JP2011013327A - Electronic document browsing system and method and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic document browsing system allowing any person to browse the information included in one electronic document and requiring no concealment, and also allowing only an authorized person to browse not only the information requiring no concealment but also the information requiring concealment.SOLUTION: In this system, a cipher program 10a used in preparing an electronic sentence 2 and being installed in a first computer performs a processing for generating a cipher object including cipher data including encrypted character lines when receiving instructions for encrypting selected character lines and replacing the character lines with display data of the cipher object. A second computer 10b used to browse the electronic document 2 performs a processing for acquiring a chunk displayed at a cursor position from the electronic document, decoding the cipher data included in the cipher object when the chunk is the display data of the cipher object, and displaying the decoded data obtained by decoding the cipher data.

Description

  The present invention relates to a technique for concealing information described in an electronic document such as an electronic mail.

  With the advent of the information-oriented society, documents that were paper media have been digitized. As represented by “confidential”, documents handled by companies are generally provided with a security level as needed. Even if the document is an electronic document, It is necessary to control browsing of electronic documents according to this security level.

  If the document is a paper medium, a cabinet that can be locked / unlocked with a physical key is used, and if the physical key is passed only to a viewer who has the authority to view the document, only the viewer can view the document. However, in the case of an electronic document, only the viewer can encrypt the electronic document in advance and distribute an encryption key that can decrypt the encrypted electronic document to the viewer. It is common to be able to view electronic documents.

  For example, in Patent Document 1, an electronic document (electronic book in Patent Document 1) is encrypted with a browsing key, and a public key of a viewer (purchaser in Patent Document 1) who has the authority to browse the electronic document is used. Encrypt the viewing key, and send the electronic document encrypted with the viewing key and the viewing key encrypted with the public key to the viewer, so that the user possesses the IC card storing the secret key that is paired with the public key A system is disclosed in which only a viewer can view an electronic document.

Japanese Patent Laid-Open No. 2000-113047

  However, the conventional technology encrypts all one electronic document, even though one electronic document handled by a company includes not only confidential information but also information that does not require confidentiality. For those who are not authorized to know the information that needs to be concealed, information that does not need to be concealed can be viewed. For those who have the authority to know the information that needs to be concealed, in addition to the information that does not need to be concealed, information that needs to be concealed Could not be viewed.

  Therefore, the present invention makes it possible for a person who does not have the authority to know information that needs to be concealed to view only information that does not require secrecy contained in one electronic document, and to a person who has the authority to know information that needs to be concealed. Therefore, it is an object of the present invention to provide a system or the like that enables browsing of confidential information in addition to confidential information.

  A first invention for solving the above-described problem is an electronic document browsing system including at least a first computer used for creating an electronic text and a second computer used for browsing the electronic document. When the first computer receives an instruction to encrypt the selected character string included in the electronic document, the first computer is an encryption that is a data object including encrypted data obtained by encrypting the character string with an encryption key. An encryption unit that generates an object and executes processing for replacing the character string with display data of the encryption object is provided, and the second computer executes the chunk displayed at the cursor position from the displayed electronic document. If the chunk is display data of an encryption object, the encryption data included in the encryption object is paired with the encryption key. Decoded by comprising decryption key, an electronic document browsing system characterized by comprising a decoding means for performing a process of displaying the decoded data obtained by decoding the encryption data.

  Further, the second invention is the electronic document browsing system according to the first invention, wherein the display data of the encryption object generated by the encryption means provided in the first computer is the encryption object display data. An electronic document browsing system characterized by being text data or image data in which the encryption object is concealed.

  Further, a third invention is the electronic document browsing system according to the first invention or the second invention, wherein the encryption means provided in the first computer has a security level set by the creator. A plurality of encryption keys are stored in accordance with the security level, the security level acquired from the creator of the electronic document is included in the encryption object, and the encryption key corresponding to the security level is used for encryption of the character string The decryption means provided in the second computer stores a plurality of decryption keys corresponding to a security level set by a viewer, and decrypts the encrypted data included in the encrypted object. The security level is stored only when the decryption key corresponding to the security level included in the encryption object is stored. An electronic document browsing system characterized by at the corresponding the decryption key is a means for performing a decoding process of the encrypted data.

