JP2002108851A - Sentence processor, method therefor and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embed transparent information into text data without permitting a user to be conscious of an unnatural feeling in a text by converting the code of text data based on transparent information of the corresponding code. SOLUTION: At first, text data and transparent information are inputted (step S1001), and the inputted text data is normalized so that 'the data is expressed by one character without using connection characters in the voiced consonant syllable character and the p-sound character of HIRAGANA and KATAKANA (the Japanese cursive and square syllabaries)' (step S1002). Then the same character is expressed as another kind of encoding data with respect to normalized text data and transparent information is buried (step S1003).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a text processing apparatus and method for embedding watermark information in text data, or extracting watermark information from text data in which watermark information is embedded, and a storage medium. .

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet and the improvement of communication technology, all information has been digitized and can be distributed on the Internet. Digitizing data has improved reusability and convenience, while digital content such as image data and audio data has become easier to process and copy, which raises a serious problem in terms of copyright protection. are doing.

[0003] In view of the above background, a digital watermarking technique for image data and audio data has been proposed for the purpose of copyright protection. The digital watermarking technology is a technology for embedding watermark information in digital data to the extent that human beings cannot perceive it, in which the name of the copyright holder, the ID of the purchaser, and the like are embedded. Unauthorized use due to processing or duplication can be tracked by the above watermark information.

[0004] In general, the digital watermarking technique is applied to a data format having many redundant parts, such as image data and audio data. On the other hand, as a digital watermark for a document, a defense large system (Yasuhiro Nakamura, Koshio Matsui, embedding a signature in a hard copy of an electronic document for copyright protection, Transactions of Information Processing Society of Japan Vol. 36 No. 8, 1995)
And Japanese Unexamined Patent Publication No. Hei 9-186603, "Encoding and decoding methods using the length of a space between words in an electronic document, a method for embedding signature information in an electronic document, and a method for encrypting a confidential document") Has been proposed, but a digital watermarking technique is only applied as image data, not as text data. Specifically, watermark information is embedded by manipulating the interval between words.

[0005] As similar systems, Japanese IBM systems (Tomio Amano, Yuki Hirayama, embedding a digital watermark in a page description using a layout structure, IPSJ research report, multimedia communication and distributed processing 90-9, computer security 2-9, 1998, JP-A-2000-995
No. 01 (P2000-99501A), “Method and System for Embedding Information in Document Data”), in which watermark information is embedded by manipulating the spacing between characters.

As a digital watermark for text data itself, a method of forcibly inserting a line feed character and a method of forming a plurality of blank characters between words have been known for a long time. Tsutomu Matsumoto, Hiroshi Nakagawa, Ichiro Murase, Research and Development of Secure Communication Using Steganography (The 18th IPA Technology Presentation Papers p
p. 51-60), a method for replacing words in a document by a dictionary conversion method has been proposed. This method uses a dictionary in which synonyms are defined, and embeds watermark information by replacing a word in a sentence with another word.

[0007]

The above prior art has the following problems. The digital watermarking technique that changes the positional relationship of a document, such as manipulating the spacing between words or characters, that is, changing layout information, can only be applied to a data format having layout information.

That is, when text data, which is a document itself obtained by removing layout information from a document, is extracted, the watermark data cannot be restored. There is also a problem that unnaturalness remains at first glance for operating the layout information. Also. In the digital watermarking method using the dictionary conversion method, the context is disturbed by the word conversion, and similarly, there is a problem that unnaturalness remains.

The present invention has been made in view of the above-mentioned problems, and converts a text data code into a corresponding code based on watermark information without causing the user to feel unnaturalness of the text. The purpose is to embed watermark information in text data.

[0010]

In order to achieve the object of the present invention, for example, a text processing apparatus of the present invention has the following arrangement. That is, a text processing device that embeds watermark information in text data,
The apparatus includes a normalizing unit that normalizes using a predetermined normalization method, and a converting unit that converts the text data normalized by the normalizing unit into other text data based on the watermark information.

Further, a normalized data generating means for generating normalized data obtained by normalizing the text data in which the watermark information is embedded, and a calculating means for calculating a value based on the normalized data Means for generating embedded data from a value based on the normalized data using the information on the text data, and embedding the data generated by the embedded data generating means by the embedding means. Embed.

