# Energy Efficient Dynamic Symmetric Key Based Protocol for Secure Traffic Exchanges in Smart Homes
## 2 Related Work
However, a single trusted third party is responsible for access control and authorization, which presents a single point of failure. In addition, these protocols have scalability issues [19; 52]. Biometric-based protocols have been introduced to overcome the shortcomings inherent in static credentials-based authentication schemes [53; 54]. Although these schemes have faster response times, many smart devices still lack inbuilt biometric authentication capabilities. In addition, they are not privacy-preserving [55] and present challenges in revoking compromised biometric information. Moreover, many users regard biometric authentication as intrusive and a violation of their privacy. To offer secure communication, a robust protocol is developed in [56]. Unfortunately, this protocol is vulnerable to stolen user devices and privileged insider attacks. The scheme in [57] can solve this problem by upholding confidentiality and user and device authenticity. In addition, it prevents server spoofing, user impersonation, man-in-the-middle, replays, and offline password-guessing attacks. Unfortunately, it is vulnerable to de-synchronization attacks. Based on digital certificates, a security protection scheme is introduced in [58]. In this approach, subsequent session keys are derived using some master keys and hence cannot assure forward key secrecy upon disclosure of these keys. In addition, a malfunctioning key derivation function (KDF) may lead to connection termination. On the other hand, the security technique in [59] is noted to be vulnerable to de-synchronization attacks [60]. Tocurb this challenge, a novel security preservation scheme is presented in [60]. Although the approach employed by the authors in [14] can uphold data confidentiality, it is unable to sustain authentication parameters privacy [61]. This problem is solved by the blockchain-based protocols in [62; 63]. However, the deployed blockchain technology incurs heavy computation and storage overheads [64]. On its part, the temporal identity-based solution presented in [65] is vulnerable to attacks such as known-key and DoS. This is because it uses static parameters during the session key generation process. Due to computationally intensive cryptographic operations and heavy signaling during the authentication procedures, this approach incurs high communication and computation costs. A scheme based on fuzzy extraction is introduced in [66]. However, vulnerability to traceability attacks and inability to provide identity protection, as well as session key agreement, are its major challenges [67]. Conversely, the scheme in [8] dynamically renews the session key to thwart replay attacks. However, this approach has high computation costs due to a myriad of cryptographic operations involved. Table 1 presents a summary of the cons and pros of some of these schemes. In summary, the current authentication and key agreement protocols cannot offer complete security and privacy protection at low energy, execution time, and communication overheads. For instance, the asymmetric key protocols in [31; 33] have higher costs compared with their symmetric counterparts in [14; 59; 60]. However, the communication and computation complexities of these symmetric protocols are still unsuitable for smart home devices such as sensors and smart switches. Although LoRaWAN and NB-IoT technologies can address the inefficiency issues in current schemes, these technologies have numerous security challenges. For instance, LoRaWAN is susceptible to attacks such as bit-flipping and replay. As explained in [25], LoRaWAN authentication procedures are vulnerable to network flooding, man-in-the-middle, eavesdropping, sinkhole, jamming,