Self-authenticated quantum key-exchange protocols

It significantly enhances the key exchange rates compared to traditional ones, utilising quantum key distribution methods, and addresses the authentication challenge. This integration offers a more robust and efficient cryptographic solution, streamlining quantum-secure communications across platforms.

Application

• Encryption
• Quantum cryptography

Development status

Technology validation is actively underway

IP Status

PCT patent application filed in May 2025

Commercial offering

Technology is available for licensing

Opportunity

Physically Unclonable Functions, or PUFs for short, are a clever and lightweight tech solutions that help secure storage or sharing of a secret key, based on physical properties of a device, such as their natural randomness from their own manufacturing process.

They can be embedded in systems such as IoT networks or even your mobile phones, to enhance the security of key-storage and bring trust against attackers and even the manufacturers. They can be used like a physical fingerprint to prove the authenticity of a person or a message, without relying on any other assumptions than the trust on the device itself. This tech is about keeping things safe and simple. But the downside is that using only PUF might not be the most secure solution and there are sophisticated attacks that can break the security of PUF-based systems.

This exciting new technology, developed by University of Edinburgh researchers, merges classical and cutting-edge quantum methods into a single, hybrid system: it combines classical hardware modules such as PUFs and the exchange of quantum information over a quantum communication channel, to achieve a high level of security that the classical hardware-based systems alone cannot achieve.

This upgrade significantly enhances the security of today's both classical and quantum systems and allows for much more efficient sharing of keys compared to existing methods like conventional quantum key distribution (QKD). It's a smarter, more efficient, and safer way for quantum-safe communication. We are now seeking a partner for licensing and commercialisation.

Technology overview

In our approach, we leverage the established technology of classical physical unclonable functions (PUFs) and enhance their cryptographic utility through quantum communication techniques. Our model eliminates the need for separate authentication channels, integrating both authentication and key exchange in a single protocol.

Additionally, our findings indicate that this method achieves a significantly higher secret-key rate in comparison to conventional quantum key distribution protocols, offering a more efficient solution for secure communications.

Benefits

• Our construction is designed to be implemented using today's quantum communication technologies.
• Our protocols uniquely feature challenge-reusability, an advantage not achievable with purely classical methods under similar conditions.
• Our protocol eliminates the need for separate classical authentication channels by simultaneously achieving authentication and key exchange using the same communication rounds. As such it addresses the crucial bottleneck of authentication that exists for QKD.
• Our protocol achieves the functionality of key-exchange/key-agreement provably, with strong security guarantees.
• Our protocol uses a smart, but easily implementable combination of quantum and classical encryption as well as hardware-based assumptions, to achieve security and efficiency at the same time.
• Our protocols substantially increase the key rate for key exchange/agreement compared to the standard prepare-and-measure QKD under the same conditions and parameters.
• This unique communication method outlines how to use an inherently insecure hardware module to achieve a secure key with robust security guarantees, unlike any other known PUF-based proposals.
• Our protocol is a solution for quantum-secure communications (so enhancement of security over classical solutions that are not quantum-secure, of course), and also enhances existing quantum communication solutions (i.e. QKD) in terms of authentication and efficiency.

Publications

Kaushik Chakraborty, Mina Doosti, Yao Ma, Chirag Wadhwa, Myrto Arapinis, and Elham Kashefi, “Quantum Lock: A Provable Quantum Communication Advantage”, Quantum 7, 1014 (2023).

Quote: TEC1104570