In order to achieve the object of the present invention, for example, a text processing apparatus of the present invention has the following configuration. That is,
What is claimed is: 1. A text processing apparatus for extracting watermark information from text data in which watermark information is embedded, wherein normalized data is generated by performing normalization on the text data by a predetermined normalization method. Generating means for comparing the normalized data with the text data to generate difference information, and generating watermark information by generating a bit string based on the difference information.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail according to preferred embodiments with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a block diagram for explaining a method of embedding watermark information in a sentence (text data) in this embodiment.

First, a document (text data) into which watermark information (watermark data) is to be embedded is input (10).
0). Text data is a collection of character data. Usually, when a computer handles characters, the characters are often represented in correspondence with certain numerical values. A character code (charac
ter code). Converting a character to a number is called encoding. That is, the text data is a group of encoded data expressed using a certain character code.

Next, the input text data is normalized in accordance with the normalization method (102) (10).
1).

Next, a watermark information embedding process for embedding the watermark information 104 is performed by utilizing the representation of the same character as different encoded data (103).

As a specific example of the text input 100, U
Combining Characters in nicode
The method using is described below.

Unicode is a character set standardized by the Unicode Consortium, and UTF-8 and UTF-16 are available as character encoding systems. Un
icode has a group of characters called combining characters,
"゛" represented by the numerical value U + 3099 in Japanese
The clouded point and U + 309A (“゜” semi-clouded point) are combined characters.

On the other hand, in Unicode, U + 304C
Because "ga" also exists, U + 304C "ga"
{U + 304B, U + 3099} "Ka" has the same value. As described above, even if the same meaning is expressed as a character, it may be different as encoded data.

Here, the step normalization processing 101 requires a normalization method 102. As the normalization method, "a hiragana and katakana voiced character and a semi-voiced character are represented by one character without using a combined character." If you adopt the method, you can embed watermark information as follows. One bit of watermark information is associated with every voiced character and half voiced character in the text data. When the bit 0 is embedded, the watermark information embedding process 103 is performed such that the one-character expression (that is, the combined character is not used) is used, and when the bit 1 is embedded, the combined character is used. For example, with respect to “ga” after the normalization, the watermark information is converted into “ga” when embedding bit 0 and “ka「 ”(“ ka ”+“ ゛ ”) when embedding bit 1 to convert the watermark information. Embed.

FIG. 10 shows a flowchart of the watermark information embedding process. Since the description of this flowchart is the same as the above description, it will be briefly described here.

First, text data and watermark information are input (step S1001), and the above-described normalization is performed on the input text data (step S1002). Then, the same character is expressed as different encoded data in the normalized text data, and watermark information is embedded (step S1003).

FIG. 5 is a diagram showing a schematic configuration of a device (watermark information embedding device) for performing the above-described process of embedding watermark information. Inputs to the device are a text document 501 and watermark information 502. The watermark information embedding device includes a normalization processing device 50 that performs a normalization process 101.
3, a normalization method storage device 504 for storing the normalization method 102, and an embedding processing device 505 for performing the watermark information embedding process 103.
06 is output. Further, each of the above devices can also be realized by a device having a configuration as shown in FIG. 7 described below.

The program code according to the flowchart shown in FIG. 10 is stored in a memory such as a ROM or a RAM (not shown), and is read and executed by a CPU (not shown).

In FIG. 7, the host computer 701
Is, for example, a personal computer that is widely used. Various instructions and the like from a user are performed by input from a mouse 712 and a keyboard 713, and text data is transmitted to the printer 71.
5 can be printed.

In the host computer 701, each block described later is connected by a bus 716.
Various data can be exchanged.

Reference numeral 702 denotes a monitor used to display instructions to a user including system messages and text data.

703 controls the operation of each internal block;
Alternatively, it is a CPU that executes various programs stored in the ROM 704 or the RAM 705.

Reference numeral 704 denotes a ROM for storing a specific image which is not permitted to be printed, or for storing a necessary image processing program and the like (including a program according to the flowchart shown in FIG. 10) in advance. . It also stores character codes and the like.

