TW468124B - Method of invisible electronic signature - Google Patents

Abstract

There is provided a method of electronic signature which is invisible and resistant to artificial damage or distorted compression. The present invention utilizes the comparing relation among pixels, error distribution, channel coding and interlaced coding techniques to provide a novel electronic signature technique. After the electronic signature is hidden, the original signature can still be visually recognized even when the generated image is artificially damaged or distortedly compressed.

Description

V. Description of the invention (1) 丨 1 ~ [Field of invention] The invention is a method for hiding electronic signatures, especially an electronic signature method that hides early information of electronic signatures in the image, making it difficult for human eyes to detect) BACKGROUND OF THE INVENTION Due to the advent of computer network technology, 'the result of comprehensive information', however, 'protection of network security issues. In addition, national defense applications or modern weapons and equipment all say, ‘therefore, how confidential information is important and urgently needs to be resolved. An electronic signature technology that steals the information of others and extracts information from meaningful images. The focus of the electronic signature is on the visual quality of the product, and it is not easy to be made, so that the digital copyright belongs to the final electronic signature technology referred to here. The destruction of resources. In the case of electronic signature technology (host image), the information image (watermarked image) has been rapidly developed. The digital era has made information flow easier, and knowledge sharing has gradually threatened the intellectual property rights on the Internet. The information is gradually passed through the computer network to obtain security certification on the road. It has become important in practice to prevent non-ownership from being copied and modified, so that legitimate users can get authenticated messages. This is called Zhang Yu. Research on digital copyright judgment to ensure that the added seal will not alter the original work, and the attacker will be tampered with or removed to get the correct judgment. The technique means that the image is hidden during transmission-the section 'Unauthorized third party is difficult to remove Transmission of information, so as to avoid deliberately common methods for people with intentions is to choose one of the originals and hide it, and then create another new one. I found that there are messengers on the Internet, so for those who are hidden, but generally (1) is not easy to detect and looks like the original picture, He information contained in it. For this user, 'can't distinguish many images on the Internet with electronic signature images, can quickly hide its sub-signature technology must have detection (Undetectable): easy to use general image processing methods to find it naked eye Seeing (Invisible to human eyes, it is difficult to distinguish from (2) difficult-to-use images. (3) difficult to delete chapters and not easy (4) anti-destructive image manipulation ^ is damaged. The direction of the electronic signature, in _ The effect is not good. (1) The amount of calculation should be relatively suitable. = Injury is reported in the image containing the signature. 3 Whether the image with the signature is hidden in other images. It is difficult for unauthorized persons to distinguish But for a legal use of the electronic signature, the following characteristics are extracted: The electronic signature is after the image, not 0) _ For the electronic signature image that has been added, it can be seen that it is divided from the original image. The electronic signature in the original image is deleted through a simple image processing method. 'Resistant to image maipulati〇n: In the meantime, even intentional destruction by interested people is not easy to make information in early technology. Model to do electronic signature wrong 'but there are the following three disadvantages: Too big: conversion to Lai rate. The domain requires complex calculations, and the receiver should convert.

Page 5 αβΒ1 2 4 V. Description of the invention (3) In the block with edges to avoid the damage of distortion compression, so that for the interested person, it is easy to hit the hidden information β (3) can The hidden information is relatively reduced: the frequency domain can only hide information in a fixed frequency band, so the information that can be hidden is relatively small. In the spatial domain, there is a Vector Quantization method that is often used to hide information. It uses a code book shared by the sender and receiver to hide the electronic pen chapter. The processing at the sending end is first The sender cuts the image to be hidden ('electronic signature) into & blocks of the same size as the codebook' and finds similar blocks from the codebook and replaces this block with its 'index value' The information is hidden in the picture, and then transmitted to the web. When the receiving end receives the image map containing the information, it takes out the index value and decrypts it, and then compares the codebook with the index value to restore the information. The disadvantage of this method is that it will cause a large distortion of the actual information, and the image after hiding the information is not easy to withstand the damage of the distortion. To hide information from a fixed area of an image pixel ’such as fixed range quantization (F ixed Range

