Security Analysis and Improvement of an Anonymous Authentication Scheme for Roaming Services

Algorithm 2

The login and key agreement phase of our improved scheme.

inputs and

retrieves the timestamp

            checks the freshness of

            retrieves the timestamp

                         checks the freshness of

                     Does yield and ?

                       Does yield ?

                        Does yield ?

                        retrieves the timestamp

            checks the freshness of

           Does yield & ?

checks the freshness of

Does yield , and ?