This work proposes authentication based on identity as a way to increase the efficiency and security of communications in vehicular ad-hoc networks. When using identity-based cryptography to achieve certificateless authentication, membership revocation is not a trivial problem. Thus, in order to improve the performance of revocation in such networks, the use of a dynamic authenticated data structure based on perfect k-ary hash trees combined with a duplex version of the new standard SHA-3 is here presented. Efficient algorithms in the used revocation trees allow reaching a refresh rate of at most simple updates per inserted node. Consequently, the proposal is especially useful for situations with frequent revocations, which are foreseeable when vehicular ad- hoc networks are widely deployed.
 ETSI (2012) Intelligent Transport Systems. http://http://www.etsi.org/index.php/technologies-clusters/technologies/intelligent-transport
 Blake-Wilson, S. (2000) Information Security, Mathematics, and Public-Key Cryptography. Designs, Codes and Cryptography, 19, 77-99. http://dx.doi.org/10.1023/A:1008345904539
 Hubaux, J.P., Capkun, S. and Luo, J. (2004) The Security and Privacy of Smart Vehicles. IEEE Security and Privacy, 2, 49-55. http://dx.doi.org/10.1109/MSP.2004.26
 Chang, S., Perlner, R., Burr, W., Turan, M., Kelsey, J., Paul, S. and Bassham, L. (2012) Third-Round Report of the Sha-3 Cryptographic Hash Algorithm Competition. NIST. nvlpubs.nist.gov/nistpubs/ir/2012/NIST.IR.7896.pdf
 Bertoni, G., Daemen, J., Peeters, M. and Assche, G.V. (2012) Duplexing the Sponge: Single-Pass Authenticated Encryption and Other Applications. Selected Areas in Cryptography, LNCS 7118, 320-337.