Equal izat ion), this method is used to hide the image gray value of the image is divided into 16 fixed intervals 'hidden information in bytes, according to the space where the input value belongs' find a point to hide the original value to be hidden For information replacement, for example, the value of information is Feng 17, choose a point in the interval [16 ~ 31] and replace it with the value of 17. There is also a method called LSB, which is also the most commonly used method of Ife to collect information. LSB is to place the electronic signature in the lower (ie less important) position, because of the lower bit value. The effect of the change on the overall pixel value is relatively small, so the damage to the image is less obvious. However, the above two

A6 81 24 V. Description of the invention (4) '' One '-= method can not tolerate distortional damage after hiding information. [Summary and purpose of the invention] The present invention proposes that a Jewish Ding 3 person uses several types of images. Skillful electronic signers. The method is to send a new electronic sign. Chapter method. First, the blue primary band (B channel) of the R, G, and B images of the top shirt is used to hide the shell. Because the B channel is less sensitive to the human eye, the interlaced coding, general coding, and pixel position relationship are used to embed information. . Utilizing the editing / demapping technology ^ The pairwise relationship between adjacent pixels to hide information can effectively prevent the information from being tampered with. At the same time, the method of the present invention can withstand distortion because of the channel coding recovery ability and the comparison relationship between adjacent pixels. After sexual compression, the data can still be restored correctly. The method provided by the present invention can protect information, and can tolerate distortion damage. With channel coding techniques and the good use of the characteristics of the image before and after, combined with some basic image hiding techniques, it creates an electronic signature of $ 1 responsibility. The technical method 'is intended to have a practical purpose for the determination of copyright and the application of information disguise ^. The detailed content and technology of the invention are described below in conjunction with the drawings: [Detailed description of the invention] The original image (Host Image; H >) used by the invention to hide information is a color R, G, B each size The image of m χ η has a value of β between 0 ~. 2 5 5 and the information to be hidden in the original image is a bit string of L size. The information to be embedded in the original image is expressed in the following manner :

46 81 24 V. Description of the invention ⑸: — HI < n ^ ij ^ fO ^ SS]}-W = (w, | QSiKL ^^ lO ,!]}, *: For any 7 pixels t in the original picture 4 pixels around the right half of the perimeter and define a set of the method of hiding the electronic signature of the present invention. The flow chart is shown in Figure 1. It contains three steps: information rotation coding (step 1〇 ), Information interlacing step 20), and information. Into the image (step 30), the method is processed on the blue primary color; & (.Β channe 1), and after completing the three-step process, the image will be embedded The electronic signature in the image is transmitted (step 4). In the method flow of the method of concealing electronic signatures invented by Shi, the first step is to perform information rotation coding, which is a kind of channel coding. The purpose of the channel is to make the information resistant to transmission after encoding. Dali uses the characteristics of Yuxun hidden in the original image, so that after the code is passed, Asia will not increase the size of the original image, and it can also be restored under image compression or intentional destruction. The implementation is to use (2, the wheeze) to input the information to be hidden into the rotary encoder to produce twice the output of the original information, and use the extra encoding information to correct the error in the transmission process. Among them, "2" in "2,1,7" means that the encoded output is two bits. "" Γ means that the input information is in a unit of 俾 孓, and 7 " means that there is 6 (7- 1) registers. And round codes of different complexity can be used on hardware that is not ^ 'so if the hardware can provide greater computing power, you can use more complex round coders' and then Produces better anti-jamming effect. Figure 2 is the functional diagram of the application of the gyro code in the present invention.

Page 8 4 6 812 4 V. Description of the invention (6) (2, 2130 The hardware architecture requires 2 registers (50, 52). The second step is to perform f-signal interleaving coding, the information Interleaving coding uses the IL number generator of Linear Feedback Shift Register to generate a set of random numbers called m-sequence. The seed used is used as a private key. It must be used at the receiving end. This key can be used to extract information. This is the first key for information restoration. If the information is 8 bits, it can be generated by hardware as shown in Figure 3, where Figure 3 is provided by the present invention. Hardware circuit diagram of the interleaving code generator, which

The feedback function is f (xl, x2, x3) = xl + x3, which can generate a random number sequence with a period of 7, and the state diagram of the random number sequence is shown in Figure 4, where V The digital information in the figure such as (〇 丨 〇) represents the content of the temporary register (54, 56, 58) in the third type, and different initial values can be treated as different seed numbers (seeds) to generate different orders. Random number. The 8 bits of information are rearranged in this different order to produce an interlaced effect. Since this method has better chaos than the conventional interleaving method (matrix reading and writing), and does not need to save the entire table, only an initial value is needed, which can save a lot of space.