Reference numeral 705 denotes a RAM for temporarily storing a program and text data to be processed for the CPU 703 to perform processing.

Reference numeral 706 denotes a hard disk (HD) capable of storing programs and text data to be transferred to the RAM 705 and the like in advance and storing processed text data.

Reference numeral 708 denotes a CD which is one of the external storage media.
This is a CD drive that can read or write data stored in (CD-R).

Reference numeral 709 denotes F as in the case of the CD drive 708.
It is an FD drive that can read from D and write to FD. 710, like the CD drive 708,
DV that can read from VD and write to DVD
D drive. If an editing program or a printer driver is stored in a CD, FD, DVD, or the like, these programs are installed on the HD 706 and transferred to the RAM 705 as necessary.

Reference numeral 711 denotes a mouse 712 or a keyboard 7
13 is an interface (I / F) connected to these for accepting input instructions from 13.

A modem 718 is connected to an external network via a public line via an interface (I / F) 719.

Reference numeral 707 denotes a network connection device, which is connected to an external network via an interface (I / F) 714.

Next, the process of extracting the watermark information will be described. FIG. 2 is a block diagram illustrating a method for extracting watermark information from a sentence (text data) in which the watermark information is embedded according to the present embodiment.

First, text data in which watermark information is embedded is input (200).

Next, the input text data is normalized at the character code level in accordance with a later-described normalization method 202 (201). The text data input at 200 is stored in a predetermined memory (not shown).
A copy of the text data is generated, and a normalization process is performed on the copy.

Next, a comparison process between the text data before normalization (the text data stored in a predetermined memory not shown) and the text data after the normalization (the result of performing the normalization process on the copy) To generate difference information (2
03).

Next, watermark information is specified from the difference information obtained in 203, and the watermark information is extracted.

In this embodiment, as the normalization method 202,
A method is adopted in which a hiragana character, a katakana character, and a semi-voiced character are represented by one character without using a combined character, and 1-bit watermark information is associated with each of the above-described voiced character and semi-voiced character. It is assumed that extraction is performed by the method.

As a result, in the watermark information extraction processing 204, bit 0 is set in the case of a one-character expression (that is, a combined character is not used) at the voiced character or semi-voiced character, and bit 1 is set if the combined character is used. Can be extracted. For example, a comparison is made with "GA" after normalization, and if the data before normalization is expressed as "GA", bit 0 is set,
If it is expressed as “゛”, bit 1 can be extracted.

FIG. 11 shows a flowchart of the above watermark information extraction processing, which will be described below. Since the description of this flowchart is the same as the above description, it will be briefly described here.

First, text data in which watermark information is embedded is input, stored in a predetermined memory (not shown), and a copy is generated (step S1101). next,
The above-described normalization processing is performed on the copied text data (step S1102). Next, difference information between the text data before normalization and the text data after normalization is generated (step S1103). Next, it is determined whether or not the combined character is used for all the voiced characters and the semi-voiced characters based on the difference information (step S11).
04), if used, set the bit to 1 (step S1
105), if not used, a bit string is generated with the bit set to 0 (step S1106), and this search is performed for all voiced and semi-voiced characters (step S11).
07). Then, the watermark information can be extracted by obtaining the bit strings generated for all the voiced and semi-voiced characters (step S1108).

FIG. 6 is a diagram for explaining a watermark information extracting device as a device for performing the above-described process of extracting watermark information. The input to the device is a watermarked text document 601. The watermark information extraction device performs a normalization process 2
01 and a normalization method 202
Storage unit 603 for storing the
3 and the watermark information extraction processing 2
04, and an extraction processing device 605 for performing
6 is output. The program code according to the flowchart shown in FIG. 11 is stored in a memory (not shown) in the apparatus shown in FIG. 6, and is read and executed by a CPU (not shown).

Each of the above devices can also be realized by a signal processing device having a configuration as shown in FIG. In this case, the program code according to the flowchart shown in FIG. 11 is stored in the ROM 704, read by the CPU 703, and executed.

