A Method of Generating Multi-level Chaotic Pseudo-Random Sequences with Variable Parameters for Image Encryption

Abstract

The invention provides a generating method of a variable-parameter multistage chaotic pseudorandom sequence, comprising the following steps of: selecting chaotic mapping 1, setting an initial value z0and iterating for N times according to the operation relationship of the mapping 1 to output ZN; selecting chaotic mapping 2, setting an initial value (x0, y0), and iterating for N times according to the operation relationship of the mapping 2 to output (xn, yn); selecting chaotic mapping 3, setting an initial value of the mapping 3 w0 to be equal to ZN, dynamically controlling the order of the mapping 3 by the output of the mapping 2, wherein when the iteration is carried out for even times, the order is controlled by xn, and when the iteration is carried out for odd times, the order is controlled by yn; iterating and outputting wn by virtue of the initial value and the order according to the operation relationship of the mapping 3; forming a variable-parameter multistage chaotic model by the mapping 1, 2, 3, and iterating for N times to generate a decimal chaotic pseudorandom sequence wN with the length of N; and outputting a binary chaotic pseudorandom sequence through a threshold comparison. By adopting the generating method of the variable-parameter multistage chaotic pseudorandom sequence, the chaotic pseudorandom sequence of which the related function is approximate to impact, the mutual related function is approximate to 0 and the power spectrum is approximate to a constant can be generated flexibly and conveniently; and the requirement of users on the image encryption can be satisfied.

Description

technical field [0001] The invention belongs to the technical field of chaotic pseudo-random sequence generation, and in particular relates to chaotic mapping, model combination and sequence conversion methods. The sequence generation method of the invention is especially suitable for the field of image encryption. Background technique [0002] At present, the methods used to generate chaotic pseudo-random sequences usually include discrete chaotic systems based on one-dimensional chaotic maps and discrete chaotic systems based on multidimensional chaotic maps. The former commonly uses a single Rochester (Logistic) map or Chebyshev (Chebyshev) map, which is characterized by a simple structure and easy implementation, but a single one-dimensional map has a small key space and weak anti-attack performance, and cannot be used for image encryption security. Guarantee; the latter is commonly used in three-dimensional chaotic Lü (Lü) system, although it can increase the key s...

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Problems solved by technology

The former commonly uses a single Rochester (Logistic) map or Chebyshev (Chebyshev) map, which is characterized by a simple structure and easy implementation, but a single one-dimensional map has a small key space and weak anti-attack performance, and cannot be used for image encryption security. Guarantee; the latter is commonly used in three-dimensional chaotic Lü (Lü) system, although it can increase the key space and increase the complexity of the sequence, but the corresponding controller is more complicated, which is not practical in image encryption

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