JP4218539B2 - Digital watermark embedding device, digital watermark detection device, digital watermark embedding method, and digital watermark detection method - Google Patents

Description

  The present invention relates to an electronic watermark embedding device, an electronic watermark detection device, an electronic watermark embedding method, and an electronic watermark detection method. In particular, in an electronic watermark for embedding information in an image, information is embedded in an edge portion of the image or region. The present invention relates to a technology for improving memory use efficiency and processing speed by facilitating the process.

  In recent years, illegal copying, falsification, and theft of digital contents have become a problem. In order to prevent these problems, a digital watermark technique has been developed that embeds additional data such as a digital signature, copyright information, and a message while adding minute processing that cannot be perceived to the content. With digital watermarking technology, additional data is integrated into the content itself, and it is used to prevent tampering, illegal duplication, and unauthorized transfer without increasing the storage capacity when uncompressed.

  There are two methods of embedding an electronic watermark, such as a method that is easily broken by alteration and cannot be detected, and a method that is not easily detected by alteration. Fragile digital watermarks are used for tamper detection and the like, and digital watermarks that are not easily broken are used for copyright protection. Hereinafter, a fragile digital watermark is referred to as a “fragile digital watermark”, and a hard-to-break digital watermark is referred to as a “robust digital watermark”.

In a fragile digital watermark used for image falsification detection, an electronic signature is embedded as additional data in an image, and falsification is detected by a mismatch between signature values on the embedding side and the verification side. For example, if the bitmap image embedding fragile watermark, as shown in FIG. 25, when verifying bit plain (strictly non LSB is a bit plane of non-LSB, is not used to embed LSB A hash value is calculated from all bits), and a hash value (electronic signature) encrypted by a public key cryptosystem is embedded in the LSB as additional data. Normally, the embedding position in the LSB is randomized using a pseudo-random sequence using a key as a seed.

  When the image is verified by this method, as shown in FIG. 26, the embedding position is determined from the LSB portion of the image in which the digital signature is embedded in the same procedure as that for embedding, and the embedded data is extracted. The hash value generated at the time of embedding the digital watermark is decrypted from the extracted data. Also, a hash value is calculated from the portion other than the LSB by the same algorithm as that on the embedding side, and the decrypted hash value is compared. As a result of comparison, if the hash values match, it can be seen that the image has not been tampered with. Normally, the bit length of the hash value generated compared to the image data is very short (for example, in the case of the hash algorithm called SHA1, the output data is 160 bits regardless of the input data length). If there is a slight change in the image due to the characteristics of the hash operation, the generated hash value will be completely different. Therefore, if even one pixel is falsified by comparing the hash values, tampering will occur. Can be detected.

  Further, if the range for calculating one hash value is not the entire image but a range divided by M × N pixel size blocks in the image, it is possible to detect alteration of the image in units of M × N blocks. , It is possible to specify the tampering location in the image in units of blocks.

  In some fragile digital watermarks, hash values and signature data are embedded in coefficients in a frequency space after wavelet transform, discrete cosine transform (DCT), quantization, and the like. These methods are also basically the same as digital watermarking for bitmaps, in which the hash value calculation target and signature data embedding target are simply replaced with the coefficients after frequency conversion from the image data itself. The detection method is the same as that of the bitmap.

  In addition, there are other methods such as changing the coordinates of the hash calculation target and the embedding target, and these also use the same detection method.

JP-A-9-318152 JP 2002-109657 A

  By the way, in the conventional digital watermark technology, the embedded blocks are scanned in the raster scan order to embed the digital watermark. However, when an image is divided by a fixed rectangular block, in many cases, the end block of the image is smaller than the rectangular block. In image coding processing, end blocks are often processed as small blocks as they are, or are often encoded with the same size as other blocks by adding dummy data such as edge extension or 0 data. On the other hand, in the case of embedding a digital watermark, the embeddable capacity in the end block becomes smaller than that in other blocks, and therefore there may be a case where the size of signature data cannot be secured. FIG. 27A shows embedding in a normal block, and shows a case where the embedding size of signature data is secured. On the other hand, FIG. 27B shows embedding in the end block, and shows a case where the embedding size of the signature data cannot be secured. Therefore, in order to avoid such a problem, as shown in FIG. 27 (c), processing is performed by integrating the adjacent blocks on the inner side of one stage into one block.

  However, during the encoding process, the coefficients that are the direct conversion of the image data are often held only in units of blocks, and since the processes are independent in units of blocks, the encoding process and electronic When watermark processing is integrated, the processing becomes very complicated, and the memory use efficiency becomes very poor.

  In addition, in digital watermarking for alteration detection, in order to prevent clipping in each block, which is a processing unit, there is a case where a key is devised or a signature of the entire image is embedded in the entire image to cope with clipping. It was. However, when the key is devised, there is a problem that it is not possible to detect replacement between blocks embedded at the same position using the same key. In addition, when embedding the signature of the entire image, replacement of blocks in the same position embedded using the same key can only detect that there is a replacement, and cannot identify the location. It was.

  As described above, conventionally, the end block is integrated with the inner block at the time of embedding the digital watermark, so that the processing becomes complicated, the speed is reduced, and the memory use efficiency is also reduced.

  The present invention has been made in view of the above problems of the conventional digital watermark technology, and the object of the present invention is to change the scan order, improve the memory usage efficiency, reduce the complexity of processing, New and improved integration of block signature data into other block signature data generation, allowing multiple signatures to be retained without increasing the embedded capacity, enabling block-based cut / paste detection and location An electronic watermark embedding device, an electronic watermark detection device, an electronic watermark embedding method, and an electronic watermark detection method are provided.

