Intermediate solutions for quantum resistant key exchange

Quantum computers pose a real threat to cryptography if and when they are realized in full scale. Certain hard problems are much easier to solve with a quantum computer. This holds in particular for cryptography based on factoring and computing discrete logarithms. Standardization bodies have already begun the process of finding new quantum resistant primitives that can replace current schemes based on problems that are easy to solve with quantum computer. However, this process will take some time, while current projections estimate that it is not unlikely that a cryptographically relevant quantum computer is realized in the next 10-15 years. Governments are taking action right now. In particular, systems that carry information that requires protection for a long time (15 yrs) should replace algorithms that can be broken by quantum computers now. However, this is difficult without a post quantum replacement at hand. The goal of this project is to investigate candidate hybrid solutions for key exchange for the intermediate period between pre and post-quantum era. In hybrid solutions for key exchange one combines classical key exchange algorithms with quantum resistant algorithms that has not been analysed that well. The idea is that one gets classical security and at least some post-quantum security. Examples of hybrid schemes include ECDH+pre-placed key, ECDH+lattice key exchange(New Nope, Chrome browser) and so on. The goal of the project is to investigate the limitations of the di↵erent hybrid solutions proposed in literature, in particular when implemented in current protocols and systems.