Post-quantum Cryptography

Quantum computers are a new type of computers using quantum mechanical phenomena to allow solving certain problems substantially faster than the best knownalgorithms for solving them using normal computers.

This has a big impact on cryptography as a quantum computer could theoreticallybreak a lot of the cryptography in use today. Symmetric cryptography, where parties already share a secret key, is only marginally impacted by a quantum computer. A quantum computer could however break almost all asymmetric cryptography in use today. Asymmetric cryptography allows secure communication between parties who do not have a pre-shared secret key and as such is more or less a requirement for secure web browsing.

Quantum computers are under development but are still a long way away from being a serious threat to the cryptography in use today. However, for data encrypted to be kept secret for longer periods of time the threat have to be considered as the used algorithms have to remain safe for at least as long as the data is to be kept secret.

Luckily, there are other algorithms for asymmetric cryptography that neither a quantum computer nor a normal computer is believed to be able to break. This project will study these algorithms for post-quantum cryptography with a special focus on lattice based cryptography.

Publications

J. Gärtner, "NTWE: A Natural Combination of NTRU and LWE". In: Johansson, T., Smith-Tone, D. (eds) Post-Quantum Cryptography. PQCrypto 2023. Lecture Notes in Computer Science, vol 14154. Springer, Cham, doi: 10.1007/978-3-031-40003-2_12

J. Gärtner, "Concrete Security from Worst-Case to Average-Case Lattice Reductions". In: El Mrabet, N., De Feo, L., Duquesne, S. (eds) Progress in Cryptology - AFRICACRYPT 2023. AFRICACRYPT 2023. Lecture Notes in Computer Science, vol 14064. Springer, Cham, doi: 10.1007/978-3-031-37679-5_15