CN-122020689-A - Three-dimensional image encryption method, system and medium based on four-dimensional hyper-chaotic system

CN122020689ACN 122020689 ACN122020689 ACN 122020689ACN-122020689-A

Abstract

The invention relates to a three-dimensional image encryption method, a system and a medium based on a four-dimensional hyper-chaotic system in the technical field of information security. The three-dimensional image encryption method comprises mapping all vertexes in V into bytes to obtain an original byte matrix . And constructing a four-dimensional hyper-chaotic system and generating a rank key K perm and a diffusion key K dpff . First by K perm pair Scrambling is performed and diffusion is performed through K dpff . The invention maps the grid vertex coordinates of the three-dimensional image into a two-dimensional unsigned integer matrix in an equivalent way, on the basis, a designed four-dimensional hyper-chaotic system is introduced to generate a row scrambling sequence, a column scrambling sequence and a diffusion mask matrix respectively, scrambling and exclusive-or diffusion processing are carried out on vertex data at a byte level, so that encryption security is ensured, encryption and decryption reversibility is strong, flexible expansion can be realized under different file formats, different chaotic parameters and different projection strategies, and the method is suitable for engineering realization and subsequent optimization.

Inventors

DING DAWEI
Liu Wangcan
CHENG HONG
ZHANG HONGWEI
YANG ZONGLI
LI BINGJIE
YANG TIANYU

Assignees

安徽大学

Dates

Publication Date: 20260512
Application Date: 20260202

Claims (10)

