# Defense and Security Mechanisms in the Internet of Things: A Review
## 4 Security Mechanisms in IoT Environments
### Authentication Protocols for IoT Environments  
In [110], [PERSON] et al. presented a mutual authentication protocol for crowdsourcing IoT [111] with session key establishment. Their work incorporated the use of chaotic maps and authenticated encryption in communications. They stated that the protocol is secure due to ROM validation and an informal security analysis. They also used the Scyther tool to ensure the security of the proposed protocol. The investigations above established that the proposed protocol offers security services such as information and message integrity, anonymity, and untraceability. Also, this protocol is secure against replay, man-in-the-middle (MITM), impersonation, and Temporary Parameter Leakage attacks. In the work by [PERSON] et al. published in [112], the authors proposed a cross-domain authentication protocol for the interaction between the blockchain-based infrastructure and the industrial IoT centralised networks. They applied the blockchain method in the safe and reliable verification process. Additionally, to ensure the security and privacy of the communication channels, they used an end-to-end encrypted communication architecture with the TLS (Transport Layer Security) protocol [113]. This approach ensures that the data exchange between the authenticated nodes is not interfered with or altered in transit. The authors have demonstrated the application of the suggested protocol in the factory IoT environment and increased security while maintaining efficiency. [PERSON] et al. in [114] focussed on solutions based on the IoT cloud. They proposed a secure mutual authentication mechanism based on visual cryptography for encrypting and decrypting sensitive images. This type of authentication involves two secure photos and tickets. The user requires a ticket from the authentication server to gain permission to use the cloud services. Three shared secret keys are used in the authentication process to encrypt and decrypt the authentication information. The system was also analysed through BAN logic, and the authors established that the system was secure with data integrity, secrecy, and authenticity properties. In the paper by [PERSON] et al. published in [115], the authors proposed a PUF-based end-to-end anonymous authentication protocol. This protocol provides strong anonymity and the ability for the two parties to authenticate each other directly and simultaneously with the help of a third party. The authors proved their solution using the random oracle model and informal analysis. They checked its features and proved that the proposed protocol provides perfect forward secrecy and is invulnerable to physical and modelling attacks [116]. [PERSON] et al. in [117] proposed an enhanced three-factor remote user authentication protocol. They applied passwords, smart cards, and biometrics to authenticate the users. The authors of this protocol evaluated it using BAN logic and the AVISPA tool. The research demonstrates that the presented protocol is immune to password-guessing attacks, identity-guessing attacks, user impersonation attacks, gateway node impersonation attacks, sensor node impersonation attacks, smart card stolen attacks, replay attacks, insider attacks, user untraceability attacks, sensor node capture attacks, and session key temporary information attacks. Also, it satisfies the mutual authentication property, the proper session key establishment, and the correct password change phase. In the study by [PERSON] et al. published in [118], the authors suggested the blockchain and PUFs to implement an authentication protocol as an extension of [PERSON]'s protocol [119]. The research was focused on medical IoT and aimed at providing a secure and efficient authentication mechanism for these devices. This protocol incorporates distributed and immutable ledgers, PUFs for device authentication, anomaly detection with AI, and data transmission through the IoT. The authors verified this protocol using the AVISPA tool and Random Oracle Model.