  Vehicular Ad Hoc Networks (VANETs) are a particular subclass of mobile ad hoc
networks that raise a number of security challenges, notably from the way users
authenticate the network. Authentication technologies based on existing
security policies and access control rules in such networks assume full trust
on Roadside Unit (RSU) and authentication servers. The disclosure of
authentication parameters enables user's trace-ability over the network.
VANETs' trusted entities (e.g. RSU) can utilize such information to track a
user traveling behavior, violating user privacy and anonymity. In this paper,
we proposed a novel, light-weight, Adaptive Group-based Zero Knowledge
Proof-Authentication Protocol (AGZKP-AP) for VANETs. The proposed
authentication protocol is capable of offering various levels of users' privacy
settings based on the type of services available on such networks. Our scheme
is based on the Zero-Knowledge-Proof (ZKP) crypto approach with the support of
trade-off options. Users have the option to make critical decisions on the
level of privacy and the amount of resources usage they prefer such as short
system response time versus the number of private information disclosures.
Furthermore, AGZKP-AP is incorporated with a distributed privilege control and
revoking mechanism that render user's private information to law enforcement in
case of a traffic violation.
