Transmission encryption and decryption method for encrypted image

Abstract

The invention provides a transmission encryption and decryption method for an encrypted image, and belongs to the technical field of image encryption, and the encryption process comprises the steps: carrying out the gray processing of an image, segmenting the image after the gray processing to obtain segmented image blocks, recognizing the pixel points at the two sides of the segmented image blocks, obtaining the coordinates of the pixel points and the mean value of the peripheral pixel points, and obtaining the coordinates of the pixel points and the mean value of the peripheral pixel points; and adding the x-axis absolute value and the y-axis absolute value of the pixel point coordinate axes on the two sides of the segmentation to obtain pixel coordinate values, sequentially synthesizing new image blocks according to the size of the pixel coordinate values, disorganizing the new image blocks and the segmented image blocks to generate a new image, encrypting the generated new image by using a chaotic encryption algorithm, and modulating and transmitting after encryption is completed. The image is disordered and recombined at the front end, and then the recombined image is encrypted for the second time, so that the image is difficult to decrypt after being stolen in the transmission process, and the security of the image in the transmission process is ensured.

Description

[0001] This application is a divisional application of the invention patent application with the application date of December 17, 2022, named "A system and method for transmitting encrypted images" and application number 202211628478.X. Technical Field

[0002] The present invention relates to the field of image encryption technology, and in particular to a method for transmitting encryption and decryption of an encrypted image. Background Art

[0003] Information devices carry a wide range of sensitive, private, and confidential information, making it vulnerable to theft during network transmission. Many existing images are transmitted as plaintext files, which can be intercepted during transmission, leading to privacy breaches. This is particularly true for everyday communication apps and other office applications, where private or confidential images, especially top-secret ones, are vulnerable to leaks. Therefore, a system with real-time encryption and transmission is needed to meet the needs of transmitting both private and top-secret images. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for transmitting encrypted images and decrypting encrypted images, so as to solve the technical problem of insecure image transmission.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A transmission encryption method for an encrypted image is characterized by: grayscale processing of an image, then segmenting the grayscale-processed image to obtain segmented image blocks, identifying pixel points on both sides of the segmented image blocks, and obtaining the coordinates of the pixel points and the average values of the surrounding pixels, adding the absolute x-axis values and the absolute y-axis values of the pixel coordinate axes on both sides of the segmentation to obtain pixel coordinate values, synthesizing new image blocks in sequence according to the sizes of the pixel coordinate values, scrambling the new image blocks and the segmented image blocks to generate a new image, and then encrypting the generated new image using a chaotic encryption algorithm, and modulating and transmitting after encryption is completed.

[0007] Furthermore, the specific process of synthesizing a new image block is to take a corner of the original image as the origin of the two-dimensional coordinate axis, add the absolute x-axis value and the absolute y-axis value of the coordinate axis of the pixel points on both sides of the dividing line to obtain the pixel coordinate value, sort the order according to the size of the pixel coordinate value, and then organize the corresponding pixel points into a marked image block in order, and mark the pixel point's neighboring pixel average on the superscript of the pixel at that point. When the pixel points on both sides of the dividing line are placed, if the marked image block is smaller than the divided image block, then the points with fixed pixel values are added in the empty space. If there are still dividing line pixels left after forming a marked image block, another marked image block is generated until all the pixels on both sides of the dividing line are used up.

[0008] Furthermore, the specific process of generating a new image is as follows: the new image block and all the segmented image blocks are randomly distributed to form a new image. When there is a gap in the combined image, a blank image block is added, and the pixel of each pixel point of the blank image block is a fixed value.

[0009] A method for transmitting and decrypting an encrypted image comprises receiving a modulation signal of the encrypted image, demodulating the modulation signal using a linear transformation network frequency discrimination method to obtain an encrypted image, and then performing chaotic reverse decryption on the encrypted image to obtain a chaotic image. A new image block is then found, and each pixel in the new image block is compared with a pixel of the remaining image. The dividing line is then found, and the image is reassembled into a civilized image according to the coordinates of the edge pixels, and the decryption is completed.

[0010] Furthermore, each pixel in the new image block is compared with the pixels of the remaining image, and then the dividing line is found, and the image is reassembled into a civilized image according to the coordinates of the edge pixels. The specific process is as follows: all the pixels of the new image block are taken into an array, and then the points in the image that are the same as each element of the array are traversed. When more than one point in the image is found to coincide with an element in the array, the superscript of the array element is compared with the mean of the pixels around the pixel point in the image, and then the image dividing line is determined, the image is divided into several image blocks, and then the image is reassembled according to the coordinates of the edge pixels of the image blocks to obtain the initial image.