  According to the first invention described above, if the information that needs to be concealed is selected as a character string on the electronic document creation side, only the information that needs to be concealed contained in one electronic document is encrypted. For those who do not have the authority to know the information, only the confidential information contained in one electronic document can be viewed.

  Also, if the browsing computer is not equipped with decryption means, the encrypted data contained in the electronic document cannot be decrypted. Therefore, only the computer operated by a person who has the authority to know confidential information is provided with the decryption means. If so, a person who has the authority to know the information that needs to be concealed can decipher the encrypted data contained in the electronic document, so that in addition to the information that does not need to be concealed, information that needs to be concealed can be viewed. Become.

  The reason why the display data of the encryption object is inserted into the electronic document is to allow the viewer to recognize that the information that needs to be concealed is encrypted. As in the second invention, the display data of the encrypted object inserted into the electronic document may be the text data of the encrypted object. However, when the image data is used, the recognizability of the encrypted object can be improved.

  Further, as in the third invention, on the creator side, the encryption key corresponding to the security level is used for encryption of the character string, and the security level is included in the encryption object. Only when the decryption key corresponding to the security level included in the encryption object is stored, the decryption key is decrypted with the decryption key corresponding to the security level, so that the creator can view it. The viewable range can be set in the electronic document according to the security level of the person.

  Further, according to a fourth aspect of the present invention, when an instruction for encrypting a selected character string included in the electronic document is received by the first computer used for creating an electronic text, the character string is encrypted with an encryption key. A second computer used for browsing the electronic document, and a cryptographic step for generating a cryptographic object, which is a data object including encrypted cryptographic data, and executing processing for replacing the character string with display data of the cryptographic object If the chunk displayed at the cursor position is obtained from the displayed electronic document and the chunk is the display data of the encryption object, the encryption data included in the encryption object is decrypted with the encryption key. A decrypting step for executing a process of displaying decrypted data obtained by decrypting with the key and decrypting the encrypted data; It is an electronic document browsing method.

  Further, a fifth invention is the electronic document browsing method according to the fourth invention, wherein in the encryption step, the display data of the encryption object is the text data of the encryption object or the encryption object is concealed. The electronic document browsing method is characterized in that the image data is processed image data.

  Further, a sixth invention is the electronic document browsing method according to the fourth invention or the fifth invention, wherein the first computer has a number of the ciphers corresponding to the security level set by the creator. A key is stored, and the encryption step includes causing the first computer to include the security level acquired from the creator of the electronic document in the encryption object, and adding the encryption key corresponding to the security level to the character string. The second computer stores a number of the decryption keys corresponding to the security level set by the viewer, and the encryption step stores the encryption key in the second computer. When decrypting the encrypted data included in the object, the decryption key corresponding to the security level included in the encrypted object is stored. If only an electronic document browsing method, characterized in that the step of executing a decryption process of the encrypted data in the decryption key corresponding to the security level.

  The seventh invention is a data object including encrypted data obtained by encrypting the character string with an encryption key when the computer receives an instruction to encrypt the selected character string included in the electronic document. It is a computer program for functioning as encryption means for generating a cryptographic object and executing processing for replacing the character string with display data of the cryptographic object.

  Furthermore, in an eighth aspect of the invention, the computer acquires the chunk displayed at the cursor position from the displayed electronic document, and when the chunk is a cryptographic object, the cryptographic data included in the cryptographic object is encrypted. It is a computer program for functioning as decryption means for executing a process of decrypting with a decryption key paired with a key and displaying the decrypted data obtained by decrypting the encrypted data.

  The fourth to sixth inventions described above relate to methods.

  The seventh and eighth inventions described above relate to computer programs.

  According to the above-described invention, for a person who does not have the authority to know the information that needs to be concealed, only the information that does not need to be concealed contained in one electronic document can be browsed. On the other hand, it is possible to provide a system or the like that enables browsing of confidential information as well as confidential information.

The figure explaining the structure of an electronic document browsing system. The figure explaining the function to decrypt an encryption object. The figure explaining the function which produces | generates a cryptographic object. The block diagram of the computer which a viewer and a creator use. The flowchart which showed the operation | movement procedure of the encryption program. The flowchart which showed the operation | movement procedure of the decoding program.

  The present invention will now be described with reference to the drawings. FIG. 1 is a diagram for explaining the configuration of an electronic document browsing system 1 according to the present invention. FIG. 2 is a diagram for explaining a function of decrypting an encrypted object in the computer 1. FIG. It is a figure explaining the function which produces | generates a cryptographic object.

