JP5660918B2 - Information processing apparatus, computer program, and information processing method - Google Patents

Description

  The present invention relates to an information processing apparatus, a computer program, and an information processing method.

  Techniques have been proposed for embedding a digital watermark into 3D graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a 3D graphic (see, for example, Non-Patent Documents 1 and 2).

In the technique described in Non-Patent Document 1, in the digital watermark embedding process, vertices are classified into insertion vertices (mark vertices), adjusting vertices (adjusting vertices), etc., and vertex data (x ₁ , x ₂ , the x ₁ coordinates x _3), embedded information indicating that the insertion vertex, an electronic watermark embedded in the x ₂ coordinate, the hash value of the electronic watermark is embedded in x ₃ coordinates.

when embedding the hash value digital watermark embedding x ₃ coordinates x ₂ coordinate, first, the center of gravity of the center of gravity and x ₃ coordinate values of x ₂ coordinate values of the vertices adjacent to the inserted vertex is calculated, and their values a value uniquely obtained from the value and the hash value of the electronic watermark is substituted respectively x ₂ coordinate and x ₃ coordinate of vertex data. Then, in order to compensate for variations of the center of gravity of the change and x ₃ coordinate value of the center of gravity of the x ₂ coordinate values caused by the implantation of the hash value to the digital watermark embedding and x ₃ coordinate to x ₂ coordinate, position of the adjustment vertex (x ₂ coordinate values and x ₃ coordinate value) is adjusted.

Then, in the extraction process of the electronic watermark, inserting a vertex based on the values of x ₁ coordinates of the vertex data of each vertex are identified and removed watermark and hash value from the x ₂ coordinate and x ₃ coordinate of the vertex data of the inserted vertices Then, the hash value of the extracted digital watermark is calculated, and authentication is performed by comparing the calculated hash value with the extracted hash value. If the calculated hash value and the extracted hash value are the same, it is determined that there is no falsification, and authentication is successful.

  However, in this method, if each coordinate of the vertex data is floating point real number data, an operation error such as a rounding error occurs. Therefore, even if there is no alteration, the calculated hash value and the extracted value are extracted in the digital watermark extraction process. The hash value may not match, which is not practical.

In the technique described in Non-Patent Document 2, in the digital watermark embedding process, insertion vertices (mark vertices) are designated so as not to be adjacent to each other, and x in the vertex data (x ₁ , x ₂ , x ₃ ) of the insertion vertices some of the mantissa of the floating-point number data of the _first coordinate, embedded information indicating that the insertion vertex, an electronic watermark is embedded in a part of the mantissa of the floating-point number data x ₂ coordinate, x ₃ A hash value of the electronic watermark is embedded in a part of the mantissa part of the floating point real number data of the coordinates.

x when embedding the hash value digital watermark embedding x ₃ coordinate _two coordinates, first, the center of gravity and x ₃ for some mantissas of floating-point number data x ₂ coordinate values of the vertices adjacent to the inserted vertex The centroid is calculated for a part of the mantissa part of the floating point real number data of the coordinate value, and the exclusive OR obtained by bit operation between the value, the digital watermark value, and the hash value is the x ₂ coordinate of the vertex data each of which is assigned to and x ₃ coordinates.

Then, in the extraction process of the electronic watermark, inserting a vertex based on the values of x ₁ coordinates of the vertex data of each vertex is identified, the digital watermark and hash bits calculated from x ₂ coordinate and x ₃ coordinate of the vertex data of the inserted vertices A value is extracted, a hash value of the extracted digital watermark is calculated, and authentication is performed by comparing the calculated hash value with the extracted hash value. If the calculated hash value and the extracted hash value are the same, it is determined that there is no falsification, and authentication is successful.

In the Non-Patent Document 2 technique, since the embedding and extraction of watermark and hash values are performed with respect to x ₂ coordinate and x ₃ coordinate insertion vertex bit operations, operations such as rounding errors in floating point operations as described above There is no error.

`` A public fragile watermarking scheme for 3D model authentication '', Chang-Min Chou, Din-Chang Tseng, Computer-Aided Design, Volume 38, Issue 11, November 2006 `` A numerically stable fragile watermarking scheme for authenticating 3D models '', Wei-Bo Wang et al., Computer-Aided Design, Volume 40, Issue 5, May 2008

  However, in the technique described in Non-Patent Document 2 described above, since the hash value of the digital watermark is embedded only in a part of the mantissa part of the floating point real number data of the x3 coordinate in the vertex data of the insertion vertex, the remaining mantissa part There is a problem that even if this part is tampered with, authentication is successful. In addition, there is a problem that the amount of information that can be embedded is reduced as compared with the method of Non-Patent Document 1.

  The present invention has been made in view of the above problems, and in embedding additional information such as a digital watermark into three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic. It is an object to obtain an information processing apparatus, a computer program, and an information processing method that make it easy to detect tampering.

  In order to solve the above problems, the present invention is configured as follows.

An information processing apparatus according to the present invention stores a three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic, reads the three-dimensional graphic data from the storage means, For at least one vertex data of the vertex data, additional information is embedded in a part of the mantissa part of the floating point real data of one coordinate in the vertex data, and the mantissa part of the floating point real data of another coordinate in the vertex data Information embedding means for embedding a code obtained by a one-way function from the remaining part of the mantissa part of the floating-point real number data of another coordinate and additional information, and a part or all of a plurality of vertices And vertex classification means for classifying into an insertion vertex, an adjustment vertex, and an isolated vertex . The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. Then, the information embedding unit embeds a predetermined first identification value indicating the insertion vertex in a part of the mantissa part of the floating point real number data of the remaining coordinates in the vertex data of the insertion vertex, A predetermined second identification value indicating that the vertex is an isolated vertex is embedded in a part of the mantissa part of the floating-point real number data of the remaining coordinates in the data. This second identification value is different from the first identification value.