[0011] Furthermore, the specific process of modulation is: setting the first preset difference frequency signal u s1 (τ) and the second preset difference frequency signal u s2 (τ), receiving FM signal u i (τ), the received FM signal u i (τ) are respectively related to the first preset difference frequency signal u s1 (τ) and the second preset difference frequency signal u s2 (τ) performs multiplication and integration operations to obtain the first operation result u n1 and the second operation result un2 , take the first operation result u n1 and the second operation result u n2 Perform linear transformation to obtain the modulated signal.

[0012] The present invention has the following beneficial effects due to the adoption of the above technical solution:

[0013] The present invention scrambles and reorganizes the image at the front end, and then performs secondary encryption on the reorganized image, so that it is difficult to decrypt the image even if it is stolen during transmission, thereby ensuring the security of the image during transmission. At the same time, at the receiving end, initial decoding can only be performed after using the decoding key provided by the setting device, and then secondary decryption is performed according to the segmented pixel points of the image to generate a complete image. This image transmission process prevents the content of the image from being leaked. At the same time, a new demodulation method is used at the receiving end, so that modulation and demodulation can be completed using ordinary equipment, which greatly saves the price of the equipment at the receiving end and the modulation end. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a block diagram of the encryption and decryption system of the present invention;

[0015] Figure 2 This is a comparison diagram of the image before and after encryption of the transmission image of the present invention;

[0016] Figure 3 This is the chaotic reverse decryption flow chart of the present invention. DETAILED DESCRIPTION

[0017] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and by way of preferred embodiments. However, it should be noted that many of the details listed in this specification are merely provided to help the reader gain a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be practiced even without these specific details.

[0018] like Figure 1-2 As shown, a transmission system for implementing encryption and decryption includes an image encryption subsystem and an image decryption subsystem. The image encryption subsystem is connected to the image encryption subsystem wirelessly or by wire. The image encryption subsystem includes an image primary encryption unit and an image secondary encryption unit. The image primary encryption unit is connected to the image secondary encryption unit. The image primary encryption unit encrypts the plaintext image once and then transmits the encrypted image to the image secondary encryption unit. The image secondary encryption unit encrypts the image twice using a hardware encryption key and then modulates the encrypted image. The modulated data is then transmitted to the image decryption subsystem. The image decryption subsystem receives the data, demodulates it, and then decrypts the encrypted image to obtain the plaintext image.

[0019] like Figure 2 As shown, Figure 2 A is the plaintext image before transmission, Figure 2 B is the image encrypted by the image secondary encryption unit, which is then modulated into a digital signal and sent to the image decryption subsystem for demodulation. Figure 2 The image of C is then decrypted by the image decryption subsystem to obtain Figure 2 The image of D is transmitted to complete the encrypted image.

[0020] The image one-time encryption unit includes an image preprocessing module, an image segmentation module, a pixel recognition module on both sides of the image segmentation line, a new block synthesis module and a block reconstructed image module. The image preprocessing module is connected to the image segmentation module. The image preprocessing module performs grayscale processing on the image to obtain a grayscale image. The image segmentation module divides the image into several blocks. The image segmentation module is connected to the pixel recognition module on both sides of the image segmentation line. The pixel recognition module on both sides of the image segmentation line identifies the pixels of the pixels on both sides of the segmentation line of the image segmented in the image segmentation module, and marks the coordinate axis of each pixel point. It also identifies the pixels of the pixels around the pixel point to obtain the pixel values of the pixel points and extracts all the pixels on both sides of the segmentation line. The new block synthesis module generates a new image block from all the pixels on both sides of the extracted segmentation line to obtain a marked image block. The new block synthesis module is connected to the block reconstructed image module. The block reconstructed image module randomly distributes the marked image block and all the segmented image blocks to form a new image. When there is a gap in the combined image, a blank image block is added. The pixel value of each pixel in the blank image block is a fixed value.

