1 bitcoin up for grabs if you manage to break 'toy bitcoin' with a quantum computer

As the bitcoin (BTC) community is paying increasing attention to possible quantum computing threats, a new quantum security-focused team has launched a competition that should test the current resistance of bitcoin's cryptography.

The recently launched Project11, with its team having experience in cryptography, software engineering, AI, blockchain, computer science, theoretical physics, and more, has offered 1 BTC as the Q-Day Prize to the first team that manages to break a "toy version of bitcoin’s cryptography using a quantum computer." The deadline for this competition is April 5th, 2026.

The point of the competition is to test elliptic curve cryptography (ECC) by trying to break the largest ECC key possible using Shor's algorithm on a quantum computer. ECC is a more efficient form of public-key cryptography that secures many things, including bitcoin wallets. Meanwhile, according to Project11, Shor’s algorithm proves that a sufficiently powerful quantum computer can break ECC.

However, the contestants won't need to break bitcoin's 256-bit ECC, as a set of ECC keys for security levels from 1 to 25 bits has been prepared specifically for this game.

"This is only the start – If somebody breaks a 5-bit key, it will be a breakthrough. That’s much smaller than BTC’s 256-bit keys, but quantum computers will get there too. When that happens, we need to know," the team said.

They estimate that quantum computers might be able to break a 256-bit ECC key within the decade. According to the team's calculations, more than 6.26 million BTC are currently at risk of quantum attacks, which is almost 30% of the total BTC supply. More than 10 million BTC addresses with a non-zero balance and exposed public key are also at risk. BTC addresses are a human-readable version of public keys that are used for receiving BTC.

Project11 has published a database of vulnerable addresses where you can look for your own BTC address.

"Your bitcoin address appears here if its public key has been revealed on the blockchain (for example, through certain script types like P2PK or by having previously spent from a P2PKH address). This means it is at risk once attacks with quantum computers become viable, namely through Shor's algorithm," the team explained, urging users to move their funds to a newly generated address (one whose public key has never been exposed on-chain) as soon as possible.

"Make sure you generate the new address with secure, up-to-date wallet software and avoid reusing addresses once they have been spent from," they added.