1. The three-dimensional image encryption method based on the four-dimensional hyper-chaotic system is characterized by only encrypting a vertex matrix V of a three-dimensional image, and the method for encrypting V comprises the following steps: Converting three-dimensional coordinates of p-th vertex V p in V into floating point number, expanding it into A-bit binary bit representation, packing every B bits into 1 byte to obtain A/B bytes sigma p,1 …σ p,A/B of V p , traversing all vertices to obtain original byte matrix ; Constructing a four-dimensional hyper-chaotic system and fixing a parameter vector lambda: ; ; ; X h,k is the state vector of the h dimension at the k moment, Q (X k ) is an orthogonal rotation matrix, and R is a diagonal matrix; Setting 2 initial value groups containing four dimensions based on four-dimensional hyper-chaotic system 、 And 2 iterative reject steps L p 、L d ; Through lambda (lambda), L p forms a rank key K perm , by lambda, L d constitutes a diffusion key K dpff ; generation with K perm Generating a row scrambling index vector Pr and a column scrambling index vector Pc by using K dpff Is a diffusion mask matrix of (a) ; First pass Pr pair Is rearranged by the rows of Pc pairs Is rearranged to obtain a row-column permutation matrix ; By aligning Performing bit-wise exclusive or diffusion to obtain ciphertext byte matrix ; Will be Restoring to a floating point number, reconstructing an encrypted vertex matrix V (c) , and combining V (c) with F to obtain an encrypted three-dimensional image.
2.V p , the three-dimensional coordinate conversion floating point number is unfolded to be expressed in a 96-bit binary bit mode, and is packaged into 1 byte every 8 bits to obtain 12 bytes sigma p,1 …σ p,12 ; And/or the number of the groups of groups, The expression of (2) is: 。
3. The three-dimensional image encryption method based on four-dimensional hyper-chaotic system according to claim 1, wherein in the four-dimensional hyper-chaotic system, an initial value group is 、 All include four dimensional initial values, the expression of which is: ; ; the expression of K perm 、K dpff is: K perm =(λ, , L p ); K dpff =(λ, , L d , γ); where γ is the scaling factor of the diffusion phase.
4. The three-dimensional image encryption method based on the four-dimensional hyper-chaotic system according to claim 1, wherein the method for generating the row scrambling index vectors Pr, pc comprises: To be used for Iteration four-dimensional hyper-chaotic system L p +P+12 times is adopted as a starting point, wherein P is the total number of vertexes in V; Discarding the first L p iteration values, forming a line scrambling sequence by the subsequent P iteration values, and sorting the line scrambling sequence according to ascending order to obtain Pr; And forming a column scrambling sequence by the last 12 iteration values, and arranging the column scrambling sequence in an ascending order to obtain Pc.
5. The three-dimensional image encryption method based on four-dimensional hyper-chaotic system according to claim 1, wherein a ciphertext byte matrix is generated The method of (1) comprises: To be used for Iteration four-dimensional hyper-chaotic system L d +A/B multiplied by P times is adopted as a starting point, wherein P is the total number of vertexes in V; discarding the previous L d iteration values, sequentially taking out the subsequent A/B multiplied by P iteration values to form a chaotic real sequence with the length of A/B multiplied by P; the chaotic real number sequence is rearranged into a matrix M according to the sequence from left to right and from top to bottom according to the column, and mapped into a byte space to obtain a diffusion mask matrix 。
6. The three-dimensional image encryption method based on four-dimensional hyper-chaotic system according to claim 5, wherein a process expression of mapping M to a byte space is: ; Where s is the row number in the matrix and t is the column number in the matrix.
7. The four-dimensional hyper-chaotic system based three-dimensional image encryption method according to claim 1, further comprising generating a two-dimensional projection thumbnail of an original three-dimensional image, comprising: Selecting an observation view angle of an original three-dimensional image, and projecting the three-dimensional image to a two-dimensional plane to obtain a projection view; constructing a two-dimensional pixel network on the projection view and rasterizing to obtain a gray thumbnail; and outputting the gray thumbnail in the form of an image file, and packaging the gray thumbnail with the encrypted three-dimensional image.
8. A three-dimensional image encryption system based on a four-dimensional hyper-chaotic system, which is characterized in that the three-dimensional image encryption system based on the four-dimensional hyper-chaotic system according to any one of claims 1 to 7 is used, wherein the three-dimensional image encryption system comprises: A coordinate mapping module for converting the three-dimensional coordinates of the p-th vertex V p in the vertex matrix V of the three-dimensional image into a floating point number and expanding the floating point number into an A-bit binary bit mode to be expressed, then packing each B bit into 1 byte to obtain A/B bytes sigma p,1 …σ p,A/B of V p , traversing all the vertices to obtain an original byte matrix ; The key generation module is used for constructing a four-dimensional hyper-chaotic system and fixing a parameter vector lambda: ; ; ; X h,k is the state vector of the h dimension at the k moment, Q (X k ) is an orthogonal rotation matrix, R is a diagonal matrix, and 2 initial value sets comprising four dimensions are set based on the four-dimensional hyper-chaotic system 、 And 2 iterative reject steps L p 、L d , by lambda, L p forms a rank key K perm , by lambda, L d constitutes a diffusion key K dpff ; An encryption module for generating using K perm Generating a row scrambling index vector Pr and a column scrambling index vector Pc by using K dpff Is a diffusion mask matrix of (a) First pass Pr to Is rearranged by the rows of Pc pairs Is rearranged to obtain a row-column permutation matrix By means of For a pair of Performing bit-wise exclusive or diffusion to obtain ciphertext byte matrix Will (i) be Restoring to a floating point number, reconstructing an encrypted vertex matrix V (c) , and combining V (c) with F to obtain an encrypted three-dimensional image.
9. A cloud storage encryption method for a medical three-dimensional model is characterized by comprising the steps of storing the medical three-dimensional model into a standard grid format, uploading the medical three-dimensional model to a cloud storage, and encrypting the medical three-dimensional model by the three-dimensional image encryption method based on the four-dimensional hyper-chaotic system according to any one of claims 1 to 7 before uploading the medical three-dimensional model to the cloud storage.
10. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program which, when executed by a processor, implements the steps of the four-dimensional hyper-chaotic system based three-dimensional image encryption method according to any one of claims 1 to 7.

