Static Timing Analysis of Nonlinear-Feedback Shift Register

An 8-bit Non-Linear Feedback Shift Register (NLFSR) is designed and implemented using Verilog, with synthesis and timing analysis conducted on the Vivado platform. The NLFSR employs a non-linear feedback function with a dynamic feedback selection mechanism, enhancing the randomness of the generated keystream. In contrast, the conventional LFSR utilizes a fixed polynomial feedback, resulting in simpler architecture but comparatively weaker randomness in the keystream. Worst Negative Slack (WNS) and Worst Hold Slack (WHS) are measured to evaluate the performance. The WNS of NLFSR and LFSR are 7.165ns and 7.820ns, whereas the WHS are 0.284ns and 0.132ns, respectively. The findings show that while NLFSRs are more complex due to nonlinear feedback, they produce a more robust and random keystream compared to LFSRs, which are simpler but less random. This highlights the trade-off between complexity and performance, with NLFSRs offering superior keystream quality.