Differential and Linear Cryptanalysis of the IoT-Friendly MGFN Block Cipher

Developed in 2023, the Modified Generalized Feistel Network (MGFN) is a block cipher that complies with Malaysia’s national cryptographic and cybersecurity policies. MGFN is a 64-bit block cipher with a 128-bit master key, specifically designed to deliver lightweight cybersecurity in resource-constrained Internet of Things (IoT) environments. In this paper, we analyze the security of the full-round MGFN against differential and linear cryptanalysis. We present concrete key recovery strategies for both attacks by employing multiple peeling-off steps. As a result, for the first time, we demonstrate a practical differential cryptanalysis of the full-round MGFN within a realistic time bound. In addition, we propose a practical linear cryptanalysis of the round-reduced MGFN. Our results provide the first practical security assessment of MGFN and offer concrete insights into its resistance against differential and linear cryptanalysis, thereby supporting the design and evaluation of lightweight block ciphers for IoT environments.