What Happened to The QDay Prize?

The QDay Prize emerged in April 2025 as a significant initiative by Project Eleven, a quantum computing-focused company, aiming to accelerate the understanding and mitigation of the quantum threat to modern cryptography. The competition offered a bounty of 1 Bitcoin to any individual or team capable of breaking an Elliptic Curve Cryptography (ECC) key using Shor's algorithm on a quantum computer, without classical shortcuts or hybrid tricks. The stated goal was to promote open, verifiable demonstrations of quantum capabilities in cryptanalysis, stress-test advances in Shor's algorithm, and establish a clear benchmark for quantum performance in breaking real-world encryption.

The competition's deadline was set for April 5, 2026, and it garnered attention within both the quantum computing and cryptocurrency communities, particularly given the reliance of major digital assets like Bitcoin and Ethereum on ECC for their security. Project Eleven emphasized the urgency of migrating to post-quantum cryptography, highlighting that current estimates suggested around 2,000 logical qubits could break a 256-bit ECC key within the decade.

A key turning point occurred on April 24, 2026, when Project Eleven announced it had awarded the 1 Bitcoin prize to independent researcher Giancarlo Lelli. Lelli successfully broke a 15-bit ECC key on publicly accessible quantum hardware, a feat that Project Eleven lauded as the 'largest public demonstration to date' of a quantum attack on ECC, representing a 512-fold increase in complexity over a previous 6-bit demonstration in September 2025 by Steve Tippeconnic. This achievement was presented as a practical counterpart to theoretical advancements that had sharply reduced the estimated qubit requirements for a full 256-bit attack.

However, the triumph was quickly met with significant controversy. On April 25, 2026, Craig Gidney, a prominent research scientist on Google's quantum computing team, published a scathing critique titled 'The predictable failure of the QDay Prize'. Gidney, who had declined an invitation to participate in May 2025, argued that the competition's premise was flawed. His central objections were that Shor's algorithm requires quantum error correction for cryptographically meaningful instances, which current noisy quantum computers lack, and that small Shor-style problems can yield successful results even when the quantum hardware contributes no meaningful computational value, a phenomenon he termed 'Falling With Style'. He suggested the winning submission's results were indistinguishable from random guesses.

The consequences of this criticism were immediate and significant. The debate over the prize's validity overshadowed the initial announcement, leading to questions about Project Eleven's credibility. As of April 28, 2026, Alex Pruden, CEO of Project Eleven, publicly acknowledged that the contest 'was certainly imperfect' and admitted that Gidney's criticisms were valid. He also noted the lack of clear benchmarks in the quantum cryptanalysis space and called for feedback on how to better incentivize open benchmarking for 'Q-Day' risk. The incident has highlighted the ongoing challenges in accurately assessing and demonstrating quantum computing's real-world cryptographic threat.