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Certificate status validation is one of the main operations conducted in all PKI-based security systems to ensure the validity of digital certificates. In this paper, a new certificate validation scheme is proposed which adjusts the OCSP responses validity period according to the trust level of certificate authority on the certificate owner. As a result, the OCSP responses validity period of more trusted nodes are increased while the less ones' are decreased. On the client side, the OCSP responses validity period can be used to tune the certificate status information (CSI) caching period which has direct effect on the overheads and freshness of CSI in MANET. Our proposed solution improves the availability of CSI for more trusted nodes and better isolates the malicious ones. Extensive simulation results indicate that our solution efficiently reduces the CSI inconsistency problem and mitigates the overheads of certificate status validations in MANET. [ABSTRACT FROM AUTHOR]

Freshness of certificate status information is very important in validating public key certificates. However, existing certificate validation schemes suffer from high inconsistency, which makes network vulnerable to various security attacks. In this paper, we propose a new publish/subscribe-based certificate validation scheme that provides fresh certificate status information in the mobile ad hoc networks. This scheme increases the security of public key infrastructure-based security systems and improves the scalability of certificate validation systems. Also, according to the simulation results, our solution effectively decreases the processing overheads on responder nodes and reduces the messaging overhead of certificate status validations in mobile ad hoc networks. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Providing consistent certificate status information (CSI) in dynamic environment of MANET is a challenging issue. Inconsistent CSI decreases the network security and makes the network vulnerable to CSI replay attacks which previously issued valid CSI are forwarded for the status of a revoked certificate. In this paper, we propose a new certificate validation solution for hybrid MANETs which decreases the OCSP responses' validity period according to the accusations issued against the certificates. As a result, the OCSP responses of revoked certificates will be valid for shorter time and for less time will be available for malicious nodes. Furthermore, in this scheme the number of accusations issued against each certificate is added to the OCSP response's validity period which can be very useful on client side for tuning the certificate validation parameters and localized certificate revocations. Simulation results indicate that our solution effectiveness of our solution. [ABSTRACT FROM AUTHOR]

In mobile ad hoc networks (MANETs), the IEEE 802.11 CSMA/CA is deployed as the primary medium access control (MAC) layer protocol to schedule the access to the wireless medium. The IEEE 802.11 standard was designed with the assumption that nodes would never deviate from the protocol. However, MANET nodes may purposefully show misbehavior at the MAC layer to obtain more bandwidth or degrade the network performance and disrupt the network services. This paper reviews and classifies the most important strategies generating MAC layer misbehavior based on their objectives and operating principles. Then, it examines some of the recent proposed solutions and mechanisms for detecting and preventing MAC layer misbehavior. A comparison of the studied solutions is carried out using a set of critical evaluation metrics. Finally, the paper concludes with a brief summary of key ideas and a general direction that can provide a basis for future work. [ABSTRACT FROM AUTHOR]

In the IEEE 802.11 standard, network nodes experiencing collisions on the shared medium need a mechanism that can prevent collisions and improve the throughput. Furthermore, a backoff mechanism is used that uniformly selects a random period of time from the contention window (cw) that is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. Prior research has proved that the BEB scheme suffers from a fairness problem and low throughput, especially under high traffic load. In this paper, we present a new backoff control mechanism that is used with the IEEE 802.11 distributed coordination function (DCF). In particular, we propose a dynamic, deterministic contention window control (DDCWC) scheme, in which the backoff range is divided into several small backoff sub-ranges. In the proposed scheme, several network levels are introduced, based on an introduced channel state vector that keeps network history. After successful transmissions and collisions, network nodes change their cw based on their network levels. Our extensive simulation studies show that the DDCWC scheme outperforms four other well-known schemes: Multiplicative Increase and Linear Decrease, Double Increment Double Decrement, Exponential Increase Exponential Decrease, and Linear/Multiplicative Increase and Linear Decrease. Moreover, the proposed scheme, compared with the IEEE 802.11 DCF, gives 30.77% improvement in packet delivery ratio, 31.76% in delay, and 30.81% in throughput. [ABSTRACT FROM AUTHOR]