# Energy Efficient Dynamic Symmetric Key Based Protocol for Secure Traffic Exchanges in Smart Homes
## 2 Related Work  
Numerous security and privacy schemes have been developed to protect the packets exchanged over smart home networks. For instance, a 3-dimensional S-box scheduling algorithm is presented in [27]. Although this scheme is efficient, its formal and informal security analyses are not carried out. In contrast, public key cryptosystems (PKC) based key agreement protocols are presented in [28; 29; 30; 31]. However, PKC-based techniques have high communication and computational overheads [32]; hence they are unsuitable for ISDs. Although the protocol in [31] is resilient against attacks, it can neither withstand known-key attacks nor offer confidentiality, freshness checks, and anonymity [16; 33]. Additionally, it incurs extremely high execution time and communication costs [16]. Although the protocol in [34] is robust against cloning, impersonation, traceability, and physical attacks,it involves extensive hashing operations and message exchanges which are not ideal for resource-constrained ISDs. Conversely, the device security protocol in [35] cannot offer secure mutual authentication and is susceptible to impersonation, stolen smart devices, and session key disclosure attacks [1]. To address the resource-constrained nature of ISDs, lightweight authentication protocols have been presented in [36; 37]. Although the security model in [38] potentially protects user privacy, it has high power consumption due to the requirement for the installation of rechargeable batteries. Although the user authentication scheme in [39] can alleviate this problem, it is susceptible to a privileged insider, gateway bypass, offline password guessing, and replay attacks [40]. Therefore, a user authentication protocol has been proposed in [40] to address these issues. On the other hand, the scheme based on identity, password, and digital signatures is developed in [41]. However, it is based on PKI, which requires entities to maintain a pair of private and public keys, which increases its computation and communication complexities [42]. The protocols in [43; 44; 45] are efficient and can solve the problems in [41].However, the scheme in [43] cannot withstand de-synchronization attacks. In addition, it utilizes verification tables during authentication, which are susceptible to stolen verifier attacks [40]. Similarly, the protocol in [45] has some security issues that limit its applicability [41]. On its part, the scheme in [44] incurs low latency, storage costs, and power consumption, but its security analysis is not carried out.To boost efficiency and reliability, a smart card-based algorithm is developed in [46]. Although this approach has low computation and communication overheads, it cannot resist gateway spoofing, session key disclosure, and impersonation attacks. In addition, it cannot provide anonymity and secure mutual authentication [41]. The two-factor scheme in [47] is anonymous and can address anonymity issues in [46]. Unfortunately, it is vulnerable to password guessing, stolen user device, and impersonation attacks. In addition, it cannot provide mutual authentication [40]. Even though the anonymous security technique developed in [11] provides user anonymity and secure mutual authentication, it is susceptible to attacks such as impersonation, MitM, and session key disclosure [2]. On the other hand, the protocol in [48] assumes that the short-range channel between the ISDs and HGs is secure and that these devices are trustworthy. However, these assumptions are not viable as the open wireless channel is susceptible to a myriad of attacks, and the devices are not tamper-proof and may have inbuilt backdoors [6]. To offer protection against malicious activities in distributed smart environments, a scheme based on implicit certificates is developed in [16]. However, certificate revocation and storage require large memory and elongated execution time [49]. Alternatively, a privacy-preserving scheme is introduced in [50; 51].