A new milestone in quantum computing has brought fresh urgency to long-standing concerns about blockchain security. Project Eleven awarded its Q-Day Prize, a one Bitcoin bounty, to independent researcher Giancarlo Lelli after he successfully broke a 15-bit elliptic curve key on a publicly accessible quantum computer.
The result marks the largest public demonstration so far of a quantum attack against elliptic curve cryptography, the system that secures networks such as Bitcoin and Ethereum. The bounty carries a value of roughly $78,000 based on current market prices.
Lelli derived a private key from its public counterpart across a search space of 32,767 possibilities using a variant of Shor’s algorithm. This algorithm targets the Elliptic Curve Discrete Logarithm Problem, the mathematical foundation behind digital signatures used across most blockchain systems.
Project Eleven Awards 1 BTC Q-Day Prize for Largest Quantum Attack on Elliptic Curve Cryptography to Date
— Project Eleven (@projecteleven) April 24, 2026
Researcher breaks 15-bit ECC key on publicly accessible quantum hardware in a 512x jump from the previous public demonstration.
Project Eleven today awarded the Q-Day…
From theory to early-stage execution
Quantum attacks on elliptic curve cryptography have moved beyond theoretical discussion within a short period. In September 2025, Steve Tippeconnic demonstrated a 6-bit key break on quantum hardware. That experiment marked the first public proof that such attacks could run outside simulations.
Lelli’s 15-bit result expands that benchmark by a factor of 512 in less than a year. The experiment used cloud-accessible quantum hardware rather than specialized infrastructure, which reduces the barrier to entry for similar research.
“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. “The winning submission came from an independent researcher working on cloud-accessible hardware. No national lab, no private chip. It shows that tangible progress is possible and highlights the urgency to migrate to post-quantum cryptography sooner rather than later. Google just committed to being quantum-secure by 2029. The window to get ahead of this is closing.”
Despite the progress, the gap between current demonstrations and real-world cryptographic standards remains large. Bitcoin relies on 256-bit elliptic curve security. A 15-bit key exists on a vastly smaller scale. The difference represents a jump from tens of thousands of possibilities to a number that exceeds practical brute-force limits.
Resource estimates fall sharply
While practical demonstrations remain limited in scale, theoretical estimates for larger attacks have declined. A recent whitepaper from Google placed the requirement for breaking 256-bit elliptic curve cryptography below 500,000 physical qubits. A separate study from California Institute of Technology and Oratomic suggested the threshold could fall to as low as 10,000 qubits under specific architectures.
These estimates represent rapid advances in quantum hardware and error correction. Current systems remain far below these thresholds, but the pace of change has shortened earlier timelines.
Exposure within existing blockchain systems
The potential risk extends to assets already on-chain. Project Eleven estimates that roughly 6.9 million Bitcoin sit in wallets with publicly visible keys. These addresses include early holdings associated with Satoshi Nakamoto.
If a quantum system reaches the capability to break 256-bit elliptic curve keys, such wallets could become vulnerable without additional safeguards. The concern applies across all blockchains that rely on similar cryptographic structures.
Developers across major networks have started to explore mitigation strategies. Bitcoin proposals such as BIP-360 aim to introduce quantum-resistant address formats. Other ecosystems, including Ethereum, Tron, StarkWare, and Ripple, have outlined transition plans that incorporate post-quantum cryptography.
Industry response and ongoing debate
The pace of development has triggered debate within the crypto community. Some researchers describe quantum risk as a medium- to long-term issue, while others point to recent breakthroughs as evidence of accelerating timelines.
HodlFM coverage has highlighted advances in quantum hardware. IBM announced plans for its fault-tolerant quantum system, Starling, with deployment targeted by 2029. The company stated that improvements in error correction and architecture could significantly reduce the number of qubits required for complex computations.
Large technology firms and blockchain developers face different constraints. Centralized platforms can enforce upgrades across their systems, while decentralized networks depend on coordinated adoption among users, developers, and infrastructure providers.
Project Eleven continues to expand its research initiatives. The firm confirmed that its next challenge will explore the intersection of advanced artificial intelligence and quantum cryptanalysis.
A narrowing window for preparation
The distance between a 15-bit demonstration and full-scale cryptographic break remains substantial. However, recent progress has shifted the conversation from theoretical risk to measurable experimentation.
Lelli’s result does not signal an immediate threat to blockchain security. It does, however, provide a concrete data point that aligns with declining resource estimates and accelerating hardware development.
The combination of these trends places increasing pressure on both technology companies and crypto networks to prepare for a post-quantum environment before the gap closes.
Gunel Ismayilova
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