On the analysis of time-aware protocols in universal composability framework

Abstract

We consider the analysis of time-aware cryptographic protocols in the universal composability (UC) framework (Canetti in 2000). The tasks we consider are the timeliness of messages within an instance as well as the time of validity of cryptographic credentials where the lifetime of time stamps overlaps lots of instances. We point out that the UC analysis of time-aware protocols with global access to real time clock cannot be carried out directly within the standard model. For the resolution of the corresponding problem, we considered two ways: one is the introduction of an auxiliary timing oracle into the ideal system, while the other consists of two time models: a quantized real time source and an abstract "random-time" source, and we show an essential equivalence between them. The time models provide not only theoretical but also practical benefits.