The use of Boolean functions in stream ciphers

Cryptographic properties of Boolean functions such as balancedness, high nonlinearity and high algebraic degree play an important role in the design of the symmetric key encryption schemes, especially the design of S-boxes for block ciphers and the design of robust pseudo-random generators for stream ciphers. In this paper, we focus on Boolean functions for the design of stream ciphers. First, we give brief introduction to stream ciphers and Boolean functions. Then, we provide the ways of constructing appropriate Boolean functions with good cryptographic characteristics needed to design stream ciphers. Last, we survey the resistance of Boolean function against algebraic attack which is a powerful tool of cryptanalysis.