A secure blind signature method based on chaotic embedding of weak passwords

Abstract

The invention discloses a weak password chaos embedding security blind signature method, which relates to the technical field of data encryption and digital signature, and solves the problems that in the existing image transmission process, the sender denies the sent image, the receiver cannot confirm the sender's identity, and the encryption algorithm is single. The method of the invention first performs bitwise XOR diffusion during the encryption process, and then performs simultaneous scrambling and diffusion operations on the diffused matrix, thereby improving the encryption effect while achieving a secure encryption effect, and blinding the image; through the blind signature, the identity of the sender in the interaction process is authenticated, so that the sender cannot deny the information it sends, and because the sender has blinded the image before the signer signs, the signer cannot know the signature content, thereby reducing the risk of image leakage; the invention makes the encryption process safer and reduces the risks of signature fraud and theft.

Description

Technical Field

[0001] The invention relates to the technical field of data encryption and digital signature, and in particular to a weak password chaos embedding security blind signature method. Background Art

[0002] With the diversification of information transmission methods, images have become an indispensable part of data information transmission, and more and more image encryption algorithms are emerging. Traditional image encryption algorithms change the position and size of pixels through the scrambling-diffusion process to achieve the purpose of hiding plaintext image information. Although such encryption methods can ensure the security of images to a certain extent, the security is not very high during the transmission process.

[0003] There are various potential risks in the transmission of images, such as malicious tampering and attack, the sender denies the sending of the image, and the receiver cannot confirm the identity of the sender. Although more and more image encryption algorithms have emerged in recent years, they only perform a single encryption operation on the image and fail to solve the above problems well. Summary of the invention

[0004] The present invention provides a weak password chaotic embedding secure blind signature method to solve the problems that the sender denies the sent image, the receiver cannot confirm the sender's identity and the encryption algorithm is single in the existing image transmission process.

[0005] A secure blind signature method for embedding weak password chaos is implemented by the following steps:

[0006] Step 1: Select a color image with a size of M×N×3 as the original image Image, and the original image Image is used as the image Image sent by the sender;

[0007] Step 2: encrypt the image Image described in step 1 using a chaotic sequence generator and an encryption algorithm to obtain a ciphertext image Enimage, and send the ciphertext image Enimage to the signatory;

[0008] Step 3: The signatory generates a signature image Sig related to the identity of the sender, and calculates the chaotic key Key based on the signature image Sig. sig ;

[0009] Step 4: The signer uses the chaotic key Key in step 3 sig Performing an encryption operation on the signature image Sig to obtain a weak password signature image Ensig;

[0010] Step 5: embed the weak password signature image Ensig into the ciphertext image Enimage described in step 2 through discrete wavelet transform to obtain the signed image Signature;

[0011] Step 6: The signer uses the chaotic key Key in step 3 sig Encrypt and obtain the secure chaos key Enkey sig ;

[0012] Step 7: The signer sends the ciphertext image Enimage described in step 2, the signed image Signature described in step 5, and the secure chaotic key Enkey described in step 6 to ... sig Form a signature group Sig_group and send it to the recipient;

[0013] Step 8: After receiving the signature group Sig_group, the receiver uses the inverse discrete wavelet transform to extract the cryptographic signature image Ensig * ;

[0014] Step 9: The receiver Enkeys the secure chaotic key in the signature group sig Perform decryption operation to obtain the decryption chaos key Key sig * ;

[0015] Step 10: The receiver uses the decryption chaotic key Key described in step 9 sig * For the cryptographic signature image Ensig described in step eight * Decrypt and obtain the sender's decrypted signature image Sig * ;

[0016] Step 11: The receiving party decrypts the ciphertext image Enimage described in step 2 to obtain the decrypted image Image * .