In order to solve the above-described problems, according to a first aspect of the present invention, there is provided a digital watermark embedding apparatus that embeds a digital watermark in image data. A digital watermark embedding apparatus according to the present invention includes a blocking unit (100) that divides image data to be embedded with a digital watermark into blocks of a predetermined size, and a signature generation unit (101) that generates signature data in units of blocks. And a signature embedding unit (102) for embedding signature data obtained from the signature generation unit in each block obtained from the blocking unit, and storing the signature data generated by the signature generation unit in response to a request from the signature embedding unit A signature storage unit (103) for outputting the signature data stored in the block, and the signature embedding unit embeds the signature data generated from each block in a plurality of blocks by concatenating with the signature data of surrounding blocks. It shall be the feature.

According to this configuration, the signature storage unit that stores the signature data generated by the signature generation unit is provided, and the stored signature data can be connected to the signature data of surrounding blocks and embedded in a plurality of blocks. In this way, it is possible to detect cut / paste in block units. Further, since the correlation between blocks is only signature data, most processing can be closed in units of blocks, and the memory usage efficiency is improved.

  In the digital watermark embedding apparatus of the present invention, the following applications are possible.

But it may also be the further include encrypting unit (104) for encrypting a plurality bind the signature data embedded in each block. In the present invention, since the signature data generated from each block is embedded in a plurality of blocks, there are a plurality of blocks in which the signature data is embedded. Some data sizes can be made constant. In this way, it is possible to detect cut / paste in block units without changing the amount of signature data to be embedded.

In order to solve the above-described problem, according to another aspect of the present invention, in an electronic watermark embedding apparatus for embedding an electronic watermark in image data, image data to be embedded with an electronic watermark is divided into blocks of a predetermined size and peripheral portions of the image data. If the block cannot be divided into blocks of a predetermined size, a block forming unit that divides the block into blocks of a predetermined size, a signature generation unit that generates signature data in units of blocks of a predetermined size, and a block forming unit. In each block, a signature embedding unit that embeds signature data obtained from the signature generation unit, a signature data generated by the signature generation unit, and a signature storage that outputs the stored signature data in response to a request from the signature embedding unit , A random value generator that generates a random value, and a signature pad before the signature generator generates signature data. A random value embedding unit that embeds a random value in a block of a size less than a predetermined size that is not used for embedding signature data of a block of a predetermined size. There is provided a digital watermark embedding device characterized in that the generated signature data is embedded in a plurality of blocks . The random value to be embedded here can be a value generated based on the key. By embedding a random value in a block not used for embedding signature data, the verification side can use the random value as a check value for interrupting the verification process early. In this case, the verification side generates a random value based on the key, and compares this random value with the extracted random value. If the comparison result does not match, it is handled as a tampered block, and it is not necessary to generate verification signature data or extract signature data. In this way, the calculation amount can be reduced.

Signature embedding unit, by changing the processing order of the blocks, but it may also be so embedded signature data blocks of less than a predetermined size to another moiety. If the end block is combined with the adjacent block and processed as a large block as in the prior art, after the signature generation and embedding of the two blocks, encoding processing such as image compression must be performed. This is accompanied by a significant control change such as dividing a normal image compression processing sequence in the middle of processing, and increases the amount of memory required. In this regard, if the signature data of the end block is embedded in another part by changing the block processing order, only the order of the blocks to be processed can be changed without changing the image compression processing sequence itself. It becomes possible to deal with it, and the required amount of memory remains the same as before. Also, when using encryption, the signature data embedded in the block adjacent to the end block does not increase.

In order to solve the above-described problem, according to another aspect of the present invention, a digital watermark verification apparatus for verifying a digital watermark embedded in image data is provided. The digital watermark verification apparatus of the present invention includes a blocking unit (200) that divides image data for verifying a digital watermark into blocks of a predetermined size, and a signature extraction unit (201) that extracts signature data in units of blocks. ) And a signature generation unit (202) that generates signature data in block units, a signature comparison unit (203) that compares the signature data extracted by the signature extraction unit and the signature data generated by the signature generation unit ) and comprises a signature comparator unit, for each block, it and comparing the signature data extracted from the concatenated plurality of blocks surrounding, and a signature data signature generating unit has generated.

According to such a configuration, for example, Upon verification of the electronic watermark embedded by the above electronic watermark embedding apparatus, it can detect the cut / paste of the block unit. Further, since the correlation between blocks is only signature data, most processing can be closed in units of blocks, and the memory usage efficiency is improved.

  The digital watermark verification apparatus according to the present invention can be applied as follows.

You may further provide the random value verification part (205) which verifies the random value obtained from a signature extraction part . Also, the signature comparison unit, but it may also be configured to compare the random value embedded into a plurality of blocks. By using a random value on the digital watermark embedding side, even if the digital watermark is embedded using the exact same key for the same image data, the embedded data can be changed. An embedded digital watermark can be verified using such a random value.

Random value verification unit, when a random value that is generated on the basis that was used a key to embedding a digital watermark has been tampered with, but it may also be so as to stop the process. If the result of comparing the random values does not match, it is handled as a falsified block, eliminating the need to generate verification signature data or extract signature data. In this way, the calculation amount can be reduced.

In order to solve the above problems, according to another aspect of the present invention, a digital watermark embedding method for embedding a digital watermark in image data is provided. The digital watermark embedding method of the present invention includes a block forming step for dividing image data to be embedded with a digital watermark into blocks of a predetermined size, a signature generating step for generating signature data in blocks, and a block forming step. The signature embedding process for embedding the signature data obtained in the signature generation process in each obtained block, the signature data generated by the signature generation process are stored, and the signature data stored in response to the request of the signature embedding process is output. includes a storing step, a signature embedding step, the signature data generated from each block, characterized by embedding a plurality of blocks in conjunction with the signature data of the surrounding blocks.

