Self-shrinking chaotic stream ciphers

In the last two decades, a growing number of chaos-based cipher systems have been suggested for use in cryptographic applications. Most of these systems were subject to cryptanalytic attacks, and many of them were shown to suffer from a lack of security. In this paper, we export the self-shrinking technique used in classical cryptography into chaotic systems to develop chaotic keystream generators capable of generating keystreams featuring very good statistical properties, and possessing high level of security. This paper proposes a sample self-shrinking chaos-based keystream generator implemented using a 1-D chaotic tent map. Randomness properties and results of statistical testing of keystream bits generated by applying the self-shrinking technique on chaotic maps with suitable parameters are found encouraging. Furthermore, chaotic cipher systems based on such technique are demonstrated to have a better performance in terms of randomness properties and security level than many existing cipher systems.