Stream Cipher Design Based on Chaotic S-Box and LFSR-FCSR Cascade Structure

Shift registers are widely used in cryptography as a key component in stream cipher generation. LFSR, as the simplest feedback shift register, is susceptible to algebraic attacks, linear attacks, and so on, due to its linear structure, which seriously lacks security. FCSR introduces a feed register to eliminate the linear structure, but its output sequences are insecure in the 2 -adic number domain. LFSR-FCSR cascade structure has higher security, but FCSR has the risk of degradation. S-box is the core component in AES encryption, which has good confusion and diffusion properties, and has good nonlinear, anti-differential analysis and linear analysis ability. In this paper, we design Sboxes based on chaotic mapping and incorporate S -boxes into the LFSR-FCSR cascade structure. According to the test, the S-box has the performance of approximating the AES S-box and the final generated stream cipher sequence passes the randomness test.