Optical image encryption and decryption method and system

Abstract

This application relates to an optical image encryption and decryption method and system, belonging to the field of optical information processing technology. The optical image encryption and decryption method includes: dividing the original image into blocks, encrypting each block using a dynamically transformed key to generate an encrypted image, and mapping the key to a mode light characterized by the light field intensity distribution; encoding the encrypted image and mode light into different frequency components of the same collimated beam for modulation, and outputting a multiplexed optical signal including encrypted image information and key information; receiving the multiplexed optical signal and separating the encrypted image signal and mode light signal from the multiplexed optical signal; inputting the encrypted image signal and mode light signal into a neural network model for decoding, and outputting a reconstructed original image, wherein the neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the mode light. This application can effectively enhance the randomness and security of the encrypted transmission process.

Description

Technical Field

[0001] This invention relates to the field of optical information processing technology, specifically to an optical image encryption and decryption method and system. Background Technology

[0002] With the advent of the information age and the era of big data, various digital images are being used more and more widely in fields such as surveillance and healthcare. These images often carry a large amount of sensitive information, making image information security an urgent challenge. While traditional electronic encryption methods have contributed to confidentiality, they often incur high computational costs and are slow when processing massive amounts of image data, making it difficult to meet the needs of efficient real-time applications.

[0003] In contrast, optical information processing technology, with its high speed and parallel processing capabilities, as well as its characteristics of different wavelengths and large information capacity, provides new ideas for image encryption. In recent years, optical encryption technology has developed rapidly as a new security protection method and has become a hot topic in modern encryption technology research.

[0004] Existing optical image encryption methods are numerous, including dual random phase coding, encryption methods based on fractional Fourier transform and Fresnel transform, joint transform correlator systems, digital holography, and related imaging techniques. These methods have achieved parallelization and multi-dimensional encryption to some extent, but still face many challenges: on the one hand, while parallel encryption of multiple images can improve processing efficiency, it usually requires complex optical configurations and frequency and spatial domain switching, resulting in unsatisfactory encryption efficiency; on the other hand, as the encryption capacity increases, the complexity of the system and the computational burden also increase significantly, and traditional schemes often suffer from image distortion during decryption or fail to balance security and transmission efficiency. Summary of the Invention

[0005] This application provides an optical image encryption and decryption method and system, which can effectively enhance the randomness and security of the encrypted transmission process.

[0006] In a first aspect, embodiments of this application provide an optical image encryption / decryption method, the optical image encryption / decryption method comprising: The original image is divided into blocks, each block is encrypted using a dynamically transformed key to generate an encrypted image, and the key is mapped to a pattern light that characterizes the key information through the light field intensity distribution. The encrypted image and mode light are encoded into different frequency components of the same collimated light beam and modulated to output a multiplexed optical signal that includes encrypted image information and key information. Receive the multiplexed optical signal and separate the encrypted image signal and the mode optical signal from the multiplexed optical signal; The encrypted image signal and the pattern light signal are input into a neural network model for decoding, and the reconstructed original image is output. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the pattern light.

[0007] In conjunction with the first aspect, in one implementation, dividing the original image into blocks and encrypting each block using a dynamically transformed key includes: The original image is divided into n×n pixel blocks, where n is a positive integer; An n-order binary key matrix is ​​generated for the first pixel block in a pseudo-random manner, and the key matrix is ​​rotated or flipped in a pseudo-random manner before processing the next pixel block.

[0008] In conjunction with the first aspect, in one implementation, mapping the key to a pattern light characterizing key information through an optical field intensity distribution includes: The key matrix generated by pseudo-random means is mapped to bright and dark spots of Hermite-Gaussian mode light; In this key matrix, the position of the first value corresponds to the dark spot of the Hermite-Gaussian mode light, and the position of the second value corresponds to the bright spot of the Hermite-Gaussian mode light.