  The electronic document browsing system 1 illustrated in FIG. 1 is installed on the side where the electronic document 2 is created, and is installed with an encryption program 10 that inserts a character string encryption object included in the electronic document 2 into the electronic document 2. 1 computer 3a and at least a second computer 3b installed on the side viewing the electronic document 2 and installed with a decryption program 10b having a function of decrypting an encrypted object included in the electronic text 2, The electronic document 2 is transmitted from the first computer 3 a to the second computer 3 b via the network 4.

  The encryption program 10 and the decryption program 10b are computer programs different from an application (for example, an e-mail mailer) having a function of creating and browsing the electronic document 2, and are preferably computer resident programs. , An application plug-in having a function of creating and browsing the electronic document 2 may be used.

In FIG. 2, the electronic document 2 is an e-mail, and the electronic document 2 shown in FIG. 2 includes display data 2b1 (encrypted object display data generated by the first computer 3a arranged on the creation side of the electronic document 2. In FIG. 2, the text data of the encryption object is included.
The encryption object has a specific structure. In this embodiment, the structure of the encryption object is “● dark”, which is a character string indicating encryption data, and the header including the object ID for identifying the encryption object, and then the electronic document 2. Is a structure in which encrypted data obtained by encrypting a character string included in a character string with a predetermined encryption key is enclosed in “”. In FIG. 1, “● dark 1“ 8dske2j3 $ -fnee ”” is illustrated as an encryption object.

  While the decryption program 10b installed in the second computer 3b is activated, the decryption program 10b acquires a chunk (data chunk) displayed at a cursor position coordinate such as a pointing device (for example, a mouse). If it is determined that the object is an encrypted object, the encrypted data contained in the encrypted object is decrypted using a predetermined decryption key, and the decrypted data obtained by decrypting the encrypted data using the window 2b2 that covers the encrypted object ( Here, the process of displaying “July 1”) is executed.

  In FIG. 3, as in FIG. 1, the electronic document 2 is an e-mail, and the encryption program 10 installed in the first computer 3a is in a state in which a character string that needs to be concealed is selected while it is running. , 2a1 is selected to select the menu for generating a cryptographic object, and the encrypted data obtained by encrypting the selected character string 2a2 with a predetermined encryption key (here, “8dske2j3 $ -fnee”) is calculated. Display data 2a3 (here, text data) of a cryptographic object including the encrypted data (here, “● dark 1“ 8dske2j3 $ -fnee ””) is generated, and the character string 2a2 in the electronic document 2 is encrypted. Processing to replace the object display data 2 a 3 is executed, and the encryption object is inserted into the electronic document 2.

FIG. 4 is a block diagram of a computer used by a viewer and a creator.
Since the functions necessary for the computer 3a and the computer 3b for realizing the present invention are provided by the encryption program 10a and the decryption program 10b, respectively, general-purpose computers can be used as the computer 3a and the computer 3b.

  As shown in FIG. 4, a general-purpose computer 30 includes a CPU 31 (CPU: Central Processing Unit), a RAM 33 (RAM: Random Access Memory), which is a main memory of the computer, and a ROM 32 (in which a BIOS is mounted). ROM (Read-Only Memory), an input / output interface 35 for data communication with an external device, a network interface 36 for network communication, a hard disk 34 which is a large-capacity data storage device as an external storage device, and a display A device 37 (for example, a liquid crystal display), a character input device 38 (for example, a keyboard), a pointing device 39 (for example, a mouse), and the like are provided. A computer program for controlling the behavior of the CPU 31 is stored in the hard disk 34. Yes.

  As described above, the encryption program 10a is stored in the computer 3a used by the creator of the electronic document 2, and the decryption program 10b is stored in the computer 3b used by the viewer of the electronic document 2. The decryption program 10b may be stored in 3a, and the encryption program 10a may be stored in the computer 3b.

  From here, operations of the encryption program 10 and the decryption program 10b will be described. FIG. 5 is a flowchart showing the operation procedure of the encryption program 10, and FIG. 6 is a flowchart showing the operation procedure of the decryption program 10b.

