IAESR: IoT-oriented authenticated encryption based on iShadow round function

With the growing popularity of the Internet of Things (IoT) devices and the widespread application of embedded systems, the demand for security and resource efficiency in these devices is also increasing. Traditional authenticated encryption (AE) algorithms are often unsuitable for lightweight devices due to their complexity and resource consumption, creating a need for lightweight AE algorithms. Lightweight devices typically have limited processing power, storage capacity, and energy resources, which necessitates the design of simple and efficient encryption algorithms that can function within these constraints. Despite these resource limitations, security remains of paramount importance. Therefore, lightweight AE algorithms must minimize resource consumption while ensuring adequate security. This article presents a theoretical lightweight AE scheme based on Shadow, a lightweight block encryption algorithm, to address the requirements for secure communication in resource-constrained environments. The scheme first enhances the Shadow algorithm by introducing the improved Shadow (iShadow) algorithm. It then combines this with the duplex sponge structure to propose the IoT-oriented authenticated encryption based on the iShadow round function (IAESR). The integration of iShadow with the duplex sponge structure achieves a balance between security and efficiency through three key mechanisms: (1) The sponge's capacity (64/128-b for IAESR-32/64) provides provable indistinguishability under chosen-plaintext attack (IND-CPA) and chosen-ciphertext attack (IND-CCA) security bounds, effectively resisting generic attacks with an adversarial advantage limited to <i>O</i>(<i>q</i> ²/2 <i>^c</i> ); (2) the duplex mode's single-pass processing reduces memory overhead by reusing the permutation state; and (3) iShadow's ARX operations reduce energy consumption to 0.4-0.5 µJ/byte on 32-b microcontrollers, outperforming AES-GCM by 20-30%. Empirical tests on an Intel i5-1035G1 CPU demonstrate stable execution times. This design ensures the security and integrity of communication while balancing efficiency, and resource utilization. This design ensures IND-CCA secure confidentiality and integrity against plaintext (INT-PTXT), as demonstrated by the security bounds of the sponge construction. Specifically, IAESR guarantees both confidentiality and authenticity. Additionally, it is particularly well-suited for scenarios with lightweight requirements, such as those found in the IoT.