Algebraic Attack on LCB and Improved LCB

Various lightweight block cipher algorithms have been proposed to address the security requirements of Internet of Things (loT) devices, one of which is the Light Cipher Block (LCB). Initially proposed by Roy and colleagues in 2021, LCB underwent extensive evaluation against multiple cryptographic attacks. In 2023, Chan and colleagues identified a critical vulnerability in LCB's substitution box (S-box), which increased the cipher's linearity. To mitigate this issue, they improved LCB by integrating the S-box from the PRESENT cipher. This study conducts an algebraic analysis of LCB, identifying the algebraic characteristics underlying its vulnerabilities. In addition, an algebraic attack is performed on the improved LCB to evaluate its resilience against such attacks. Our findings reveal that while the original LCB remains susceptible to algebraic attacks, the improved version exhibits enhanced resistance. These results emphasize the importance of selecting appropriate S-boxes for cryptographic algorithms to strengthen their security against algebraic attacks.