As described above, in the present embodiment, Japanese voiced characters and semi-voiced voice characters are taken as combined characters. However, the present embodiment is not a technique specialized only for Japanese text data, but a German umlaut. And the like, and can be applied to all encoding processing codes using combined characters.

Further, as a case where the same character is represented but the encoded data is different, it is also possible to use a data swing of whether a comma, a colon, or a semicolon is converted to a half-width character or a full-width character.

[Second Embodiment] In the first embodiment,
The method of extracting the watermark information from the difference from the data before normalization caused by performing the normalization has been described. However, in the first embodiment, unlike digital watermarking for an image, it has low durability and can easily remove watermark information. Therefore, the first embodiment cannot be used for applications in which it is difficult to delete watermark information. For example, there is a case where copyright protection is performed by embedding the copyright information of the author or the ID of the purchaser. However, it can guarantee the authenticity of the text data and can be used for falsification detection.

FIG. 3 is a block diagram for explaining a method of embedding watermark information in a sentence (text data) according to the present embodiment.

First, text data in which watermark information is embedded is input (300). The text data to be processed in the following is a copy of the input text data.

Next, normalization processing is performed on the input text data in accordance with the normalization method 302 (301).

Next, a later-described hash value of the normalized data is calculated (303).

Next, using the secret key of the signature creator described later, signature data described later is created from the hash value obtained in the hash value calculation processing 303 (304).

Next, the signature data obtained in the signature calculation processing 304 is embedded in the input text data as watermark information (305).

In the present embodiment, the configuration of the watermark information embedding apparatus that performs the above-described processing is the apparatus shown in FIG. 5, and the secret key is further input to the embedding processing apparatus 505 and To calculate the hash value,
Create signature data. Note that this hash value calculation,
For the creation of the signature data, a dedicated device may be provided instead of the embedded processing device 505.

[Hash Value] A hash value is an output value of a hash function h, which is a one-variable function, and a hash function is a compression function that does not easily cause collision. Here, collision means that for different input values x1 and x2, h (x1) = h
(X2). The compression function is a function for converting a bit string having an arbitrary bit length into a bit string having a fixed length.

Accordingly, a hash function is a function for converting a bit string having an arbitrary bit length into a bit string having a certain length.
X1 and x2 satisfying (x1) = h (x2) cannot be easily found. Representative hash functions include MD5 (Message Digest 5),
SHA (Secure Hash Algorithm)
m).

[Signature Data] As a method for creating signature data, there is a method using a public key cryptosystem, but the present embodiment is not particularly limited. Hereinafter, a signature scheme using a public key encryption scheme will be described.

The public key cryptosystem is a cryptosystem in which an encryption key and a decryption key are different, and the encryption key is made public and the decryption key is kept secret. When the encryption operation using the public encryption key kp is E (kp, M) for the communication message M and C = E (kp, M) (C is a communication encrypted by the encryption key kp). Sentence M), a decryption operation using a secret decryption key ks is performed by D (ks,
If C), the public key encryption algorithm satisfies the following three conditions.

(1) When kp is given, E (k
Calculation of (p, M) is easy. Given ks,
Calculation of D (ks, M) is easy.

(2) If ks is not known, even if the calculation procedure of kp and E and C = E (kp, M) are known, M
Is difficult in terms of computational complexity.

(3) For all messages (plaintext) M, E
(Kp, M) can be defined, and D (ks, E (kp, M))
= M holds.

The user P signs the document M using the public key cryptosystem satisfying the above properties. That is, a method for proving that M is indeed a document created by P is as follows.

P uses its own secret key ks to send a message C = D (k
s, M) is generated and sent to the user V together with M.

User V uses user P's public key kp and C
Is subjected to restoration conversion M ′ = E (kp, C). M 'is document M
Check if it matches. This operation of the user V is called signature verification.

Generally, encryption using public key cryptography has a disadvantage that it takes time. Therefore, instead of performing the above-described operation on the document M itself, the data is once compressed using a hash function, and the signature processing is performed. This method is often performed, and the signature calculation processing of 304 also employs this method.

