Image encryption method based on hyper-chaotic system and variable step size Josepher problem

Abstract

The invention provides an image encryption method based on a hyper-chaotic system and a variable step size Josepher problem, which comprises the following steps of inputting an original image into a key generation function to generate a binary sequence, and calculating an initial value of the hyper-chaotic system; iterating by utilizing the hyper-chaotic system to generate four pseudo-random sequences X, Y, Z and W; inputting the sequence X as a secret key into a variable step size Josepher function to scramble each line in the original image to obtain an image I1; taking the element of the sequence Y as a secret key to perform Josepher ring-based pixel position scrambling on the image I1 to obtain an image I2; inputting the sequence Z as a secret key into the variable step size Josepher function to scramble each column of the image I2 to obtain an image I3; and carrying out two-bit binary addition/subtraction operation on the image I3 by using the element of the sequence W to obtain aciphertext image. According to the invention, the plaintext is linked with the key, so that the method has plaintext sensitivity and can resist selection plaintext attacks and has a strong key spaceand the acute key sensitivity.

Description

Technical field [0001] The invention relates to the technical field of image safe transmission, in particular to an image encryption method based on a hyperchaotic system and a variable step length Joseph problem. Background technique [0002] In recent years, the commonly used SHA-1 cipher algorithm and MD5 cipher algorithm have been cracked. In the past, the SHA-1 cipher algorithm and MD5 cipher algorithm were very secure. Even if the most advanced computer is used for cracking operations, it will take nearly a hundred years. However, the proposed modular differential bit analysis method increases the probability of cracking five internationally-used hash function algorithms, including SHA-1 and MD5 cryptographic algorithms, so that these algorithms can be cracked in a short time. In the face of powerful cracking attacks by hackers, traditional cryptographic systems based on mathematical calculations cannot fully meet the needs of information encryption due to insufficient sec...

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Problems solved by technology

[0004] Aiming at the technical problem that the existing encryption method is insufficient in security and cannot fully meet the requirements of information encryption, the present invention proposes an image encryption method based on a hyperchaotic system and a variable step size Joseph problem, which has a large key space and good Pseudo-randomness, very sensitive to plaintext, can resist various typical attacks, and can be used in the field of image encryption

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