Public key cryptographic systems are based on the assumed difficulty of certain mathematical operations, which may become vulnerable to attack in the future, especially in light of advances in quantum computing. Though specific timescales in relation to the latter are difficult to establish, for certain classes of data, the threat is already imminent, given that currently encrypted communications can be stored now and “broken” in the future, when the tools exist. Clearly new approaches to security are required.
Quantum mechanics dictates that when any of us try to measure or interact with a quantum system to learn about what it is doing, we inevitably and irreversibly disturb it. This relationship between disturbance and information gained is fundamental. It is not something that can be overcome by building better measurement devices and probes in the future – it is built into Nature. Taken into the context of communications scenarios, it simply means that where the distribution of encryption keys for securing sensitive messages is implemented with quantum light signals, anyone covertly attempting to gain information about the keys will necessarily disturb the light signals as they do so. Thus, Nature ensures that eavesdroppers cannot avoid being detected – in fact even if they try to use other quantum technologies to examine the light signals.
Quantum secure communication systems use these quantum effects to distribute encryption keys, which are then utilised to secure all manner of sensitive data transmissions, such as bank transactions, or health records. Given current reliance on the security of information and communications, in transit and in storage, across all aspects of daily lives (government infrastructure and civil service, financial transactions and e-commerce, defence and security, private data in e.g. the employment context), specific applications for these new quantum secure systems are numerous, but early adoption can be implemented mainly in the sectors of finance; ICT; defence and security; and space.
Financial institutions need to protect transactions, client data and proprietary information. Private payments rely on processing card numbers, which must be encrypted to prevent identity theft. Most financial transactions, small and large, take place electronically, and rely on encryption to shield them from cyber-attacks. All such transactions will be compromised if current encryption can be cracked by quantum computers. The scale of the risk means that the financial services sector should start preparing soon. Even short-term, deploying quantum security in combination with existing encryption methods, will bring advantages, not the least benefits in terms of reassuring customers that long-term security of their data is being taken seriously.
Quantum secure communications systems, mainly in the form of QKD, a mature quantum technology for the secure distribution of encryption keys, that has been already successfully trialled for the secure transmission of sensitive financial transactions, can be delivered over private networks. A potential near-term application, where a QKD network could already be cost effective, could be for CHAPS payments. Another application could be in two-factor transaction authentication. QKD could create multiple one-time ‘passwords’, which could be dispensed in a contactless manner to a mobile device via a ‘quantum ATM’. These can verify in-person or online transactions, and are safer than passwords or PIN numbers which are frequently copied or stolen. This technology is expected to be ready for commercialisation in the next few years, but would take time to be implemented on a large scale. QKD has already been demonstrated at chip scale, wirelessly, and over fibre networks, paving the way for quantum secured transactions from consumer devices. These technologies may take a decade or more to realise on a practical scale, but they are coming.
Companies and governments rely on being able to encrypt data for secure information sharing, from financial transactions, to sharing health records, to managing smart grids. They turn to the ICT industry to install and manage the systems that deliver this encryption. In a quantum-enabled world, it will be vital that the ICT industry has quantum safe encryption, including QKD, a mature quantum technology for the secure distribution of encryption keys, as part of its arsenal. QKD will need physical integration into network infrastructure, as well as accompanying software to deploy it effectively. The ICT industry will be required to both develop new QKD products, and to deliver them as part of an integrated network solution. Those that get involved early will find themselves leading the sector when QKD reaches commercial maturity. Commercial offerings are already viable in highly secure applications, where the benefit of securing information from future hacking outweighs the current cost. A number of projects are exploring QKD links between secure corporate networks and data centres, for example. Over the next five years significant work will go into improving transmission rates and reducing size, weight and power - and of course cost - of quantum devices, bringing QKD solutions closer to market, and leading to the first commercial use cases.
Governments depend on encryption for mission critical data, from managing tax returns online to coordinating counter-terrorism operations. However, today’s public key encryption is already vulnerable to future quantum attacks, creating major security risks. Quantum safe approaches, including QKD, a mature quantum technology for the distribution of encryption keys, will be needed to secure future communications. Organisations that rely on secure communications need to start preparing soon.
Meanwhile there is a huge commercial opportunity for defence and security contractors to develop capabilities to deliver the world’s future secure communications infrastructure. Public services – from tax payments, to healthcare, to driving licence applications - are increasingly managed online. Future smart grids will use encryption to prevent cyber-attacks. Any discussions about e-voting depend on voter data being encrypted. These will all be compromised if current encryption can be cracked. Organised malicious actors and nation states are already collecting encrypted information with the plan to crack it later. So, there is already an imperative to adopt “quantum safe” security in some cases, such as when sharing national security data that needs to stay secret for 20 years or more.
In parallel to the development of quantum communications, research and development is also being pursued with other forms of “quantum-safe” communications – secure against eavesdroppers or adversaries armed with arbitrarily powerful quantum computers or sensors working at the absolute quantum limit. One such direction is with new mathematical approaches, called post-quantum cryptography (PQC), which are known to be immune to current quantum computer algorithms and thought to be immune to any that might be developed in the future. It is anticipated that the most flexible and secure communications in the future will incorporate both QKD and PQC.
Quantum secure communications, and in particular QKD, a mature quantum technology for the distribution of encryption keys, have the potential to one day underpin the world’s digital communications. To deliver quantum secured communication between continents, techniques need to be developed to transfer encryption (quantum) keys between ground stations and satellites, and between satellites. This represents a huge opportunity for the space industry. There is growing international interest and investment around Satellite QKD, creating global market opportunities. Early large-scale QKD deployment will be over (already laid down) optical fibre. But quantum keys cannot be transmitted through undersea cables over long distances as photons are lost and cannot pass through the optical amplifiers used in underwater cables. The only way to create global QKD-secured communications will be with satellites. Although there is some photon loss in the atmosphere, it is low enough that quantum light signals can be sent between satellites and ground stations. To make this work, there is a need for collaboration with the space industry to develop new technology and infrastructure to transmit and receive quantum keys between ground stations, satellites and other aerial vehicles. As the technology advances, the space sector will become relied upon to launch and manage the QKD satellites that will become an integral part of the world’s future communications infrastructure.
Quantum communications in space opens up new opportunities for the UK space sector in areas including: satellite hosts - delivery platform options, dedicated or shared (for hosted payloads); satellite systems and sub-systems - acquisition, pointing and tracking, fine steering mirrors, system and flight software; quantum payloads, photonics components - lasers, non-linear crystals, detectors; optimisation of size, weight and power constraints on small satellites; optical ground stations - telescopes and mounts, tracking systems.
The EPSRC Quantum Communications Hub can help UK companies get involved with all of the above opportunities. The Hub runs a significant free-space communications work programme to explore QKD approaches, including single photon, entangled photons, and continuous quantum light signals. This programme includes launch of a research satellite to communicate with a ground-based receiver. Many of the Hub’s technology partners, companies such as BT and Toshiba, which serve government customers, are already involved in the QKD industry. The Hub has established the UK’s first Quantum Network, launched in 2019 and connecting Bristol, Cambridge and BT’s Adastral Park. This provides a testbed, comparable to national communications infrastructure, on which ICT companies can test and validate new quantum communications devices such as transmitters and receivers, and work with current innovators to learn about the practicalities of real-world deployment. As technologies move towards commercialisation, input is needed from those familiar with highly secure environments to shape the development of the technology and the standards that support it, such as those being developed by the ETSI Industry Specification Group on QKD (ETSI ISG-QKD).