An Improved Delegation-Based Authentication Protocol for PCSs

A new delegation-based authentication protocol was proposed by Lee and Yeh in 2005, claiming that they have provided users with Portable Communication Systems (PCS), which are anonymity and non-repudiation. However, they have also pointed out that their protocol has a weakness in off-line authentication processes. That is, a malicious who visits location register (VLR) can masquerade another mobile user to login to home location register (HLR)....