  First, the operation procedure of the encryption program 10 will be described with reference to FIG. FIG. 5 shows a procedure executed whenever a character string included in the electronic document 2 is selected and the encryption program 10 receives an instruction to generate a cryptographic object, and the character string included in the electronic document 2 is selected. When the cryptographic program 10 receives an instruction to generate a cryptographic object (S1), the cryptographic program 10 executes a process of encrypting a selected character string using a predetermined cryptographic key (S2).

  The encryption key that uses the selected character string for encryption may be encoded in the program code of the encryption program 10, or may be stored in a file format separately from the program code of the encryption program 10.

When the encryption program 10 calculates the encryption data of the character string selected by the creator, the encryption program 10 executes a process of generating an encryption object including the encryption data (S3).
For example, the cryptographic program 10 has a counter that counts the object ID of the cryptographic object. When the cryptographic object is generated, “● dark”, which is a character string indicating the cryptographic object, is incremented by one. A cryptographic object header is generated from the chunk ID obtained in this manner, and the cryptographic data generated in S is enclosed in “” to generate a cryptographic object of the character string selected by the creator.

  When the encryption program 10 generates the encryption object of the character string selected by the creator, after generating the display data of the encryption object (S4), the encryption program 10 uses the character string selected by the creator of the electronic document 2 as the display data of the encryption object. By executing the replacement process, the encrypted object is inserted into the electronic document 2 (S5), and this procedure is terminated.

  The encryption program 10 generates the display data of the encryption object so that the viewer can recognize that the encryption object is included in the electronic text. The display data of the encryption object generated by the encryption program 10 is encrypted. Although it may be text data of data included in the object, as will be described later, if the display data of the encryption object is image data, the recognition of the encryption object can be improved.

  Next, the operation procedure of the decryption program 10b will be described with reference to FIG. FIG. 6 shows a procedure executed each time the decryption program 10b acquires a chunk displayed at the position coordinates of the cursor such as the pointing device. The decryption program 10b is activated while the cursor such as the pointing device is activated. The position coordinates are monitored, and the chunk (data chunk) displayed at the position coordinates of the cursor is acquired (S10).

  For example, the decoding program 10b monitors the movement of the cursor of the pointing device, and if the position coordinate of the cursor does not change for a predetermined time (for example, 1 second) after the cursor moves, the position coordinate of the pointer of the pointing device Get the chunk (data chunk) displayed in.

When the decryption program 10b acquires the chunk, the decryption program 10b determines whether the chunk is display data of the encryption object (S11).
The structure of the encryption object is stored in advance in the decryption program 10b, and the decryption program 10b uses the structure of the encryption object to determine whether the acquired chunk is display data of the encryption object.

  If the chunk is not the display data of the encryption object, the decryption program 10b ends the procedure of FIG. 6 without executing the subsequent steps. If the chunk is the display data of the encryption object, the decryption program 10b uses a predetermined decryption key. After decrypting the encrypted data included in the encrypted object (S12) and using the window that covers the encrypted object, the process of displaying the decrypted data obtained by decrypting the encrypted data (S13) is executed, and then FIG. This procedure ends.

  The process for displaying the decrypted data obtained from the cryptographic object is arbitrary. For example, an opaque box that covers the entire cryptographic object is generated, and this box is placed at the display position of the display data of the cryptographic object. If the decrypted data is displayed inside, the cryptographic object is apparently deleted.

  The present invention is not limited to the embodiments described so far, and various modifications and changes can be made.

  In FIG. 2 and FIG. 3, the display data of the cryptographic object is the text data of the cryptographic object. However, the display data of the cryptographic object may be image data that hides the cryptographic object. When the image data is inserted into the electronic text, it becomes possible to improve the recognizability of the encrypted object for the viewer of the electronic document 2.

  In this case, upon receiving an instruction to generate a cryptographic object, the cryptographic program 10 uses a steganography technique to execute a process of hiding the cryptographic object from the basic image data so that the cryptographic object is hidden. To generate the image data.

  In addition, when the image data in which the encryption object is concealed is selected, the decryption program 10b uses a steganography technique to extract the encryption object from the image data and decrypt the extracted encryption object. Execute.

  Further, in the present invention, by including the security level in the encryption object, the creator can set the viewable range in the electronic document 2 in accordance with the security level of the viewer. .