  As a result, a code obtained by a one-way function is embedded from at least the remaining mantissa part and the additional information, so that alteration of the data is easily detected when the additional information is extracted.

The information processing apparatus according to the present invention stores storage means for storing 3D figure data having a plurality of vertex data corresponding to a plurality of vertices constituting the 3D figure, and reads out the 3D figure data from the storage means. For at least one vertex data of a plurality of vertex data, additional information is embedded in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, and the mantissa of the floating point real number data of another coordinate in the vertex data Information embedding means for embedding a sign obtained by a one-way function from the remaining part of the mantissa part of the floating-point real number data of another coordinate and additional information in a part of the part, a part of a plurality of vertices or Vertex classification means for classifying all into an insertion vertex and an adjustment vertex . The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Then, the information embedding means calculates a predetermined parameter value for each coordinate by integer arithmetic from a part of the mantissa part of the floating point real number data of one coordinate and another coordinate in the vertex data of the vertex adjacent to the insertion vertex, and adjusts it. A part of the mantissa part of the floating point real data of one coordinate and another coordinate in the vertex data of the vertex is changed in order to compensate for a variation in a predetermined parameter value.

  Thereby, since the value of the predetermined parameter is calculated by integer calculation, no calculation error such as a rounding error occurs, and authentication using the predetermined parameter can be accurately performed when the additional information is extracted.

A computer program according to the present invention provides a computer in an information processing apparatus having storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic. Read data, and for at least one vertex data of a plurality of vertex data, embed additional information in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, and the floating point of another coordinate in the vertex data Information embedding means for embedding a code obtained by a one-way function from at least the remaining part of the mantissa part of floating-point real data of another coordinate and additional information in a part of the mantissa part of real number data , and a plurality of vertices some or all insertion vertex of regulation vertices, and machine as the vertex classification means for classifying the isolated vertices Make. The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. Then, the information embedding unit embeds a predetermined first identification value indicating the insertion vertex in a part of the mantissa part of the floating point real number data of the remaining coordinates in the vertex data of the insertion vertex, A predetermined second identification value indicating that the vertex is an isolated vertex is embedded in a part of the mantissa part of the floating-point real number data of the remaining coordinates in the data. This second identification value is different from the first identification value. As a result, a code obtained by a one-way function is embedded from at least the remaining mantissa part and the additional information, so that alteration of the data is easily detected when the additional information is extracted.

Further, the computer program according to the present invention provides a computer in an information processing apparatus having storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic. Dimensional figure data is read, and for at least one vertex data of a plurality of vertex data, additional information is embedded in a part of the mantissa part of the floating-point real number data of one coordinate in the vertex data, and another coordinate in the vertex data is Information embedding means for embedding a sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and additional information in a part of the mantissa part of the floating-point real number data, and a plurality of Function as a vertex classification means to classify some or all of the vertices into insertion vertices and adjustment vertices . The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Then, the information embedding means calculates a predetermined parameter value for each coordinate by integer arithmetic from a part of the mantissa part of the floating point real number data of one coordinate and another coordinate in the vertex data of the vertex adjacent to the insertion vertex, and adjusts it. A part of the mantissa part of the floating point real data of one coordinate and another coordinate in the vertex data of the vertex is changed in order to compensate for a variation in a predetermined parameter value. As a result, a code obtained by a one-way function is embedded from at least the remaining mantissa part and the additional information, so that alteration of the data is easily detected when the additional information is extracted.

An information processing method according to the present invention includes a step of reading from a storage means three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic, and at least one vertex of the plurality of vertex data for data, the steps of embedding the additional information in a part of the mantissa of the floating-point number data for one coordinates in the vertex data, a part of the mantissa of the floating-point number data of another coordinates in the vertex data, at least a separate A step of embedding a sign obtained by a one-way function from the remaining mantissa part of the floating point real number data of coordinates and additional information, and a part or all of a plurality of vertices are inserted vertices, adjustment vertices, and isolated vertices Categorizing into: The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. Then, a predetermined first identification value indicating the insertion vertex is embedded in a part of the mantissa part of the floating point real data of the remaining coordinates in the vertex data of the insertion vertex, and the remaining coordinates in the vertex data of the isolated vertex are embedded. A predetermined second identification value indicating that the vertex is an isolated vertex is embedded in a part of the mantissa part of the floating-point real number data. This second identification value is different from the first identification value.

  As a result, a code obtained by a one-way function is embedded from at least the remaining mantissa part and the additional information, so that alteration of the data is easily detected when the additional information is extracted.

Further, the information processing method according to the present invention includes a step of reading from the storage means three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic, and at least one of the plurality of vertex data For one vertex data, the step of embedding additional information in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, and a part of the mantissa part of the floating point real number data of another coordinate in the vertex data, The step of embedding the sign obtained by the one-way function from the remaining part of the mantissa part of the floating-point real number data of the different coordinates and additional information, and classifying some or all of the vertices into insertion vertices and adjustment vertices And a step of performing. The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Then, a predetermined parameter value is calculated for each coordinate from one part of the vertex data of the vertex adjacent to the insertion vertex and a part of the mantissa part of the floating-point real number data of another coordinate by an integer operation, and one point in the vertex data of the adjustment vertex is obtained. A part of the mantissa part of the floating point real number data of the coordinate and another coordinate is changed in order to compensate for a variation of a predetermined parameter value.

  As a result, since a code obtained by a one-way function from at least the remaining part of the mantissa part and the additional information is embedded, it is easy to detect data tampering when the additional information is extracted.