According to this method, it is possible to include the signature storing step of storing the signature data generated in the signature generating step, and the stored signature data can be connected to the surrounding signature data and embedded in a plurality of blocks. In this way, it is possible to detect cut / paste in block units. Further, since the correlation between blocks is only signature data, most processing can be closed in units of blocks, and the memory usage efficiency is improved.

  The digital watermark embedding method of the present invention can be applied as follows.

But it may also be so further includes an encryption process for encrypting a plurality bind the signature data embedded in each block. In the present invention, since the signature data generated from each block is embedded in a plurality of blocks, there are a plurality of blocks in which the signature data is embedded. Some data sizes can be made constant. In this way, it is possible to detect cut / paste in block units without changing the amount of signature data to be embedded.

In order to solve the above-described problem, according to another aspect of the present invention, in a digital watermark embedding method for embedding a digital watermark in image data, image data to be embedded with a digital watermark is divided into blocks of a predetermined size and peripheral portions of the image data. If the block cannot be divided into blocks of a predetermined size, a block forming step for dividing the block into blocks of a predetermined size, a signature generating step for generating signature data in a block unit, and each block obtained from the block forming step A signature embedding step for embedding signature data obtained from the signature generation step, a signature storage step for storing the signature data generated by the signature generation step, and outputting the stored signature data in response to a request for the signature embedding step, Random value generation process that generates random values and signature data is generated in the signature generation process In addition, the signature embedding process includes a random value embedding process that embeds a random value in a block smaller than a predetermined size that is not used for embedding signature data of a block of a predetermined size in the signature embedding process. There is provided a digital watermark embedding method characterized in that signature data generated from each block is concatenated with signature data of surrounding blocks and embedded in a plurality of blocks. The random value to be embedded here can be a value generated based on the key. By embedding a random value in a block not used for embedding signature data, the verification side can use the random value as a check value for interrupting the verification process early. In this case, the verification side generates a random value based on the key, and compares this random value with the extracted random value. If the comparison result does not match, it is handled as a tampered block, and it is not necessary to generate verification signature data or extract signature data. In this way, the calculation amount can be reduced.

In the signature embedding process, by changing the processing order of the blocks, but it may also be so embedded signature data less than a predetermined size to another moiety. If the end block is combined with the adjacent block and processed as a large block as in the prior art, after the signature generation and embedding of the two blocks, encoding processing such as image compression must be performed. This is accompanied by a significant control change such as dividing a normal image compression processing sequence in the middle of processing, and increases the amount of memory required. In this regard, if the signature data of the end block is embedded in another part by changing the block processing order, only the order of the blocks to be processed can be changed without changing the image compression processing sequence itself. It becomes possible to deal with it, and the required amount of memory remains the same. Also, when using encryption, the signature data embedded in the block adjacent to the end block does not increase.

In order to solve the above problems, according to another aspect of the present invention, a digital watermark verification method for verifying a digital watermark embedded in image data is provided. Watermarking verification method of the present invention, the image data to verify the electronic watermark, and more blocks Kako divided into blocks of a predetermined size, in the units blocked, and the signature extraction process of extracting the signature data is blocked A signature generation step for generating signature data in units of the data, a signature comparison step for comparing the signature data extracted in the signature extraction step and the signature data generated in the signature generation step. , for each block, you and comparing the signature data extracted from the concatenated plurality of blocks surrounding, and a signature data generated in the signature generation process.

According to this method, for example, Upon verification of embedded digital watermark by digital watermark embedding method of the above SL, it can detect cut / paste of the block unit. Further, since the correlation between blocks is only signature data, most processing can be closed in units of blocks, and the memory usage efficiency is improved.

  In the digital watermark verification method of the present invention, the following applications are possible.

Random value verifying step of verifying the random values obtained may also further including I a in the signature extraction process. In the signature comparison step, random values embedded in a plurality of blocks may be compared. By using a random value on the digital watermark embedding side, even if the digital watermark is embedded using the exact same key for the same image data, the embedded data can be changed. An embedded digital watermark can be verified using such a random value.

In a random value verification process, if the random value that is generated on the basis that was used a key to embedding a digital watermark has been tampered with, but it may also be so as to stop the process. If the result of comparing the random values does not match, it is handled as a falsified block, eliminating the need to generate verification signature data or extract signature data. In this way, the calculation amount can be reduced.

  According to another aspect of the present invention, there are provided a program for causing a computer to function as the digital watermark embedding device or the digital watermark verification device, and a computer-readable recording medium on which the program is recorded. . Here, the program may be described in any programming language. In addition, as a recording medium, for example, a recording medium that is currently used as a recording medium capable of recording a program, such as a CD-ROM, a DVD-ROM, or a flexible disk, or any recording medium that is used in the future should be adopted. Can do.

  In the above description, the reference numerals in parentheses attached to the constituent elements are merely shown as examples of corresponding constituent elements in the embodiments and drawings described below for easy understanding. It is not limited to.

  As described above, according to the present invention, the scan order is changed, the memory use efficiency is improved and the processing complexity is reduced, and the signature data of the block is integrated into the signature data generation of other blocks and embedded. A plurality of signatures can be held without increasing the capacity, and cut / paste detection and position specification can be performed in block units.

