Bit-level encryption algorithm based on logic-sine-cosine chaotic system
Through the bit-level encryption algorithm based on the logic-sine-cosine chaos system, through bit plane decomposition, key stream generation and bit-level scrambling diffusion processing, the problems of small key space and insufficient security in the existing technology are solved, and efficient data encryption and anti-quantum computing capabilities are achieved.
Patent Information
- Application Number
- CN202511124698.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-12
- Publication Date
- 2025-10-17
AI Technical Summary
Existing encryption technologies are inefficient when processing high-dimensional data, have limited key space, and are difficult to resist brute force cracking. The encryption methods of single chaotic systems have single dynamic characteristics and insufficient security. Bit-level encryption fails to meet the security and robustness requirements of medical data.
A bit-level encryption algorithm based on a logic-sin-cosine chaotic system is adopted. The key stream is generated by decomposing the bit plane and constructing a two-dimensional logic-sin-cosine chaotic system. The bit plane matrix is subjected to bit-level scrambling and diffusion processing to generate a ciphertext image.
The key space has been increased and the ability to resist differential attacks has been enhanced. The key space has been expanded to 2128, which can resist quantum computing brute force cracking, reduce the risk of information leakage, and realize dynamic protection of high-bit bit planes.
Smart Images
Figure CN120811570A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of data encryption technology, and in particular to a Bit-level encryption algorithm based on a logistic-cosine chaotic system. BACKGROUND
[0002] With the rapid development of medical informatization, the secure transmission and storage of sensitive data such as electronic medical records and medical images face serious challenges. Existing data encryption technologies have many shortcomings when dealing with sensitive information such as medical images:
[0003] Traditional encryption algorithms (such as AES and DES) have low encryption efficiency for high-dimensional data, and the key space is limited, making it difficult to resist brute force attacks.
[0004] Encryption methods based on a single chaotic system (such as logistic mapping) have a single dynamic characteristic and exhibit periodic window phenomena, resulting in insufficient randomness of the encrypted data.
[0005] The common permutation algorithm in Bit-level encryption does not incorporate the high sensitivity of chaotic systems, and cannot meet the strict requirements of medical data for security and robustness.
[0006] Existing similar technologies such as "Image Encryption Method Based on Logistic Chaotic Mapping" have the following obvious limitations: only a single logistic mapping is used, which may exhibit subtle periodicity after long-term iteration, resulting in insufficient security; Bit-level operations are not considered, and the entire pixel value is directly encrypted, which cannot resist attacks on high-order significant bits; the key space is only composed of the initial value and the number of iterations, with a space size of approximately 32 bits, making it difficult to resist brute force attacks with modern computing power.
[0007] Therefore, the present application provides a Bit-level encryption algorithm based on a logistic-cosine chaotic system. SUMMARY
[0008] To overcome the shortcomings of the prior art, the present application provides a Bit-level encryption algorithm based on a logistic-cosine chaotic system.
[0009] To solve the above technical problems, the basic technical scheme of the present application is as follows:
[0010] A Bit-level encryption algorithm based on a logistic-cosine chaotic system, comprising the following steps:
[0011] Performing bit-plane decomposition on the encrypted image to obtain a bit-plane matrix;
[0012] Constructing a two-dimensional logistic-cosine chaotic system to generate a key stream;
[0013] Bit-level scrambling the bit-plane matrix based on the key stream;
[0014] Bit-level diffusion processing the scrambled bit-plane matrix;
[0015] Synthesizing the diffused bit-plane matrix into a ciphertext image.
[0016] Preferably, the specific steps of the bit-plane decomposition are: decomposing the stego image matrix A according to the formula to obtain the three-dimensional bit-plane matrix B, where a(i,j) and b(i,j,k) are the pixel values of the matrices A and B at (i,j), respectively, k=0,1,…,7, denotes the floor operation.
[0017] Preferably, the construction formula of the two-dimensional logistic-sine chaos system is: where α,γ∈(0,4),β,δ∈[0,4], the initial values x0,y0∈(0,1), and the key streams C1 and C2 are generated by the parameters key=(α,β,γ,δ,x0,y0).
[0018] Preferably, the specific steps of the Bit-level scrambling are: arranging the key stream C1 in ascending order to obtain C1', generating a mapping sequence U, rearranging the initial one-dimensional sequence f according to U to obtain the scrambled sequence f', where f'(k)=f(u k ), u k is the position of the kth element in C1 in C1'.
[0019] Preferably, the specific steps of the Bit-level diffusion are: converting the key stream C2 into a binary sequence V, diffusing the scrambled sequence f' to obtain the diffused sequence f", and the diffusion formula is where denotes the XOR operation.
