Researchers develop quantum-safe blockchain protocol

Researchers from CSIRO’s Data61 and the Monash Blockchain Technology Centre have developed an efficient blockchain protocol which they say is secure against quantum computers and protects the privacy of its users and their transactions.

The protocol — a set of rules governing how a blockchain network operates — is called MatRiCT, and is patented by CSIRO and licensed to Australian cryptocurrency developer HCash.

The technology can be applied beyond cryptocurrencies, such as digital health, banking, finance and government services, as well as services that require accountability to prevent illegal use.

The cryptocurrency market is valued at more than US$325 billion, with approximately US$50 billion traded daily over the past year.

However, blockchain-based cryptocurrencies like Bitcoin and Ethereum are vulnerable to attacks by quantum computers, which can perform complex calculations and process substantial amounts of data to break blockchains, much faster than current computers.

Lead researcher Dr Muhammed Esgin warns that quantum computing can compromise the signatures or keys used to authenticate transactions, as well as the integrity of blockchains.

“Once this occurs, the underlying cryptocurrency could be altered, leading to theft, double spend or forgery, and users’ privacy may be jeopardised. Existing cryptocurrencies tend to either be quantum-safe or privacy-preserving, but for the first time our new protocol achieves both in a practical and deployable way,” Dr Esgin said.

The protocol is based on hard lattice problems, which are quantum secure, and introduces three key features: the shortest quantum-secure ring signature scheme to date, which authenticates activity and transactions using only the signature; a zero-knowledge proof method, which hides sensitive transaction information; and an auditability function, which could help prevent illegal cryptocurrency use.

Blockchain technologies present significant challenges in terms of speed and energy consumption, which can lead to inefficiencies and increased costs.

Associate Professor Ron Steinfeld is co-author of the research, and notes that the protocol is designed to address the inefficiencies in previous blockchain protocols, such as complex authentication procedures, thereby speeding up calculation efficiencies and using less energy to resolve.

“Our new protocol is significantly faster and more efficient, as the identity signatures and proof required when conducting transactions are the shortest to date, thereby requiring less data communication, speeding up the transaction processing time and reducing the amount of energy required to complete transactions,” Professor Steinfeld said.

Associate Professor Joseph Liu is Director of Monash Blockchain Technology Centre and Hcash Chief Scientist.

“Hcash will be incorporating the protocol into its own systems, transforming its existing cryptocurrency, HyperCash, into one that is both quantum safe and privacy protecting,” Dr Liu said.

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