[0021] The specific process of synthesizing the marked image block is to take a corner of the original image as the origin of the two-dimensional coordinate axis, add the absolute value of the x-axis and the absolute value of the y-axis of the coordinate axis of the pixels on both sides of the dividing line to obtain the pixel coordinate value, sort the order according to the size of the pixel coordinate value, and then organize the corresponding pixels into a marked image block in order. The average value of the pixels of the neighboring points of the pixel point is marked on the superscript of the pixel of the point. When the pixels on both sides of the dividing line are placed, if the marked image block is smaller than the divided image block, then the points with fixed pixel values are added in the empty space. If there are still remaining dividing line pixels after forming a marked image block, another marked image block is generated until all the pixels on both sides of the dividing line are used up.

[0022] The image secondary encryption unit includes a reconstructed image secondary encryption module, a hardware encryption key module and an encrypted image modulation module. The hardware encryption key module and the encrypted image modulation module are both connected to the reconstructed image secondary encryption module. The hardware encryption key module provides an encryption key for the reconstructed image secondary encryption module. The encryption key is fixed on the encryption key and cannot be transmitted. It can only be accessed by local hardware. The reconstructed image secondary encryption module uses a chaotic image encryption method to encrypt the image to obtain an encrypted image, which is then transmitted to the encrypted image modulation module for modulation to obtain a transmission signal.

[0023] The image encryption subsystem includes an encrypted image demodulation module, an image one-time decryption module, a hardware decryption key module, an identification block search module, an image restoration module and a plaintext image display module. The encrypted image demodulation module receives the modulated signal and uses the linear transformation network frequency discrimination method to demodulate the signal to obtain an encrypted image. The encrypted image demodulation module and the hardware decryption key module are both connected to the image one-time decryption module. The hardware decryption key module transmits the decryption key to the image one-time decryption module. The image one-time decryption module uses a reverse decryption method to decrypt the image once to obtain a reconstructed image. The image one-time decryption module is connected to the identification block search module. The identification block search module finds the marked image block from the reconstructed image and then takes out the pixel points of the marked image block. The image restoration module searches for the corresponding image block for the pixel points of the marked image block and then reversely restores the original image according to the corresponding pixel points and the superscripts of the pixels. The plaintext image display module displays the original color of the image for the user to view. The specific process of restoring the image by the image restoration module is to take out all the pixel points of the marked image block and put them into an array, and then traverse the points in the image that are the same as each element of the array. When more than one point in the image is found to coincide with an element in the array, the superscript of the array element is compared with the mean of the pixels around the pixel point in the image, and then the image segmentation line is determined, the image is segmented into several image blocks, and then the image is reintegrated according to the coordinates of the edge pixels of the image blocks to obtain the initial image.

[0024] The hardware decryption key module is fixed on the device and cannot be changed once installed. That is, when the image encryption subsystem is first installed, the hardware decryption key module is transferred to the corresponding hardware and cannot be accessed by the external network.

[0025] When identifying the segmentation line, if a small part cannot be identified or the pixel and the superscript of the pixel are the same as the mean of the surrounding pixels, that is, the pixel point is not unique, then the point is abandoned and the next comparison is continued. When the comparison is completed and more than 85 pixels are compared, the task is completed and the identified loudness points are connected with a straight line in the image. The middle of the two straight lines is the segmentation line, and the segmented image blocks are obtained. The assembly can be completed according to the coordinates. During the recognition process, the filled image blocks are discarded because they were originally automatically added.

[0026] A transmission encryption method, the method comprising the following steps:

[0027] The image is grayscale processed, and then the grayscale processed image is segmented to obtain segmented image blocks. The pixel points on both sides of the segmented image block are identified, and the coordinates of the pixel points and the mean of the surrounding pixels are obtained. The pixel points on both sides of the segmentation are synthesized into a new image block. The new image block and the segmented image block are scrambled to generate a new image. The generated new image is then encrypted using a chaotic encryption algorithm to complete the encryption. The specific effect is as follows: Figure 2 As shown in A and B.

[0028] The specific process of synthesizing a new image block is to take a corner of the original image as the origin of the two-dimensional coordinate axis, add the absolute x-axis value and the y-axis absolute value of the coordinate axis of the pixels on both sides of the dividing line to obtain the pixel coordinate value, sort the order according to the size of the pixel coordinate value, and then organize the corresponding pixels into a marked image block in order. The average value of the pixels of the neighboring points of the pixel point is marked on the superscript of the pixel of the point. When the pixels on both sides of the dividing line are placed, if the marked image block is smaller than the divided image block, then the points with fixed pixel values are added in the empty space. If there are still dividing line pixels after forming a marked image block, another marked image block is generated until all the pixels on both sides of the dividing line are used up.

