Message-Embedded Cryptosystems: Cryptanalysis and Identifiability

The aim of this paper is to compare two encryption schemes, the standard stream cipher and a so-called message-embedded cryptosystem. The comparison is based on two main aspects. The first aspect deals with the synchronization of the time-varying keys at the transmission side and at the reception side. The second aspect focuses on the cryptanalysis of the encryption algorithms. The cryptanalysis is concerned with the system parameter retrieving. The key point of the paper is that, for message-embedded cryptosystems, the cryptanalysis can be treated as a parametric identifiability issue. Two methods, the local state isomorphism approach and the Gröbner bases method, are presented for systems including polynomial nonlinearities. It is shown that these systems are weak against algebraic attack.