## 5 Fuzzy Logic Approaches in Trust Management
### Effective Metrics and Comparative Analysis of Methods Based on These Metrics
#### 5.2.1 Comparative Analysis Based on Metrics
* Privacy: The framework includes a trust management module that ensures the privacy of sensitive data by monitoring and evaluating the trustworthiness of network entities. * Dynamicity: The framework is designed to address the dynamicity of 5G infrastructure threats and multitenancy security risks, providing solutions to ensure secure and trustworthy communication in multitenant environments. * Context awareness: The framework includes an intra-domain module that uses dynamic traffic analysis to identify attacks and vulnerabilities within the 5G infrastructure, as well as in a multi-tenant/multi-domain environment, demonstrating context awareness in trust evaluation. Several significant scalability, integrity, dynamicity, and context awareness criteria were covered in [45]:
* Scalability: This approach allows for a scalable framework in which decision makers can customize the trust evaluation criteria based on specific application contexts, thereby enhancing the scalability of the model. * Integrity: By incorporating probabilistic linguistic term sets and the MULTIMOORA method, the model aims to provide accurate and reliable trust assessments, thereby upholding integrity in the decision-making processes. * Dynamicity: This model accounts for the dynamic reliability of opinions provided by recommenders and the evolving nature of trust assessments in different contexts. By incorporating dynamic trustworthiness criteria and adapting them to changing trust-related attributes, the model demonstrates the level of dynamicity in trust evaluation. * Context awareness: By allowing the trustor to define trustworthiness criteria based on specific application scenarios, the model exhibits context awareness and tailors trust assessments according to the unique requirements of different contexts. Several crucial factors for assessing trust were covered in the article in [43], including context awareness, scalability, integrity, availability, privacy, and dynamicity:
* Scalability: By utilizing fuzzy trust evaluation and outlier detection mechanisms, the protocol can scale effectively to accommodate a large number of sensor nodes while maintaining efficient cluster formation and secure communication. * Integrity: By incorporating fuzzy logic, transmission overhearing, and outlier detection, the protocol enhances the integrity of the network by ensuring that trustworthy nodes are assigned leadership roles within the clusters, thereby maintaining data integrity and security. * Availability: By balancing energy savings and security assurance in cluster head selection, the protocol optimizes resource utilization and prolongs the network's lifetime, enhancing overall availability. * Dynamicity: The adaptive trust thresholds, outlier detection, and fuzzy-based trust evaluation methods of the protocol enable dynamic adjustments to trust levels based on changing network conditions and node behaviors. This dynamicity allows the protocol to adapt to evolving threats and uncertainties in the network environment, thereby enhancing its responsiveness and effectiveness. * Context Awareness: The fuzzy trust evaluation method considers multiple factors and parameters, such as past interactions, QoS metrics, and energy levels, to assess the trust levels among nodes. By incorporating contextual information into the trust evaluation process, the protocol demonstrated a level of context awareness that enhanced the accuracy and relevance of trust assessments in diverse network scenarios. In [42], the authors addressed several important criteria in trust evaluation, including scalability, integrity, availability, privacy, dynamicity, and context awareness:  
* Integrity: The scheme focuses on maintaining the integrity of trust management processes by utilizing fuzzy logic for accurate decision making and by considering both direct and indirect trust factors. This ensured that the trustworthiness of the sensor nodes was evaluated in terms of integrity and precision.