Project Eleven Awards 1 BTC Bounty After Researcher Cracks 15-Bit ECC Key With Quantum Computer
Blockchains including Bitcoin and Ethereum use elliptic-curve cryptography (ECC) to verify control of assets. A sufficiently powerful quantum computer could use Shor’s algorithm to derive a private key from a public key. Nonprofit Project Eleven created the Q-Day Prize to track that risk through real-world testing and encourage the industry’s transition to post-quantum cryptography (PQC). The latest result, however, remains far below the 256-bit security scale used by Bitcoin.
Project Eleven announced on April 24, 2026, that it had awarded the 1 BTC Q-Day Prize to Giancarlo Lelli. Using a variant of Shor’s algorithm on a publicly accessible quantum computer, Lelli derived a 15-bit ECC private key from its public key. The search space of 32,767 possibilities was 512 times larger than the 6-bit record set in September 2025, establishing a new high for a public demonstration at the time.
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The history behind this eventGoogle Research Finds Quantum Threat to Bitcoin Lower Than Expected
Bitcoin and Ethereum rely on elliptic-curve cryptography to safeguard assets. A quantum computer capable of deriving a private key from a public key could potentially steal funds. Bitcoin activated Taproot on November 14, 2021, and because some transactions expose public keys in advance, the potential window for attack has widened.
The latest research from Google Quantum AI estimates that about 500,000 error-corrected physical qubits could be enough to crack a key within Bitcoin’s roughly nine-minute transaction confirmation window, far below previous estimates of several million qubits. No funds have been reported stolen through such an attack, but the researchers are urging the community to begin planning a migration to post-quantum cryptography.
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