An information processing apparatus according to the present invention includes a storage unit that stores three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic, and reads the three-dimensional graphic data from the storage unit, For at least one vertex data of the vertex data, additional information is extracted from a part of the mantissa part of the floating-point real data of one coordinate in the vertex data, and the mantissa part of the floating-point real data of another coordinate in the vertex data Information extracting means for extracting a code from a part and authenticating the extracted code with a value obtained by a one-way function from at least the extracted code and the remaining mantissa part of floating-point real number data of another coordinate; When the value of a part of the mantissa part of the floating point real number data of the remaining coordinates in the vertex data of a certain vertex is the predetermined first identification value Identifies the inserted vertex the vertex, if some of the values of the mantissa is a predetermined second identification value, and a vertex type specifying means for specifying that vertex and isolated vertices. The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. The second identification value is different from the first identification value. Then, the information extracting means extracts additional information and a sign from the vertex data of the insertion vertex and the isolated vertex, and uses a one-way function from at least the extracted sign and the remaining part of the mantissa part of the floating-point real number data of the other coordinate. The extracted code is authenticated with the value obtained by the above. As a result, since a code obtained by a one-way function from at least the remaining part of the mantissa part and the additional information is embedded, it is easy to detect data tampering when the additional information is extracted.

A computer program according to the present invention provides a computer in an information processing apparatus having storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic. Read data, and for at least one vertex data of a plurality of vertex data, extract additional information from a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, and the floating point of another coordinate in the vertex data The code is extracted from a part of the mantissa part of the real data, and at least the obtained code and the remaining part of the mantissa part of the floating-point real data of another coordinate are authenticated by the value obtained by a one-way function. information extraction means for performing, and floating point actual remaining coordinates in the vertex data of a vertex If the partial value of the mantissa part of the data is a predetermined first identification value, the vertex is specified as the insertion vertex, and if the partial value of the mantissa part is the predetermined second identification value, the vertex is It functions as a vertex type specifying means for specifying an isolated vertex . The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. The second identification value is different from the first identification value. Then, the information extracting means extracts additional information and a sign from the vertex data of the insertion vertex and the isolated vertex, and uses a one-way function from at least the extracted sign and the remaining part of the mantissa part of the floating-point real number data of the other coordinate. The extracted code is authenticated with the value obtained by the above.

  As a result, since a code obtained by a one-way function from at least the remaining part of the mantissa part and the additional information is embedded, it is easy to detect data tampering when the additional information is extracted.

An information processing method according to the present invention includes a step of reading from a storage means three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic, and at least one vertex of the plurality of vertex data A step of extracting additional information from a part of a mantissa part of floating point real number data of one coordinate in the vertex data, and a step of extracting a sign from a part of mantissa part of floating point real number data of another coordinate in the vertex data And an authentication step for authenticating the extracted code with a value obtained by a one-way function from at least the extracted code and the remainder of the mantissa part of the floating-point real number data of another coordinate, and vertex data of a certain vertex If the value of a part of the mantissa part of the floating point real number data at the remaining coordinates is the predetermined first identification value, It was identified as the insertion vertex, if some of the values of the mantissa is a predetermined second identification value, and a step of specifying the vertex and isolated vertices. The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. The second identification value is different from the first identification value. In the authentication step, the additional information and code are extracted from the vertex data of the insertion vertex and the isolated vertex, and at least the extracted code and the remaining part of the mantissa part of the floating-point real number data of the other coordinate are extracted by a one-way function. The obtained code is authenticated with the obtained value.

  As a result, since a code obtained by a one-way function from at least the remaining part of the mantissa part and the additional information is embedded, it is easy to detect data tampering when the additional information is extracted.

  According to the present invention, data tampering is easily detected in embedding additional information such as a digital watermark into three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic.

FIG. 1 is a block diagram showing the configuration of the information processing apparatus according to the embodiment of the present invention. FIG. 2 is a block diagram illustrating a processing unit realized by executing a program by the CPU in FIG. FIG. 3 is a diagram showing an example of the structure of each vertex data in the embodiment of the present invention. FIG. 4 is a flowchart for explaining embedding of additional information in the embodiment of the present invention. FIG. 5 is a diagram for explaining the classification of the insertion vertex and the adjustment vertex according to the embodiment of the present invention. FIG. 6 is a flowchart for describing extraction of additional information according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the information processing apparatus according to the embodiment of the present invention. An information processing apparatus 1 shown in FIG. 1 has a built-in computer, and executes various programs to perform calculations and processes. For example, a personal computer is used as the information processing apparatus 1.

  In the terminal device 1, a CPU (Central Processing Unit) 11 is an arithmetic processing device that executes processing described in a program. A ROM (Read Only Memory) 12 is a nonvolatile memory that stores programs and data in advance. A RAM (Random Access Memory) 13 is a memory that temporarily stores the program and data when the program is executed.

  The CPU 11, the ROM 12 and the RAM 13 are connected to each other via a bus and a controller chip, and are further connected to the storage device 14, the display device 15, and the input device 16 via a bus, a control chip, an interface, and the like.

  The storage device 14 is a device having a recording medium for storing an operating system (not shown), various programs, and various data. As the storage device 14, a nonvolatile semiconductor memory, a hard disk drive device, a disk array device, or the like is used. The display device 15 is a device that displays an operation screen or the like. For example, a liquid crystal display is used as the display device 15. The input device 16 is a device for inputting an operation on the operation screen. For example, a keyboard or a mouse is used as the input device 16.

  In this embodiment, the storage device 14 stores an embedding program 21, an extraction program 22, and graphic data 23. Note that the programs 21 and 22 may be recorded on a portable recording medium such as a CD-ROM or a DVD-ROM, and installed in the information processing apparatus 1 from the recording medium.

  The embedding program 21 is a computer program for embedding additional information such as a digital watermark in the graphic data 23.

