In this note, a novel symmetric (also known as private-key or secret-key) cryptosystem is designed based on chaotic oscillators such as Du$ng's or a generalized Van der Pol's oscillator.
Cryptography is one of the oldest human practices for communicating secretly with intended parties; see, e.g., references [1}3] for history and non-technical description of cryptography. In recent decades, cryptography has become exceedingly prevalent in information technology since: (1) there has been an explosive increase in the transmission of information by di!erent wired and wireless means; (2) such transmissions require security and privacy. For instance, currently, computers have become major components of information technology for communications, electronic mail, on-line banking and shopping, transmission of "nancial and medical reports, to name a few. Also, wireless communication systems have become another important component of information technology and provide connectivity at local and global scales.
Information technology has thus created a great demand for security and privacy of information transmission and data storage. Security and privacy are provided by cryptosystems, which for instance, keep the transmitted data secret and tamper-proof, protect information from unintended parties aiming to eavesdrop, prevent fraud, and ensure the privacy of citizens. Due to their crucial role, cryptosystems have become major elements of information technology.
Cryptosystems are mostly designed based on mathematical theories. Some cryptosystems, however, are designed based on the theory of dynamical systems. In this note, the latter approach is taken to design a novel cryptosystem based on chaotic oscillating systems and the inversion of such systems by a feedback loop. The organization of the note is as follows. In section 2, the basic structure of cryptosystems is described brie#y. In section 3, a cryptosystem is proposed. In section 4, two examples are given to illustrate the superb performance of the proposed cryptosystem.