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Today the internet is an inescapable fact of life for all of us – for many it may be so self-evident that we might scarcely notice its importance.

Quantum computers, on the other hand, are not yet a fact of everyday life. In fact, a fully functional quantum computer is yet to be built. This is not for lack of trying, as there are great expectations for quantum computing. A functioning quantum computer will make it possible to supercharge research and product development that is now done on a supercomputer, and to achieve innovation leaps never seen before.

Shor’s quantum algorithm breaks existing encryption keys

Quantum computers will have uses that go beyond research and product development. One reason for this is the quantum algorithm presented in 1994 by Peter Shor, which divides integers into their constituent parts. For example, it tells that to get the number 15, you have to multiply 3 x 5. Significantly, the algorithm is also efficient for very large numbers. This is decisively linked with the internet of today.

A large part of telecommunications is encrypted using encryption based on public keys. This method assumes that multiplying two large integers is a fast calculation, but the inverse calculation, to ascertain the prime factors of a large integer, is impossible for all practical purposes.

In fact, this is the case with ordinary computers. Even the most efficient supercomputers in existence would require billions upon billions of years of computing time to break the encryption keys currently in use. With Shor’s quantum algorithm, on the other hand, it would only take hours, perhaps just minutes, to decipher the keys. Of course, breaking the encryptions also requires an efficient and functioning quantum computer.

Nevertheless, it is only a matter of time before an efficient quantum computer will be a reality. Astounding leaps in development have been made in recent years. This means that the encryption of data communications must be updated into a quantum-resistant form. We also cannot wait for the emergence of an efficient quantum computer before the encryption methods are solidified. Eavesdropping on data communications is already possible, and the data can be stored in order to be deciphered by the quantum computers of the future.

Quantum-safe encryption for the Funet network

Now it is also time for Funet to move to the age of quantum security. Work on reaching this goal is moving ahead fast. Improving quantum security involves two mutually reinforcing solutions.

The first is based on replacing existing encryption algorithms with quantum-safe options (Post-Quantum Cryptography, PQC). In PQC, data is still transferred in the traditional manner using fibre and the mobile network, but the data is encrypted in a different way.

Another method is based on Quantum Key Distribution (QKD). In it, encryption keys are exchanged between sender and recipient using individual photons. Owing to the natural laws of quantum mechanics, eavesdropping on this key exchange cannot be done undetected. In this way it is possible to ensure that only the sender and recipient know the encryption key. Using QKD requires new devices, which is why its introduction is more demanding than with PQC.

The first quantum safeguards are already in use within Funet. Meanwhile, the QKD encryption network is being set up in the national project. It is part of an EU-wide project aimed at creating a quantum-secure telecommunications network covering the entire European Union. CSC and Funet lead the work on the public network side. The goal is to get to test quantum-secure data transfer already next year together with our clients.

Data security experts have carefully monitored the risks posed by quantum computing for existing encryption protocols, and preparations have been made for threats. Encryption settings are being exchanged for those that already give better security against breaking encryption with the help of quantum computing.

Standardisation is needed

One impediment to a shift to quantum-secure encryption is the lack of official standards. Latest next year, the National Institute of Standards and Technology (NIST) in the United States is expected to release its recommendations for new encryption algorithms. This will undoubtedly considerably speed up the deployment of new algorithms.

For quantum key distribution the standards are even less complete. On the other hand, the technology itself is also in its early stages. Consequently, finalizing standards might even be harmful. Practical testing and research are still needed.

Quantum encryption can be done

It is important to keep in mind that the quantum computers of the future will primarily be beneficial to society. Combining efficient quantum computers with traditional supercomputers will revolutionise science and innovation, and computational modelling will take a big quantum leap.

The threats posed by quantum computers to data communications have been known already for 30 years. Already changing the encryption methods based on public keys for new quantum-resistant algorithms protects our digital selves efficiently. The shift is possible as long as steps are taken at all levels of society.

For very strong encryption it is possible to simultaneously use QKD. This brings us to the quantum internet. At CSC we are actively working on enabling its development as well.

Mikael Johansson

Manager, Quantum Technologies