  The extracting program 22 is a computer program for extracting additional information from graphic data in which additional information such as a digital watermark is embedded.

  The graphic data 23 is 3D graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the 3D graphic. The graphic data 23 is, for example, data in STL format.

  The CPU 11 loads a program stored in the ROM 12 or the storage device 14 to the RAM 13 and executes it. Thus, a processing unit that executes processing described in the program is realized.

  FIG. 2 is a block diagram showing a processing unit realized by executing the programs 21 and 22 by the CPU 11 in FIG.

  In this embodiment, the embedding program 21 is executed to embed additional information in the graphic data 23, whereby the vertex classification unit 31 and the information embedding unit 32 are realized, and additional information is added from the embedded graphic data. By executing the extraction program 22 to extract information, the vertex type identification unit 41 and the information extraction unit 42 are realized.

  FIG. 3 is a diagram showing an example of the structure of each vertex data in the embodiment of the present invention.

  FIG. 3A is a diagram showing the data structure of floating point real number data defined by IEEE754. S (1 bit) is a sign bit, EXP (8 bits) is an exponent part, and FRAC (23 bits) is a mantissa part.

When the vertex data is floating point real number data, for the vertex data (x ₁ , x ₂ , x ₃ ) in which the additional information is embedded, the mantissa part FRAC of the floating point real number data at each coordinate x ₁ , x ₂ , x ₃ Nx _i (i = 1, 2, 3) is changed. As shown in FIG. 3B, here, nx _i is, for example, a lower-order bit length (here, 5 bits) portion.

  The vertex classification unit 31 classifies some or all of the plurality of vertices into insertion vertices, adjustment vertices, and isolated vertices based on the link between the vertices in the graphic data 23. The insertion vertex is a vertex that is paired with the adjustment vertex and embeds additional information in the vertex data. The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value can be changed in order to compensate for a variation in a predetermined parameter value caused by embedding additional information in the insertion vertex. Isolated vertices are vertices in which all adjacent vertices are adjustment vertices and additional information is embedded in the vertex data. A vertex and a vertex adjacent to the vertex are directly connected by a single link.

In this embodiment, the above-mentioned parameters are the centroids nx ^c ₂ and nx ^c ₃ for the x ₂ coordinate and the x ₃ coordinate, respectively, and are expressed by the equation (1).

Here, N (v) is a set of vertices adjacent to the target vertex (inserted vertex or isolated vertex) (that is, a vertex having a link with the target vertex), and nx _j is x of each adjacent vertex. _{This is} the value of a predetermined portion of the data of _j- coordinate (in the case of FIG. 3 (B), continuous lower 5 bits), and | N (v) | is the number of vertices adjacent to the target vertex. Max _i is a numerical value obtained by adding 1 to the maximum value max _i of nx _i . For example, when the bit length of nx _i is 5, Max _i is 32. key _{j (j} = 2,3) is a predetermined diffusion coefficient of _{x 2} coordinate for adjusting the range of the modulo operation mod (j = 2) and _{x 3} coordinate (j = 3). Note that key _j is concealed and is not disclosed.

Information embedding unit 32 reads the graphic data 23 from RAM13 or storage device 14, for at least one vertex data of a plurality of vertex data, floating point numbers one coordinates in the vertex data (here x ₂ coordinate) embedding the additional information in a part of the mantissa data, the part of the mantissa of the floating-point number data of another coordinate (where x ₃ coordinates) in the vertex data, adds at least the remainder of the mantissa information A code obtained by a one-way function is embedded from In this embodiment, the one-way function is a hash function.

Specifically, the information embedding unit 32, a part nx ₁ mantissa floating-point number data of the remaining coordinates in the vertex data of the insertion vertex (where x ₁ coordinates) indicates that an insertion vertex embedding a predetermined first identification value, a part of the mantissa of the floating-point number data of the remaining coordinates in the vertex data of the isolated vertices (where x ₁ coordinates), the predetermined indicating that the vertex is isolated vertices The second identification value is embedded. This second identification value is different from the first identification value.

For example, the information embedding unit 32 substitutes nx ′ ₁ for the original nx ₁ according to the equation (2) for the x ₁ coordinates of the insertion vertex and the isolated vertex. That is, the nx ₁ part of the mantissa part is changed.

Here, key is the first identification value, and the second identification value is key / 2. Note that key is data having the same bit length as nx _1, and key / 2 is an integer. The key is concealed and is not disclosed.

If nx ₁ of a vertex that is neither an insertion vertex nor an isolated vertex is identical to either key or key / 2, nx ′ ₁ is set to key / 3. Note that key / 3 is also an integer. For vertices that are neither insertion vertices nor isolated vertices, nx ′ ₁ = nx ₁ if nx ₁ is neither key nor key / 2.

Further, for example, the information embedding unit 32 performs nx on the x ₂ coordinate and the x ₃ coordinate of the insertion vertex and the isolated vertex by bit operation (exclusive OR for each bit in Equation (3)) according to Equation (3). 'calculates the _j, nx to nx _2' by substituting _2, substituting nx _'3 to nx _3.

Here, w _i is additional information such as the i-th digital watermark, h is a hash function, and Nvh is the value of the remaining part other than nx _j in the mantissa part.

In this embodiment, the information embedding unit 32, w _i and Nvh as arguments, calculates the value of the hash function h, exclusive of nx _'3 between the value and the nx ^c ₃ of the hash function h Calculate as

Further, the information embedding unit 32, from the part of the mantissa of the floating-point number data for one coordinate of the vertex data of the vertex adjacent to the insertion vertex (here x ₂ coordinate) and another coordinate (x ₃ coordinate in this case) , calculated in integer arithmetic a predetermined parameter value for each coordinate, the mantissa of the floating-point number data for one coordinate of the vertex data of the adjustment vertices (here x ₂ coordinate) and another coordinate (x ₃ coordinate in this case) one Is changed to compensate for variations in the predetermined parameter value.

