A Connection Between Chaotic and Conventional Cryptography

Many encryption methods involving chaotic dynamics have been proposed in the literature since the 1990´s. Most of them consist of ldquomixingrdquo the confidential information being transmitted through an insecure channel, with a chaotic analog or digital sequence. The recovering of the original information usually calls for reproducing, at the receiver side, the same chaotic signal as at the transmitter side. The synchronization mechanism of the two chaotic signals is known as chaos synchronization. In this paper, a connection between chaotic and conventional encryption is established with special emphasis on two of the most attractive schemes, namely, message embedding and hybrid message embedding. The main point can be stated as follows: the (hybrid) message-embedded cryptosystem is equivalent to a conventional self-synchronizing stream cipher under flatness conditions.