# A Secure Opportunistic Network with Efficient Routing for Enhanced Efficiency and Sustainability
## 1 Introduction  
In the ever-evolving landscape of wireless communications, characterized by a complex interplay of technological advancements, the convergence of cybersecurity and opportunistic networks (OppNets) emerges as a catalyst for a profound paradigm shift. This convergence signifies more than a mere juxtaposition of innovative concepts; it heralds the onset of a new era marked by transformative innovation and heightened potential within the wireless communication domain. In an age where the seamless exchange of data assumes unparalleed importance for individuals and organizations alike, the imperative for networking solutions transcends mere efficiency and reliability, extending into the realms of sustainability and long-term viability. The backdrop of opportunistic networks, defined by their intermittent connectivity and dynamic environmental conditions, presents a distinct set of challenges that necessitate solutions beyond conventional approaches. This paper serves as a vanguard, introducing a groundbreaking paradigm that intricately intertwines the fundamental principles of cybersecurity and some concepts related to blockchain technology with the complex fabric ofopportunistic networks. At the core of this exploration lies the revelation of a meticulously crafted routing protocol, a novel entity designed with the explicit intention of not merely surpassing current solutions but redefining benchmarks in key performance metrics. These metrics not only encompass the traditional domains of delivery probability, overhead ratio, and communication delay but also extend into the broader landscape of holistic network efficiency and sustainability. The added value of our proposed protocol lies in its adept use of the inherent strengths embedded within the cybersecurity protocols. Beyond the conventional fortification of the network's security posture, our protocol lays a foundation for a holistic augmentation of efficiency and sustainability within opportunistic networks. It represents not merely an incremental enhancement but a transformative leap forward, addressing the intricacies of data exchange in a dynamic and unpredictable environment. As the digital realm increasingly intertwines with our daily lives, the outcomes of this study hold the promise of redefining the standards by which wireless communication networks operate, using in a new era where innovation and sustainability become inseparable facets of the technological scenery. Furthermore, to ensure a high security level in distributed networks like OppNets, this study incorporates aspects proposed in blockchain technology, namely the trust value computation, the consensus algorithm, and the block generation process to establish a preliminary connection to blockchain technology, demonstrating its relevance and significance. The adoption of these specific components aligns with the fundamental principles and functionalities inherent in blockchain systems. This paper is organized into six main sections that lay the foundation by highlighting the convergence of cybersecurity and blockchain with opportunistic networks, underscoring the imperative for reliable and sustainable networking solutions. Sections 1-4 delve into fundamental aspects, exploring challenges in routing within opportunistic networks and examining existing protocols integrated with cybersecurity. Section 5 introduces the proposed solution, detailing a two-layered organizational structure. The first layer presents the FT-OLSR protocol based on aspects implemented in blockchain, emphasizing fuzzy logic for trust evaluation and introducing the Proof-of-Trust consensus algorithm. This section also outlines the block generation process for permanently isolating malicious nodes. The second layer focuses on the proposed routing protocol specifically designed for opportunistic networks, elucidating protocol requirements, initialization, exchange of deliverable messages, procedures for non-deliverable messages, sending of accepted messages, and the criteria for message acceptance.