next up previous
Next: Enhancements of the protocol Up: An example of verification Previous: A flaw

Corrected protocol

 

A way to prevent the attack is to add to the acknowledgement a unique identifier of the registration. The random number used in the GQ verification is the right candidate. This number is meant to be different at each registration. Its integration into the signature of the fourth message will allow the user to check its freshness. Here is the corrected version of our registration protocol:

tex2html_wrap_inline836
tex2html_wrap_inline844
tex2html_wrap_inline846
tex2html_wrap_inline880
tex2html_wrap_inline882

Aldebaran states that all the properties, including P4, are fulfilled with this version. Hence, the mutual authentication and the transmission of the public key succeed despite the attempts of the intruder.