Security weakness of two identity-based multiple key agreement protocols

Multiple key agreement (MKA) protocols allow two parties to generate two or more session keys in a run, which will be used for future secure communications in public network. In recent years, many MKA protocols have been proposed. However, most of them do not consider ephemeral key compromise resilience and also suffer from other security flaws. In this paper, we analyze Dehkordi and Alimoradi´s MKA protocol and Tan´s MKA protocol. We will present ephemeral key compromise attack against Dehkordi and Alimoradi´s MKA protocol, and prove that Tan´s MKA protocol cannot provide mutual security.