{The application of $σ$-LFSR in Key-Dependent Feedback Configuration for Word-Oriented Stream Ciphers

In this paper, we propose and evaluate a method for using $\sigma$-LFSRs with key-dependent feedback configurations (KDFC) in stream ciphers. This method can be applied to any stream cipher that uses a word-based LFSR. Here, a configuration generation algorithm uses the secret key(K) and the initialization vector (IV) to generate a feedback configuration. We have mathematically analysed the feedback configurations generated by this method. As a test case, we have applied this method on SNOW 2.0 and have analysed its impact on resistance to algebraic attacks. Further, we have also tested the generated keystream for randomness.