In this embodiment, since the vertex data of the insertion vertex is changed according to the equation (3), the same predetermined portion as that of nx _j in the data of the x ₂ coordinate and the x ₃ coordinate of the adjustment vertex (FIG. 3B) In this case, the value of the lower 5 bits) nx ′ _ad is changed according to the equation (4).

Here, N (mv) is a set obtained by removing the adjustment vertex from the vertex adjacent to the insertion vertex. k is a coefficient having a value of 0 or 1, and when the value obtained by subtracting the second term from the first term on the right side of the equation (4) is negative, k = 1 is set, and the equation (4 When the value obtained by subtracting the second term from the first term on the right side of) is positive, k = 0. That is, when nx ′ _ad is 5 bits, the value of nx ′ _ad is any value from 0 to 31 (that is, max _i ) and is not negative, and thus is calculated in this way.

Further, the vertex type specifying unit 41, the vertex data of a vertex, the mantissa part of the floating point number data of the remaining coordinates other than the two coordinates as the extraction source of the additional information and the code will be described later (wherein x ₁ coordinates) If some of the values are the above-mentioned first identification values, the vertex is identified as the insertion vertex, and if some values of the mantissa are the above-mentioned second identification value, the vertex is identified as the isolated vertex To do.

The information extraction unit 42 reads the three-dimensional graphic data (not shown) in which the additional information is embedded by the method shown in this embodiment from the RAM 13 or the storage device 14 and reads at least one vertex from the plurality of vertex data for data, it retrieves the additional information from the part of the mantissa of the floating-point number data for one coordinate (here x ₂ coordinate) in the vertex data, floating point numbers of different coordinates in the vertex data (where x ₃ coordinates) A code is extracted from a part of the mantissa part of the data, and the extracted code is authenticated with a value obtained by a one-way function from at least the extracted code and the remaining part of the mantissa part. This one-way function is the same function as the above-described one-way function used when embedding additional information.

  Specifically, the information extraction unit 42 extracts additional information and code from the vertex data of the insertion vertex and the isolated vertex, and is a value obtained by a one-way function from at least the extracted code and the remaining part of the mantissa part. Then, authentication of the extracted code is performed.

Information extraction unit 42, the insertion vertex and the vertex data of the isolated vertices, according to equation (1), as well as calculating the centroid ^nx _c 2, ^nx _{c 3} of _{x 2} coordinate and _{x 3} coordinate, _{x 2} coordinate and _{x 3} coordinate the predetermined portion of the mantissa data nx extracts _'2, nx' _3, according to equation (5), retrieves the additional information w _'i and code (hash value at the time of embedding) h' _i. Note that w ′ _i indicates the i-th additional information, and h ′ _i indicates the i-th code. That is, if the total number of insertion vertices and isolated vertices is n, n pairs of additional information and codes are extracted.

  Next, the operation of the information processing apparatus will be described. Here, an operation for embedding additional information and an operation for extracting additional information will be described.

(1) Embedding additional information

  FIG. 4 is a flowchart for explaining embedding of additional information in the embodiment of the present invention.

  First, the vertex classification unit 31 reads the graphic data 23, selects the vertices in the graphic data 23 one by one as the target vertex, and performs classification processing.

  First, the vertex classification unit 31 sets all the vertices in the graphic data 23 as adjustment vertex candidates (step S1). For example, in association with the vertex data of each vertex, vertex type data indicating the type of the vertex is provided on the RAM 13, and the initial value of the data is a value indicating the adjustment vertex candidate.

  Next, the vertex classification unit 31 determines whether there is a vertex that has not yet been processed as a target vertex (step S2).

  If there is one or more vertices that have not yet been processed as attention vertices (that is, not determined as insertion vertices, adjustment vertices, and isolated vertices and not selected as attention vertices), the vertex classification unit 31 One vertex is selected as a target vertex from one or a plurality of vertices (step S3), a vertex adjacent to the target vertex is specified based on the graphic data 23, and the vertex type data of the adjacent vertex is referred to. It is determined whether all vertices adjacent to the target vertex are adjustment vertices (step S4).

  When all the vertices adjacent to the target vertex are adjustment vertices, the vertex classification unit 31 classifies the target vertex as an isolated vertex, and sets the value of the vertex type data of the target vertex as a value indicating that it is an isolated vertex (Step S5).

  On the other hand, if at least one of the vertices adjacent to the target vertex is not the adjustment vertex, the vertex classification unit 31 determines whether at least one of the vertices adjacent to the target vertex is the adjustment vertex candidate (step S6). ).

  If none of the vertices adjacent to the target vertex is an adjustment vertex candidate, the processing of the target vertex is terminated, and the process returns to step S2.

  On the other hand, if at least one of the vertices adjacent to the target vertex is an adjustment vertex candidate, the vertex classification unit 31 selects the target vertex as the insertion vertex, and selects one of the adjustment vertex candidates adjacent to the target vertex, The selected vertex is set as an adjustment vertex paired with the insertion vertex (step S7). At this time, the vertex classification unit 31 sets the value of the vertex type data of the target vertex as a value indicating the insertion vertex, and indicates the value of the vertex type data of the selected adjacent vertex as the adjustment vertex. Value. Information indicating that these two vertices are a pair is also included in the vertex type data.

  And the vertex classification | category part 31 remove | excludes vertices other than an adjustment vertex among the vertices adjacent to the attention vertex from an adjustment vertex candidate (step S8). At this time, the vertex classification unit 31 changes the value of the vertex type data of vertices other than the adjustment vertex among the vertices adjacent to the attention vertex from the value of the adjustment vertex candidate to another predetermined value.

