Citation: Chiejina, E.; Xiao, H.;
Christianson, B.; Mylonas, A.;
Chiejina, C. A Robust Dirichlet
Reputation and Trust Evaluation of
Nodes in Mobile Ad Hoc Networks.
Sensors 2022, 22, 571. https://
doi.org/10.3390/s22020571
Academic Editor: Charalampos
Konstantopoulos
Received: 18 November 2021
Accepted: 7 January 2022
Published: 12 January 2022
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Article
A Robust Dirichlet Reputation and Trust Evaluation of Nodes
in Mobile Ad Hoc Networks
Eric Chiejina * , Hannan Xiao, Bruce Christianson, Alexios Mylonas and Chidinma Chiejina
School of Physics, Engineering, and Computer Science, University of Hertfordshire, College Lane,
Hatfield AL10 9AB, Hertfordshire, UK; h.xiao@herts.ac.uk (H.X.); b.christianson@herts.ac.uk (B.C.);
a.mylonas@herts.ac.uk (A.M.); c.o.chiejina2@herts.ac.uk (C.C.)
* Correspondence: e.chiejina@herts.ac.uk
Abstract:
The distributed nature of mobile ad hoc networks (MANETs) presents security challenges
and vulnerabilities which sometimes lead to several forms of attacks. To improve the security in
MANETs, reputation and trust management systems (RTMS) have been developed to mitigate some
attacks and threats arising from abnormal behaviours of nodes in networks. Generally, most repu-
tation and trust systems in MANETs focus mainly on penalising uncooperative network nodes. It
is a known fact that nodes in MANETs have limited energy resources and as such, the continuous
collaboration of cooperative nodes will lead to energy exhaustion. This paper develops and evaluates
a robust Dirichlet reputation and trust management system which measures and models the reputa-
tion and trust of nodes in the network, and it incorporates candour into the mode of operations of the
RTMS without undermining network security. The proposed RTMS employs Dirichlet probability
distribution in modelling the individual reputation of nodes and the trust of each node is computed
based on the node’s actual network performance and the accuracy of the second-hand reputations
it gives about other nodes. The paper also presents a novel candour two-dimensional trustworthi-
ness evaluation technique that categorises the behaviours of nodes based on their evaluated total
reputation and trust values. The evaluation and analyses of some of the simulated behaviours of
nodes in the deployed MANETs show that the candour two-dimensional trustworthiness evaluation
technique is an effective technique that encourages and caters to nodes that continuously contribute
to the network despite the reduction in their energy levels.
Keywords:
cooperative nodes; reputation; trust; candour; total reputation; trust values; trustworthi-
ness; MANETs
1. Introduction
The absence of centralised authority in a Mobile Ad Hoc Network (MANETs), poses a
key challenge due to the dire need for cooperative network operation amongst nodes. In
MANETs, some nodes may exhibit behaviours that negate the routing protocol functionality
through the disruption of the route discovery process [
1
]. To ensure that data is readily
available in a MANET, all nodes must function as a forwarder and participate in the
transmission of data packets from the source to the desired destinations [
2
]. MANETs can
generally be set up anywhere and anytime due to their dynamic nature. However, as a
result of their unique characteristics, MANETs are more vulnerable to various security
threats [
3
] such as grey-hole attacks, black-hole attacks, eavesdropping, denial of service
attacks (DoS), etc. when compared to traditional networks.
Security in MANETs generally involves ensuring and maintaining the integrity and
confidentiality of data, in addition to the legitimate use and availability of network service
provided by each network node [
1
]. The viability of a MANET is solely dependent on
the reliability of nodes to actively participate in the route discovery processes and to
honestly forward data packets for other nodes in the network. To attain optimal network
Sensors 2022, 22, 571. https://doi.org/10.3390/s22020571 https://www.mdpi.com/journal/sensors
