A quantum security startup, Project Eleven, has awarded its 1 bitcoin (BTC) Q-Day Prize to researcher Giancarlo Lelli for demonstrating a significant advancement in quantum computing. On Friday, Lelli successfully broke a 15-bit elliptic curve key using publicly accessible quantum hardware, deriving the private encryption key from its public equivalent.
The award, valued at approximately $78,000, marks the largest known public demonstration of a quantum attack that could potentially threaten Bitcoin and other major blockchains like Ethereum. The attack targeted elliptic curve cryptography (ECC), crucial for proving control over crypto wallets without exposing their private keys. While ECC allows public keys to be openly shared, deriving the corresponding private key should theoretically remain infeasible.
Quantum computers employing Shor’s algorithm—introduced in 1994—challenge this security by undermining the logic that secures digital signatures. Lelli’s breakthrough does not immediately threaten Bitcoin, which uses a more robust 256-bit elliptic curve security; however, it represents a significant leap from previous demonstrations.
Previously, Steve Tippeconnic had demonstrated a similar attack on a 6-bit key using IBM’s 133-qubit quantum computer in September 2025. Lelli’s achievement expanded this by a factor of 512 within seven months. In computing terms, while a bit is the smallest information unit in classical computers, qubits serve as the quantum equivalent.
Recent theoretical estimates suggest that a full-scale 256-bit attack could be feasible with fewer than 500,000 physical qubits, down from prior estimates in the millions. “The resource requirements for this type of attack are continually decreasing,” noted Project Eleven CEO Alex Pruden. He highlighted Lelli’s achievement as particularly notable due to its execution on cloud-accessible hardware rather than within a national lab or private quantum facility.
The implications are most concerning for Bitcoin wallets with publicly visible keys, with an estimated 6.9 million bitcoins (about one-third of the total supply) potentially at risk. Among these is the approximately 1 million bitcoins attributed to Satoshi Nakamoto, untouched since Bitcoin’s inception.
In response, developers have proposed solutions like BIP-360, a Bitcoin Improvement Proposal for quantum-safe addresses. Similarly, Ethereum, Tron, StarkWare, and Ripple have each outlined plans for transitioning to post-quantum cryptography. Although 15 bits is far from the 256-bit threshold, Lelli’s breakthrough has intensified interest in this area among Bitcoin developers and the wider community.