[0029] The new image block and all the segmented image blocks are randomly distributed to form a new image. When there is a gap in the combined image, a blank image block is added. The pixel of each pixel of the blank image block is a fixed value.

[0030] A method for transmitting and decrypting encrypted images, which receives the modulated signal of the encrypted image, uses the linear transformation network frequency discrimination method to demodulate the modulated signal to obtain the encrypted image, and then performs chaotic reverse decryption on the encrypted image to obtain a chaotic image, and then finds a new image block, compares each pixel in the new image block with the pixel of the remaining image, and then finds the dividing line, and reassembles the image into a civilized image according to the coordinates of the edge pixels, and the decryption is completed. The specific effect is as follows Figure 2 As shown in C and D.

[0031] Compare each pixel in the new image block with the pixels of the remaining image, then find the dividing line, and reassemble the image into a civilized image according to the coordinates of the edge pixels. The specific process is as follows: take out all the pixels of the new image block and put them into an array, then traverse the points in the image that are the same as each element of the array. When more than one point in the image is found to coincide with an element in the array, take the superscript of the array element and compare it with the average of the pixels around the pixel point in the image, then determine the image dividing line, divide the image into several image blocks, and then reassemble the image according to the coordinates of the edge pixels of the image blocks to obtain the initial image.

[0032] The specific process of the chaotic encryption algorithm is as follows:

[0033] Step 1: Load the generated new image P and external key. Read the generated new image P with a pixel size of m*n. The external key is a 32-byte integer sequence between [0, 255].

[0034] Step 2: Fill the external key into the grayscale image, obtain a quantized fractional matrix and obtain a chaotic sequence through the PWLCM chaotic system.

[0035] The PWLCM chaotic system is:

[0036]

[0037] In the above formula x(i)∈(0,1), when β∈(0,0.5), the system is in a chaotic state and β is used as a key.

[0038] The process of obtaining the quantized fractional matrix is to divide the generated new image P into m rows, multiply the elements of the row from left to right, and replace it with π if the i-th element is 0. When the product value A is greater than 1014, the A value is updated by the formula A=|cos(Amod360)|. When the last element of each row is executed, a real number A is obtained. The real number A is divided by 1014 to obtain a fractional sequence d1. Repeat the above process and calculate all elements in the opposite order to obtain another fractional sequence d2. Compare the size of d1 and d2. If d1>d2, then d=d2 / d1, otherwise d=d1 / d2. The external key is quantized from left to right using the above process to obtain the fractional d ', d" is obtained according to d"=(d+d' / 2)mod0.5, and the decimals d' and d" are used as the initial value x(1) and control parameter u of the PWLCM chaotic system. The corresponding chaotic sequence x1 is obtained by using x1(i)=PWLCM(d,d"), where x1(i) is expressed as x1(i)=x1(1),x2(2)…,x1(200+m), the accuracy of x(i)∈(0,1) is 10-15, i=1,2,…200+m, and similarly, x2,x2(i)=PWLCM(d / 2,d") can be obtained. x1 and x2 are used as the initial value x(1) and control parameter u of the PWLCM chaotic system. Then, iterate n-1 times Y i-200 (j) = PWLCM(x1(i), x2(i)), and we get m groups of Y i Sequences, where i = 201, 202, ..., 200 + m and j = 1, 2, ..., n, resize the m groups of sequences to obtain a fractional matrix of size m * n.

[0039] Step 3: Map the quantized fractional matrix to two integer regions and obtain two integer matrices. The process of obtaining the integer matrix is as follows: let the integer matrices be I1 and I2, where I1 = (I*10 15 mod8)+1, I2=I*10 15 Mod256 ensures I1∈(1,8), I2∈(0,255).

[0040] Step 4: According to the chaotic sequence obtained in step 2, several values are used as the initial values of the FDHCM chaotic system, and the FDHCM is iterated x times to obtain X F1 , X F2 , X F3 and X F4 Four chaotic sequences. The FDHCM chaotic system is,

[0041]

[0042] In the above formula, x1, x2, x3, and x4 are used as the initial variables of the chaotic system, and a, b, c, and d are the control parameters of the chaotic system.