[0017] Beneficial effects of the present invention: The weak password chaotic embedding secure blind signature method proposed by the present invention first performs bitwise XOR diffusion during the encryption process, and then performs simultaneous scrambling and diffusion operations on the diffused matrix, thereby improving the encryption effect while achieving a secure encryption effect, and blinding the image; through the blind signature, the identity of the sender in the interaction process is authenticated, so that the sender cannot deny the information it sends, and because the sender has blinded the image before the signer signs, the signer cannot know the signature content, reducing the risk of image leakage;

[0018] In addition, when signing, the signer generates a signature image related to the sender's identity based on the sender's identity information, and encrypts the signature image to obtain a cryptographic signature image. This process reflects the "weak-strong-weak" change, making it more secure and reducing the risk of signature impersonation and theft. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the overall interactive framework diagram of the weak password chaos embedding security blind signature method described in the present invention;

[0020] Figure 2 It is an encryption flow chart of the weak password chaos embedding security blind signature method described in the present invention;

[0021] Figure 3 The effect diagram of the encryption and decryption method using the weak password chaotic embedding security blind signature method described in the present invention: (a) is the original image and ciphertext image of "A Corner of Changli Campus", (b) is the original image and ciphertext image of "Identity", (c) is the ciphertext image containing the signature, and (d) is the signature extracted from (c) and its decrypted image. DETAILED DESCRIPTION

[0022] Specific implementation method 1. Combination Figure 1 and Figure 2 This embodiment is described, a weak password chaos embedding secure blind signature method, which is implemented by the following steps:

[0023] Step 1: Select a color image of size M×N×3 as the original image Image;

[0024] Step 2: The sender uses the chaotic sequence generator and encryption algorithm to encrypt the image Image to be sent, obtains the ciphertext image Enimage, and then sends it to the signer;

[0025] Step 3: The signer generates a signature image Sig related to the sender's identity;

[0026] Step 4: The signer uses the signature image Sig to calculate the chaotic key Key sig ;

[0027] Step 5: The signer uses the chaotic key Key described in step 4 to generate the signature image Sig related to the sender's identity (such as the sender's identity ID, name attributes, etc.) sif Perform encryption operation to obtain the weak password signature image Ensig;

[0028] Step 6: The signer embeds the weak password signature image Ensig into the ciphertext image Enimage received from the sender through discrete wavelet transform to obtain the signed image Signature;

[0029] Step 7: The signer uses an encryption algorithm to encrypt the chaotic key Key in step 4. sig Encrypt and obtain the secure chaotic key Enkey sig ;

[0030] Step 8: The signer converts the signature group Sig_group = (Enimage, Signature, Enkey sig ) is sent to the recipient;

[0031] Step 9: After receiving the signature group Sig_group, the receiver uses the inverse discrete wavelet transform to extract the cryptographic signature image Ensig * ;

[0032] Step 10: The receiver signs the secure chaotic key Sig_group.Enkey in the signature group sig Perform decryption operation to obtain the decryption chaotic key Key sig * ;

[0033] Step 11: The receiver uses the decrypted chaotic key Key sig * Cryptographically sign the image Ensig * Decrypt and get the decrypted signature image Sig of the sender * ;

[0034] Step 12: The receiver decrypts the ciphertext image Enimage described in step 2 to obtain the decrypted image Image * .

[0035] Specific implementation method 2: Combination Figures 1 to 3 Specifically describe this implementation mode, this implementation mode is an embodiment of the weak password chaotic embedding security blind signature method described in the specific implementation mode 1, and this embodiment will be described in detail from the sender, the signer, and the receiver, and is specifically implemented by the following steps:

[0036] 1. Sender;

[0037] Step 1: Select the color image of "A corner of Changli Campus" with a size of 512×512×3 as the original image Image;

[0038] Step 2: The original image Image described in step 1 is divided into three color components by the method shown in formula (1), namely, the image red component R image , image green component G image 、Image blue component B image :

[0039]

[0040] Among them, Image(:,:,1) is used to extract the first dimension component of the image Image, Image(:,:,2) is used to extract the second dimension component of the image Image, and Image(:,:,3) is used to extract the third dimension component of the image Image;

