Independent researcher Giancarlo Lelli successfully computed a 15-bit ECC cryptographic key using a publicly accessible quantum computer, as reported by the Project Eleven startup team.
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…
Lelli applied a modified version of Shor's algorithm to a search space of 32,767 combinations. This method targets the discrete logarithm problem on elliptic curves, which is the mathematical foundation for digital signatures used in most blockchains.
Project Eleven awarded Lelli a prize of 1 BTC as part of the Q-Day Prize initiative, launched in 2025 to break keys ranging from 1 to 25 bits.
In September, engineer Steve Tippakonnick extracted a six-bit ECC key using a 133-qubit IBM computer. Developers noted that this was the first public attack of its kind on quantum hardware.
Lelli's result surpassed Tippakonnick's by a factor of 512. The project team described the latest experiment as the largest quantum attack on elliptic curves to date.
However, the scale of this demonstration is still far from real-world systems: Bitcoin uses 256-bit ECC to secure wallets. Project Eleven acknowledged this gap, but programmers believe the transition is more of an engineering challenge than a fundamental physical problem.
Preparation is Key
Project Eleven CEO Alex Pruden stated that the resource requirements for such attacks are decreasing, and the barrier to practical implementation is gradually lowering. He emphasized the growing need to transition to post-quantum cryptography.
The company also pointed out that approximately 6.9 million BTC are held in addresses where public keys are already visible on-chain. If sufficiently powerful quantum systems emerge, these wallets could become the most vulnerable.
In recent months, the community has increasingly discussed quantum risks to the crypto market. Earlier, Google researchers lowered their estimate of the quantum power needed to break Bitcoin. However, some consider the issue to be exaggerated.
Notably, Bitcoin developer Jameson Lopp and a group of experts presented a draft proposal for BIP-361, which suggests freezing coins vulnerable to quantum computers.
The community criticized this idea, labeling it authoritarian and confiscatory.
Other blockchains are also preparing to transition to post-quantum cryptography, including Ethereum and Ripple.