## 3 Related Work
### Lightweight Encryption in IoT  
[PERSON] et al. [6] proposed the SMQTT and SMQTT-SN security schemes, which utilize Key Policy and Ciphertext Policy Attribute-Based Encryption (KP/CP-ABE) in combination with lightweight Elliptic Curve Cryptography. Their work included a security analysis demonstrating robustness against several attacks. However, the study lacked a comprehensive performance evaluation, as it did not offer a comparative analysis with alternative protocols. [PERSON] et al. [7] and [PERSON] et al. [8] proposed IoT encryption using Attribute-Based Encryption (ABE) to ensure data confidentiality. However, these approaches impose considerable overhead due to the reliance on the ABE protocol, which may limit their suitability for resource-constrained publisher devices. Another ABE-based solution was presented by [PERSON] et al. [9]. It was compared with other AES protocols with different modes and demonstrated better results compared to AES. [PERSON] et al. [10] proposed a new security scheme for MQTT by integrating MQTT with the ARIA encryption algorithm for securing the MQTT payload and MbedTLS for network tunnel encryption. Some other security approaches were related to improving AES by deriving new protocols from the standard AES, such as the work presented in [11; 12; 13; 14]. [PERSON] et al. [15] presented a new enhanced protocol called SEEMQTT, which is proposed to ensure end-to-end data confidentiality, integrity, and authorization between publishers and subscribers. The framework establishes a secure communication channel between clients and KeyStore servers using Identity-Based Encryption (IBE). [PERSON] et al. [16] introduced MQTT-I, a protocol designed to provide end-to-end data flow integrity in MQTT systems, even in the presence of an untrusted broker. Leveraging Merkle Hash Trees, the approach ensures integrity across dynamic, multi-topic data streams without requiring direct coordination between publishers and subscribers. Although, it was proven by authors, the scope of this study is limited to data integrity. [PERSON] et al. [17] proposed iTLS, a lightweight secure transport protocol tailored for resource-constrained IoT environments, which employs identity-based encryption to reduce handshake complexity and session overhead. Unlike traditional TLS, iTLS employs identity-based cryptography (IBC) to enable certificate-free, implicit mutual authentication and early key generation, allowing encrypted data to be sent without additional round trips. Compatible with TLS 1.3, iTLS reduces network overhead by over 61% and handshake latency by at least 60%, offering strong security and efficiency for low-power IoT networks. Although iTLS is more lightweight than traditional TLS, it still requires the use of AES, ChaCha20, or a similar encryption scheme for payload-level protection to ensure true end-to-end security. This is particularly important when the MQTT broker is untrusted or compromised--a risk that becomes more significant in cloud-hosted broker environments. The introduction of authenticated encryption schemes has further expanded the design space for secure IoT communication. [PERSON] et al. [18] proposed securing MQTT and MQTT-SN communication in constrained environments using the ChaCha20-Poly1305 authenticated encryption with associated data (AEAD) scheme. Their approach leverages ChaCha20 as a lightweight stream cipher for confidentiality, combined with Poly1305 as a one-time message authenticator to ensure data integrity and authenticity. A similar improved security scheme was proposed by [PERSON] et al. [4], which employs Salsa20 for confidentiality and Blake2b for message integrity. A comprehensive performance evaluation was conducted against several encryption protocols, including AES variants, TinyAES-HMAC, ASCON, SIMON-HMAC, SPECK-HMAC, and ChaCha20-Poly1305, using both 128-bit and 256-bit keys where applicable. The results demonstrate that the proposed scheme achieves lower CPU cycles, faster encryption time, and higher throughput.