[0041] Step 3: Use the hash function to get the key associated with the plaintext image In this example, Key image =[52,57,49,99], the specific generation method is shown in formula (2):

[0042] Key image =SHA_256(Image) (2)

[0043] Among them, SHA_256(P) is a hash function, and P is the image to be input;

[0044] Step 4: Iterate the chaotic system to generate chaotic matrix sequences x, y, and z. Use the two-dimensional chaotic system twice, as shown in formula (3), iterate 10000+512×512 times respectively, discard the first 10000, and obtain four groups of chaotic sequences with a length of 512×512, which are recorded as x, y, z, and f respectively;

[0045]

[0046] Among them, α and β are the control parameters of the two-dimensional chaotic system. Since the system is used twice, the initial value of the first use is set to x0 = Key image0 =52,y0=Key image1 =57, the initial value when used for the second time is x0=Key image2 =49,y0=Key image3 =99;

[0047] Step 5: Take the chaotic sequences x, y, z in step 4 and convert them into three XOR matrices XI, YI, ZI of size 512×512 using formula (4):

[0048]

[0049] Among them, reshape(f, [M, N]) is a matrix conversion function, which means converting the sequence f into a matrix of size M×N;

[0050] Step 6: Use the XOR matrices XI, YI, and ZI in step 5 to calculate the R image , G image , B image Perform XOR diffusion operation to obtain the diffused matrix R image _Diffusion, G image _Diffusion, B image _Diffusion.

[0051] R image Take XI as an example:

[0052] First, the first 511 columns are operated as shown in formula (5): First, R image The pixel value R in image (i, j) and the next pixel value R image (i, j+1), and then perform an XOR operation on the result of the XOR operation and the element XI(i, j) in XI;

[0053] Secondly, the last column, i.e., the 512th column (except the last element), is operated as shown in formula (6): First, R image The pixel value R in image (i′, 512) and the next pixel value R image (i′+1,512) is XORed, and the XORed result is XORed with the element XI(i′,512) in XI;

[0054] Finally, the (512, 512)th element is operated as shown in formula (7): R image The pixel value R in image (512,512) and XI(512,512) perform an XOR operation, where the function bitxor(a,b) represents the XOR operation of a and b.

[0055]

[0056] Where i = 1, 2, ..., 512, j = 1, 2, ..., 511;

[0057]

[0058] where i′=1,2,...,511;

[0059]

[0060] Step 7: After diffusion in step 6, the matrix R image _Diffusion, G image _Diffusion, B image _Diffusion, perform simultaneous scrambling and diffusion operations to obtain the matrix R ima g e_ Enimage, G image _Enimage, B image _Enimage.

[0061] With matrix R image Take _Diffusion as an example:

[0062] First, take the high four bits and low four bits to get the matrix R image -Diffusion z (its size is 512×1024);

[0063] Secondly, for R image _Diffusion z Use the existing "Z" scrambling algorithm to perform the scrambling operation and obtain the scrambled matrix R image _Diffusion zafter (its size is 512×1024); then the matrix R image _Diffusion zafter Each decimal pixel value in is converted into a corresponding four-bit binary pixel value, and two adjacent four-bit binary pixel values ​​are combined into an eight-bit binary pixel value to obtain a binary matrix Rbin image _Diffusion zafter (its size is 512×512);

[0064] Then the binary matrix Rbin image _Diffusion zafter Convert to decimal matrix R image _Enimage (its size is 512×512). Matrix G image _Diffusion, B image _Diffusion is processed in the same way to obtain the matrix G image _Enimage, B image _Enimage;

[0065] Step 8: Matrix R in step 7 image _Enimage, G image _Enimage, B image_Enimage, and use formula (8) to get the final ciphertext image Enimage:

[0066] Enimage = cat(3, R image _Enimage, G image _Enimage, B image _Enimage) (8)

[0067] Among them, the function cat(3, R, G, B) means combining the three components of R, G, and B into a 3D color image;

[0068] Step 9: Send the ciphertext image Enimage in step 8 to the signatory.

