The blockchain project said attackers can harvest public keys now and use future quantum machines to steal assets later, while its cryptographic agility would allow quantum-resistant signatures without rebuilding consensus.
Sui said blockchains face a distinct security threat from quantum computing because public keys revealed on-chain remain permanently exposed once a transaction is made, unlike in conventional information systems. The project said the danger is not immediate, but a future quantum computer running Shor’s algorithm (quantum method to derive keys) could reconstruct private keys from those public keys. That means the threat has already started, Sui said, because attackers can collect public keys today and use more advanced machines later to steal assets. It also cited Google Quantum AI as projecting that such attacks could be executed within minutes on a fault-tolerant quantum computer (error-corrected quantum machine) with fewer than 500,000 physical qubits. Sui said its network was built with cryptographic agility (ability to swap cryptography), allowing it to adopt quantum-resistant digital signature methods without changing the existing consensus structure or rebuilding the network.