  Exemplary embodiments of a digital watermark embedding device, a digital watermark detection device, a digital watermark embedding method, and a digital watermark detection method according to the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
A digital watermark embedding device, a digital watermark verification device, a digital watermark embedding method, and a digital watermark verification method according to this embodiment will be described. First, the configuration of the digital watermark embedding device will be described. FIG. 1 is an explanatory diagram showing the configuration of the digital watermark embedding apparatus according to the first embodiment. FIG. 2 is an explanatory diagram showing a case where the digital watermark embedding apparatus of FIG. 1 is applied to a JPEG2000 compressor.

  As shown in FIG. 1, the digital watermark embedding apparatus according to the present embodiment divides an image data input terminal 1 for inputting image data and image data input from the image data input terminal 1 into blocks. Blocking unit 100, signature generating unit 101 that generates signature data from the blocked image data, signature embedding unit 102 that embeds signature data obtained from signature generating unit 101, and signature data generated by signature generating unit 103 Are stored in the signature storage unit 103 and the image data output terminal 3 for outputting the image data after the signature data is embedded.

  When the digital watermark embedding apparatus shown in FIG. 1 is applied to a JPEG2000 compressor, as shown in FIG. 2, a color conversion unit 50 that converts a color space in the case of a color image, and a wavelet conversion that performs wavelet conversion. A unit 51, a quantization unit 52 that quantizes wavelet coefficients, and an encoding unit 53 that encodes coefficients embedded with a digital watermark. Then, the image data output terminal 3 outputs a bit stream of the image in which the digital watermark is embedded.

Next, the configuration of the digital watermark verification apparatus will be described.
FIG. 3 is an explanatory diagram showing the configuration of the digital watermark verification apparatus according to this embodiment. FIG. 4 is an explanatory diagram showing a case where the digital watermark verification apparatus of FIG. 3 is applied to a JPEG2000 decompressor.

  As shown in FIG. 3, the digital watermark verification apparatus includes an image data input terminal 10 for inputting image data, and a blocking unit 200 that divides the image data input from the image data input terminal 10 into blocks. , A signature extraction unit 201 for extracting a signature embedded by the digital watermark embedding device, a signature generation unit 202 for generating signature data from the blocked image data, and a signature comparison for comparing the extracted signature with the generated signature A unit 203 and a comparison result output terminal 12 for outputting a comparison result are provided.

  In addition, when the digital watermark verification apparatus of FIG. 3 is applied to a JPEG2000 decompressor, as shown in FIG. 4, it further comprises a decoding unit 204 that decodes the JPEG2000 bitstream and outputs wavelet coefficients.

  The digital watermark embedding device and the digital watermark verification device according to the present embodiment are configured as described above. Next, operations of the digital watermark embedding device and the digital watermark verification device will be described.

First, the operation of the digital watermark embedding apparatus will be described.
The image data of the target image in which the electronic watermark is embedded is input to the image data input terminal 1. When the digital watermark is directly embedded in the pixel data, the input data is pixel data. In the case of digital watermarking in the frequency space, it is a wavelet coefficient or a DCT coefficient.

  Image data input to the image data input terminal 1 is passed to the blocking unit 100. The blocking unit 100 divides the input image data into blocks of a predetermined size (M × N size). In the case of digital watermarking to pixel data, it becomes a block of M × N pixels, and in the case of digital watermarking in the frequency space, it is a block of M × N coefficients in the coefficient space after wavelet transform or DCT. Become. This block may be composed of coefficient groups having different frequencies and indicating the same position in the pixel space, or may be composed of coefficient groups having the same frequency and indicating a close position in the pixel space.

  As illustrated in FIG. 5, the signature generation unit 101 generates signature data in units that are blocked by the blocking unit 100. As the signature data, a hash value obtained by using a hash function such as SHA1 as a block coefficient, a hash value encrypted by RSA or a part of the hash value, or the like is used. The generated signature data is used for verifying tampering at the time of verification.

FIG. 6 is an explanatory diagram showing an example of signature data generation for a block.
As shown in FIG. 6, the signature data may be obtained by collecting a plurality of blocks and obtaining a hash value and dividing it by the number of blocks, or by concatenating hash values for a plurality of blocks. Also, different methods or values generated in different area units may be combined.

  The signature storage unit 103 stores the signature data generated by the signature generation unit 101. The stored signature data is output in response to a request from the signature embedding unit 102.

The signature embedding unit 102 embeds signature data obtained from the signature generation unit 101 in each block obtained from the blocking unit 100. The signature data embedding pattern is as follows.
1) The signature data generated from each block is embedded only in the generation source block.
2) The signature data generated from each block is embedded in conjunction with the signature data of surrounding blocks.

  For example, among the signature data for blocks in the vicinity of the surrounding four, already generated signature data is concatenated and embedded in the same block. In the case of FIG. 7, only the signature data of block 1 is embedded in block 1. The signature data of block 1 and block 2 are embedded in block 2. Similarly, the signature data of block 2, block 4, and block 5 are sent to block 5, the signature data of block 11, block 13, and block 14 are sent to block 14, and the signature data of block 12, block 14, and block 15 are sent to block 15. Embed.

  Of the image data of the block, the part used for generating signature data cannot be used for embedding. That is, if the part used for generating the signature data is used for embedding, the data is changed and the obtained signature data changes. Therefore, as shown in FIG. 8, the signature data is generated from a part other than the part used for embedding. To do. The block that generates the signature data may be the same as or different from the block that embeds the signature data.

  As shown in FIG. 9, the embedding position in the block can be scrambled by a pseudo random sequence or a replacement table.