  After the pair of the insertion vertex and the adjustment vertex is selected in steps S7 and S8, the processing for the target vertex is terminated, and the process returns to step S2.

  In this way, some or all of the vertices of the graphic data 23 are classified into one of an insertion vertex, an adjustment vertex, and an isolated vertex.

  Here, a specific example will be described. FIG. 5 is a diagram for explaining the classification of the insertion vertex and the adjustment vertex according to the embodiment of the present invention. FIG. 5A shows an example of vertices and links based on the graphic data 23. In this figure, vertex # 1 to vertex # 7 exist.

  First, these vertices # 1 to # 7 are set as adjustment vertex candidates (step S1). Next, vertex # 1 is selected (step S3). For vertex # 1, since at least one of the adjacent vertices is not an adjustment vertex (step S4) and at least one of the adjacent vertices is an adjustment vertex candidate (step S6), as shown in FIG. The vertex # 1 is an insertion vertex, and the vertex # 4 among the vertices adjacent to the vertex # 1 is an adjustment vertex (step S7). In FIG. 5, the black circle vertices represent insertion vertices, and the white circle vertices represent adjustment vertices. Then, the other adjacent vertices, vertex # 2, vertex # 3, and vertex # 5, are excluded from the adjustment vertex candidates (step S8).

  Next, the vertex # 2 whose vertex type is uncertain is selected (step S3). For vertex # 2, since at least one of the adjacent vertices is not an adjustment vertex (step S4) and at least one of the adjacent vertices is an adjustment vertex candidate (step S6), as shown in FIG. Vertex # 2 is the insertion vertex, and vertex # 6 of the vertices adjacent to it is the adjustment vertex (step S7). Then, the vertex # 7 of other adjacent adjustment vertex candidates is removed from the adjustment vertex candidates (step S8).

  Next, the vertex # 3 whose vertex type is undefined is selected (step S3). Regarding vertex # 3, since at least one of the adjacent vertices is not an adjustment vertex (step S4) and none of the adjacent vertices is an adjustment vertex candidate (step S6), the processing for vertex # 3 ends.

  Next, the vertex # 5 whose vertex type is uncertain is selected (step S3). For vertex # 5, at least one of the adjacent vertices is not an adjustment vertex (step S4), and at least one of the adjacent vertices is an adjustment vertex candidate (step S6), as shown in FIG. Vertex # 5 is the insertion vertex, and vertex # 7 of the vertices adjacent to it is the adjustment vertex (step S7).

  Then, since there are no unprocessed vertices whose vertex type is undetermined, the vertex type classification process ends here.

After the vertex types are classified as described above, the information embedding unit 32 first determines the insertion vertex, the adjustment vertex, the isolated vertex, and others according to the vertex type according to the equation (2). The X (x ₁ ) coordinate is changed (step S9). That is, the information embedding unit 32 specifies the vertex type based on the value of the vertex type data, specifies the changed X (x ₁ ) coordinate value according to the equation (2), and sets the vertex data of the vertex The value of the X (x ₁ ) coordinate is changed with the specified value.

Next, the information embedding unit 32 changes the values of the Y (x ₂ ) coordinate and the Z (x ₃ ) coordinate for each insertion vertex according to the equation (3) (step S10). Further, the information embedding unit 32 changes the values of the Y (x ₂ ) coordinate and the Z (x ₃ ) coordinate for the adjustment vertex that makes a pair with the insertion vertex according to the equation (4) (step S11).

Further, the information embedding unit 32 changes the values of the Y (x ₂ ) coordinate and the Z (x ₃ ) coordinate for each isolated vertex according to the equation (3) (step S12).

  In this way, graphic data in which additional information is embedded is generated from the graphic data 23. Note that the vertex type data is used only when embedding additional information in the graphic data, and is not added to the graphic data in which the additional information is embedded. The graphic data generated in this way is stored in the storage device 14, for example.

(2) Extraction of additional information

  The additional information can be extracted from the graphic data in which the additional information is embedded as described above.

  FIG. 6 is a flowchart for describing extraction of additional information according to the embodiment of the present invention.

  The vertex type identification unit 41 determines whether there is a vertex that has not yet been processed as a target vertex (step S21).

If there is one or more vertices that have not yet been processed as the target vertex, the vertex type specifying unit 41 selects one vertex from the one or more vertices as the target vertex (step S22), and the vertex of the target vertex The type is specified based on the value of the X (x ₁ ) coordinate in the vertex data of the target vertex (step S23). A vertex type is specified based on the classification shown in Expression (2).

When the vertex type of the target vertex is the insertion vertex (step S24), the information extraction unit 42 calculates the formula from the values of the Y (x ₂ ) coordinate and the Z (x ₃ ) coordinate in the vertex data of the target vertex. In accordance with (5), the additional information w ′ and the code h ′ are extracted (step S25).

Next, the information extraction unit 42 calculates the value of the hash function h in Expression (3) using the additional information w ′ and the remaining bit area Nvh ′ other than nx ₃ of the mantissa part of the x ₃ coordinate as arguments. When the value and the sign h ′ are compared, if the two match, the additional information w ′ is recognized as correct (not tampered), and if the two do not match, the additional information w ′ is incorrect (tampered). (Step S26).

On the other hand, when the vertex type of the target vertex is not an insertion vertex but an isolated vertex (step S27), the information extraction unit 42 uses the Y (x ₂ ) and Z (x ₃ ) coordinates of the vertex data of the target vertex. The additional information w ′ and the sign h ′ are extracted from the value according to the equation (5) (step S28).

Next, the information extraction unit 42 calculates the value of the hash function h in Expression (3) using the additional information w ′ and the remaining bit area Nvh ′ other than nx ₃ of the mantissa part of the x ₃ coordinate as arguments. When the value and the sign h ′ are compared, if the two match, the additional information w ′ is recognized as correct (not tampered), and if the two do not match, the additional information w ′ is incorrect (tampered). (Step S29).

