The goal of this deliverable is to describe our contributions to the design of practical quantum- safe functional encryption schemes within the FENTEC project. Towards this goal, we present two contributions.
Our first contribution is to address one of the open problems listed in Deliverables 4.1 and 4.7, concerning removing the need for a central authority during the generation of the functional keys. More precisely, we present a compiler developed in the context of FENTEC which allows us to generate functional keys in a simple decentralized manner.
The solution supports encryption labels and can be applied to any existing multi-input functional encryption (MIFE) scheme satisfying a structural property called special key-derivation. As the compiler does not rely on any computational assumption, it therefore preserves the quantum safety of the underlying scheme.