<b>Security analysis and enhancements of a three-party authenticated key agreement protocol

Resumo

Three-party authenticated key agreement (3PAKA) protocol is an important cryptographic mechanism for secure communication, which allows two clients to generate a shared session key with the help of the server. Recently, Tan proposed a communication and computation-efficient 3PAKA protocol. Compared with related protocols, Tan´s protocol requires fewer rounds, lower communication cost and smaller computation cost. Tan claimed that his protocol was secure against various attacks. Unfortunately, we found that his protocol cannot withstand the key compromise impersonation attack. To improve security, we proposed a new 3PAKA protocol. Security analysis and performance analysis show our 3PAKA protocol could overcome weakness in Tan´s protocol at the cost of increasing the computational cost slightly.