  As a result of the above operation, each adjacent block has a relationship of sharing the same signature data. Alterations such as replacing blocks at exactly the same position using images generated using the exact same key can be detected by examining this relationship.

  The embedded image data output terminal 3 outputs the image data after the signature data is embedded.

Next, the operation of the digital watermark verification apparatus will be described.
The image data of the target image for verifying the digital watermark is input to the image data input terminal 10. When the digital watermark is directly embedded in the pixel data, the input data is pixel data. In the case of digital watermarking in the frequency space, it is a wavelet coefficient or a DCT coefficient.

  Image data input to the image data input terminal 10 is passed to the blocking unit 200. The blocking unit 200 divides the input image data into blocks of a predetermined size (M × N size as in the digital watermark embedding side). In the case of digital watermarking to pixel data, it becomes a block of M × N pixels, and in the case of digital watermarking in the frequency space, it is a block of M × N coefficients in the coefficient space after wavelet transform or DCT. Become.

  The signature extraction unit 201 extracts signature data embedded in the image data. The extraction is performed by determining the embedding position by the same method as that for embedding signature data, and extracting data from the embedded position. If multiple signatures are combined or divided on the digital watermark embedding side, the reverse processing is performed to generate the original signature. In the case where the hash value or the like is encrypted on the digital watermark embedding side, the encryption is decoded here, returned to the original data, and passed to the signature comparison unit 203.

  The signature generation unit 202 generates signature data in units that are blocked by the blocking unit 200. The generation is performed by the same method as the digital watermark embedding side. However, when encryption or the like is used on the digital watermark embedding side, it is not necessary to perform encryption here, and the signature extraction unit 201 decodes the encryption. The signature generation unit 202 passes the generated signature data to the signature comparison unit 203.

  The signature extraction unit 201 acquires signature data for one block from a plurality of blocks.

  The signature comparison unit 203 compares the signature data of the signature extraction unit 201 and the signature generation unit 202. It is assumed that the blocks whose signature data match are not tampered with, and the blocks which do not match are tampered with.

  In the case of FIG. 7, signature data of one block is embedded in a maximum of three places. The comparison with the signature data generated by the signature generation unit 202 is performed with the signature data embedded in the own block or with the block that has already been determined not to be falsified. If the block that has not been tampered with does not match the signature data embedded in the surrounding blocks, the boundary with the surrounding blocks can be marked as a boundary that has been tampered with, such as by cutting, and can be notified to the user.

When a boundary determined to be cut and a block determined to be tampered constitute a closed curve, all blocks inside the closed curve can be handled as a tampered block. Further, by comparing the area of the closed curve inside and closed curve outside, when the area of the inner closed curve is small, all tamper blocks all blocks inside the closed curve, when the area of the closed curve outside is small, tamper block all the blocks of the closed curve outside It can be.

(Effects of the first embodiment)
As described above, according to this embodiment, it is possible to detect cut / paste in units of blocks. Further, since the correlation between blocks is only signature data, most processing can be closed in units of blocks, and the memory usage efficiency is improved.

(Second Embodiment)
FIG. 10 is an explanatory diagram showing the configuration of the digital watermark embedding apparatus according to the second embodiment. The digital watermark embedding apparatus according to the first embodiment shown in FIG. 1 further includes an encryption unit 104.

  The configuration of the digital watermark verification apparatus according to the present embodiment is substantially the same as that of the digital watermark verification apparatus according to the first embodiment shown in FIG.

  The operation of this embodiment will be described.

  The encryption unit 104 encrypts signature data to be embedded in the block. For encryption, common key encryption such as DES or public key encryption such as RSA can be used. When a hash value such as SHA1 is used for signature data and encryption is performed with a private key using public key encryption such as RSA for encryption, these are equivalent to a general electronic signature generation method. When embedding a plurality of signature data in one block as shown in FIG. 12, the encryption is performed after concatenating the signature data for a plurality of blocks as shown in FIG.

  In general, block cipher processing is the size of the encrypted data that is output regardless of the size of the data when encrypting data that is less than the encryption processing unit, regardless of public key encryption / common key encryption. Is constant. If the signature data is a hash value based on 160-bit SHA1 and the encryption processing is a 1024-bit RSA public key cryptosystem, the signature data is output from the encryption unit 104 when the number of signature data is one or three. The embedded data length is the same.

  The signature embedding unit 102 embeds the encrypted signature data output from the encryption unit 104 in each block.

  On the other hand, on the digital watermark detection apparatus side, as shown in FIG. 13, the digital watermark extraction unit 201 extracts the encrypted signature data embedded on the digital watermark embedding side, and decodes the cipher.

  Since other operations are substantially the same as the operations of the first embodiment, a duplicate description is omitted.

(Effect of the second embodiment)
As described above, according to the present embodiment, it is possible to detect cut / paste in units of blocks without changing the amount of signature data to be embedded. Further, since the correlation between the blocks is only the signature data, most of the processing can be closed in units of blocks, and the memory usage efficiency is improved.

(Third embodiment)
14 and 15 are explanatory diagrams illustrating the configuration of the digital watermark embedding device according to the third embodiment. The digital watermark embedding apparatus shown in FIG. 14 is that the signature storage unit 103 is deleted and the random value generation unit 105 is added to the digital watermark embedding apparatus according to the second embodiment shown in FIG. Features. Further, the digital watermark embedding apparatus shown in FIG. 15 is characterized in that a random value generation unit 105 is added to the digital watermark embedding apparatus according to the second embodiment shown in FIG.

