Further simplified servers assisted threshold RSA signature

Server assisted threshold signatures provide a user with controllability for activating his private signing function in a certain enhanced way. In this paper, we present a simple, efficient and adaptively secure server assisted threshold RSA signature protocol. The proposed protocol is claimed to be correct, consistent and t-1 unforgeability. As a separate contribution we prove that it is also secure in the universal composability framework. The proposed scheme reduces large amounts of modular exponential computations and communications. It can be applied to the mobile agent system, regardless what the environment it interacts with.