Quantum-safe blockchain platform developed

Russian scientists have developed a method that could protect blockchains from being attacked by quantum computers.

The researchers from the Russian Quantum Center in Moscow developed a solution to the quantum-era blockchain challenge, using quantum key distribution (QKD).

The blockchain is a distributed ledger platform that allows consensus in a large decentralised network of parties who do not trust each other.

Transactions are accountable and transparent, making it useful for a variety of applications from smart contracts and finance, to manufacturing and healthcare.

One of the most prominent applications of blockchains is cryptocurrencies, such as Bitcoin.

"Blockchain is promising for a wide range of applications. But current platforms rely on digital signatures, which are vulnerable to attacks by quantum computers," said Evgeniy Kiktenko from the Russian Quantum Center.

"This also applies to the cryptographic hash functions used in preparing new blocks, meaning those with access to quantum computation would have an unfair advantage in procuring mining rewards, such as Bitcoins," said Kiktenko.

These risks are significant - it is predicted that 10 per cent of global GDP will be stored on blockchains or blockchain-related technology by 2025, researchers said.

To overcome these risks, they developed a blockchain platform combining original state-machine replication - a general method for implementing a fault-tolerant service by replicating servers and coordinating client interactions with server replicas - without the use of digital signatures, and QKD for providing authentication.

The researchers then ran an experiment to test its capability in an urban QKD network.

"Using QKD for blockchains may appear counterintuitive, as QKD networks rely on trust among nodes, whereas many blockchains lack such trust," said Aleksey Fedorov from the Russian Quantum Center.

"More specifically, one may argue that QKD cannot be used for authentication because it requires an authenticated classical channel for operation itself," said Fedorov.

However, each QKD communication session generates a large amount of shared secret data, part of which can be used for authentication in subsequent sessions.

"Therefore, a small amount of 'seed' secret key that the parties share before their first QKD session ensures their secure authentication for all future communication. This means QKD can be used in lieu of classical digital signatures," Fedorov said.