[0020] Preferably, the Bit-level encryption algorithm based on the logistic-sine chaos system according to claim 1, wherein the encryption process further comprises: after decomposing the stego image into a bit-plane matrix, converting it into a one-dimensional sequence f; restoring the diffused one-dimensional sequence f" into a bit-plane matrix, and then synthesizing it into a ciphertext image.
[0021] Preferably, it further includes a decryption process, and the specific steps are: decomposing the ciphertext image into a bit-plane matrix, performing diffusion decryption and scrambling decryption on it to obtain a decrypted one-dimensional sequence, restoring it to a bit-plane matrix and synthesizing it into a decrypted image, wherein the diffusion decryption and scrambling decryption are the inverse operations of the diffusion and scrambling in the encryption process.
[0022] The beneficial effects of the present invention are:
[0023] The technical solution of the present invention generates a key stream period of more than 10 by coupling the dual chaotic system. 100 , which is much larger than the cycle of a single logic mapping (about 10 30 ), the ability to resist differential attacks is improved; the key space is expanded: the key is composed of α, β, γ, δ, x0, y0 and the number of iterations, and the key space size is 2 128 The above can resist quantum computing brute force cracking; Bit-level operation flexibility: The chaotic system parameters can be dynamically adjusted for high-bit planes (such as BP7) to achieve key protection of sensitive information. Compared with traditional pixel-level encryption, the risk of information leakage is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a flowchart of the bit-level encryption process of the present invention. DETAILED DESCRIPTION
[0025] The following will be combined with the Figure 1 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.
[0026] Please refer to Figure 1 As shown in the figure, a bit-level encryption algorithm based on a logic-sine-cosine chaotic system specifically includes the following contents:
[0027] Overall encryption and decryption framework: This algorithm generates a ciphertext image by sequentially performing scrambling and diffusion operations on the encrypted image, providing dual protection for electronic medical records and medical images. The encryption process includes image decomposition, bit-plane decomposition, bit-level scrambling, bit-level diffusion, and bit-plane synthesis. The decryption process is the inverse of the encryption process, consisting of bit-plane decomposition, scrambling decryption, diffusion recovery, and bit-plane synthesis.
[0028] Bit plane decomposition and one-dimensional rearrangement For grayscale images with grayscale values between 0 and 255, each pixel can be represented by a unique 8-bit binary sequence, thereby subdividing the image into 8 bit planes. The specific decomposition formula is: Among them, a(i,j) and b(i,j,k) are the pixel values at (i,j) of the original image matrix and the decomposed bit plane matrix respectively. Indicates a floor operation.
[0029] Two-dimensional logistic-cosine chaotic system is constructed, and its mathematical expression is: wherein, α, β, γ, δ are system parameters, α, γ ∈ (0, 4), (β, δ ∈ [0, 4]; initial value x0, y0 ∈ (0, 1). The key stream C1 = {x1, x2, …, x n}) and (C2 = {y1, y2, …, y n}) are generated by the parameters key = (α, β, γ, δ, x0, y0) through the above formula.
[0030] Bit-level scrambling determines the elements of the sequence U = {u1, u2, …, u n} through the mapping relationship between the key stream C1 and the sorted key stream C1'. The initial one-dimensional sequence f is rearranged according to the element order in U, and scrambling is realized. Wherein, C1' = sorted(C1), (sorted) represents ascending arrangement of elements, and the relationship between the scrambled sequence f' and the original sequence f is: f'(k) = f(u k ), wherein u k (k = 1, 2, …, n) represents the position of the kth element in C1 in C1'.
[0031] Bit-level diffusion converts the key stream C2 into a binary sequence V containing only 0 or 1, and diffuses the scrambled sequence f' combined with the key stream V to obtain the diffused sequence f". The diffusion formula is: wherein, represents the exclusive or operation.
[0032] Encryption process
[0033] The key stream C1 and C2 are generated by the key as the control parameter and the initial condition.
[0034] The steganographic image A is decomposed into a three-dimensional matrix B by bit plane, and the size is M × N × 8.
[0035] The bit plane matrix B is converted into a one-dimensional sequence f.
[0036] The sequence U is generated by the mapping relationship between the key stream C1 and the ascendingly arranged key stream C1'.
[0037] f' is generated by scrambling f according to the sequence U.
[0038] The key stream C2 is converted into a binary sequence V.
[0039] According to sequence V, sequence f' is diffused to generate new sequence f''.
[0040] Sequence f'' is reduced to three-dimensional matrix B'.
[0041] Matrix B' is synthesized to ciphertext image A'.
[0042] Decryption process
[0043] The decryption process is the inverse operation of the encryption process, and the specific steps are as follows:
[0044] The ciphertext image is decomposed into 8 bit planes.
[0045] The bit planes are decrypted in sequence by diffusion and permutation to obtain a one-dimensional sequence.
