TTP Based High-Efficient Multi-Key Exchange Protocol

With a trusted-third-party (TTP)-based key exchange protocol, when a user would like to transmit a message to another user, the transmitted data are encrypted by a session key exchanged between the two ends of the corresponding connection with the help of the TTP. Up to present, due to the assistance of a TTP, this type of protocols has performed well in protecting messages delivered between two authorized users. Even this, inflexibility, unreliability, and inefficiency problems still exist in these previously proposed protocols. Therefore, in this paper, a multi-key exchange protocol, named the TTP-based high-efficient multi-key exchange protocol (THMEP), is proposed to provide users with a secure and efficient protocol, which employs the elliptic curve cryptography, a 2-D operation, and a current time encryption key, to exchange their session keys. The proposed protocol not only effectively hides important encryption parameters, but also achieves fully mutual authentication between a user and his/her trusted server. It can resist known-key, impersonation, replay, eavesdropping, and forgery attacks. Besides, the THMEP generates 40 session keys in a key exchange process, meaning the proposed protocol can support 40 sessions simultaneously. It also shortens the processing time, which is 3.78 times faster than that of a specific previous study. Its security level and performance are higher than those of the compared state-of-the-art protocols. In other words, the THMEP is very suitable for IoT applications.