Two-Way Authentication Scheme for Railway Time Synchronization Protocol Based on Hybrid Key Enhancement

Aiming at the problem of missing client authentication in the NTP protocol of railroad time synchronization network, we propose a two-way authentication scheme based on hybrid key enhancement. The scheme securely transmits the public key based on the cryptography of the identity and securely negotiates a temporary key by asymmetric encryption. At the same time, we utilize the host's current time as a sequence number to defend against replay attacks. Two-way authentication is accomplished through the identity checksum generated from the temporary key and the sequence number. Subsequently, we use the temporary key encryption to protect the subsequent message transmission. This scheme not only reduces the lack of client authentication, but also provides forward and backward security. Finally, we formally verified the scheme using the proverif tool. The validation results show that our method outperforms other methods in terms of security and authentication overhead, and is able to satisfy the security and real-time requirements of bidirectional authentication for NTP protocols.