FIG. 12 shows a flowchart of the above processing. This flowchart is based on the premise that text data in which watermark information is embedded, which is generated by the processing according to the flowchart shown in FIG. 10, is input. Therefore, the process performed by the watermark information embedding device in the present embodiment is a process according to a flowchart in which the process after step S1201 is performed instead of step S1003.

The program code according to this flowchart is stored in a memory such as a ROM or a RAM (not shown), and is read and executed by a CPU (not shown).

First, text data and a secret key are input (step S1201). Next, normalization processing is performed on the input text data (step S1202), and a hash value is calculated from the normalized copy data (step S1203). Next, using the entered secret key,
The signature data is created from the calculated hash value (step S1204). The signature data is embedded in the input text data (step S120).
5).

FIG. 4 is a block diagram illustrating a method for obtaining and verifying signature information from text (text data) in which watermark information is embedded according to the present embodiment.

First, text data in which watermark information is embedded is input (400). Next, a normalization process is performed on the copy of the input text data in accordance with the normalization method 402 (401).

Next, a comparison process is performed between the text data before normalization and the text data after normalization to generate difference information (403).

Signature data is obtained from the difference information obtained in 403 (404).

The verification of the signature data obtained in 404 is performed as described above.

The configuration of the watermark information extraction device in this embodiment is different from the device shown in FIG. 6 in that the verification of the signature data obtained from the extraction processing device 605 is performed together with the input of the verification key corresponding to the secret key used at the time of embedding. Figure 6 shows the equipment
The above-mentioned verification can be performed by adding to the apparatus shown in FIG.

FIG. 13 is a flowchart of the above-described processing performed by the watermark information extracting apparatus according to the present embodiment.
Also, the program code according to this flowchart is:
It is stored in a memory such as a ROM or a RAM (not shown), and is read and executed by a CPU (not shown).

First, text data in which watermark information is embedded is input, and a verification key corresponding to a secret key used at the time of embedding is also input (step S1301). Next, the copy of the input text data is normalized (step S1302), and the text data before normalization and the text data after normalization are compared to generate the above-described difference information (step S1302). S1303). next,
The signature data is obtained from the difference information (step S
1304), this signature data is processed in step S13.
Verification is performed using the secret decryption key input at 01 (step S1305).

As described above, according to the present embodiment, the signature data can be embedded as the watermark information, the authenticity of the text data can be guaranteed by the signature data, and the data can be used for falsification detection.

[Third Embodiment] As a special case of the second embodiment, embedding of signature information in an XML document will be described in this embodiment.

XML (extensible Mark)
up Language) is a markup language defined by the W3C. The standard is W3C Recommended
ation, Extensible Markup
Language (XML) 1.0, http: //
/ Www. w3. org / TR / 1998 / REC-
xml-19980210. html.

XML is a readable data format described by text data. For example, “<Tag>” and “<//
Data items are represented by tags of the form “<” and “>”, such as “Tag>”, and various data are represented by surrounding other data in a nested structure with this tag.

Further, in this tag, characteristic data called a property, which is related to the tag, can be described. For example, “<Tag prop =” Property
y ″>... </ Tag> ”, a character string“ property name = “value” ”is replaced with a tag name (“ Ta
g ") and a space, followed by interpolation into the tag.

An XML document is divided into the following three parts.

(1) An XML declaration part for declaring a version or character code.

(2) A DTD (Do) that declares a document structure of an XML instance described later and defines a tag syntax
document type definition) part.

(3) XML which is an actual tagged document
The part of the instance.

Since XML is a data format called text data, it can be easily created and edited by general document editing software (text editor or the like). This is an advantage in that XML is easily handled, and is being used in various applications.

Data signature is an indispensable technique for the purpose of guaranteeing contract documents and the like, but there is a high demand for signatures on XML documents, and standardization of the format is being promoted in W3C and IETF, and XML-Sign is a standard.
ature Syntax and Processin
g, http: // www. w3. org / TR / xm
ldsig-core / (hereinafter xmldsig-co
re) is open to the public.

First, the signature process is performed in accordance with the canonical XMLVersion 1.
0, http: // www. w3. org / TR / x
ml-c14n (hereinafter referred to as xml-c14n)
It has been proposed to apply a signature after normalizing an XML document in accordance with a normalization method defined in (1).

