Researcher wins 1 bitcoin bounty for 'largest quantum attack' on underlying tech
TL;DR
Giancarlo Lelli won a 1 bitcoin bounty for breaking a 15-bit elliptic curve key using quantum hardware, marking a significant advancement in quantum attacks on blockchain technology. This demonstration poses a potential threat to Bitcoin and other major cryptocurrencies.
Key points
- Giancarlo Lelli won a 1 bitcoin bounty for a quantum attack
- He broke a 15-bit elliptic curve key on quantum hardware
- The attack is the largest public demonstration of its kind
- It poses a threat to Bitcoin and major blockchains
- The prize is valued at approximately $78,000
Mentioned in this story
Giancarlo LelliProject Eleven
Ether
The quantum attack Bitcoin has spent years treating as tomorrow's problem just got a little less theoretical.
Quantum security startup Project Eleven said it awarded its 1 bitcoin BTC$77,854.22 Q-Day Prize to independent researcher Giancarlo Lelli on Friday after he broke a 15-bit elliptic curve key on publicly accessible quantum hardware, deriving a private encryption key from its public counterpart.
The bounty is worth roughly $78,000 at current prices. It is said to be the largest public demonstration of the attack class that could one day threaten bitcoin, ether (ETH) and most major blockchains.
Project Eleven Awards 1 BTC Q-Day Prize for Largest Quantum Attack on Elliptic Curve Cryptography to Date
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…
— Project Eleven (@projecteleven) April 24, 2026
Elliptic curve cryptography is the math that lets a crypto wallet prove it controls funds without revealing its private key. A public key can be visible to everyone, but deriving the corresponding private key is supposed to be impossible in practical terms.
Quantum computers running Shor's algorithm, a quantum technique first proposed in 1994, challenge that assumption by attacking the underlying logic that secures those signatures.
Lelli's result does not mean bitcoin is close to being cracked. Bitcoin uses 256-bit elliptic curve security. A 15-bit key has a search space of 32,767 possibilities, tiny by comparison. The prize was designed to measure whether quantum attacks on real cryptography-based products are moving from white papers into public hardware experiments.
The previous public break was a 6-bit demonstration by Steve Tippeconnic in September 2025 using IBM's 133-qubit quantum computer. Lelli's 15-bit result expanded that by a factor of 512 in seven months.
A bit is the smallest unit of information in a regular computer, a qubit is the quantum computing equivalent.
Read more: A simple explainer on what quantum computing actually is, and why it is terrifying for bitcoin
Theoretical resource estimates have dropped even faster. A Google Research paper last month put the cost of a full 256-bit attack below 500,000 physical qubits, down from earlier estimates in the millions.
Q&A
What did Giancarlo Lelli achieve with the quantum attack?
Giancarlo Lelli broke a 15-bit elliptic curve key, demonstrating a significant quantum attack on cryptographic security.
How much is the Q-Day Prize awarded by Project Eleven worth?
The Q-Day Prize awarded by Project Eleven is worth 1 bitcoin, approximately $78,000 at current prices.
Why is this quantum attack significant for Bitcoin and other cryptocurrencies?
This quantum attack is significant because it demonstrates a practical threat to the security of Bitcoin, ether, and most major blockchains, highlighting vulnerabilities in elliptic curve cryptography.