  FIG. 16 is an explanatory diagram showing a configuration of the digital watermark verification apparatus according to the present embodiment. The digital watermark verification apparatus according to the present embodiment is characterized in that a random value verification unit 205 is added to the digital watermark verification apparatus according to the first embodiment shown in FIG.

  The digital watermark embedding device and the digital watermark verification device according to the present embodiment are configured as described above. Next, operations of the digital watermark embedding device and the digital watermark verification device will be described.

First, the operation of the digital watermark embedding apparatus will be described.
Similarly to the second embodiment, the encryption unit 104 concatenates and encrypts a single (always a single, the configuration shown in FIG. 14) or a plurality of signature data. At the time of encryption, a random value is further added to the data concatenated with the signature as shown in FIG. Random values include values obtained by calculating image contents, time stamps and network addresses, pseudo-random values generated based on them, sequential numbers, random values generated using thermal noise and noise sources, etc. , Anything is fine. The random values embedded in each block are all the same, or are values generated by hash or pseudo-random sequence based on the previously embedded random value in one or more block units. The random value is added to the signature data so that the total size of the signature data and the random value does not exceed the block cipher processing unit boundary. In this case, even if random data is added, the amount of data to be embedded does not increase.

  Other operations are substantially the same as the operations of the second embodiment, and thus redundant description is omitted.

Next, the operation of the digital watermark verification apparatus will be described.
As shown in FIG. 18, the digital watermark extraction unit 201 extracts the encrypted signature data embedded on the digital watermark embedding side, and decodes the encryption. The decoded signature data is processed in the same manner as in the first and second embodiments. The decoded random value is passed to the random value verification unit 205.

  The random value verification unit 205 verifies the random value obtained from the signature extraction unit 201. When all the same random values are embedded, the random value of the block that has not been tampered with is verified, and when there are two or more types of random values, notification is made that tampering has occurred. In this case, the block having the largest number of random values may be a block that has not been tampered with.

  Further, examples in which the pseudo value is changed by a pseudo random sequence or a hash function based on the random value are shown in FIGS. 19, 20, and 21. FIG. If the random value of the non-falsified block matches the value shifted from another block as shown in FIG. 20, the block is set to the same group as the matched block. In addition, if the value does not match the value changed from all the blocks, a new group is created. When multiple groups are created with random values, it can be notified that tampering such as cutting has occurred. Further, the group having the most belonging blocks can be regarded as a group that has not been tampered with, and the blocks to which the block belongs can be designated as non-tampered blocks.

  Other operations are substantially the same as the operations of the second embodiment, and thus redundant description is omitted.

(Effect of the third embodiment)
As described above, according to the present embodiment, it is possible to detect cut / paste in units of blocks without changing the amount of signature data to be embedded. In addition, even when an electronic watermark is embedded in exactly the same image data using the same key, the embedded data changes, so that even when such an image is used, cut / paste can be detected.

(Fourth embodiment)
FIG. 22 is an explanatory diagram showing the configuration of the digital watermark embedding apparatus according to the fourth embodiment. The digital watermark embedding device according to the present embodiment is characterized in that a random value generation unit 105 and a random value embedding unit 106 are added to the digital watermark embedding device according to the second embodiment shown in FIG. And

  The configuration of the digital watermark verification apparatus according to the present embodiment is substantially the same as that of the digital watermark verification apparatus according to the third embodiment shown in FIG.

  The operation of this embodiment will be described.

First, the operation of the digital watermark embedding apparatus will be described.
The random value embedding unit 106 embeds the random value generated by the random value generating unit 105 in the portion not used for embedding by the signature embedding unit 102.

  The signature generation unit 101 generates signature data from data in which a random value is embedded.

  The operation of the random value generation unit 105 is substantially the same as the operation of the third embodiment, and the other operations are substantially the same as the operations of the first, second, and third embodiments. Therefore, duplicate explanation is omitted.

Next, the operation of the digital watermark verification apparatus will be described.
The digital watermark extraction unit 201 extracts the random value embedded by the random value embedding unit 106 in addition to the signature data embedded on the digital watermark embedding side.

  The operation of the random value verification unit 205 is substantially the same as the operation of the third embodiment, and the other operations are substantially the same as the operation of the second embodiment. Is omitted.

(Effect of the fourth embodiment)
As described above, according to this embodiment, it is possible to detect cut / paste in units of blocks. In addition, even when an electronic watermark is embedded in exactly the same image data using the same key, the embedded data changes, so that even when such an image is used, cut / paste can be detected. In addition, the amount of calculation can be reduced.

  In addition, by setting the random value embedded on the digital watermark embedding side to a value generated based on the key, the random value can be used as a check value for interrupting the verification process early. In this case, the verification side generates a random value based on the key, and compares this random value with the extracted random value. If the comparison result does not match, it is handled as a tampered block, and it is not necessary to generate verification signature data or extract signature data.

(Fifth embodiment)
The configuration of the digital watermark embedding apparatus according to the present embodiment is substantially the same as that of the digital watermark embedding apparatus according to the first and second embodiments.

  The configuration of the digital watermark verification apparatus according to the present embodiment is substantially the same as that of the digital watermark verification apparatus according to the second and third embodiments.

  The operation of this embodiment will be described.

First, the operation of the digital watermark embedding apparatus will be described.
The signature generation unit 101 scans the blocks in the raster scan order and generates signature data. However, for the right / bottom block, if the generated signature data cannot be embedded, the processing order is changed. For example, as shown in FIG. 23, the block immediately before the right end is skipped, the signature data of the right end block is generated first, and then the signature data is generated from the block immediately before the right end. .

  The signature data at the right end and the bottom end is stored in the signature storage unit 103.

