Encryption Algorithms in IoT: Security vs Lifetime

IoT devices are inherently limited by their processing capabilities and power capacity. While aiming to maximise their lifespan, one of the biggest challenges they face is to reduce the computational burden, especially for tasks such as encryption, data transmission, or compression. This paper investigates the lifespan of an IoT device transmitting encrypted data as a function of the encryption algorithm used and the packet length. We focus the analysis particularly on lightweight algorithms popular in IoT ecosystems, such as AES, XTEA, HIGHT, KLEIN, ECC, PRESENT, Serpent, Piccolo, Blowfish, and Twofish. The results of the study indicate that the type of data encryption used for transmission has a significant impact on the IoT device lifetime, together with the data length and the input parameters used. To summarise, the Piccolo algorithm is the most energy-efficient, leading to maximum lifetime and low power consumption, followed by AES, XTEA, and KLEIN. At the other end of the spectrum, ECC, Blowfish, Twofish, PRESENT, and Serpent have high power consumption, hence they should be less preferred for the device-to-device or device-to-gateway IoT communication. Aside from the acknowledged energy efficiency of ciphers based on substitution-permutation operations versus Feistel ones, the results show that algorithms of first group, such as Serpent and PRESENT, require significant encryption and decryption times, while Feistel ciphers such as Piccolo, XTEA and HEIGHT are notably fast