A New SPN Structure for Block Ciphers

In this paper, we consider the problem of the S- boxes and diffusion layers in SPN structures, in which the algebraic expressions of some S-boxes are always too simple and the extra memory or power consumption is required in the diffusion layers. A new SPN structure is introduced in which the algebraic complexity of the S-box is increased with a new S-box structure, the diffusion layer based on the Cauchy matrix is optimal and involutory. A numerical example is given to show the advantage of the new SPN structure and its potential application.