XML in xmldsig-core
For the signature on the document, it is necessary to take the hash of the data subjected to the normalization processing by xml-c14n, calculate the signature data, and attach the following header portion indicating that the signature is applied to the original XML document. is there. <Signature>. . . <SignatureValue> ABCDEF. . . </ SignatureValue></Signature> The xml-c14n defines that the line feed character is LF, the character encoding method is always UTF-8, and the like. However, normalization at the character code level is out of the scope of the draft document, and agreements between vendors are made and depend on applications. Therefore, as a normalization before applying a signature, a normalization process is performed in the following procedure.

FIG. 9 is a block diagram illustrating a signature procedure according to the present embodiment. It is the flowchart which was performed.

First, an XML document in which watermark information is embedded is input (900).

Next, the input XML document (text data) is normalized at the character code level in accordance with the normalization method 902 (901).

Next, normalization by xml-c14n is performed (903).

Using the secret key of the signature creator, the hash value of the data subjected to the two types of normalization processing (901, 903) is obtained, and signature data is generated (904).

The signature data obtained in 904 is embedded as watermark information as a header (hereinafter, signature header) (90).
5).

As the normalization before applying a signature, xml-c
By performing the above-described normalization processing at the character code level before normalization by 14n, a signature can be performed in the same manner as in the second embodiment, and the calculated signature header can be embedded in the XML document. it can.

When the data capacity of the signature header is large, a method of embedding only a part of the signature header as watermark data as follows is also conceivable. The following is an example of a signature header when only the signature data of the signature header is embedded as watermark information. <Signature>. . . <SignatureValueOption = ”Wa
terMarked "//></Signature> From the property value" WaterMarked ",
It can be seen that the signature data is embedded.

The configuration of the watermark information embedding device in the embodiment is the same as that in the first embodiment.
2 is a flowchart in which normalization by xml-c14n is further performed in FIG. On the other hand, the configuration of the watermark information extraction device according to the present embodiment is the same as that of the first embodiment, and the process performed by the device is a flowchart in which normalization by xml-c14n is performed in step 1302. .

As described above, according to the present embodiment,
There is no need to externally manage the signature data for the XML document and separately manage it. By extracting the signature data from the XML document and verifying the signature, the authenticity of the XML document can be assured and tampering can be detected. . Further, the above method is applicable not only to XML but also to markup languages such as SGML and HTML.

[Fourth Embodiment] In the above embodiment,
The normalization process required a normalization method. In the present embodiment, a method will be described in which this normalization method is kept secret and only a specific user extracts embedded data. In addition,
The embedding processor performs normalization at the character code level by keeping the normalization method confidential, and the embedding processor secures the normalization method using an encryption communication channel only for those who permit extraction of watermark information. Share. In the present embodiment, the encryption method is not particularly limited.

FIG. 8 is a diagram showing an outline of a watermarking system holding different normalization schemes for each extractor.

The embedding device 801 has a normalization method storage device 802, and the embedding processor X sends the normalization method A (80
3) and a normalization method B (804) are created and stored in the normalization method storage device 802.

The embedding processor X is an extractor A and an extractor B
Respectively, normalization method A (803) and normalization method B
(804) is shared so as not to be known to a third party.

The extractor A having the extraction device 805 stores the normalization method A (807) in the normalization method storage device 806. Similarly, the extractor B having the extraction device 808 stores the normalization method B (810) in the normalization method storage device 809.

When the embedding processor X embeds information that can be extracted only by the extractor A, the normalization method A (803)
By performing the watermarking process using, only the extractor A can extract information using the normalization method A (807). In this case, extractor B who does not have normalization method A cannot extract watermark information.

As described above, according to the present embodiment, by having a normalization scheme for each user,
It is possible to provide a mechanism that allows only a specific extractor to extract embedded data.

[Fifth Embodiment] In the present embodiment, an example in which metadata is handled as watermark information will be described. The metadata (meta-data) is “data related to data”, and is data M that describes certain data D. However, when the data D and the metadata M exist in different files, there is a problem that the user must manage the files at the same time when moving or copying the files. Therefore, in the present embodiment, by applying metadata as watermark information, it is possible to eliminate the trouble of managing with a plurality of files.

