Paper 2004/188

Grey Box Implementation of Block Ciphers Preserving the Confidentiality of their Design

Vincent Carlier and Hervé Chabanne and Emmanuelle Dottax

Abstract

In 1997,Patarin and Goubin introduce new asymmetric cryptosystems based on the difficulty of recovering two systems of multivariate polynomials from their composition. We make a different use of this difficult algorithmic problem to obtain a way of representing block ciphers concealing their design but still leaving them executable. We show how to implement our solution with Field Programmable Gate Array. Finally, we give a compact representation of our solution using Binary Decision Diagrams.