  The practical deployment of vehicular networks is still a pending issue. In
this paper we describe a new self-organized method of authentication for
VANETs, which allows their widespread, fast and secure implementation. Our
proposal does not involve any central certification authority because the nodes
themselves certify the validity of public keys of the other nodes. On the one
hand we propose an algorithm that each node must use to choose the public key
certificates for its local store. On the other hand, we also describe a new
node authentication method based on a cryptographic protocol including a
zero-knowledge proof that each node must use to convince another node on the
possession of certain secret without revealing anything about it, which allows
non-encrypted communication during authentication. Thanks to the combination of
the aforementioned tools, the cooperation among vehicles can be used for
developing several practical applications of VANETs, such as detection and
warning about abnormal traffic conditions. One of the most interesting aspects
of our proposal is that it only requires existing devices such as smartphones,
because the designed schemes are fully distributed and self-organized. In this
work we include an analysis of both an NS-2 simulation and a real device
implementation of the proposed algorithms, which enables us to extract
promising conclusions and several possible improvements and open questions for
further research.
