Researcher Claims 1 Bitcoin Bounty for Achieving Largest Quantum Attack on Underlying Technology

The threat of quantum attacks on bitcoin has become more tangible with the latest achievement by an independent researcher. Quantum security startup Project Eleven awarded its 1 bitcoin Q-Day Prize to Giancarlo Lelli after he broke a 15-bit elliptic curve key on publicly accessible quantum hardware. The bounty, worth approximately $78,000, represents the largest public demonstration of a potential threat to bitcoin, ether, and other major blockchains. Elliptic curve cryptography, which enables a crypto wallet to prove control over funds without revealing its private key, is the foundation of this achievement. However, Lelli's result does not imply that bitcoin is on the verge of being compromised, as it uses 256-bit elliptic curve security. The prize aimed to assess whether quantum attacks on real-world cryptography-based products are transitioning from theoretical papers to public hardware experiments. Notably, Lelli's 15-bit result surpasses the previous public break of a 6-bit demonstration by Steve Tippeconnic in September 2025, using IBM's 133-qubit quantum computer, by a factor of 512 in just seven months. As the smallest unit of information in a regular computer is a bit, and the quantum computing equivalent is a qubit, the implications of this breakthrough are substantial. Theoretical resource estimates have decreased dramatically, with a recent Google Research paper suggesting the cost of a full 256-bit attack could be below 500,000 physical qubits, down from earlier estimates in the millions. Project Eleven CEO Alex Pruden noted that the barrier to running such an attack in practice is decreasing rapidly. The winning submission came from an independent researcher using cloud-accessible hardware, rather than a national laboratory or private quantum chip. The primary concern is for wallets with public keys already visible on-chain, with approximately 6.9 million bitcoin, or one-third of the total supply, including Satoshi Nakamoto's estimated 1 million untouched bitcoin, at risk. Any quantum computer capable of breaking 256-bit ECC could potentially access these wallets. To mitigate this threat, bitcoin developers have proposed migration paths, including BIP-360, which would introduce quantum-safe address types. Other platforms, such as Ethereum, Tron, StarkWare, and Ripple, have also published post-quantum transition plans. While 15 bits is significantly less than 256 bits, this achievement marks a notable milestone in the rapidly evolving landscape of bitcoin development and the broader community.