Design And Analysis Of Stream Cipher Basedon Cascaded Feedback Carry Shift Register

The design idea of stream cipher is changing from a linear sequence to a non-linear sequence,and at the same time many good nonlinear components have emerged.The Feedback Carry Shift Register(FCSR)is considered to be a good alternative to LFSR due to its inherent nonlinearity and algebraic structure similar to LFSR,which has excellent cryptographic performance.While studying the structure and generation sequence of FCSR,various new serial ciphers based on FCSR design began to appear,which led to various analysis techniques and attack methods for FCSR cryptography,which in turn promoted the further improvement of FCSR theory and structure.In this paper,the research status and theoretical results of stream cipher based on FCSR are studied.Two stream ciphers based on cascaded Ring FCSR are designed.The statistical characteristics and cryptographic structure security of pseudo-random key stream are analyzed.The content is mainly divided into the following two aspects: On the one hand: Firstly,the stream cipher based on combining Galois LFSR and Galois FCSR is analyzed,which proves that it can not resist the real-time attack proposed by M.Hell et al.Subsequently,the Galois FCSR is replaced by Ring FCSR,and propose a ring FCSR with multiple inputs.A variable structure stream cipher based on LFSR and FCSR cascade is proposed.Two schemes of variable structure are given and explaining the principle,advantages,initialization process.Then the period and complexity of the generation sequence are analyzed,which proves that it can avoid the initial collision and resist the real-time attack and the side channel attack.Finally,a digital circuit implementation is presented,which uses a random number detection standard for pseudorandomity testing.On the other hand: There is currently no good solution for the cascading of Ring FCSR.Based on the matrix representation of Ring FCSR,this paper designs a stream cipher based on Ring FCSR cascade feedback based on the principle of block matrix,gives the design structure and security parameters,and analyzes the advantages and defect of cascading mode.Based on the sequence of stream ciphers,the statistical characteristics are analyzed in detail: periodicity,complexity,balance,correlation,and so on.After discussing the security of the cryptographic structure,it is found that it can not resist the distinguishing attack proposed by Qi et al.Three simple solutions(carry addition,self-shrinking,single-bit mixing)are given.Theoretical analysis and experimental verification test the effectiveness of the program.Based on the same principle,this paper also presents the theory and basic structure of Ring FCSR cascade for software-oriented stream cipher.Finally,we implemented hardware-oriented serial ciphers on digital circuits and used the SP800-22 detection standard,GM/T0005-2012 detection standard and AIS31 standard detection for randomness detection.The two FCSR cascade-based stream ciphers designed in this paper are simple in structure and high in security.They can be implemented on ASICs and FPGAs,and have certain practical value.