[0069] 2. The signatory party;

[0070] Step 9: Based on the sender's identity information "CUST", a signature image Sig named "identity" related to the sender's identity is generated using the text-to-image operation, with a size of 128×128×3;

[0071] Step 10: Use the signature image Sig to calculate the chaotic key Key sig , as shown in formula (9). In this embodiment, the chaotic key is Key sig =[102,53,53,49],

[0072] Key sig =SHA_256(Sig) (9)

[0073] Step 11: Use the chaotic key Key to the signature image Sig sig , encrypt using the same encryption algorithm as the sender to obtain the weak cryptographic signature image Ensig;

[0074] Step 12: The weak password signature image Ensig described in step 11 is divided into three color components by the method shown in formula (10), namely, the image red component R Ensig , image green component G Ensig 、Image blue component B Ensig :

[0075]

[0076] Step 13: The ciphertext image Enimage (whose size is 512×512) received from the sender is divided into three color components by the method shown in formula (11), namely, the red component R Enimage , image green component G Enimage , image blue component B Enimage :

[0077]

[0078] Step 14: The three components R of the ciphertext image Enimage in step 13 Enimage , G Enimage , B Enimage Perform a secondary discrete wavelet transform, as shown in formulas (12), (13), (14):

[0079]

[0080]

[0081]

[0082] Among them, the function [LL, LH, HL, HH] = dwt2 (P, 'wname') is used for discrete wavelet transform to obtain four wavelet coefficients: low-frequency component LL, horizontal high-frequency component LH, vertical high-frequency component HL, and diagonal high-frequency component HH. P is the input image, and 'wname' is the wavelet name.

[0083] Step 15: The result of the secondary wavelet transform described in step 14 is used to embed the weak cryptographic signature image Ensig into the ciphertext image Enimage using formula (15), where RSig, GSig, and BSig are the results obtained by processing the red, green, and blue components, as shown in the following formula:

[0084]

[0085] Step 16: Use formula (16) to obtain the signed image Signature for RSig, GSig, and BSig in step 15;

[0086] Signature=cat(3,RSig,GSig,BSig) (16)

[0087] Step 17: The chaotic key Key in step 10 sig Using RSA encryption operation, we can get the secure chaotic key Enkey sig ;

[0088] Step 18: The ciphertext image Enimage received from the sender, the image Signature signed in step 16, and the secure chaotic key Enkey in step 17 sig Form a signature group Sig-group = (Enimage, Signature, Enkey sig ) and sends it to the recipient.

[0089] 3. Recipient;

[0090] Step 19: After receiving the signature group Sig_group from the signer, the secure chaotic key Enkey in the signature group sig Use RSA decryption operation to obtain the decryption chaotic key Key sig * =[102,53,53,49];

[0091] Step 20: The ciphertext image Enimage in the signature group is divided into three color components using the method shown in formula (17), which are the image red component R Enimage * , image green component G Enimage * 、Image blue component B Enimage * :

[0092]

[0093] Step 21: The three components R of the ciphertext image Enimage in step 20 Enimage * , G Enimage * , B Enimage * Perform a secondary discrete wavelet transform, as shown in formulas (18), (19), (20):

[0094]

[0095]

[0096]

[0097] Step 22: The signed image Signature in the signature group is divided into three color components by the method shown in formula (21), which are the image red component R signature * , image green component G signature * 、Image blue component B signature * :

[0098]

[0099] Step 23: For the three components R of the color image in step 22 signature * , G signature * , B signature *Perform a secondary discrete wavelet transform, as shown in formulas (22)(23)(24):

[0100]

[0101]

[0102]

[0103] Step 24: The results of the secondary wavelet transform described in Step 21 and Step 23 are used to extract the signature image from the signed image Signature using formula (25) to obtain the red, green and blue components R of the extracted password signature image. Ensig * , G Ensig * , B Ensig * ,