[0009] In conjunction with the first aspect, in one embodiment, the step of encoding the encrypted image and the mode light into different frequency components of the same collimated light for modulation includes: Obtain the phase modulation map corresponding to the encrypted image and the mode light; The phase modulation map corresponding to the encrypted image and the mode light is encoded onto a spatial light modulator to load the encrypted image information and key information into different frequency components of a collimated beam.

[0010] In conjunction with the first aspect, in one implementation, the phase modulation map corresponding to the encrypted image and the mode light is determined by the Gerchberg-Saxton algorithm.

[0011] In conjunction with the first aspect, in one embodiment, the spatial light modulator is a digital micromirror array, which uses the Lie hologram method or superpixel method to perform phase modulation on the direct light.

[0012] In conjunction with the first aspect, in one embodiment, receiving the multiplexed optical signal and separating the encrypted image signal and the mode optical signal from the multiplexed optical signal includes: The multiplexed optical signal is passed through a Fourier filter unit consisting of a lens and a filter; At the Fourier plane of the Fourier filter unit, the encrypted image signal and the mode light signal encoded at different frequencies are filtered out respectively.

[0013] Secondly, embodiments of this application provide an optical image encryption / decryption system, the optical image encryption / decryption system comprising: An encryption unit is used to divide the original image into blocks, encrypt each block using a dynamically transformed key, generate an encrypted image, and map the key into a pattern light that characterizes the key information through the light field intensity distribution. A collimated light source, comprising a laser and a collimator, wherein the collimated light source is used to output collimated light; A spatial light modulator is used to encode the encrypted image and pattern light into different frequency components of the collimated light for modulation, and output a multiplexed optical signal including encrypted image information and key information. A receiving unit is configured to receive the multiplexed optical signal and separate the encrypted image signal and the mode optical signal from the multiplexed optical signal; A neural network model is used to decode the received encrypted image signal and pattern light signal and output the reconstructed original image. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the pattern light.

[0014] In conjunction with the second aspect, in one implementation, the encryption unit divides the original image into blocks and encrypts each block using a dynamically changing key, including: The original image is divided into n×n pixel blocks, where n is a positive integer; An n-order binary key matrix is ​​generated for the first pixel block in a pseudo-random manner, and the key matrix is ​​rotated or flipped in a pseudo-random manner before processing the next pixel block.

[0015] In conjunction with the second aspect, in one implementation, the encryption unit maps the key to a pattern light characterized by a light field intensity distribution, including: The key matrix generated by pseudo-random means is mapped to bright and dark spots of Hermite-Gaussian mode light; In this key matrix, the position of the first value corresponds to the dark spot of the Hermite-Gaussian mode light, and the position of the second value corresponds to the bright spot of the Hermite-Gaussian mode light.

[0016] The beneficial effects of the technical solutions provided in this application include: The optical image encryption and decryption method in this application divides the original image into blocks, encrypts each block using a dynamically transformed key to generate an encrypted image, and maps the key to a mode light that represents the key information through the distribution of light field intensity. The encrypted image and mode light are encoded into different frequency components of the same collimated beam for modulation, and a multiplexed optical signal including encrypted image information and key information is output. The multiplexed optical signal is received, and the encrypted image signal and mode light signal are separated from the multiplexed optical signal. The encrypted image signal and mode light signal are input into a neural network model for decoding, and the reconstructed original image is output. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the mode light.

[0017] This application effectively improves the randomness and anti-attack capability of the encryption process by dividing the image into blocks and encrypting it with dynamically changing keys. By mapping the key to pattern light and encoding it into different frequency components of the same beam of light for transmission, the channel consistency and spatiotemporal synchronization of the key information and the image signal are ensured, reducing the risk of mismatch during transmission. Decoding is achieved by jointly learning the complex mapping relationship between the encrypted image signal and the pattern light field intensity through a neural network model, realizing computational security dependent on model parameters. Even if the transmitted signal is intercepted, the image cannot be restored. Thus, while ensuring high security, efficient and reliable optical image transmission and reconstruction are achieved. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of an embodiment of the optical image encryption / decryption method of this application; Figure 2 This is a schematic diagram of the processing flow of this application; Figure 3 This is a hardware structure block diagram of an embodiment of the optical image encryption and decryption system of this application. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application.