Further, it is also possible to embed link information indicating a data relationship such as a relationship with another document or a pointer of related information as watermark information, and the same effect as described above can be obtained.

As the link information, an identifier unique to an application or a URL (Uniform Resource) is used.
e Locator) and URI (Uniform R)
resource Identifier). The URL is a format for specifying data existing on the Internet, which is used as an HTML hyperlink, and the URI is an identifier including the URL, and is defined by the W3C.

As described above, according to the present embodiment, there is no need to externally manage and separately manage metadata and link information for a document, and it is possible to smoothly manage a document. Further, the above-mentioned method uses XML, SGML, HTML as embedded data or watermark information.
It is also possible to describe in a markup language such as.

[Sixth Embodiment] The present invention is not limited only to an apparatus and a method for realizing the above-described embodiment and a method for performing a combination of the methods described in the embodiment. Computer in the device (C
PU or MPU) is supplied with software program code for implementing the above-described embodiment, and the computer of the system or apparatus operates the various devices according to the program code, thereby realizing the above-described embodiment. Such cases are also included in the scope of the present invention.

In this case, the program code itself of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, specifically, A storage medium storing the above program code is included in the scope of the present invention.

Examples of a storage medium for storing such a program code include a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, and C drive.
D-ROM, magnetic tape, nonvolatile memory card, R
OM or the like can be used.

The computer controls the various devices in accordance with only the supplied program codes, so that the functions of the above-described embodiment are realized, and the program codes operate on the computer. Such a program code is included in the scope of the present invention even when the above-described embodiment is realized in cooperation with an OS (Operating System) or other application software.

Further, after the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, the function expansion board or function is stored based on the instruction of the program code. The case where the CPU or the like provided in the storage unit performs part or all of the actual processing, and the above-described embodiment is realized by the processing is also included in the scope of the present invention.

When the present invention is applied to the storage medium described above, the storage medium may include any of the above-described flowcharts (shown in FIG. 10, and / or FIG. 11, and / or FIG. 12, and / or FIG. 13). The corresponding program code will be stored.

[0121]

As described above, according to the present invention, by converting a code of text data to a corresponding code based on watermark information, text data can be converted into text data without causing the user to feel unnaturalness of the text. Watermark information can be embedded.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a method for embedding watermark information in a text (text data) according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method for extracting watermark information from a text (text data) in which watermark information is embedded according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a method for embedding watermark information in a sentence (text data) according to a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating a method for obtaining and verifying signature information from a text (text data) in which watermark information is embedded according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a schematic configuration of a watermark information embedding device according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a schematic configuration of a watermark information extracting device according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating a schematic configuration of a device as a watermark information embedding device according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating an outline of a watermarking system according to a fourth embodiment of the present invention, in which a different normalization method is held for each extractor.

FIG. 9 is a block diagram illustrating a signature procedure according to a third embodiment of the present invention.

FIG. 10 is a flowchart of watermark information embedding processing performed by the watermark information embedding device according to the first embodiment of the present invention.

FIG. 11 is a flowchart of a watermark information extraction process performed by the watermark information extraction device according to the first embodiment of the present invention.

FIG. 12 is a flowchart of a watermark information embedding process performed by the watermark information embedding device according to the second embodiment of the present invention.

FIG. 13 is a flowchart of watermark information extraction processing performed by the watermark information extraction device according to the second embodiment of the present invention.

Claims (26)

