2,312 publications from this institution
As a powerful cryptanalysis tool, the method of return-map attacks can be used to extract secret messages masked by chaos in secure communication schemes. Recently, a simple defensive mechanism was presented to enhance the security of chaotic parameter modulation schemes against return-map attacks. Two techniques are combined in the proposed defensive mechanism: multistep parameter modulation and alternative driving of two different transmitter variables. This paper re-studies the security of this proposed defensive mechanism against return-map attacks, and points out that the security was much over-estimated in the original publication for both ciphertext-only attack and known/chosen-plaintext attacks. It is found that a deterministic relationship exists between the shape of the return map and the modulated parameter, and that such a relationship can be used to dramatically enhance return-map attacks thereby making them quite easy to break the defensive mechanism.
This paper introduces a novel approach for generating continuous-time autonomous hyperchaotic systems with multiple positive Lyapunov exponents. In detail, this paper develops two general design principles for constructing various hyperchaotic systems with desired numbers of positive Lyapunov exponents. Two typical examples are then given to verify the proposed design principle. In particular, the developed method can design hyperchaotic systems with any multiple positive Lyapunove exponents by following a unified procedure compared with the traditional trial-and-error approach.
