“…In order to meet these requirements, cryptographic techniques should also be carefully chosen. Prior works on security issues in mobile communication systems can be found in Tatebayashi et al (1990), Hwang (1993), Coomaraswamy and Kumar (1993), Beller et al (1993), Ashar and Diffie (1994), Lin and Harn (1993) and Molva et al (1994). Most of these works are done for point-to-point communications.…”