  The signature embedding unit 102 embeds signature data in the block order in which the signature data is generated. However, in the case of an end block having a small size and incapable of embedding signature data, embedding is performed in an adjacent embeddable block as shown in FIG. 24 without embedding. Similarly to the first embodiment, the signature data may be embedded as it is, or may be encrypted and embedded as in the second embodiment.

  Except for the end blocks, signature data can be generated and embedded in units of blocks, and then image compression processing and the like can be performed. The end block can simultaneously generate signature data and perform image compression processing for each block.

Next, the operation of the digital watermark verification apparatus will be described.
The digital watermark extraction unit 201 extracts signature data from each block and performs verification. For the blocks that could not be embedded on the digital watermark embedding side, the signature data is extracted from the blocks in which the adjacent signature data is embedded and verified.

  Since other operations are substantially the same as the operations of the first, second, and third embodiments, a duplicate description is omitted.

(Effect of 5th Embodiment)
If the end block is combined with the adjacent block and processed as a large block as in the prior art, after the signature generation and embedding of the two blocks, encoding processing such as image compression must be performed. This is accompanied by a significant control change such as dividing a normal image compression processing sequence in the middle of processing, and increases the amount of memory required. In this regard, according to the present embodiment, it is possible to cope with the problem by changing only the order of blocks to be processed without changing the image compression processing sequence itself, and the required memory amount remains the same. Also, when using encryption, the signature data embedded in the block adjacent to the end block does not increase.

  The preferred embodiments of the digital watermark embedding device, the digital watermark detection device, the digital watermark embedding method, and the digital watermark detection method according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. . It will be obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the blocks in the above embodiment are tiles and precincts when JPEG2000 is used. Also, a collection of a plurality of tiles or a plurality of precincts may be used.

  The present invention can be used in a digital watermark embedding device, a digital watermark detection device, a digital watermark embedding method, and a digital watermark detection method. In particular, in a digital watermark that embeds information in an image, information on an end portion of an image or a region is used. By making it easy to embed the memory, it can be used for a technology for improving memory use efficiency and processing speed.

It is a block diagram which shows the structure of the digital watermark embedding apparatus concerning 1st Embodiment. FIG. 2 is a block diagram illustrating an application example of the digital watermark embedding apparatus of FIG. 1 to JPEG2000. It is a block diagram which shows the structure of the electronic watermark verification apparatus concerning 1st Embodiment. It is a block diagram which shows the example of application to the JPEG2000 of the electronic watermark verification apparatus of FIG. It is explanatory drawing which shows an example of the signature data generation of a block. It is explanatory drawing which shows an example of the signature data generation of a block. It is explanatory drawing which shows the example in the case of embedding a calculated hash value in an adjacent block. It is explanatory drawing which shows the example of the production | generation source of signature data, and an embedding position. It is explanatory drawing which shows the relationship between embedding data and the position to embed. It is a block diagram which shows the structure of the digital watermark embedding apparatus concerning 2nd Embodiment. It is explanatory drawing which shows the example of signature data encryption. It is explanatory drawing which shows the example which couple | bonds and calculates the calculated hash value with the hash value of an adjacent block. It is explanatory drawing which shows the example of signature data decoding. It is a block diagram which shows the structure of the digital watermark embedding apparatus concerning 3rd Embodiment. It is a block diagram which shows the structure (the 1) of the digital watermark embedding apparatus concerning 3rd Embodiment. It is a block diagram which shows the structure (the 2) of the digital watermark verification apparatus concerning 3rd Embodiment. It is explanatory drawing which shows the example of signature data encryption. It is explanatory drawing which shows the example of signature data decoding. It is explanatory drawing which shows the example (when block 1 and block 2 do not correspond) compared with a random value. It is explanatory drawing which shows the example (when block 1 and block 2 correspond) compared with a random value. It is explanatory drawing which shows the example (when the block 2 is a falsification block) compared with a random value. It is a block diagram which shows the structure of the digital watermark embedding apparatus concerning 4th Embodiment. It is explanatory drawing which shows the example of an electronic watermark embedding / verification order. It is explanatory drawing which shows the example of data embedded in an electronic watermark embedding / verification order. It is explanatory drawing which shows the operation | movement at the time of embedding a fragile digital watermark to a bitmap. It is explanatory drawing which shows the operation | movement at the time of the fragile digital watermark verification to a bitmap. It is explanatory drawing which shows the embedding to an end block.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image data input terminal 3 Image data output terminal 10 Image data input terminal 12 Comparison result output terminal 50 Color conversion part 51 Wavelet transformation part 52 Quantization part 53 Encoding part 100 Blocking part 101 Signature generation part 102 Signature embedding part 103 Signature Storage unit 104 Encryption unit 105 Random value generation unit 106 Random value embedding unit 200 Blocking unit 201 Signature extraction unit 202 Signature generation unit 203 Signature comparison unit 204 Decoding unit 205 Random value verification unit

Claims (16)

