Hybrid Protocol for Password-Based Key Exchange in Three-party Setting

Modular design is a common approach for dealing with complex tasks in modern cryptology. The critical of this approach is to design a secure hybrid protocol. In this paper, we study password-based key exchange in the three-party setting within the UC framework and design a hybrid protocol that UC-securely realizes such task. Next we partition the task into two sub-tasks, three-party key distribution and password-based two-party key exchange, and propose relevant two ideal functionalities, F3pKD, FpwKE. Finally, we present a (F3pKD, FpwKE) -hybrid protocol for password-based three-party key exchange that is proved to be UC-secure with respect to non-adaptive party corruption.