# Defense and Security Mechanisms in the Internet of Things: A Review
## 4 Security Mechanisms in IoT Environments
### Authentication and Key Agreement Protocols for IoT Environments
Their protocol addressed the primary deficiencies in this category of communication systems while also fulfilling the criteria for secure dissemination of medical information and user confidentiality. The authors validate the security of this protocol via the ROR model, informal security analysis, and the AVISPA tool. The outcome indicates that the proposed protocol is among the established protocols suitable for healthcare IoT contexts, ensuring adequate security. [PERSON] et al. in [126] observed that the proliferation of wireless communication in IoT devices demands safe and efficient communication protocols, particularly in situations susceptible to cyber-attacks. Due to inadequate security, which requires strong authentication and key exchange mechanisms capable of withstanding attacks while ensuring minimal computational overhead in current protocols, they proposed a fog-enabled network architecture incorporating IoT devices and developed the DEAC-IoT protocol. This protocol employs ECC for secure authentication and key exchange. The protocol safeguards device-to-device communication against security risks in resource-limited IoT contexts. The authors proposed that their protocol accommodates both the static and dynamic behaviours of IoT devices and fog nodes. To ensure the protocol is secure, the authors used a tool called Scyther and checked it with the ROR model. The protocol has been proven to be difficult for most traditional cyber threats in the IoT environment. In the study by [PERSON] et al. published in [61], the authors proposed a blockchain-enabled solution for authentication and key establishment to enable the sharing of health information among the hospitals that are part of a network. This protocol employs an ECC-based authentication mechanism, storing all data on the blockchain and generating a secret key for safe communication among patients, hospital servers, and IoT devices. The authors employed a Hyperledger Fabric platform [127] for the installation of blockchain technology to guarantee security and transparency. They emphasised the efficiency of data transport by removing superfluous computations in the registration and authentication processes. The authors conducted formal and informal analyses of the proposed protocol utilising the ROR model and the Scyther tool. [PERSON] et al. in [128] presented a protocol for authentication and key agreement that enables smart meters and neighbourhood gateways to authenticate one another and generate a shared session key. The proposed approach uses ECC, a lightweight cryptographic hash function, and the Schnorr signature mechanism. The Schnorr signature protocol ensures that privacy, untraceability, and user anonymity are well maintained. The proposed protocol has been tested using the ROM model and the AVISPA tool against adversary models such as Dolev-Yao [129] and Canetti-Krawczyk [130]. The authors used performance analysis to validate the protocol's communication, computing, and storage cost efficiency. [PERSON] et al. in [131] introduced a novel lightweight protocol utilising PUF for mutual robust authentication and key agreement across entities in medical IoT networks. It uses the XOR technique, a one-way hash function, and a Physical Unclonable Function (PUF). The proposed protocol is secure against physical attacks like impersonation, man-in-the-middle, insider, Known Session Key, and Known Session-Specific Temporary Information attacks as described in [132]. Also, it outperforms other existing systemsin terms of security and efficiency. The authors have also established that the proposed protocol is computationally efficient and has used only essential cryptographic functions.