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0022] In a first aspect, embodiments of this application provide an optical image encryption / decryption method.

[0023] In one embodiment, reference is made to Figure 1 , Figure 1 This is a structural block diagram of an embodiment of the optical image encryption / decryption method of this application. Figure 1 and Figure 2 As shown, the optical image encryption / decryption method includes: S1. Divide the original image into blocks, encrypt each block using a dynamically transformed key to generate an encrypted image, and map the key to a mode light that characterizes the key information through the light field intensity distribution. Specifically, step S1 involves dividing the original image into blocks and encrypting each block using a dynamically transformed key, including: The original image is divided into n×n pixel blocks, where n is a positive integer; An n-order binary key matrix is ​​generated for the first pixel block in a pseudo-random manner, and the key matrix is ​​rotated or flipped in a pseudo-random manner before processing the next pixel block.

[0024] In this embodiment, the key matrix is ​​generated using a Matlab pseudo-random number generator, and an n-order key has a total of In this case, the key matrix undergoes a structural transformation in a pseudo-random manner before processing each new block, so that different pixel blocks use different keys, thereby improving the overall randomness and security of encryption.

[0025] Furthermore, the step S1 of mapping the key to a mode light that characterizes the key information through the light field intensity distribution includes: The key matrix generated by pseudo-random means is mapped to bright and dark spots of Hermite-Gaussian mode light; In this key matrix, the position of the first value corresponds to the dark spot of the Hermite-Gaussian mode light, and the position of the second value corresponds to the bright spot of the Hermite-Gaussian mode light.

[0026] In practice, the initial binary key matrix generated using a Matlab pseudo-random number generator is mapped to bright and dark spots of Hermite-Gaussian (HG) mode light containing defective states. It is worth noting that this embodiment is not limited to the initial binary key matrix; any key matrix can be used.

[0027] In the key matrix, a position of 0 corresponds to a defective state in the HG mode, which is a dark spot; a position of 1 corresponds to a bright spot in the HG mode. After the key is mapped to HG mode light containing defective states, its intensity distribution is used as input, and the corresponding phase modulation pattern at the transmitting end can be calculated using the Gerchberg-Saxton (GS) algorithm. In this embodiment, the encryption is handled entirely by the algorithm. The generated key is stored using the bright and dark states of the HG mode light. The hardware is responsible for modulating the desired pattern.

[0028] S2. Encode the encrypted image and mode light into different frequency components of the same collimated light beam for modulation, and output a multiplexed optical signal including encrypted image information and key information; Specifically, step S2 involves encoding the encrypted image and mode light into different frequency components of the same collimated light for modulation, including: Obtain the phase modulation map corresponding to the encrypted image and the mode light; encode the phase modulation map corresponding to the encrypted image and the mode light onto a spatial light modulator to load the encrypted image information and key information into different frequency components of a collimated beam.

[0029] In this embodiment, the phase modulation map corresponding to the encrypted image and the pattern light is mainly determined by the Gerchberg-Saxton algorithm. Furthermore, preferably, the spatial light modulator is a digital micromirror array (DMI), which uses the Lie hologram method or superpixel method to perform phase modulation on the aligned direct light.

[0030] It is worth noting that by employing a digital micromirror array as the spatial modulation core, its switching rate can reach tens of thousands of hertz, far exceeding the response speed of traditional liquid crystal spatial light modulators. Leveraging this characteristic, the system can complete the refresh of the encryption pattern and the real-time switching of the key pattern in an extremely short time, ensuring that each frame of the encrypted image corresponds to a different key combination, thus forming dynamic encryption. Simultaneously, the high-speed modulation capability enables the system to meet the demands of high-speed image transmission and real-time encryption applications, offering advantages in high throughput and low latency.

