Enhancing Security in LFSR-based Stream Ciphers through Improved Non-linearity Techniques

Enhancing Security in LFSR-based Stream Ciphers through Improved Non-linearity Techniques

In many stream ciphers, Linear Feedback Shift Registers (LFSRs) are a fundamental component. Even though they are fundamental, their nature of inherent linearity can be exploited by cybercriminals through cryptanalytic attacks. In this research, we explore the importance of non-linearity in LFSR-based stream ciphers. We then propose techniques for achieving enhanced security through incorporation of strong non-linear elements. Specifically, we explore the application of S-boxes, Permutation boxes, Full Adder, and other non-linear operations in combining function and address limitations of traditional approaches. Finally, security analysis of our design is performed. We analyze Period, Linear Complexity, Randomness and Correlation Immunity. The results obtained are compared with the National Institute of Standards and Technology (NIST) requirements. All the results passed the NIST tests, indicating that our proposed enhancements offer a robust solution to the fundamental weaknesses of traditional LFSRs thereby contributing to more secure cryptographic systems.