RiR Week: Satellite Quantum Key Distribution

Share this page

Quantum computers threaten the security of the internet and secure communications. Current public key cryptography methods, such as RSA and ECC (see glossary below), could be broken by a large-scale quantum computer. Rapid advancements in quantum computing have brought closer the horizon when this could potentially occur. Alternate “quantum-secure” methods of encryption are therefore required. Post-quantum cryptography (PQC) seeks to use other types of mathematical problems that may be difficult for a quantum computer to crack, candidate cryptosystems are currently under evaluation by the National Institute of Standards and Technology (NIST). Quantum Key Distribution (QKD) is another approach that uses the laws of physics to establish the security of the encryption keys sent to users.

But currently, QKD systems using optical fibre have limited range. Satellites have been proposed as an alternate platform for securely connecting the world and the Chinese satellite, Micius, has recently proven the concept, sparking a Quantum Space Race in the process. In the UK, I lead the QUARC project to utilise small satellites, CubeSats, to develop the technology and rapidly gain the experience and knowledge required to deploy and operate satellite QKD.

A key part of my Research in Residence with the Satellite Applications Catapult is to look at enabling wide-spread adoption of SatQKD technologies and services. This is through identifying a roadmap that charts the development of key components, capabilities, and implementations that establishes short, mid, and long term prospects.

An early achievement was the award of the Innovate UK funded ViSatQT project that includes a range of UK companies (large and small), as well as academic (University of Strathclyde) and public organisations (the Satellite Applications Catapult). Led by Airbus, ViSatQT will explore a range of advanced SatQKD concepts and technologies and aims to integrate them into conventional optical communications systems that are increasingly built into satellites.

The next step will be to go beyond this initial feasibility study and develop payloads and mission for in-orbit demonstration of the technologies developed as part of the roadmap.

As part of the ViSatQT, we will be engaging with stakeholders from all parts of the supply chain, from components manufacturers to end-users. We want to identify applications, industries, and uses of satellite quantum communication so that the technology and its capabilities can be enhanced to support these. We also need to connect to the upstream suppliers to identify promising approaches and technologies that require long-term research and investment to able to provide the required capabilities. We welcome dialogue and insights from all parties who are interested in or may be impacted by SatQKD or secure communications in general.


  • RSA – Rivest–Shamir–Adleman. Public key cryptosystem (PKC) that uses the computational complexity of factorising large numbers (hundreds of digits long) into its prime factors (prime numbers that when multiplied together give the original number). This was the first wide-spread PKC that allowed (then) secure messages to be sent using a “public” encryption key. The decryption key (different from the public encryption key) is kept private by the intended recipient and difficult to find out from the public key. The internet is based upon such PKC since allows secure communications between parties that have never met before and have not been able to share a large amount of shared symmetric key, e.g. for use in a symmetric cipher such as AES (advanced encryption standard). Quantum computers will be able to break types of PKC such as RSA as they can much more easily factorise large numbers in a fraction of the time previously thought (hours instead of trillions of years).
  • ECC – Elliptic Curve Cryptography. This is a type of PKC that is an alternative to RSA in many applications. It also is vulnerable to quantum computing cryptanalysis.
  • QKD – Quantum Key Distribution. QKD exploits the laws of quantum physics to enable the sharing of symmetric encryption keys between parties with the guarantee that any attempt at interception can be detected and compensated so that the encryption key is fully private.
  • QUARC – Quantum Research CubeSat. QUARC is a UK programme to develop satellite quantum communication technologies utilising nanosatellites/CubeSats to rapidly test and demonstrate key components, systems, and capabilities. It is supported by the UK Space Agency (NSTP3-FT-063) and the EPSRC Quantum Technology Hub in Quantum Communications (EP/T001011/1). QUARC is a collaboration between the University of Strathclyde (Lead), University of Bristol, and Craft Prospect Ltd.

Useful links:

Research in Residence Q&A Session – Friday 11 September

If you would like to find out more about all our Research in Residence projects, ask questions, and connect with our academics, join us on Friday 11 September, 10.30am – 12:00pm, when we will be hosting a live Q&A session.

Click here to register