With the increasing proliferation of IoT devices, ensuring their security has become a critical challenge. Cryptographic algorithms play a crucial role in securing these devices by providing mechanisms for data protection. This paper focuses on the Ultra Lightweight Cryptosystem (ULC), a block cipher designed for low-power IoT devices, which has been found vulnerable to differential cryptanalysis attacks. We propose modifications to the ULC key schedule algorithm to enhance its security. The modification aims to address the vulnerable component properties of ULC while maintaining its performance. The modified algorithms were evaluated for security through differential cryptanalysis attacks. Results indicate that one of the modified designs, significantly enhance ULC's resistance to differential cryptanalysis without compromising its performance.

IoT,Block cipher,cryptography,Cryptanalysis,Security