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Mathematical Problems in Engineering
Volume 2010, Article ID 590590, 14 pages
Research Article

Cryptanalysis and Improvement of a Block Cipher Based on Multiple Chaotic Systems

1Department of Computer Science, East China Normal University, Shanghai 200241, China
2National Computer Network Emergency Response Technical Team (Coordination Center of China), Beijing 100029, China

Received 31 January 2010; Accepted 15 April 2010

Academic Editor: Ming Li

Copyright © 2010 Jun He et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Wang and Yu proposed a block cipher scheme based on dynamic sequences generated by multiple chaotic systems, which overcomes the problem of periodical degradation on random sequences due to computational precision. Their scheme has a feature that a plaintext is encrypted by a keystream created from several one-dimensional chaotic maps. However, this feature results in some weaknesses of the encryption algorithm. We show three kinds of attacks in this paper, through which one can recover the plaintext from a given ciphertext without the secret key. We also present an improvement on their scheme, which prevents the three attacks mentioned above. Security of the enhanced cipher is presented and analyzed, which shows that our improved scheme is secure under the current attacks.