Quantum Security

Lelli Breaks 15-Bit ECC Key on Public Quantum Hardware

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April 26, 2026 by Ivy Delaney

Giancarlo Lelli, an independent researcher, has claimed a one Bitcoin prize for achieving the largest quantum break of elliptic curve cryptography to date; he successfully derived a private key from its public counterpart across a 32,767-element search space using a variant of Shor’s algorithm. This result represents a 512x increase over the previous public demonstration in September 2025, accelerating the timeline for potential threats to digital assets secured by ECC, including Bitcoin and Ethereum. “The resource requirements for this type of attack keep dropping, and the barrier to running it in practice is dropping with them,” said Alex Pruden, CEO of Project Eleven, who awarded the prize. Google’s commitment to being quantum-secure by 2029 means the window for proactively migrating to post-quantum cryptography is shrinking.

Lelli Breaks 15-bit ECC Key with Shor’s Algorithm

This demonstration is noteworthy because it wasn’t conducted by a well-funded national laboratory or private company, suggesting a lower barrier to entry for potential attackers. Theoretical estimates for attacking a full 256-bit key, the scale currently used by Bitcoin, have also fallen sharply, with recent research from Caltech and Oratomic suggesting a viable attack could require as few as 10,000 qubits in a neutral-atom architecture. Approximately 6.9 million Bitcoin currently reside in wallets with publicly visible keys, rendering them vulnerable to this type of quantum attack, and all blockchains relying on ECC face similar risks. Pruden stated that the window to prepare is closing, referencing Google’s commitment to achieving quantum security by 2029 and emphasizing the urgent need for proactive migration to post-quantum cryptography. Project Eleven is now focusing its next challenge on the intersection of advanced AI models and quantum cryptanalysis, further exploring the evolving threat landscape.

The increasing pace of progress in quantum computing attacks on encryption is forcing a reevaluation of timelines for transitioning to post-quantum cryptography, as demonstrated by recent achievements in breaking elliptic curve cryptography. This practical demonstration is particularly significant given the source of the attack. “The winning submission came from an independent researcher working on cloud-accessible hardware,” explained Alex Pruden, CEO of Project Eleven.

The distance from 15 bits to 256 bits is large, but the gap is increasingly viewed as an engineering problem and not a fundamental physics problem.

$2.5 Trillion in ECC Assets Face Quantum Threat

This achievement represents a 512x increase in capability compared to Steve Tippeconnic’s 6-bit break in September 2025, signaling an accelerating pace of progress in quantum cryptanalysis and intensifying concerns about the security of blockchain technologies. The implications extend to a substantial portion of the digital economy, with over $2.5 trillion in ECC-secured assets now potentially vulnerable to these evolving quantum threats. Pruden added that the accessibility of this technology emphasizes the urgency for proactive migration to post-quantum cryptography, particularly as Google aims to be quantum-secure by 2029.

The resource requirements for this type of attack keep dropping, and the barrier to running it in practice is dropping with them.

Alex Pruden, CEO of Project Eleven
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Ivy Delaney

Ivy Delaney has been working with neural networks and machine learning since the mid-nineties, back when a couple of hidden layers and a long afternoon of training counted as ambitious. She has watched the field go from academic curiosity to the thing quietly running underneath everything, and she brings that long view to quantum computing. For Quantum Zeitgeist she covers the ground where the two fields meet. That means quantum machine learning and the variational algorithms it leans on, and it also means the less glamorous but more interesting story of classical machine learning already doing real work inside quantum machines, decoding error-correcting codes, calibrating noisy hardware and learning the error models that simulators depend on. She writes about the hardware those algorithms have to run on too, and about the post-quantum cryptography scramble that the same hardware has set off. Her stories typically start with the paper, whether that is peer-reviewed work, conference proceedings or an arXiv preprint, with the source linked so you can hold a claim up against the research it came from. She is unimpressed by benchmarks that will not say what they beat, and by demonstrations that only work in the press release.

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