  In this way, the additional information is extracted from the graphic data in which the additional information is embedded, and the additional information is authenticated.

  As described above, according to the above-described embodiment, when embedding additional information, the mantissa of floating-point real number data of one coordinate in the vertex data of at least one vertex data among the plurality of vertex data in the graphic data 23 Additional information is embedded in a part of the part, and a sign obtained by a one-way function from at least the remaining part of the mantissa part and the additional information is added to a part of the mantissa part of floating-point real data at another coordinate in the vertex data. Embed.

  Further, according to the above embodiment, in extracting the additional information, for at least one vertex data of the plurality of vertex data in the graphic data, one mantissa part of the floating point real data of one coordinate in the vertex data is obtained. Value is obtained by a one-way function from at least the extracted code and the remaining part of the mantissa part. Then, the extracted code is authenticated.

  As a result, a code obtained by a one-way function is embedded from at least the remaining mantissa part and the additional information, so that alteration of the data is easily detected when the additional information is extracted.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, in the above embodiment, another argument may be added to the hash function.

  In the above embodiment, the information processing apparatus shown in FIG. 1 can execute both of embedding additional information and extracting additional information, but can execute only one of embedding additional information and extracting additional information. It is good also as an apparatus.

  In the above embodiment, when the graphic data is polygon data, a side of a polygon extending from a certain vertex may be used as a link.

  In the above embodiment, another one-way function may be used instead of the hash function.

  In the above embodiment, the length of the bit part in the mantissa part changed at the time of embedding is not limited to 5 bits.

  The present invention is applicable to, for example, embedding and extracting a digital watermark.

13 RAM (an example of storage means)
14 Storage device (an example of storage means)
21 Embedded program (an example of a computer program)
22 Extraction program (an example of a computer program)
23 Graphic data (an example of three-dimensional graphic data)
31 vertex classification part (an example of vertex classification means)
32 Information embedding unit (an example of information embedding means)
41 Vertex type specifying part (an example of vertex type specifying means)
42 Information extractor (an example of information extractor)

Claims (9)

Storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic;
The three-dimensional graphic data is read from the storage means, and at least one vertex data of the plurality of vertex data is embedded with additional information in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, A sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and the additional information in a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data. Information embedding means for embedding;
Vertex classification means for classifying part or all of the plurality of vertices into insertion vertices, adjustment vertices, and isolated vertices ;
The insertion vertex is a vertex that is paired with the adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The isolated vertices are all vertices that are adjacent to each other and are vertices that embed the additional information in the vertex data,
The information embedding means embeds a predetermined first identification value indicating the insertion vertex in a part of a mantissa part of floating point real number data of the remaining coordinates in the vertex data of the insertion vertex, A predetermined second identification value indicating that the vertex is the isolated vertex is embedded in a part of the mantissa part of the floating-point real number data of the remaining coordinates in the vertex data of the vertex,
The second identification value is different from the first identification value;
An information processing apparatus characterized by the above. Storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic;
The three-dimensional graphic data is read from the storage means, and at least one vertex data of the plurality of vertex data is embedded with additional information in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, A sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and the additional information in a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data. Information embedding means for embedding;
Some or all of the plurality of vertices, a vertex classification means for classifying the inserted vertex and adjusting the vertex,
The insertion vertex is a vertex that is paired with the adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The information embedding means calculates the predetermined parameter value for each coordinate from a part of the mantissa part of the floating point real data of one coordinate and another coordinate in the vertex data of the vertex adjacent to the insertion vertex by integer arithmetic, Changing a part of the mantissa part of the floating point real data of one coordinate and another coordinate in the vertex data of the adjustment vertex in order to compensate for the variation of the predetermined parameter value;
Information processing apparatus said. A computer in an information processing apparatus having storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic,
The three-dimensional graphic data is read from the storage means, and at least one vertex data of the plurality of vertex data is embedded with additional information in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, A sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and the additional information in a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data. Embedding information embedding means, and
Vertex classification means for classifying part or all of the plurality of vertices into insertion vertices, adjustment vertices, and isolated vertices
Function as
The insertion vertex is a vertex that is paired with the adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The isolated vertices are all vertices that are adjacent to each other and are vertices that embed the additional information in the vertex data,
The information embedding means embeds a predetermined first identification value indicating the insertion vertex in a part of a mantissa part of floating point real number data of the remaining coordinates in the vertex data of the insertion vertex, A predetermined second identification value indicating that the vertex is the isolated vertex is embedded in a part of the mantissa part of the floating-point real number data of the remaining coordinates in the vertex data of the vertex,
The second identification value is different from the first identification value;
A computer program characterized by the above. A computer in an information processing apparatus having storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic,
The three-dimensional graphic data is read from the storage means, and at least one vertex data of the plurality of vertex data is embedded with additional information in a part of the mantissa part of the floating point real number data of one coordinate in the vertex data, A sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and the additional information in a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data. Embedding information embedding means , and
A part or all of the plurality of vertices function as vertex classification means for classifying into insertion vertices and adjustment vertices ;
The insertion vertex is a vertex that is paired with the adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The information embedding means calculates the predetermined parameter value for each coordinate from a part of the mantissa part of the floating point real data of one coordinate and another coordinate in the vertex data of the vertex adjacent to the insertion vertex by integer arithmetic, Changing a part of the mantissa part of the floating point real data of one coordinate and another coordinate in the vertex data of the adjustment vertex in order to compensate for the variation of the predetermined parameter value;
A computer program characterized by the above . Reading three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic from the storage means;
Embedding additional information in a part of the mantissa part of floating-point real number data of one coordinate in the vertex data for at least one vertex data of the plurality of vertex data;
A sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and the additional information in a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data. An embedding step;
Classifying some or all of the plurality of vertices into insertion vertices, adjustment vertices, and isolated vertices;
With
The insertion vertex is a vertex that is paired with the adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The isolated vertices are all vertices that are adjacent to each other and are vertices that embed the additional information in the vertex data,
A predetermined first identification value indicating the insertion vertex is embedded in a part of the mantissa part of the floating point real data of the remaining coordinates in the vertex data of the insertion vertex, and the remaining in the vertex data of the isolated vertex A predetermined second identification value indicating that the vertex is the isolated vertex is embedded in a part of the mantissa part of the floating-point real number data at the coordinates of
The second identification value is different from the first identification value;
An information processing method characterized by the above. Reading three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic from the storage means;
Embedding additional information in a part of the mantissa part of floating-point real number data of one coordinate in the vertex data for at least one vertex data of the plurality of vertex data;
A sign obtained by a one-way function from at least the remaining part of the mantissa part of the floating-point real number data of another coordinate and the additional information in a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data. An embedding step;
Classifying some or all of the plurality of vertices into insertion vertices and adjustment vertices;
With
The insertion vertex is a vertex that is paired with the adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The predetermined parameter value is calculated for each coordinate from a part of the mantissa of the floating point real data of one coordinate and another coordinate in the vertex data of the vertex adjacent to the insertion vertex by an integer operation, and in the vertex data of the adjustment vertex Changing a part of the mantissa part of floating-point real data in one coordinate and another coordinate to compensate for a variation in the predetermined parameter value;
An information processing method characterized by the above. Storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic;
Reading the three-dimensional graphic data from the storage means, for at least one vertex data of the plurality of vertex data, to extract additional information from a part of the mantissa part of the floating point real data of one coordinate in the vertex data, The sign is extracted from a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data, and at least by the one-way function from the extracted sign and the remaining part of the mantissa part of the floating-point real number data of the other coordinate Information extraction means for authenticating the extracted code with the obtained value;
When the value of a part of the mantissa part of the floating point real number data of the remaining coordinates in the vertex data of a certain vertex is a predetermined first identification value, the vertex is specified as an insertion vertex, and a part of the part of the mantissa part is specified. If the value is a predetermined second identification value, and a vertex type specifying means for specifying that vertex and isolated vertices,
The insertion vertex is a vertex that is paired with an adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The isolated vertices are all vertices that are adjacent to each other and are vertices that embed the additional information in the vertex data,
The second identification value is different from the first identification value,
The information extracting means extracts the additional information and the code for the vertex data of the insertion vertex and the isolated vertex, and at least the extracted code and the remaining part of the mantissa part of the floating-point real data of the different coordinates Authenticating the extracted code with a value obtained from a one-way function from
Information processing apparatus said. A computer in an information processing apparatus having storage means for storing three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting a three-dimensional graphic,
Reading the three-dimensional graphic data from the storage means, for at least one vertex data of the plurality of vertex data, to extract additional information from a part of the mantissa part of the floating point real data of one coordinate in the vertex data, The sign is extracted from a part of the mantissa part of the floating-point real number data of another coordinate in the vertex data, and at least by the one-way function from the extracted sign and the remaining part of the mantissa part of the floating-point real number data of the other coordinate Information extraction means for authenticating the extracted code with the obtained value ; and
When the value of a part of the mantissa part of the floating point real number data of the remaining coordinates in the vertex data of a certain vertex is a predetermined first identification value, the vertex is specified as an insertion vertex, and a part of the part of the mantissa part is specified. When the value is a predetermined second identification value, the vertex is identified as an isolated vertex and functions as a vertex type identifying unit ,
The insertion vertex is a vertex that is paired with an adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The isolated vertices are all vertices that are adjacent to each other and are vertices that embed the additional information in the vertex data,
The second identification value is different from the first identification value,
The information extracting means extracts the additional information and the code for the vertex data of the insertion vertex and the isolated vertex, and at least the extracted code and the remaining part of the mantissa part of the floating-point real data of the different coordinates Authenticating the extracted code with a value obtained from a one-way function from
A computer program characterized by the above . Reading three-dimensional graphic data having a plurality of vertex data corresponding to a plurality of vertices constituting the three-dimensional graphic from the storage means;
For at least one vertex data of the plurality of vertex data, extracting additional information from a part of a mantissa part of floating-point real number data of one coordinate in the vertex data;
Extracting a sign from a part of the mantissa of floating-point real data at another coordinate in the vertex data;
An authentication step for authenticating the extracted code with a value obtained by a one-way function from at least the extracted code and the remaining part of the mantissa part of the floating-point real number data of another coordinate ;
When the value of a part of the mantissa part of the floating point real number data of the remaining coordinates in the vertex data of a certain vertex is a predetermined first identification value, the vertex is specified as an insertion vertex, and a part of the part of the mantissa part is specified. If the value is a predetermined second identification value, identifying the vertex as an isolated vertex;
Equipped with a,
The insertion vertex is a vertex that is paired with an adjustment vertex and embeds the additional information in the vertex data;
The adjustment vertex is a vertex that is paired with the insertion vertex and whose coordinate value is changed in order to compensate for a variation in a predetermined parameter value caused by embedding the additional information in the insertion vertex.
The isolated vertices are all vertices that are adjacent to each other and are vertices that embed the additional information in the vertex data,
The second identification value is different from the first identification value,
In the authentication step, with respect to the vertex data of the insertion vertex and the isolated vertex, the additional information and the code are extracted, and at least from the extracted code and the remaining part of the mantissa part of the floating point real number data of the different coordinates Authenticating the extracted code with a value obtained by a one-way function;
An information processing method characterized by the above.

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