[0104]

[0105] Step 25: For R in step 24 Ensig * , G Ensig * , B Ensig * Using formula (26), we can get the extracted cryptographic signature image Ensig * ;

[0106] Ensig * =cat(3, R Ensig * , G Ensig * , B Ensig * ) (26)

[0107] Step 26: Ensig the cryptographic signature image extracted in step 25 * Perform the three-channel separation operation on the color image, and the three image matrices obtained are the R in step 6 Ensig * , G Ensig * , B Ensig * ;

[0108] Step 27: Enter the decryption chaos key Key in step 10 sig * , we get three XOR matrices XI of size 128×128 * , YI * , ZI* ;

[0109] Step 28: For the image matrix R in step 26 Ensig * , G Ensig * , B Ensig * , perform the inverse operation of simultaneous scrambling and diffusion, and obtain the matrix R Ensig _Diffusion, G Ensig _Diffusion, B Ensig _Diffusion.

[0110] With matrix R Ensig * For example:

[0111] First, take the high four bits and low four bits to get the matrix R Ensig _Diffusion z * (its size is 128×256);

[0112] Secondly, for R Ensig _Diffusion z * The "Z" scrambling algorithm improved by Li et al. is used to perform the inverse operation of scrambling to obtain the scrambled matrix R Ensig _Diffusion zafter * (its size is 128×256); then the matrix R Ensig _Diffusion zafter * Each decimal pixel value in is converted into a corresponding four-bit binary pixel value, and two adjacent four-bit binary pixel values ​​are combined into an eight-bit binary pixel value to obtain a binary matrix Rbin Ensig _Diffusion zafter * (its size is 128×128);

[0113] Then the binary matrix Rbin En s ig _Diffusion zafter * Convert to decimal matrix R Ensig _Diffusion * (Its size is 128×128). Ensig * , B Ensig * Process in the same way to obtain the matrix GEnsig _Diffusion * , B Ensig _Diffusion * ;

[0114] Step 29: Use the XOR matrix XI in step 27 * , YI * , ZI * For R in step 28 Ensig _Diffusion * , G Ensig _Diffusion * , B Ensig _Diffusion * Perform XOR diffusion operation to obtain the diffused matrix R Sif * , G Sig * , B Sif * .

[0115] R Ensig _Diffusion * and XI * For example:

[0116] First, operate the (128,128)th element as shown in formula (27): Ensig _Diffusion * The pixel value R in Ensig _Diffusion * (128, 128) and XI * (128,128) performs XOR operation;

[0117] Next, the last column, i.e., the 128th column (except the last element), is operated as shown in formula (28): First, R Ensig _Diffusion * The pixel value R in Ensig _Diffusion * (s′, 128) and the previous pixel value R Ensig _Diffusion * (s′+1, 128) performs an XOR operation, and then adds the XOR result to XI * Elements in XI * (s′, 128) performs an XOR operation; the first 127 columns are operated as shown in formula (29): first R Ensig _Diffusion * The pixel value R in Ensig _Diffusion* (s, t) and the previous pixel value R Ensig _Diffusion * (s, t+1) performs an XOR operation, and then adds the XOR result to XI * Elements in XI * (s, t) performs an XOR operation;

[0118] The phantom is described as follows:

[0119]

[0120]

[0121] Where s'=127, 126, ..., 1;

[0122]

[0123] Where s = 128, 127, ..., 1, t = 127, 126, ..., 1;

[0124] Step 30: The diffused matrix R in step 29 Sif * , G Sig * , B Sif * , using formula (30) to obtain the extracted decrypted signature image Sig * :

[0125] Sig * =cat(3,RS ig * , G Sig * , B Sig * ) (30)

[0126] Step 31: Decrypt the signature image Sig in step 30 * Perform image-to-text conversion to obtain the sender’s identity information “Changchun University of Science and Technology”;

[0127] Step 32: Enter the key of the ciphertext image Enimage image =[52, 57, 49, 99], decrypt the ciphertext image Enimage in the same way as steps 8 to 30 to obtain the decrypted image Image * .