[Claims] 1. A text processing device for embedding watermark information in text data, comprising: a normalization unit for normalizing the text data using a predetermined normalization method; And a converting unit for converting the converted text data into other text data based on the watermark information. 2. The text processing apparatus according to claim 1, wherein the conversion unit expresses the predetermined normalization method by a plurality of normalization methods according to the watermark information. 3. The sentence processing according to claim 1, wherein the predetermined normalization method and another normalization method corresponding to the predetermined normalization method are the same character notation normalization methods. apparatus. 4. The sentence processing apparatus according to claim 1, wherein the normalization method is a normalization method for expressing a hiragana / katakana voiced character and a semi-voiced character in one character. 5. The text processing apparatus according to claim 4, wherein the normalization method represents the voiced and semi-voiced voices with a combined character. 6. The text data is XML, HTM
6. The method according to claim 1, wherein at least one of L and SGML is included or represented by one of them.
A sentence processing apparatus according to any one of the above. 7. The text processing apparatus according to claim 1, wherein the text data is written in a markup language. 8. The text processing apparatus according to claim 1, wherein the watermark information includes metadata for the text data. 9. A normalized data generating means for generating normalized data obtained by normalizing text data in which watermark information is embedded, and calculating a value based on the normalized data. Calculating means for generating embedded data from a value based on the normalized data using information on the text data, and embedding the data generated by the embedded data generating means into the embedded data. 2. The text processing device according to claim 1, wherein the text is embedded by means. 10. The text processing apparatus according to claim 9, wherein the calculation unit calculates a hash value by a one-way hash function as a value based on the normalized data. 11. The method according to claim 9, wherein the normalized data generated by the normalized data generating means is further normalized by a normalization method according to a predetermined rule. The sentence processing device described. 12. The text processing apparatus according to claim 11, wherein the normalization method according to the predetermined rule is a normalization method specified in a W3C formulation document. 13. The text processing apparatus according to claim 9, wherein said embedding means embeds signature information of text data. 14. A text processing apparatus for extracting watermark information from text data in which watermark information has been embedded, wherein normalized text obtained by performing normalization on the text data by a predetermined normalization method is provided. Watermark information by generating a bit string based on the difference information, comprising: a normalized data generation unit that generates the data; and a difference information generation unit that compares the normalized data with the text data and generates the difference information. A sentence processing apparatus characterized in that a sentence is obtained. 15. The predetermined normalization method includes:
The sentence processing apparatus according to claim 14, wherein the condition is that one semi-voiced character is expressed. 16. The method according to claim 14, wherein the normalized data generated by the normalized data generating means is further normalized by a normalization method according to a predetermined rule. The sentence processing device described. 17. The text processing apparatus according to claim 16, wherein the normalization method according to the predetermined rule is a normalization method specified in a W3C formulation document. 18. The text processing apparatus according to claim 14, wherein the difference information includes metadata in which information on the text data is described. 19. The text processing apparatus according to claim 18, further comprising a verification unit that verifies the metadata by using information for decoding the metadata. 20. The text processing apparatus according to claim 17, wherein the verification unit extracts signature information of text data. 21. A text processing method for embedding watermark information in text data, comprising: a normalization step for normalizing the text data using a predetermined normalization method; Converting the converted text data into other text data based on the watermark information. 22. A normalized data generating step of generating normalized data obtained by normalizing text data in which watermark information is embedded, and calculating a value based on the normalized data. And an embedded data generating step of generating embedded data from a value based on the normalized data using the information on the text data, and embedding the data generated by the embedded data generating step. 22. The text processing method according to claim 21, wherein the text is embedded by a process. 23. A text processing method for extracting watermark information from text data in which watermark information is embedded, comprising: normalizing data obtained by performing normalization on the text data by a predetermined normalization method. Generating a normalized data generating step; comparing the normalized data with the text data to generate difference information; and generating a bit string based on the difference information. A sentence processing method characterized by obtaining 24. A storage medium for storing a text processing program code for embedding watermark information in text data, the program code for a normalization step of normalizing the text data using a predetermined normalization method. And a program code for a conversion step of converting the text data normalized in the normalization step into other text data based on watermark information. 25. A program code for a normalized data generation step for generating normalized data, which is obtained by normalizing text data in which watermark information is embedded, based on the normalized data. A program code of a calculating step of calculating a value, and a program code of an embedded data generating step of generating embedded data from a value based on the normalized data by using information on the text data. 25. The storage medium according to claim 24, wherein data generated in the step is embedded in the embedding step. 26. A storage medium for storing a text processing program code for extracting watermark information from text data in which watermark information is embedded, wherein the text data is normalized by a predetermined normalization method. And a program code of a difference information generating step of comparing the normalized data with the text data and generating difference information of the text data. A storage medium, wherein watermark information is obtained by generating a bit string based on difference information.