Brief Announcement: Impossibility Results for Concurrent Secure Two-Party Computation

The results regarding the concurrent composition of security two-party protocols in the plain model were described. Two types of composition were distinguished where the distinction related to the question of which protocols were being run together in the network. The first type, called self composition considered the case where a single protocol is executed many times in a network, while the second type, called general composition considered the case where many different protocols were run together in the network. The result showed that the lower bound leaves open the possibility of obtaining positive results.