Quantum Break: Researcher Wins 1 BTC for Largest ECC Attack Ever

Post-quantum startup Project Eleven has today awarded a 1 BTC ($77,736 at writing time) prize to the independent researcher Giancarlo Lelli for the latest and largest demonstration of a quantum attack on Elliptic Curve Cryptography (ECC).

Using a publicly accessible quantum computer, Lelli successfully derived a 15-bit elliptic curve private key from its public key counterpart in about 45minutes. He used a variant of Shor’s algorithm to crack the elliptic-curve discrete logarithm problem (ECDLP), which is native to the digital signatures of Bitcoin and Ethereum.

The milestone marks a 512x increase in total search space complexity, or 32,768 possible private key combinations, of which only one is true. It also breaks the previous, first-ever 6-bit break, achieved in September 2025 by Steve Tippeconnic.

Quantum computing and blockchain

While remarkable, a 15-bit crack is currently insignificant to Bitcoin’s 256-bit ECC. Lelli also utilized 27 physical qubits for the attack, while Google has estimated Bitcoin’s break requirement to be between 10,000 and 500,000 physical qubits.

Advances in artificial intelligence (AI) could enable the development of stable, high-performance quantum computers. These devices could then use AI to upscale quantum-based attacks on Bitcoin and other blockchains. 

IBM, Microsoft, and Google are among the world’s leading tech giants researching quantum technology. The latter has set a 2029 deadline for post-quantum cryptography to mitigate quantum risks.

Who is the most vulnerable?

Addresses whose public keys are exposed are some of the most vulnerable. The list includes legacy (P2PK) addresses that hold a total of 6.9 million BTC, re-used addresses, and those that have transacted on the Bitcoin taproot upgrade. In the case of Bitcoin, the 10-minute transaction confirmation window that makes public keys visible introduces a quantum breach opportunity.

Blockchains’ decentralization makes it harder to coordinate quantum-proofing efforts than for banks, which can implement a top-down security update overnight, if not instantly.

Cryptographic systems must now rise to the challenge of protecting their integrity to foster further development of what is now a $2.6 trillion industry.