[0031] S3. Receive the multiplexed optical signal and separate the encrypted image signal and the mode optical signal from the multiplexed optical signal; Specifically, step S3 includes: S31. Pass the multiplexed optical signal through a Fourier filter unit composed of a lens and a filter. S32. At the Fourier plane of the Fourier filter unit, the encrypted image signal and the mode light signal encoded at different frequencies are filtered out respectively.

[0032] It is worth noting that when collimated light is incident on the digital micromirror array, the reflected light exits at two different angles, and both reflected beams contain all the information of the encrypted image and key matrix. The optical path diagram of the system is as follows. Figure 3 As shown, using a 4f system and a filter, information encoded at two different frequencies can be filtered out separately at the Fourier plane of the 4f system. A 4f system is a typical optical imaging and filtering system, consisting of two lenses, each with a focal length of f, and a distance of 2f between them.

[0033] For better display, Figure 3 The process involves filtering out the key and the encrypted image separately in two optical paths. Each optical path has two lenses and one filter. Since both beams contain all the information of the key and the encrypted image, in the actual optical path, the positions of the filters can be adjusted to filter out the key in one optical path and the encrypted image information in the other.

[0034] Finally, the receiver is used to capture the filtered encrypted image signal and pattern light signal.

[0035] S4. Input the encrypted image signal and the mode light signal into the neural network model for decoding, and output the reconstructed original image. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the mode light.

[0036] In this embodiment, the encrypted image signal and the pattern light signal are input together into a specially designed deep neural network. This neural network model can decode and recover the original unencrypted image by learning the complex mapping relationship between the encrypted image signal and the light field intensity of the pattern light.

[0037] It is worth noting that the optical image encryption and decryption system based on spatial modulation and key co-coding in this embodiment uses a neural network model as the decryption unit. The network has undergone joint training specifically for the "key-encrypted image" pair. For attackers who do not know the network structure and training data, intercepting the encrypted image and light field information cannot directly reverse the decryption process. At the same time, since the key matrix changes after processing each pixel block, it is difficult for attackers to decode it using optical means at the physical level. Even if a third party intercepts the transmitted signal and successfully extracts the complete information of the encrypted image and key from the signal, without a fully trained neural network, the third party cannot successfully decrypt the encrypted image.

[0038] In summary, the optical image encryption and decryption method in this application divides the original image into blocks, encrypts each block using a dynamically transformed key to generate an encrypted image, and maps the key to a mode light that characterizes the key information through the light field intensity distribution; the encrypted image and mode light are encoded into different frequency components of the same collimated beam for modulation, outputting a multiplexed optical signal including encrypted image information and key information; the multiplexed optical signal is received, and the encrypted image signal and mode light signal are separated from the multiplexed optical signal; the encrypted image signal and mode light signal are input into a neural network model for decoding, and the reconstructed original image is output, wherein the neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the mode light.

[0039] This application effectively improves the randomness and anti-attack capability of the encryption process by dividing the image into blocks and encrypting it with dynamically changing keys. By mapping the key to pattern light and encoding it into different frequency components of the same beam of light for transmission, the channel consistency and spatiotemporal synchronization of the key information and the image signal are ensured, reducing the risk of mismatch during transmission. Decoding is achieved by jointly learning the complex mapping relationship between the encrypted image signal and the pattern light field intensity through a neural network model, realizing computational security dependent on model parameters. Even if the transmitted signal is intercepted, the image cannot be restored. Thus, while ensuring high security, efficient and reliable optical image transmission and reconstruction are achieved.

[0040] Secondly, embodiments of this application provide an optical image encryption / decryption system.