[0043] The process of obtaining the four chaotic sequences is as follows: the matrix A controls the pixels of the image P to shift right cyclically in the four bit planes to obtain the matrix P1, where BR is the pixel representation shifted right cyclically in the bit plane operation, i∈(1,m), A∈(1,n), X F1 , X F2 , X F3 and X F4 It is obtained by sub-quantization of the following formula:

[0044]

[0045] Step 5: Via X F1 , X F2 , X F3 and X F4 Four chaotic sequences diffuse to generate new image P. F1 , X F2 , X F3 and X F4 The four chaotic sequences control the left and right cyclic shifts of the odd and even rows of the matrix I1, and the up and down cyclic shifts of the odd and even columns.

[0046] When rows are swapped, when X F1 (i)≠X F2 (i), perform the operation P2(i,j)=ER(P2(X F1 (i),j)),P2(X F2 (i),j)), column exchange is the same as X F3 (i)≠X F4 (i), P2(i,j)=ER(P2(X F3 (i),j)),P2(X F4 (i),j)) to generate a new image P for diffusion operation,

[0047]

[0048] Step 6: Use matrix B to scramble the diffused image. The process of scrambling the diffused image is to use matrix I2 to scramble the image. The specific operation is: The final encrypted image E is obtained.

[0049] The specific process of chaos reverse decryption is as follows Figure 3 As shown in Figure 3, the specific process is the reverse process of the chaotic encryption algorithm.

[0050] The specific process of the linear transformation network frequency discrimination method is as follows. Research has shown that this method can complete the modulation and demodulation operations using ordinary equipment, greatly saving expensive chips. The specific steps are as follows:

[0051] Step 1: Set the first preset difference frequency signal u s1 (τ) and the second preset difference frequency signal u s2 (τ), receiving FM signal u i (τ). Preset difference frequency signal u s1 and u s2 The frequency of f1 and f2 must satisfy the greatest common divisor f0, so that f1 = n1f0, f2 = n2f0, n1 and n2 are positive integers, then f f =xf0, where x is a positive real number. Let τ = f0t, and the final actual FM signal and preset difference frequency signal are expressed as follows:

[0052] FM signal

[0053] Preset difference frequency signal u s1 (τ)=sin2πf1t=sin2πn1τ;

[0054] Preset difference frequency signal u s1 (τ)=sin2πf2t=sin2πn2τ.

[0055] In the frequency modulation process, let the carrier signal be u c (t) = U cm cosω c t,U cm is the carrier amplitude, ω c is the carrier angular frequency, and the modulation signal is u Ω (t) = U Ωm cosΩt,U Ωm is the modulation signal amplitude, Ω is the modulation signal angular frequency, and the actual angular frequency of the FM signal is

[0056] ω f =ω c +Δω(t)=ω c +k f u Ω (t) = ω c +k f U Ωm cosΩt=ω c +Δω fm cosΩt.

[0057] Δω(t) is the modulation angle frequency deviation, k f is the FM sensitivity, which indicates the frequency change caused by the unit modulation signal amplitude; the actual frequency of the FM signal is

[0058]

[0059] Among them, f c is the carrier center frequency, Δf(t) is the modulation frequency deviation; Δω fm / 2π is the maximum frequency deviation of the FM wave, which represents the swing amplitude of the FM wave frequency and is a constant in the FM signal.

[0060] Step 2: Convert the received FM signal u i (τ) are respectively related to the first preset difference frequency signal u s1 (τ) and the second preset difference frequency signal u s2 (τ) performs multiplication and integration operations to obtain the first operation result u n1 and the second operation result u n2 .

[0061] When performing multiplication-integration transformation, the integration time is set to the period corresponding to f0 That is, the integration time of τ is τ0=f0t0=1, and the result of multiplication and integration transformation with the preset difference frequency signal is:

[0062]

[0063] The specific process of multiplication integration is as follows:

[0064]

[0065]

[0066] Step 3: Take the first operation result u n1 and the second operation result u n2 Perform linear transformation to obtain the modulated signal.

[0067] After the multiplication and integration network, the FM signal is transformed into a quantity related to the FM signal frequency and the difference frequency signal frequency. In the linear transformation restoration network, the multiplication and integration transformation result u is first converted into n1 and u n2 By dividing, we can get the relationship between x and n1 and n2 as shown in formula (1).

[0068]

[0069] The actual frequency f of the FM signal f =xf0 is composed of two parts: the carrier center frequency and the modulation signal influence frequency. After the linear transformation shown in formula (2), the amplitude of the modulation signal can be obtained to achieve accurate frequency discrimination.

