CoinDesk
Independent researcher Giancarlo Lelli broke a 15-bit elliptic curve key on publicly accessible quantum hardware, winning Project Eleven's 1 BTC Q-Day Prize — the largest public demonstration of a quantum attack relevant to cryptocurrencies. The 15-bit break expands the previous public record, a 6-bit demonstration by Steve Tippeconnic in September 2025 using IBM's 133-qubit machine, by a factor of 512 in just seven months. The bounty itself is worth roughly $78,000 at current prices.
Why it matters
A 15-bit key has a search space of 32,767 possibilities — vanishingly small next to bitcoin's 256-bit elliptic curve security — so the result doesn't move the needle on breaking the network today. But the trajectory is the story. Resource estimates for a full 256-bit break have collapsed: a Google Research paper last month put the figure below 500,000 physical qubits, down from earlier estimates in the millions. "The resource requirements for this type of attack keep dropping, and the barrier to running it in practice is dropping with them," Project Eleven CEO Alex Pruden said, noting the winning submission came from an independent researcher on cloud hardware, not a national lab.
Market impact
The result is sharpening focus on the roughly 6.9 million bitcoin sitting in addresses with exposed public keys — about one-third of total supply, including the estimated 1 million BTC held by Satoshi Nakamoto untouched since the network's earliest years. Any quantum machine capable of breaking 256-bit ECC could work through those wallets at leisure, and the threat is dragging post-quantum migration plans back into active discussion: Bitcoin's proposed BIP-360 would add quantum-safe address types, while Ethereum, Tron, StarkWare and Ripple have each published transition roadmaps. Fifteen bits is not 256, but the gap is closing faster than the industry expected.
Frequently asked questions
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Did a researcher actually break bitcoin's encryption?
No. Lelli broke a 15-bit elliptic curve key, a tiny search space of 32,767 possibilities. Bitcoin uses 256-bit elliptic curve security, which is orders of magnitude harder. The result is a public-hardware milestone, not a threat to the network today.
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What is Project Eleven's Q-Day Prize?
A 1 bitcoin bounty (~$78,000) awarded by quantum security startup Project Eleven for the largest public demonstration of a quantum attack on cryptography relevant to cryptocurrencies. The 15-bit ECC break on April 24, 2026 is its first award.
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How close are quantum computers to breaking bitcoin for real?
A Google Research paper last month estimated a full 256-bit break below 500,000 physical qubits, down from earlier estimates in the millions. The hardware doesn't exist yet, but the resource gap is closing faster than expected.
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Which bitcoin wallets are most at risk from a future quantum attack?
Wallets whose public keys are already visible on-chain. Project Eleven estimates roughly 6.9 million bitcoin sit in such addresses — about one-third of supply — including the ~1 million BTC attributed to Satoshi Nakamoto, untouched since the network's earliest years.
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What is being done to make bitcoin quantum-resistant?
Bitcoin developers have proposed BIP-360, a Bitcoin Improvement Proposal that would add quantum-safe address types. Ethereum, Tron, StarkWare and Ripple have each published their own post-quantum transition roadmaps, though no major chain has fully migrated yet.
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