# Blockchain-Based Lightweight Trust Management in Mobile Ad-Hoc Networks
## 1 Introduction
To take advantage of the decentralized nature of blockchain technology, one must consider the limited resources of MANETs when designing a trust system. For example, implementing a blockchain implementing a blockchain with proof-of-work (PoW), the complex computational consensus mechanism and long validation time in MANET nodes without any centralized party would be highly impractical. Therefore, we propose a lightweight consensus algorithm for trust management in MANETs called delegated proof-of-trust (DPoT), which achieves reasonable validation times based on peer-to-peer (p2p) concepts. Although various attacks can occur in any security layer of a MANET, in this study, we decided to focus on evaluating the trust of a node based on routing issues, which occur in the network layer and represent a critical research issue in dynamic MANET environments. OLSR [14] was selected as a representative routing protocol for implementing blockchain operations since it is one of the proactive protocol which maintains the neighbor information. The proposed system is \begin{table}
\begin{tabular}{c c} \hline \hline
**MANET Layers** & **Attacks** \\ \hline Application Layer & Malicious code, Repudiation \\ Transport Layer & Session hijacking, SYN Flooding \\ Network Layer & Flooding, Blackhole, Geryhole, Wormhole, Link Spoofing, etc. \\ Data Link Layer & Traffic analysis and monitoring \\ Physical Layer & Traffic jamming, Eavesdropping \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Example Attacks in Different Network Layers. a trust management system using a policy-based and reputation-based trust management framework. Therefore, a policy-based mechanism that can generate binary results according to whether or not a node is trusted is defined such that trust evaluation (reputation-based evaluation) can be performed based on binary results. We implemented denial contradictions with a fictitious node mechanism (DCFM) [15] as a representative detection mechanism for identifying malicious attackers and trusted nodes as this is one of the effective schemes that was introduced recently. Moreover, this paper considers to reduce the unnecessary bandwidth and energy usage by introducing the collaborative detection process based on predefined principles. Most security solutions in OLSR, including DCFM, force nodes in the network to perform excessive operations based on frequently updated topology information, which is periodically exchanged and sometimes contains additional messages, which incur unnecessary bandwidth and energy usage. Furthermore, nodes are suspicious of each other since they are on their own without any authentication process. This gives attackers a chance to compromise networks easily and manipulate residential nodes repeatedly which makes the overall network efficiency is decreased. The main contributions of this paper can be summarized as follows. * We design a trust evaluation system that can fulfill the objectives of MANETs based on blockchain technology. * The blockchain implementation is described based on a series of steps, transaction validation, block configuration, block validation, and block chaining and maintenance in MANETs. Furthermore, a suitable consensus mechanism for MANETs called DPoT is successfully embedded in OLSR for the validation of blockchains. * We designate several principles to determine if nodes can implement a particular security mechanism to mitigate attacks in a collaborative manner to reduce energy consumption and network vulnerability. The remainder of this paper is organized as follows. In Section 2, we discuss background information and related works. In Section 3, we introduce the proposed method. In Section 4, we describe our simulation environment and test results. Our final conclusions are discussed in Section 5.