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.
NEW YORK, April 24, 2026 /PRNewswire/ -- Project Eleven today awarded the Q-Day Prize, a one Bitcoin bounty, to Giancarlo Lelli for breaking a 15-bit elliptic curve key on a publicly accessible quantum computer. The result is the largest public demonstration to date of the attack class that threatens Bitcoin, Ethereum, and over $2.5 trillion in ECC-secured digital assets.
"The resource requirements for this type of attack keep dropping, and the barrier to running it in practice is dropping with them," said Alex Pruden, CEO of Project Eleven. "The winning submission came from an independent researcher working on cloud-accessible hardware. No national lab, no private chip. It shows that tangible progress is possible and highlights the urgency to migrate to post-quantum cryptography sooner rather than later. Google just committed to being quantum-secure by 2029. The window to get ahead of this is closing."
Lelli derived a private key from its public key across a search space of 32,767 using a variant of Shor's algorithm. Shor's targets the Elliptic Curve Discrete Logarithm Problem (ECDLP), the math underlying the digital signature schemes securing Bitcoin, Ethereum, and most blockchains.
Quantum attacks on ECC have moved from theory to practice over the last seven months. Steve Tippeconnic's 6-bit demonstration in September 2025 was the first public break on quantum hardware. Lelli's 15-bit result extends it by a factor of 512.
Theoretical resource estimates for a full 256-bit attack, the scale Bitcoin operates at, have fallen sharply over the same period. Google's April 2026 whitepaper put the requirement at under 500,000 physical qubits. A subsequent paper from Caltech and Oratomic brought that figure as low as 10,000 qubits in a neutral-atom architecture.
Lelli's result is the practical counterpart to those optimizations. The distance from 15 bits to 256 bits is large, but the gap is increasingly viewed as an engineering problem and not a fundamental physics problem.
Roughly 6.9 million Bitcoin sit in wallets whose public keys are visible on-chain, exposing them to quantum attack. All blockchains using ECC share similar risks with vulnerable assets.
Project Eleven is developing its next challenge, focused on the intersection of frontier AI models and quantum cryptanalysis.
Alex Pruden is available for interview
About Project Eleven
Project Eleven builds resilient infrastructure and tooling for the post-quantum era. The company develops scalable solutions that strengthen security across a rapidly evolving quantum threat landscape. With deep expertise in cryptography, blockchain, and financial systems, Project Eleven bridges advanced post-quantum research with real-world implementations that prepare the digital asset ecosystem for the future. For more information, visit www.projecteleven.com.
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