[0070]

[0071] This study compares the frequency modulation distortion test data of the commonly used phase frequency detection method and the difference frequency multiplication-integral linear transformation network frequency detection method for frequency modulation signals with different frequency modulation indices. At low frequency modulation indices, both detection methods accurately restore the original modulated signal. However, for signals with higher frequency modulation indices, the distortion of the phase detection method increases with the increase in the frequency modulation index. The difference frequency multiplication-integral linear transformation network frequency detection method, on the other hand, exhibits virtually no signal distortion regardless of the frequency modulation index, with an unlimited detection bandwidth, resulting in higher quality modulation signal restoration. For an frequency modulation index of 0.02, the detection results of both methods exhibit very low distortion. For an frequency modulation index of 0.5, the conventional phase detector exhibits significant even-order harmonic distortion in the demodulated signal, while the proposed method exhibits minimal distortion. For an frequency modulation index of 2.4, the conventional phase detector exhibits higher-order even-order harmonic distortion in the demodulated signal, while the proposed method exhibits minimal distortion.

[0072] Matters not covered by the present invention are known technologies.

[0073] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for transmitting encrypted images, characterized in that: The image is grayscale processed, and then the grayscale processed image is segmented to obtain segmented image blocks. The pixel points on both sides of the segmented image blocks are identified, and the coordinates of the pixel points and the average of the surrounding pixels are obtained. The absolute values of the x-axis and y-axis of the pixel coordinate axes on both sides of the segmentation are added to obtain the pixel coordinate values. New image blocks are synthesized in sequence according to the size of the pixel coordinate values. The new image blocks and the segmented image blocks are scrambled to generate a new image. The generated new image is then encrypted using a chaotic encryption algorithm, and modulated and transmitted after encryption is completed.

2. The method for transmitting and encrypting an encrypted image according to claim 1, wherein: The specific process of synthesizing a new image block is to take a corner of the original image as the origin of the two-dimensional coordinate axis, add the absolute x-axis value and the y-axis absolute value of the coordinate axis of the pixels on both sides of the dividing line to obtain the pixel coordinate value, sort the order according to the size of the pixel coordinate value, and then organize the corresponding pixels into a marked image block in order. The average value of the pixels of the neighboring points of the pixel point is marked on the superscript of the pixel of the point. When the pixels on both sides of the dividing line are placed, if the marked image block is smaller than the divided image block, then the points with fixed pixel values are added in the empty space. If there are still dividing line pixels after forming a marked image block, another marked image block is generated until all the pixels on both sides of the dividing line are used up.

3. The method for transmitting and encrypting an encrypted image according to claim 1, wherein: The specific process of generating a new image is as follows: the new image block and all the segmented image blocks are randomly distributed to form a new image. When there is a gap in the combined image, a blank image block is added, and the pixel value of each pixel point of the blank image block is a fixed value.

4. A method for transmitting and decrypting an encrypted image, characterized in that: After receiving the modulated signal of the encrypted image, the linear transformation network frequency detection method is used to demodulate the modulated signal to obtain the encrypted image, and then the encrypted image is subjected to chaotic reverse decryption to obtain a chaotic image. Then, a new image block is found, and each pixel in the new image block is compared with the pixels of the remaining image. Then, the dividing line is found, and the image is reassembled into a civilized image according to the coordinates of the edge pixels. The decryption is completed.

5. The method for transmitting and decrypting an encrypted image according to claim 4, characterized in that: Compare each pixel in the new image block with the pixels of the remaining image, then find the dividing line, and reassemble the image into a civilized image according to the coordinates of the edge pixels. The specific process is as follows: take out all the pixels of the new image block and put them into an array, then traverse the points in the image that are the same as each element of the array. When more than one point in the image is found to coincide with an element in the array, take the superscript of the array element and compare it with the average of the pixels around the pixel point in the image, then determine the image dividing line, divide the image into several image blocks, and then reassemble the image according to the coordinates of the edge pixels of the image blocks to obtain the initial image.

6. The method for transmitting and encrypting an encrypted image according to claim 1, wherein: The specific process of modulation is: set the first preset difference frequency signal u s1 (τ) and the second preset difference frequency signal u s2 (τ), receiving FM signal u i (τ), the received FM signal u i (τ) are respectively related to the first preset difference frequency signal u s1 (τ) and the second preset difference frequency signal u s2 (τ) performs multiplication and integration operations to obtain the first operation result u n1 and the second operation result u n2 , take the first operation result u n1 and the second operation result u n2 Perform linear transformation to obtain the modulated signal.

Images