Bitcoin Quantum Threat Prize Criticized After Researcher Challenges Q-Day Benchmark

A Google quantum researcher has challenged Project Eleven’s “Q-Day Prize,” aimed at measuring quantum risk to Bitcoin. In an April 25 blog post, Craig Gidney argued the winning submission did not provide cryptographically meaningful progress and that the contest’s benchmark is poorly matched to today’s quantum hardware. Project Eleven previously said it awarded the Q-Day Prize to Giancarlo Lelli after breaking a 15-bit elliptic-curve key on public quantum hardware, calling it the largest such elliptic-curve attack to date. Gidney’s critique centers on two points: (1) Shor’s algorithm needs quantum error correction for real cryptographic relevance, and (2) small “Shor-style” circuits can appear to work due to randomness or luck rather than true quantum computation. He cited a “Falling With Style” scenario and claimed a GitHub user reproduced results by swapping quantum calls with random calls, making the outcomes “indistinguishable.” Project Eleven defended the broader intent: the prize was meant to show an attack class where resource requirements are dropping, with arguments referencing estimates of required physical qubits for larger (e.g., 256-bit) attacks. CEO Alex Pruden later conceded the prize’s small factoring yardstick is imperfect, but said it helped bridge quantum researchers’ results with cryptographers’ and Bitcoin developers’ risk thresholds. At the time of writing, BTC traded around $77,750. The dispute highlights a credibility risk for quantum-safe messaging: if Bitcoin quantum benchmarks can be matched by randomness, skeptics may gain ammunition—while legitimate long-run post-quantum migration concerns remain.