[0041] In one embodiment, reference is made to Figure 3 , Figure 3 This is a hardware block diagram (software components are not shown) of an embodiment of the optical image encryption / decryption system of this application. Figure 3 As shown, the optical image encryption / decryption system includes: An encryption unit is used to divide the original image into blocks, encrypt each block using a dynamically transformed key, generate an encrypted image, and map the key into a pattern light that characterizes the key information through the light field intensity distribution. A collimated light source, comprising a laser and a collimator, wherein the collimated light source is used to output collimated light; A spatial light modulator is used to encode the encrypted image and pattern light into different frequency components of the collimated light for modulation, and output a multiplexed optical signal including encrypted image information and key information. A receiving unit is configured to receive the multiplexed optical signal and separate the encrypted image signal and the mode optical signal from the multiplexed optical signal; A neural network model is used to decode the received encrypted image signal and pattern light signal and output the reconstructed original image. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the pattern light.

[0042] Furthermore, in one embodiment, the receiving unit includes: A first optical path is used to filter out the mode light signal. The first optical path includes two first lenses with a focal length of f and a first filter located between the two first lenses. The distance between the two first lenses is 2f. The first optical path also includes a first receiver for receiving the mode light signal. The second optical path is used to filter out the encrypted image signal. The second optical path includes two second lenses, each with a focal length of f, and a second filter located between the two second lenses. The distance between the two second lenses is 2f. The second optical path also includes a second receiver for receiving the encrypted image signal.

[0043] Furthermore, in one embodiment, the encryption unit divides the original image into blocks and encrypts each block using a dynamically changing key, including: The original image is divided into n×n pixel blocks, where n is a positive integer; An n-order binary key matrix is ​​generated for the first pixel block in a pseudo-random manner, and the key matrix is ​​rotated or flipped in a pseudo-random manner before processing the next pixel block.

[0044] Further, in one embodiment, the encryption unit maps the key to a pattern light that characterizes the key information through an optical field intensity distribution, including: The key matrix generated by pseudo-random means is mapped to bright and dark spots of Hermite-Gaussian mode light; In this key matrix, the position of the first value corresponds to the dark spot of the Hermite-Gaussian mode light, and the position of the second value corresponds to the bright spot of the Hermite-Gaussian mode light.

[0045] Further, in one embodiment, the spatial light modulator encodes the encrypted image and pattern light into different frequency components of the same collimated beam for modulation, including: Obtain the phase modulation map corresponding to the encrypted image and the mode light; The phase modulation map corresponding to the encrypted image and the mode light is encoded onto a spatial light modulator to load the encrypted image information and key information into different frequency components of a collimated beam.

[0046] Furthermore, in one embodiment, the phase modulation map corresponding to the encrypted image and the mode light is determined by the Gerchberg-Saxton algorithm.

[0047] Furthermore, in one embodiment, the spatial light modulator is a digital micromirror array used to perform phase modulation on aligned direct light using the Lie hologram method or superpixel method.

[0048] Further, in one embodiment, the receiving unit receives the multiplexed optical signal and separates the encrypted image signal and the mode optical signal from the multiplexed optical signal, including: The multiplexed optical signal is passed through a Fourier filter unit consisting of a lens and a filter; At the Fourier plane of the Fourier filter unit, the encrypted image signal and the mode light signal encoded at different frequencies are filtered out respectively.

[0049] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0050] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0051] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An optical image encryption / decryption method, characterized in that, The optical image encryption / decryption method includes: The original image is divided into blocks, each block is encrypted using a dynamically transformed key to generate an encrypted image, and the key is mapped to a pattern light that characterizes the key information through the light field intensity distribution. The encrypted image and mode light are encoded into different frequency components of the same collimated light beam and modulated to output a multiplexed optical signal that includes encrypted image information and key information. Receive the multiplexed optical signal and separate the encrypted image signal and the mode optical signal from the multiplexed optical signal; The encrypted image signal and the pattern light signal are input into a neural network model for decoding, and the reconstructed original image is output. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the pattern light.

