The Bitcoin (BTC) network now faces the largest quantum threat after a researcher cracked a 15-bit elliptic curve cryptography (ECC) key on a publicly accessible quantum computer.

On April 24, Project Eleven, a quantum computing research organization, awarded 1 BTC to independent researcher Giancarlo Lelli after he successfully derived a private key from its public key across a search space of 32,767 possible combinations. Lelli used cloud-based quantum hardware available to the general public to crack the 15-bit ECC.

The previous public demonstration of such an attack class was a 6-bit break, achieved in September 2025 by Steve Tippeconnic. As such, the possibility of a quantum attack on Bitcoin surged 512-fold in 8 months.

“The resource requirements for this type of attack keep dropping, and the barrier to running it in practice is dropping with them,” Alex Pruden, CEO of Project Eleven, stated.

What does this ECC attack mean for Bitcoin?

Notably, every Bitcoin wallet uses a private key, a unique 256-bit number that is mathematically related to its public key. As such, the break of 15-bit ECC is not an immediate threat to BTC, but a notable leap in less than a year.

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Featured Press Release

Apr 9, 2026

Google researchers previously estimated that a strong enough quantum computer could break the Elliptic Curve Discrete Logarithm Problem (ECDLP) by 2029. Furthermore, Google predicted that a capable quantum computer could intercept a Bitcoin transaction by decoding its private keys from the public key in 9 minutes, before the 10-minute confirmation time, by 2029.

With roughly 6.9 million Bitcoin, valued at approximately $534.3 billion at press time, held in wallets whose public keys are publicly visible, Project Eleven highlighted the need for blockchains to transition to post-quantum encryption. Moreover, the leap from 15-bit to 256-bit is an engineering headwind that could progress faster than expected.

​Currently, Project Eleven is developing its next challenge, focusing on the intersection of top-tier artificial intelligence (AI) models and quantum cryptanalysis.