[0128] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A secure blind signature method with weak cryptographic chaos embedding, characterized by: The method is implemented by the following steps: Step 1: Select a color image with a size of M×N×3 as the original image Image, and the original image Image is used as the image Image sent by the sender; Step 2: encrypt the image Image described in step 1 using a chaotic sequence generator and an encryption algorithm to obtain a ciphertext image Enimage, and send the ciphertext image Enimage to the signatory; In step 2, the specific process of obtaining the ciphertext image Enimage is as follows: Step 21: Divide the original image Image described in step 1 into three color components, namely, the image red component Rimage, the image green component Gimage and the image blue component Bimage; Step 2: Using a hash function to obtain a key Keyimage related to the original image Image; Step 23: Use the key Keyimage to iterate the chaotic system to generate chaotic matrix sequences x, y, and z; convert the chaotic matrix sequences x, y, and z into three XOR matrices XI, YI, and ZI of size M×N; Step 24, perform XOR diffusion operations on the image red component Rimage, image green component Gimage and image blue component Bimage in step 21 respectively using the XOR matrices XI, YI and ZI described in step 23 to obtain diffused matrices Rimage_Diffusion, Gimage_Diffusion and Bimage_Diffusion; Step 25: Perform simultaneous scrambling and diffusion operations on the diffused matrices Rimage_Diffusion, Gimage_Diffusion, and Bimage_Diffusion described in step 24 to obtain matrices Rimage_Enimage, Gimage_Enimage, and Bimage_Enimage; Step 26: Combine the three components of the matrix Rimage_Enimage, Gimage_Enimage, and Bimage_Enimage described in step 25 into a color image to obtain the final ciphertext image Enimage; Step 3: The signatory generates a signature image Sig related to the identity of the sender, and calculates the chaotic key Keysig based on the signature image Sig; Step 4: The signer uses the chaotic key Keysig obtained in step 3 to perform an encryption operation on the signature image Sig to obtain a weak password signature image Ensig; Step 5: embed the weak password signature image Ensig into the ciphertext image Enimage described in step 2 through discrete wavelet transform to obtain the signed image Signature; Step 6: The signer encrypts the chaotic key Keysig in step 3 to obtain the secure chaotic key Enkeysig; Step 7, the signer forms a signature group Sig_group consisting of the ciphertext image Enimage described in step 2, the signed image Signature described in step 5, and the secure chaotic key Enkeysig described in step 6 and sends it to the receiver; Step 8: After receiving the signature group Sig_group, the receiver uses the inverse discrete wavelet transform to extract the cryptographic signature image Ensig* from the signed image Signature in the signature group; Step 9: The receiver performs a decryption operation on the secure chaotic key Enkeysig in the signature group to obtain the decrypted chaotic key Keysig*; Step 10: The receiver uses the decrypted chaotic key Keysig* described in step 9 to decrypt the cryptographic signature image Ensig* described in step 8 to obtain the sender's decrypted signature image Sig*; Step 11: The receiving party decrypts the ciphertext image Enimage described in step 2 to obtain a decrypted image Image*.

2. The method for secure blind signature based on weak password chaos embedding according to claim 1 is characterized in that: In step 5, the specific process of obtaining the signed image Signature is as follows: Step 51: Divide the weak password signature image Ensig into three color components, namely, the image red component REnsig, the image green component GEnsig and the image blue component BEnsig: Step 52: Divide the ciphertext image Enimage described in step 2 into three color components, namely, the image red component REnimage, the image green component GEnimage and the image blue component BEnimage; Step 53: Perform a secondary discrete wavelet transform on the image red component REnimage, the image green component GEnimage and the image blue component BEnimage described in step 52, and embed the weak cryptographic signature image Ensig into the ciphertext image Enimage according to the result of the wavelet transform to obtain the final signed image Signature.

Images