On the decorrelated fast cipher (DFC) and its theory

Abstract

In the first part of this paper the decorrelation theory of Vaudenay is analysed. It is shown that the theory behind the proposed constructions does not guarantee security against state-of-the-art differential attacks. In the second part of this paper the proposed De- correlated Fast Cipher (DFC), a candidate for the Advanced Encryption Standard, is analysed. It is argued that the cipher does not obtain provable security against a differential attack. Also, an attack on DFC reduced to 6 rounds is given.