[0046] The decrypted one-dimensional sequence is reduced to a bit plane matrix.
[0047] Bit plane synthesis is performed to output the decrypted image.
[0048] Specifically, the following embodiments are included:
[0049] Taking the encryption of a 1024x1024 medical CT image as an example, the specific implementation steps are as follows:
[0050] Parameter setting Select control parameters (α, β, γ, δ) = (1.2, 2.5, 1.8, 2.3), initial value (x0, y0) = (0.3257, 0.7875).
[0051] Key stream generation According to the mathematical expression of the two-dimensional logistic-sine chaos system, the key stream C1 and C2 are iteratively generated, and the iteration number is 1024x1024x8.
[0052] Bit plane decomposition The CT image matrix A is decomposed into 8 bit plane matrices B according to the bit plane decomposition formula, with a size of 1024x1024x8, and is converted into a one-dimensional sequence f with a length of 1024x1024x8.
[0053] Bit-level permutation The key stream C1 is arranged in ascending order to obtain C1', and a mapping sequence U is generated, and the one-dimensional sequence f is permuted according to U to obtain the permuted sequence f'.
[0054] Bit-level diffusion The key stream C2 is converted into a binary sequence V, and the permuted sequence f' is diffused according to the diffusion formula to obtain the diffused sequence f''.
[0055] Ciphertext generation The sequence f'' is reduced to a three-dimensional matrix B', and is synthesized to a ciphertext image A'.
[0056] The decryption verification uses the inverse process of the encryption to decrypt the ciphertext image A', and obtains a decrypted image. Through testing, the peak signal-to-noise ratio (PSNR) of the decrypted image and the original image is greater than 40 dB, the information entropy is 7.998 bits, close to the theoretical maximum value of 8 bits, indicating that the encryption algorithm has good security and reversibility.
[0057] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present application should fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience of description and do not constitute any limitation on the present application.
Claims
1. A bit-level encryption algorithm based on a logic-sine-cosine chaotic system, characterized in that: The following steps are involved: Perform bit plane decomposition on the encrypted image to obtain a bit plane matrix; Construct a two-dimensional logic-sine-cosine chaotic system to generate key stream; Performing bit-level scrambling processing on the bit plane matrix based on the key stream; Perform bit-level diffusion processing on the scrambled bit plane matrix; The diffused bit plane matrix is synthesized into a ciphertext image.
2. A bit-level encryption algorithm based on a logic-sine-cosine chaotic system according to claim 1, characterized in that: The specific steps of the bit plane decomposition are: Decompose it and get the three-dimensional bit plane matrix B, where a(i, j) and b(i, j, k) are the pixel values of matrices A and B at (i, j), k = 0, 1, ..., 7, Indicates floor operation.
3. The bit-level encryption algorithm based on the logic-sine-cosine chaotic system according to claim 1 is characterized in that: The construction formula of the two-dimensional logic-sine-cosine chaotic system is: Among them, α, γ∈(0,4), β, δ∈[0,4], initial values x0, y0∈(0,1), and key streams C1 and C2 are generated by parameters key=(α, β, γ, δ, x0, y0).
4. A bit-level encryption algorithm based on a logic-sine-cosine chaotic system according to claim 3, characterized in that: The specific steps of the bit-level scrambling are: arranging the key stream C1 in ascending order to obtain C1', generating a mapping sequence U, and rearranging the initial one-dimensional sequence f according to U to obtain a scrambled sequence f', where f'(k) = f(u k ),u k is the position of the kth element in C1 in C1'.
5. The bit-level encryption algorithm based on the logic-sine-cosine chaotic system according to claim 4 is characterized in that: The specific steps of the bit-level diffusion are: converting the key stream C2 into a binary sequence V, diffusing the scrambled sequence f', and obtaining the diffused sequence f", the diffusion formula is f"(k) = f'(k) ⊕ f'(k-1) ⊕ V k , where ⊕ represents the exclusive OR operation.
6. The bit-level encryption algorithm based on the logic-sine-cosine chaotic system according to claim 1 is characterized in that: The encryption process also includes: decomposing the encrypted image into a bit plane matrix, converting it into a one-dimensional sequence f; restoring the diffused one-dimensional sequence f" into a bit plane matrix, and then synthesizing it into a ciphertext image.
7. The bit-level encryption algorithm based on the logic-sine-cosine chaotic system according to claim 1 is characterized in that: It also includes a decryption process, the specific steps of which are: decomposing the ciphertext image into a bit plane matrix, performing diffusion decryption and scrambling decryption on it, obtaining a decrypted one-dimensional sequence, restoring it to a bit plane matrix and synthesizing it into a decrypted image, wherein diffusion decryption and scrambling decryption are the inverse operations of diffusion and scrambling in the encryption process.