The company also highlighted a specific vulnerability: approximately 6.9 million BTC sit at addresses where public keys are already visible on-chain. Should sufficiently powerful quantum systems emerge, these wallets would be the most exposed.

Discussion around quantum threats to the crypto industry has intensified in recent months. Google researchers previously revised downward their estimate of the quantum resources needed to break Bitcoin's encryption, though some experts still consider the threat overstated.

Developer Response and Community Pushback

Bitcoin developer Jameson Lopp, alongside a group of experts, published a draft proposal called BIP-361. The initiative proposes freezing coins deemed vulnerable to quantum attacks. The community largely rejected the idea, with users labeling it authoritarian and tantamount to confiscation.

Other blockchain projects have also begun preparing for a post-quantum future. Ethereum and Ripple are among those actively working on quantum-resistant upgrades.

Lelli's result shows that quantum computing continues to advance toward cryptographic relevance. While a genuine threat to 256-bit keys remains distant, the pace of progress is forcing the industry to take preventive measures seriously.