In a digital watermark embedding device that embeds a digital watermark in image data,
A blocking unit that divides image data in which a digital watermark is embedded into blocks of a predetermined size;
A signature generation unit for generating signature data in the block unit;
A signature embedding unit that embeds signature data obtained from the signature generation unit in each block obtained from the blocking unit;
A signature storage unit that stores the signature data generated by the signature generation unit and outputs the stored signature data in response to a request of the signature embedding unit;
With
The signature generation unit generates signature data by scanning the blocks in raster scan order,
The signature embedding unit, the signature data generated from one block, among the surrounding blocks, and wherein the embedding prior SL one block in conjunction with the signature data of the block signature data is generated already , Digital watermark embedding device. 2. The data processing apparatus according to claim 1, further comprising an encryption unit configured to combine and encrypt a plurality of signature data embedded in each block , wherein a data size after encryption by the encryption unit is constant. Digital watermark embedding device. In a digital watermark embedding device that embeds a digital watermark in image data,
A block forming unit that divides image data in which a digital watermark is embedded into a block of a predetermined size and a block of a predetermined size when the image data cannot be divided into peripheral blocks of the image data;
A signature generation unit that generates signature data in the unit of the predetermined size or less than the predetermined size ; and
A signature embedding unit that embeds signature data obtained from the signature generation unit in the block of the predetermined size obtained from the blocking unit;
A signature storage unit that stores the signature data generated by the signature generation unit and outputs the stored signature data in response to a request of the signature embedding unit;
A random value generator for generating random values;
A random value embedding unit that embeds the random value in a block smaller than the predetermined size that is not used by the signature embedding unit to embed signature data of the block of the predetermined size before the signature generating unit generates signature data;
With
The signature generation unit generates signature data by scanning the blocks in raster scan order,
The signature embedding unit, the signature data generated from blocked one block at a predetermined size, out of the surrounding blocks, linked to previous SL first and the signing data of the block in which signature data is generated already A digital watermark embedding device characterized in that it is embedded in a block. The digital watermark according to claim 3, wherein the signature embedding unit embeds the signature data of the block smaller than the predetermined size in an adjacent block that can be embedded by changing a processing order of the blocks. Implantation device. In a digital watermark verification apparatus for verifying a digital watermark embedded in image data,
A blocking unit that divides image data for verifying a digital watermark into blocks of a predetermined size;
A signature extractor for extracting signature data in the block units;
A signature generation unit for generating signature data in the block unit;
A signature comparison unit that compares the signature data extracted by the signature extraction unit with the signature data generated by the signature generation unit;
With
The signature comparison unit includes, for one block, signature data of the one block extracted from a block that has already been determined not to be tampered among a plurality of surrounding connected blocks, and the signature generation unit A digital watermark verification apparatus for comparing the generated signature data of the one block .   The digital watermark verification apparatus according to claim 5, further comprising a random value verification unit that verifies a random value obtained from the signature extraction unit.   6. The digital watermark verification apparatus according to claim 5, wherein the signature comparison unit compares random values embedded in a plurality of blocks.   The electronic device according to claim 6, wherein the random value verification unit stops processing when a random value generated based on a key used for embedding a digital watermark is falsified. Watermark verification device. In a digital watermark embedding method for embedding a digital watermark in image data,
A block forming step for dividing image data to be embedded with a digital watermark into blocks of a predetermined size;
A signature generating step for generating signature data in the block unit;
A signature embedding step of embedding signature data obtained in the signature generation step in each block obtained in the blocking step;
Storing the signature data generated by the signature generation step, and outputting the stored signature data in response to the request of the signature embedding step;
Including
The signature generation step generates signature data by scanning each block in raster scan order,
The signature embedding step includes a feature to embed signature data generated from one block, among the surrounding blocks, coupled with the signature data of the block in which signature data is generated even before Symbol one block Yes, digital watermark embedding method. Wherein the signature data embedded in each block plurality bonded further seen containing an encryption step of encrypting the data size after encrypted by the encryption process is constant, to claim 9 The electronic watermark embedding method described. In a digital watermark embedding method for embedding a digital watermark in image data,
A block forming step of dividing the image data in which the digital watermark is embedded into a block of a predetermined size and a block of a predetermined size when the image data cannot be divided in a peripheral portion of the image data;
A signature generation step of generating signature data in the unit of the predetermined size or less than the predetermined size ; and
A signature embedding step of embedding signature data obtained from the signature generation step in the block of the predetermined size obtained from the blocking step;
Storing the signature data generated by the signature generation step, and outputting the stored signature data in response to the request of the signature embedding step;
A random value generation step for generating a random value;
Before generating signature data in the signature generation step, the random value embedding step of embedding the random value in a block of less than the predetermined size not used for embedding signature data of the block of the predetermined size in the signature embedding step;
Including
The signature generation step generates signature data by scanning each block in raster scan order,
The signature embedding step, said signature data generated from blocked one block at a predetermined size, out of the surrounding blocks, linked to previous SL first and the signing data of the block in which signature data is generated already A method of embedding a digital watermark, wherein the method is embedded in a block. 12. The digital watermark embedding according to claim 11, wherein, in the signature embedding step, signature data of a block smaller than the predetermined size is embedded in an adjacent block that can be embedded by changing a processing order of the blocks. Method. In a digital watermark verification method for verifying a digital watermark embedded in image data,
A block forming step of dividing image data for verifying a digital watermark into blocks of a predetermined size;
A signature extraction step of extracting signature data in the block units;
A signature generating step for generating signature data in the block unit;
A signature comparison step for comparing the signature data extracted in the signature extraction step with the signature data generated in the signature generation step;
Including
In the signature comparing step, one of the blocks, of the concatenated plurality of blocks around, when not tampered with already signature data of the one block extracted from the judgment block, in the signature generation step A digital watermark verification method comprising comparing the generated signature data of the one block .   The digital watermark verification method according to claim 13, further comprising a random value verification step of verifying a random value obtained in the signature extraction step.   14. The digital watermark verification method according to claim 13, wherein the signature comparison step compares random values embedded in a plurality of blocks. 15. The electronic device according to claim 14, wherein, in the random value verification step, the processing is stopped when a random value generated based on a key used for embedding a digital watermark has been falsified. Watermark verification method.

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