Description

Three-dimensional image encryption method, system and medium based on four-dimensional hyper-chaotic system Technical Field The invention relates to the technical field of information security, in particular to a three-dimensional image encryption method, system and medium based on a four-dimensional hyper-chaotic system. Background With the rapid development of applications such as virtual reality, three-dimensional printing, digital Wen Bo, medical imaging, industrial CAD, etc., a large number of three-dimensional images (e.g., mesh models, point cloud objects) are frequently stored and transmitted in a network environment, and the demands for privacy and copyright protection of three-dimensional data are increasingly prominent. A typical three-dimensional mesh model consists of a set of vertices, which are continuous real numbers, and a set of patches, which record vertex indices, so that the underlying data structure of the three-dimensional image contains both continuous geometric data and discrete topological information. The existing three-dimensional object encryption method can be divided into two types, namely, one type is used for carrying out simple geometric transformation or random scrambling on node coordinates, such as translation, scaling and symmetrical transformation on coordinates or rearrangement on vertex indexes, the method is low in computational complexity and easy to realize, but insufficient in diffusion capability and difficult to resist statistical analysis and differential attack, the other type is used for attempting to map floating point coordinates into binary or integer space, such as encrypting coordinates in bits based on PEEE floating point format, or dividing the three-dimensional object into a plurality of blocks to be encrypted respectively, and the method is high in safety, complex in design and often lacks a unified mathematical framework. Disclosure of Invention The invention provides a three-dimensional image encryption method, system and medium based on a four-dimensional hyper-chaotic system, which aims to solve the technical problems that the existing three-dimensional image encryption mode is low in safety or complex in encryption process. In a first aspect, the present invention provides a three-dimensional image encryption method based on a four-dimensional hyperchaotic system, which encrypts only a vertex matrix V of a three-dimensional image, and the method for encrypting V includes: And converting the three-dimensional coordinates of the p-th vertex V p in V into floating point numbers, and expanding the floating point numbers into A-bit binary bit representations. Every B bits are then packed into 1 byte, resulting in a/B bytes σ p,1…σp,A/B of v p. Traversing all vertices to obtain an original byte matrix . Constructing a four-dimensional hyper-chaotic system and fixing a parameter vector lambda: ; ; ; X h,k is the state vector of the h dimension at time k, Q (X k) is the orthogonal rotation matrix, and R is the diagonal matrix. Setting 2 initial value groups containing four dimensions based on four-dimensional hyper-chaotic system 、 And 2 iterative reject steps L p、Ld. Through lambda (lambda),L p constitutes a rank key K perm. Through lambda (lambda),L d constitutes the diffusion key K dpff. Generation with K permA row scrambling index vector Pr and a column scrambling index vector Pc. Generation with K dpffIs a diffusion mask matrix of (a)。 First pass Pr pairIs rearranged by the rows of Pc pairsIs rearranged to obtain a row-column permutation matrix. Then pass throughFor a pair ofPerforming bit-wise exclusive or diffusion to obtain ciphertext byte matrix. Will thenReverting to the floating point number and reconstructing the encrypted vertex matrix V (c). And finally, combining V (c) with F to obtain an encrypted three-dimensional image. In a second aspect, the present invention further proposes a three-dimensional image encryption system based on the four-dimensional hyperchaotic system, which uses the three-dimensional image encryption method based on the four-dimensional hyperchaotic system in the first aspect. The three-dimensional image encryption system comprises a coordinate mapping module, a secret key generation module and an encryption module. The coordinate mapping module is used for converting the three-dimensional coordinates of the p-th vertex V p in the vertex matrix V of the three-dimensional image into floating point numbers and expanding the floating point numbers into an A-bit binary bit mode for representation. Then packed into 1 byte every B bits, resulting in a/B bytes σ p,1…σp,A/B of v p. Traversing all vertices to obtain an original byte matrix. The key generation module is used for constructing a four-dimensional hyper-chaotic system and fixing a parameter vector lambda: 。。。 X h,k is the state vector of the h dimension at time k, Q (X k) is the orthogonal rotation matrix, and R is the diagonal matrix. And 2 initial value grou