Quantum Computing Milestone: Researcher Breaks ECC Key in Major Proof-of-Concept

Project Eleven has awarded a 1 BTC bounty, valued at approximately $78,000, to researcher Giancarlo Lelli after he successfully derived a private encryption key from a public counterpart using a 15-bit elliptic curve cryptography (ECC) key. The achievement was completed using publicly accessible quantum hardware, signaling a shift from theoretical research to practical experimentation. The 'Q-Day Prize' was designed to measure the progression of quantum attacks on real-world cryptography. Lelli's success represents a 512-fold increase in capability over the previous public record of 6 bits established in September 2025. While a 15-bit key has a search space of only 32,767 possibilities, the speed of advancement is raising concerns among developers. Technical resource requirements for these attacks are falling rapidly. A recent Google Research paper estimated that a full 256-bit attack could cost fewer than 500,000 physical qubits, a sharp decline from previous estimates that placed the requirement in the millions. This suggests the barrier to executing such attacks in practice is lowering faster than previously anticipated. The risk is most acute for wallets where public keys are already visible on-chain. Project Eleven estimates that roughly 6.9 million BTC—approximately one-third of the total supply—reside in such addresses, including the early holdings of Satoshi Nakamoto. Any quantum computer capable of breaking 256-bit ECC could potentially access these funds. In response, the industry is exploring migration paths to quantum-resistant security. Bitcoin developers have proposed BIP-360 to introduce quantum-safe address types, while other major networks, including Ethereum, Ripple, and Tron, have already published their own post-quantum transition plans.