International Association
for Cryptologic Research

Physically related functions~(PReFs) are hardware primitives proposed to establish key-exchange between resource-constrained devices with no pre-established secrets. In this paper, we introduce XOR composition of PReFs to eliminate the requirement of revealing the complete functionality of the hardware primitive during the setup phase, which is a prerequisite to setup PReFs. We evaluate the quality of XOR\_PReF design by implementing them on Artix-7 FPGAs.