International Association for Cryptologic Research (IACR)
Abstract
Vehicular ad-hoc networks (VANETs) have been
emerging due to the recent technologies in wireless and network
communications. The most fundamental part in VANETs is to
enable message authentications between vehicles and roadside
units. Message authentication using proxy vehicles has been
proposed to reduce the computational overhead of roadside units
significantly. In this type of message authentication schemes,
proxy vehicles with verifying multiple messages at the same time
improve computational efficiency of roadside units when there
are a large number of vehicles in their coverage areas. In this
paper, first we show that the only proxy-based authentication
scheme (PBAS) presented for this goal by Liu et al. cannot achieve
authenticity of messages, and also it is not resistant against
impersonation and modification attacks and false acceptance of
batching invalid signatures. Next, we propose a new identity based
message authentication using proxy vehicles (ID-MAP).
Then, to guarantee that it can satisfy message authentication
requirement, existential unforgeability of underlying signature
against adaptively chosen-message and identity attack is proved
under Elliptic Curve Discrete Logarithm Problem in the random
oracle model. It should be highlighted that ID-MAP not only is
more efficient than PBAS since it is pairing-free and does not
use map-to-point hash functions, but also it satisfies security and
privacy requirements of vehicular ad hoc networks. Furthermore,
analysis shows that the required time to verify 3000 messages in
ID-MAP is reduced by 76% compared to that of PBAS