## 4 Security and Privacy in Edge Frameworks
### Hardware-Assisted Security--Puf  
HAS refers to security mechanisms implemented at the hardware level to protect data, the hardware itself, or the entire system. HAS involves integrating dedicated security hardware components, modifying hardware designs, or altering system-level architectures to meet specific security requirements. It facilitates the implementation of SbD and Privacy-by-Design (PbD) principles, both of which emphasize proactive security integration during system development [43]. HAS contributes to overall cybersecurity by supporting a range of security functions, as illustrated in Figure 2.  
HAS complements traditional software defenses by embedding protection mechanisms at the hardware level, offering enhanced isolation, observability, resilience, and performance. Despite its advantages, challenges remain in implementation correctness, integration, and long-term adaptability. HAS targets a wide range of threats and vulnerabilities, including software-based attacks such as code flaws, malicious software behavior, and control-flow attacks. It also addresses microarchitectural and hardware-level exploits like side-channel attacks, fault injection, and unpatched hardware flaws. Additionally, HAS mitigates access control violations stemming from improper resource isolation and unauthorized peripheral access. Broader concerns such as hardware immutability, supply chain threats, and policy enforcement issues also fall within the scope of HAS-enabled protections [44].  
PUFs, in the context of cybersecurity for IoT devices, offer a hardware-based solution by generating unique, device-specific responses based on intrinsic manufacturing variations. PUFs eliminate the need to store secret keys, making devices more resistant to physical and invasive attacks such as eavesdropping, side-channel attacks, and unauthorized access resulting from insecure key storage. They play a critical role in secure authentication and  
Figure 2: Cybersecurity functions realized through HAS in SbD paradigm.  
lightweight encryption schemes, providing cost-effective security tailored for resource-constrained environments while addressing both privacy and integrity concerns in IoT systems [45].  
Utilizing the intrinsic manufacturing variations in a device to generate a unique fingerprint of that hardware offers the advantage of unclonability. This property of the PUFs gives an edge over other hardware-based security methods as the hacker cannot clone the intrinsic properties of the device. Thus, PUFs can provide a low-cost hardware-based security to enable device identification and cryptographic key generation.  
PUFs are integrated into various systems to bolster security and trust. They find applications in various environments of smart city and smart village infrastructure, providing low-power security solutions in resource-constrained ecosystems. Some of the applications where PUFs are employed are shown in Figure 3.  
When employing PUFs for security, several parameters must be carefully considered. Key indicators for assessing the robustness of a well-designed PUF include the amount of helper data required, reliability, security strength, uniqueness, flexibility, and portability.