Study on Algebraic Attack Based on Stream Cipher and the Immunity of Boolean Function
|School||National University of Defense Science and Technology|
|Keywords||Stream Cipher Boolean function Algebraic attack Zeroing function Algebraic Immunity|
Algebraic attacks as a new method of attack on many cryptographic system security challenges. It was originally used for public key cryptography and analysis of block ciphers , stream ciphers was first used on Toyocrypt cryptosystem Courtois relevant characteristics of internal analysis, followed by algebraic attacks on stream ciphers has also been widely used. Because of its simple stream cipher , the encryption speed in the military, commercial and other fields have already been widely used. Convection password attack analysis method has many mature . This paper describes the various methods of attack stream cipher ; and outlines the algebraic attacks on stream ciphers general principles and methods. The main idea of ??algebraic attacks is to establish the initial key and the output keystream bits between the algebraic equations , and then using linear methods or XL algorithm to solve equations to obtain the initial secret key . However, with the increase in the number of variables solution of equations of the constant increase in complexity . Generation of Boolean functions to measure immunity to resist the ability of algebraic attacks , which is defined as the minimum number of Boolean function of the function of the number zero . Algebraic attack success lies in the ability to find low-order zero Boolean function of function , thereby reducing the complexity of solution of equations . In this paper, a detailed study of the idea of ??set theory zeroing function in nature, and based on a collection of functions between the zero- based pay has been included and several algebraic immunity of Boolean functions relationship between the size of the . Therefore, the nature of the zero of the function on the algebraic immunity has some influence ; in this study based on the algebraic immunity and the nature of the relationship between the other passwords , and has been used to estimate the weight of Boolean functions whose algebraic immunity of an expression style . Strike algebraic immunity for the design of Boolean functions Boolean functions and to determine the ability to resist algebraic attacks have a very important significance. This paper presents a new strike algebraic immunity algorithm that does not require solution of equations thus avoiding Gaussian elimination .