Anonymous roaming authentication protocol for wireless network with backward unlinkability and natural revocation

An anonymous secure roaming authentication protocol can be used in wireless network for authentication between a mobile device and a foreign server when the mobile device is away from its home network and wants to use the services of the foreign network. In a two-party roaming authentication protocol, a mobile user and a foreign server authenticate each other without the active help of the home server. Group signature-based protocols are the obvious choice for the design of two-party protocol due to inherent anonymous nature of group signature. Among the existing group signature-based roaming authentication protocols, only the protocol of Liu et al. supports natural revocation without periodic updates of the master public key at the mobile user and foreign server, but it does not support backward unlinkability. Therefore, we propose a two-party anonymous roaming authentication protocol in which the mobile user supports natural revocation along with backward unlinkability without periodic updates of either public key or private key. In addition, the proposed protocol is provably secure in the random oracle model.