Analysis of Security of Chaotic Sequence

It is proved theoretically that two chaotic maps,which have the topological conjugation relationship,hold the same Lyapunov Exponent.The security is limited if only using the Lyapunov exponent as the description of cryptology characteristics of the chaotic map.By means of pseudo-random features of the chaotic sequence,the security of chaotic sequence is analyzed through the calculation of auto-correlation function and cross-correlation function combing with the Lyapunov exponent.