Integrating a trust framework with a distributed certificate validation scheme for MANETs

Abstract

Many trust establishment solutions in mobile ad hoc networks (MANETs) rely on public key certificates. Therefore, they should be accompanied by an efficient mechanism for certificate revocation and validation. Ad hoc distributed OCSP for trust (ADOPT) is a lightweight, distributed, on-demand scheme based on cached OCSP responses, which provides certificate status information to the nodes of a MANET. In this paper we discuss the ADOPT scheme and issues on its deployment over MANETs. We present some possible threats to ADOPT and suggest the use of a trust assessment and establishment framework, named ad hoc trust framework (ATF), to support ADOPT's robustness and efficiency. ADOPT is deployed as a trust-aware application that provides feedback to ATF, which calculates the trustworthiness of the peer nodes' functions and helps ADOPT to improve its performance by rapidly locating valid certificate status information. Moreover, we introduce the TrustSpan algorithm to reduce the overhead that ATF produces, and the TrustPath algorithm to identify and use trusted routes for propagating sensitive information, such as third parties' accusations. Simulation results show that ATF adds limited overhead compared to its efficiency in detecting and isolating malicious and selfish nodes. ADOPT's reliability is increased, since it can rapidly locate a legitimate response by using information provided by ATF.