Chaotic Cryptography in Digital World: State-of-the-Art, Problems and Solutions

Since 1989, many contributions have been devoted to the methods of using chaos to construct digital ciphers. Although some chaotic ciphers have been known insecure and several defects have been found, a large number of chaotic ciphers still remain secure till now. Furthermore, in the past few years, some novel chaotic ciphers have been proposed, which avoid some weaknesses in previous chaotic ciphers and seem to have stronger cryptographic properties. In this paper, we first review the progress of the digital chaotic ciphers nowadays from 1989 till now (2002), and then discuss some problems in the general design of digital chaotic ciphers and possible solutions. Some suggestions are given on the future directions in chaotic cryptography. We believe that the research on chaotic cryptography will be helpful to benefit the conventional cryptology and open a broader road to more perfect ciphers.