The third step is to embed the information. The step of embedding the information consists of location selection and information implantation. It consists of two parts, which are selected by the original image from the original image, and then the information to be hidden. When adding the original image to each bit, you need to consider the image points around the thick image (pixels. The present invention uses a number generator to perform dice on the original image from left to right and from top to bottom. Dice — If the sub is successful, the pixel point of the original image is selected as the information adding point. If the pixel hu is the information adding point, the position of the relevant pixels around it

Page 9 5. Description of the invention (7) The relationship is shown in Figure 5. Use the random number generator's 100% ratio to determine L (or its multiplication, which is different due to the characteristics of the convolutional code) as the information adding point for adding information. For example, the random number generator can generate values between 10 and 10, And the number of bits of information to be hidden accounts for 30% of the total number of pixels in the original image B cha η ne 1, so for each ..: Zhixiang dice, roll the number of Bu 3, and treat this pixel as Information to add points, otherwise the next pixel is processed. This, the random number is regarded as the second key to extract information (hidden electronic signature). The method of information embedding is the input information after the round-robin processing. ------------ ------·. It becomes a multiple of L and the round-robin code (2, 1 , 7), or produce twice as much information as L, that is, 2 L. If the current information bit to be added is 1 — .. — w, set the information addition point relative to the original image as hi j, and use the following formula to calculate the temporary variable h ': ---- a ----,- h- (hi.iJ.1 + hijJ.1 + hi.1J + 1 + hul > J + hiJ) / 5 ^ Adjust the values of hy and ASET ^ with the following algorithm: for each hrj. ASETj j do hi ,! j, = hil) j, + ((h, + (2w-l) xth) -hi j) / 4; hi j = h '+ (2w-l) xth; this th is a threshold value, the larger the value is, the The stronger the ability to resist damage, but the visual distortion of the image is also more serious, so through the ._. Operation of all the pixels described above, the information of the electronic signature can be successfully embedded in the film.

Page 10 46 81 24 l Description of the invention quot "-and Figure 6 is a flowchart of the method of extracting electronic signatures of the present invention, after the image is transmitted to the receiving end for reception (step 60), according to the above hidden electronic signature The chapter's method flow reverses the steps to extract the information. In the information extraction step, 'the image containing the electronic signature is calculated sequentially from left to right and top to bottom. Use the second key to calculate the position where the information is hidden (step 70). j is the same as adding the electronic signature information, using the following formula to calculate h ': then use the following formula to restore the relative information at this position; if (hr ^ h | j) w = l; else w—〇 sequentially restore each One bit of information is sent to the interleaved decoding (step, step 80) function. Interleaving decoding is to use the first key when information is added to reconstruct the scrambled information. This recording key is the random number generator of the above-mentioned interleaved linear feedback shift register (Linear Feedback Shift Register). The number of seeds used (seed) 'Re-run the random number generator with this number, calculate the original address of each point, then rearrange the information and restore the order before interleaving coding. The last step of information extraction is to devolve the gyro code (step 90). The Viterbi algorithm is used to correct the error information. The sof input can be used to increase the decoding ability.

46 8 彳 24 Jade, invention description (9) (trel 1 is diagram) can be created first to save the time of information restoration, so the information hidden by the gyrolysis function can be re-displayed. As confirmed by Annexes 1 to 4, the original image with hidden information can still clearly identify the electronic signature information after being artificially damaged or JPEG compressed. [Effects of the invention] According to the electronic signature method which is difficult to detect by human eyes according to the present invention, the following effects can be achieved: (1) The technique of dispersing and hiding information makes the image difficult to detect. (2) Use B channel to store information, which can achieve the effect that it is hard to distinguish with the naked eye. (3) Under the protection of virtual garbled information, it is difficult to delete information. (4) The function of using convolutional coding is to correct errors that may occur during transmission. (5) The use of interlaced coding enables the information to be fully dispersed and prevents continuity errors ---___ • one-by- .. burst errors. (6) Using the method of information embedding, 'proximity points share the information hidden by a single pixel' to hide the power of the information '§ · —the ability to prevent single points from being destroyed' and the function of information dissemination makes the original image more difficult destroyed. (Using two keys to prevent information from being stolen by unauthorized persons, providing an extra layer of security, and providing a secure transmission option for today's Internet popularity. Although the present invention is disclosed in the aforementioned preferred embodiment, As above, however, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and decorations without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention

