A plaintext-dependent image encryption method based on bidirectional dynamic window

By combining the generated session key with a chaotic sequence, image pixel positions are scrambled and bidirectional dynamic window diffusion is performed, which solves the problem of weak correlation between the key stream and plaintext, and improves the security and anti-attack capability of the image encryption algorithm.

CN122457233APending Publication Date: 2026-07-24NANCHANG UNIV
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Patent Information

Application Number
CN202610552196.8
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-04-24
Publication Date
2026-07-24

AI Technical Summary

Technical Problem

In existing image encryption algorithms, the key stream has a weak correlation with the plaintext, making it difficult to effectively resist chosen-plaintext attacks. Furthermore, the fixed-pattern pixel diffusion mechanism is highly regular, affecting the overall security of the system.

Method used

A session key is generated by combining the hash value of the plaintext image with the master key. The session key is then used to perturb the chaotic system to generate multiple chaotic sequences, which are then used to scramble pixel positions and swap values. Finally, diffusion calculations are performed using forward and reverse dynamic window scheduling tables to generate the ciphertext image.

Benefits of technology

It improves the encryption algorithm's ability to resist chosen-plaintext and known-plaintext attacks, increases the exhaustive difficulty of cryptanalysis, and improves the avalanche effect of the encryption algorithm, thereby enhancing overall security.

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Abstract

The application relates to the technical field of image encryption, and discloses a plaintext-related image encryption method based on a bidirectional dynamic window, which comprises the following steps: calculating the hash value of a plaintext image, combining the hash value with a master key to generate a session key, using the session key to disturb a chaotic system to generate first to fourth chaotic sequences; using the first chaotic sequence to perform pixel position replacement on the plaintext image to obtain a scrambled image; performing high-low bit exchange of pixel values on the scrambled image to output an intermediate image; using the second and third chaotic sequences to construct a forward dynamic window scheduling table and a reverse dynamic window scheduling table respectively, and sequentially performing forward window-by-window diffusion calculation and reverse traversal diffusion calculation on the intermediate image; and using a two-dimensional matrix remodeled by the fourth chaotic sequence to perform feedback superposition calculation to output a ciphertext image. The application establishes the correlation between plaintext and encryption parameters, and introduces a bidirectional dynamic window diffusion mechanism, thereby avoiding the regularity of fixed diffusion step length, and improving the ability of the algorithm to resist selective plaintext attacks and the avalanche effect.
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