ON STREAM CIPHER BASED ON FAMILY OF GRAPHS D(n,q)˜ OF INCREASING GIRTH

Abstract

In this short paper we present symmetric encryption algorithm based on family of bipartite graphs $\widetilde{D(n,q)}$. It is a fast stream cipher with computation speed $O\left(n\right)$ for the key of fixed length. If the key is linear function from $n$ the efficiency is $O\left(n^2\right)$. Encryption map has a multivariate nature, so the security level can be evaluated via degrees and other parameters of corresponding multivariate polynomials. We show that the degree of graph based encryption maps are growing with the growth of the dimension of the plain space. Therefore this algorithm is resistant to linearization attacks.