2. The optical image encryption / decryption method as described in claim 1, characterized in that, The step of dividing the original image into blocks and encrypting each block using a dynamically transformed key includes: The original image is divided into n×n pixel blocks, where n is a positive integer; An n-order binary key matrix is ​​generated for the first pixel block in a pseudo-random manner, and the key matrix is ​​rotated or flipped in a pseudo-random manner before processing the next pixel block.

3. The optical image encryption / decryption method as described in claim 2, characterized in that, The step of mapping the key to a mode light that characterizes key information through an optical field intensity distribution includes: The key matrix generated by pseudo-random means is mapped to bright and dark spots of Hermite-Gaussian mode light; In this key matrix, the position of the first value corresponds to the dark spot of the Hermite-Gaussian mode light, and the position of the second value corresponds to the bright spot of the Hermite-Gaussian mode light.

4. The optical image encryption / decryption method as described in claim 1, characterized in that, The step of encoding the encrypted image and mode light into different frequency components of the same collimated light beam for modulation includes: Obtain the phase modulation map corresponding to the encrypted image and the mode light; The phase modulation map corresponding to the encrypted image and the mode light is encoded onto a spatial light modulator to load the encrypted image information and key information into different frequency components of a collimated beam.

5. The optical image encryption / decryption method as described in claim 4, characterized in that: The phase modulation map corresponding to the encrypted image and the mode light is determined using the Gerchberg-Saxton algorithm.

6. The optical image encryption / decryption method as described in claim 4, characterized in that: The spatial light modulator is a digital micromirror array, which uses the Lie hologram method or superpixel method to perform phase modulation on direct light.

7. The optical image encryption / decryption method as described in claim 1, characterized in that, The step of receiving the multiplexed optical signal and separating the encrypted image signal and the mode optical signal from the multiplexed optical signal includes: The multiplexed optical signal is passed through a Fourier filter unit consisting of a lens and a filter; At the Fourier plane of the Fourier filter unit, the encrypted image signal and the mode light signal encoded at different frequencies are filtered out respectively.

8. An optical image encryption / decryption system, characterized in that, The optical image encryption / decryption system includes: An encryption unit is used to divide the original image into blocks, encrypt each block using a dynamically transformed key, generate an encrypted image, and map the key into a pattern light that characterizes the key information through the light field intensity distribution. A collimated light source, comprising a laser and a collimator, wherein the collimated light source is used to output collimated light; A spatial light modulator is used to encode the encrypted image and pattern light into different frequency components of the collimated light for modulation, and output a multiplexed optical signal including encrypted image information and key information. A receiving unit is configured to receive the multiplexed optical signal and separate the encrypted image signal and the mode optical signal from the multiplexed optical signal; A neural network model is used to decode the received encrypted image signal and pattern light signal and output the reconstructed original image. The neural network model is obtained by learning the mapping relationship between the encrypted image signal and the light field intensity of the pattern light.

9. The optical image encryption / decryption system as described in claim 8, characterized in that, The encryption unit divides the original image into blocks and encrypts each block using a dynamically changing key, including: The original image is divided into n×n pixel blocks, where n is a positive integer; An n-order binary key matrix is ​​generated for the first pixel block in a pseudo-random manner, and the key matrix is ​​rotated or flipped in a pseudo-random manner before processing the next pixel block.

10. The optical image encryption / decryption system as described in claim 9, characterized in that, The encryption unit maps the key to a pattern light that characterizes the key information through an optical field intensity distribution, including: The key matrix generated by pseudo-random means is mapped to bright and dark spots of Hermite-Gaussian mode light; In this key matrix, the position of the first value corresponds to the dark spot of the Hermite-Gaussian mode light, and the position of the second value corresponds to the bright spot of the Hermite-Gaussian mode light.

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