Construction of Involutional Linear Transformation with a Branch Number of 4
Chao Li · Communications technology · 2010
Diffusion layer plays an important role in block cipher components. SPN ciphers, in particular, and Feistel ciphers with SPN round functions as well, usually employ a nonsingular linear transformation as their diffusion layer. Good branch-number and involutional property of the linear transformation could cause fast diffusion effect and also improve the efficiency in the implementation of block ciphers. This paper, based on rotations and xors, proposes three constructions of linear transformation with a branch number of 4. Meanwhile, the involutional property is proved under certain conditions.