# Energy Consumption Analysis of ISO/IEC 29192-2 Standard Lightweight Ciphers
## 6 Considerations for Enhancing ISO/IEC 29192-2 Lightweight Ciphers
Therefore, determining the appropriate number of rounds is not only a matter of performance optimization, but also a fundamental requirement for maintaining the integrity and reliability of encryption in resource-constrained environments. The key scheduling stage is one of the components that contributes significantly to the total energy consumption of encryption algorithms. This phase involves the process of transforming the key into subkeys and requires different computational costs depending on the design of the algorithm. The key scheduling mechanisms of the CLEFIA, PRESENT, and LEA algorithms analyzed in this study differ in terms of energy consumption. Although PRESENT has a relatively simple key planning mechanism, the high total number of rounds and the repetition of key scheduling at the time of encryption cause an increase in energy consumption. Although CLEFIA improves security by using a more complex key expansion mechanism, this structure creates an additional burden in terms of energy. LEA, on the other hand, provides a lower energy consumption during the key generation phase owing to its ARX-based operations. In general, the computational load and memory access used during key generation directly affect the total energy consumption. For lightweight encryption algorithms to be used more effectively in IoT applications, optimizing key planning processes is a critical factor in reducing the computational load and, thus, energy consumption. To achieve this, a foundational structure that is both secure and streamlined should be employed. Studies on lightweight cryptographic algorithms have outlined key criteria for designing future encryption methods. The trend of development shows that the most recent lightweight block ciphers implement a single 4-bit S-box, apply a 128-bit or lower key size, and execute more than 20 encryption rounds according to their structure [38]. Additionally, ARX-based designs have gained popularity due to their efficiency in software and hardware implementations and their ability to provide strong security with minimal computational overhead [25]. These design choices aim to balance security, efficiency, and low power consumption, which are critical for resource-constrained environments such as the IoT and embedded systems. To ensure both security and energy efficiency, future lightweight encryption algorithms should focus on optimizing the number of rounds, selecting efficient key scheduling mechanisms, and minimizing computational complexity through techniques such as ARX operations, all while maintaining resistance to cryptanalysis. In recent years, the field of lightweight cryptography has seen substantial advancements, particularly with the emergence of ARX-based algorithms that offer a strong trade-off between energy efficiency and security. ARX-based encryption algorithms, which utilize simple operations such as addition, rotation, and XOR, are particularly well-suited for resource-constrained devices, especially in the Internet of Things (IoT) domain. Their lightweight structure enables efficient implementation on low-power microcontrollers, minimizing computational overhead and energy consumption. At the same time, their design ensures a reasonable level of cryptographic security, offering resistance to differential and linear cryptanalysis. Due to their balance between performance and robustness, ARX-based ciphers have become a popular choice for securing communication in embedded and IoT environments, where efficiency and reliability are both critical. In this context, recently developed ciphers such as SIMON and SPECK--both based on ARX principles--have drawn attention for their ability to offer high efficiency and flexibility across various hardware and software platforms. Similarly, LBlock, although based on a Feistel structure rather than ARX operations,has demonstrated lightweight characteristics suitable for constrained environments.