Modified SPECK (M-SPECK) Lightweight Cipher Architecture for Resource-Constrained Applications

The Internet of Things (IoT) devices have grown in recent years and are applied to various fields, with the development of new applications in the automotive industry, health care, agriculture, etc. The IoT system demands that data exchange be highly secured, especially in low-resource-constrained devices. The major challenge of IoT is providing data security with a low-complexity cryptography algorithm. However, traditional encryption algorithms are unsuitable for IoT applications due to their high complexity, whereas lightweight block ciphers have become promising solutions for resource-constrained applications. Meanwhile, a trade-off exists between the hardware complexity and performance of the lightweight block cipher. This paper proposes the modified SPECK (M-SPECK) block cipher with a novel key schedule mechanism. The proposed M-SPECK is a modified Addition-Rotation-XOR (ARX) structure that encrypts a 32-bit plaintext with a 64-bit key. The proposed key schedule mechanism is verified for randomness through 15 National Institute of Standards and Technology (NIST) benchmark statistical tests from the NIST SP 800-22 suite. The proposed M-SPECK cipher architecture is implemented and analyzed over the existing lightweight ciphers on the Artix-7 (XC7A100T) FPGA platform. Furthermore, the proposed cipher is analyzed for performance parameters like entropy, correlation coefficient, and histogram using MATLAB for image applications.