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Page 13 4 6 81 2 4 Schematic description [Schematic description] Figure 1 is a flowchart of the method for hiding electronic signatures of the present invention; Figure 2 is a functional diagram of the application of the gyro code input and input according to the present invention Figure 3 is a schematic diagram of the hardware circuit of the interleaving code generator of the present invention; Figure 4 is a state diagram of the random number sequence of the temporary register of the present invention; Figure 5 is the information of the present invention Figure of the embedded information adding point and its surrounding pixels; Figure 6 is a flowchart of the method for extracting the electronic signature of the present invention; Attachment 1 is the original image map; Attachment 2 is the electronic signature information to be hidden; Attachment 3 It is the image map after the information is hidden; and Attachment 4 is the image map after man-made destruction. [Symbol description] Step 1 0 Information rotation coding Step 2 0 Information interleaving coding Step 3 0 Information embedded image Step 4 0 Transmission 5 0,52,54,56,58 Register step 6 0 Receiving step 70 Information will be hidden Position calculation step 8 0 interleaving decoding step 9 0 round decoding to obtain information

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Claims (1)

4 6 81 24 6. Scope of patent application The method includes at least the following steps: An electronic menu method that is difficult for human eyes to detect. The steps are as follows: using the information convolutional coding to conceal the rotary encoder, and generating a multiple of the information interleaving coding to generate a Randomly count a key, and use a random number generator to select an original number as the second key by a random number sequence. Enter the code of the information by using the image adding point and the electronic signature information Information; sequence, the number of the random number is regarded as the first, 'Flat code information is re-interlaced; the pixel points of the shirt image, the voxel point of the random number are used as the blue primary color band of the information point of the coding information Information is lost in the pixels of the original image. 2. The electronic signature method that is hard to detect by human eyes as described in the first target of the patent application, wherein the information rotation code uses the coded information to correct transmission process errors or human damage. -_ 3, as described in the first patent application scope of the human eye is not easy to detect the electronic signature method, wherein the random number sequence is produced by a linear feedback offset recorder • 0, as claimed, Please refer to the electronic signature method that is hardly detectable by human eyes as described in the third item of the patent scope, wherein the linear feedback offset recorder includes a plurality of registers. 5. The electronic signature method that is hard to detect by human eyes as described in item 1 of the scope of patent application, further includes the step of information extraction: using the second key to calculate the embedding position of the encoded information; using the first key Rearrange the encoded information to return to the order before the information was interleaved; and 4 6 8124 6. Scope of patent application Decode the encoded information by using the derotation code. 6. The electronic signature method that is hard to detect by the human eye as described in item 1 of the scope of patent application, wherein the original image 定义 is defined as an image of size m X η and the information to be embedded in the electronic signature size L is below W Column mode representation: H = (hij I m, 0 ^ j <[0,255]}; W = {w; I 0 ^ i < for any pixel in the original image, surround the right half of its periphery 'ii J -A set of 4 pixels is defined as: ASEmu, hi + U + l}. 7 · An electronic signature method that is difficult to detect by the human eye as described in item 6 of the scope of patent application, which defines a temporary variable: 8. The electronic signature method, as described in item 6 of the scope of patent application, which is hard to detect by human eyes, includes adjusting the values of huj and ASETu: for each h;-:, ASET :: do hi.J.-hi.J ^ ((h, + (2w-l) xth) -hij) / 4; hi ^ h '+ pw- 1) xth. 9. The electronic signature method as described in item 8 of the scope of patent application, which is not easily detectable by human eyes, wherein the th value is a threshold value. 1 〇 If the human eye described in the fifth scope of the patent application is not easy to detect ~: Electric soil _ stamp _ chapter method, in which the second key is used to _ _ the desired position of the coded information Page 16 6. The steps of applying for a patent are based on the information of the electronic signature when h ′. 11. The electronic signature method that is hard to detect by human eyes as described in the scope of the patent application, wherein the derotation code is a Viterbi algorithm. Page 17