  In this case, a plurality of encryption keys are stored in the first computer 3a according to the security level set by the creator, and when the encryption program 10 receives an instruction to generate an encryption object, the security set for the encryption object is set. A screen for selecting a level is displayed on the computer, and the character string selected by the creator is encrypted using an encryption key corresponding to the security level selected by the creator of the electronic document 2 using the screen. Include the security level in the cryptographic object.

  Further, the second computer 3b stores a plurality of decryption keys in accordance with the security level set by the viewer, and when the decryption program 10b decrypts the encrypted data contained in the encrypted object, It is confirmed whether or not a decryption key corresponding to the included security level is stored in the second computer 3b, and only if it is stored, it is included in the encrypted object using the decryption key corresponding to the security level included in the encrypted object. A process of decrypting the encrypted data is executed.

DESCRIPTION OF SYMBOLS 1 Electronic document browsing system 2 Electronic document 3a 1st computer 3b 2nd computer 10a Encryption program 10b Decryption program

Claims (8)

  An electronic document browsing system comprising at least a first computer used for creating an electronic text and a second computer used for browsing the electronic document, wherein the first computer When receiving an instruction to encrypt a selected character string included in a document, an encryption object, which is a data object including encrypted data obtained by encrypting the character string with an encryption key, is generated, and the character string is The second computer obtains the chunk displayed at the position of the cursor from the displayed electronic document, and the chunk is the display data of the encrypted object. In this case, the encrypted data included in the encrypted object is decrypted with a decryption key paired with the encryption key, and the encrypted data is decrypted. Electronic document reading system, characterized in that it comprises a decoding means for performing a process of displaying the decoded data obtained by decoding the.   2. The electronic document browsing system according to claim 1, wherein the display data of the encryption object generated by the encryption means included in the first computer is text data of the encryption object or the encryption object. An electronic document browsing system characterized by being concealed image data.   3. The electronic document browsing system according to claim 1 or 2, wherein the encryption means provided in the first computer stores a plurality of the encryption keys according to a security level set by the creator. The second computer is configured to include a security level acquired from the creator of the electronic document in the encryption object and use the encryption key corresponding to the security level for encryption of the character string. The provided decryption means stores a plurality of the decryption keys according to the security level set by the viewer, and when decrypting the encrypted data included in the encrypted object, the security included in the encrypted object is stored. Only when the decryption key corresponding to the level is stored, the previous decryption key corresponding to the security level is used. Electronic document reading system, characterized in that the means for performing a process for decrypting data.   Data including encrypted data obtained by encrypting the character string with an encryption key when the first computer used for creating the electronic text receives an instruction to encrypt the selected character string included in the electronic document An encryption process that generates an encryption object that is an object, and executes a process of replacing the character string with display data of the encryption object, and is displayed at the position of the cursor in the second computer used for browsing the electronic document. If the chunk is the display data of the encrypted object, the encrypted data included in the encrypted object is decrypted with the decryption key paired with the encryption key, and the encrypted An electronic document browsing method comprising a decrypting step for executing a process of displaying decrypted data obtained by decrypting data .   5. The electronic document browsing method according to claim 4, wherein, in the encryption step, the display data of the encryption object is text data of the encryption object or image data concealing the encryption object. To view electronic documents.   The electronic document browsing method according to claim 4 or 5, wherein the first computer stores a number of the encryption keys corresponding to a security level set by a creator, and the encryption step includes: The step of causing the first computer to include the security level acquired from the creator of the electronic document in the encryption object and using the encryption key corresponding to the security level for encryption of the character string; The second computer stores the number of the decryption keys corresponding to the security level set for the viewer, and the encryption step decrypts the encrypted data included in the encryption object in the second computer. The security key is stored only when the decryption key corresponding to the security level included in the encryption object is stored. Electronic document browsing method, characterized in that in the decryption key corresponding to the bell is a process to execute a decryption process of the encrypted data.   When the computer receives an instruction to encrypt a selected character string included in the electronic document, the computer generates an encryption object, which is a data object including encrypted data obtained by encrypting the character string with an encryption key, and A computer program for functioning as encryption means for executing processing for replacing a column with display data of an encryption object. When the computer obtains the chunk displayed at the cursor position from the displayed electronic document and the chunk is an encrypted object, the encrypted data contained in the encrypted object is decrypted with the decryption key paired with the encryption key. A computer program for functioning as decryption means for executing a process of decrypting and displaying decrypted data obtained by decrypting the encrypted data.

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