JP2006040116A - File encryption/decryption method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a file encryption/decryption method that can be adaptive to encryption/decryption processing not only of a file form which can be browsed off line but of other general-purpose forms and that can establish local file security. <P>SOLUTION: The file encryption/decryption method includes the steps of: encrypting a file 21 by encryption software; generating a package file including local server software 25 and the encrypted file 21; developing the package file executed by a local host; executing the local server software 25, generating a local server program and storing the local server program into a system memory of the local host; and dynamically decoding the file 21 by the local server program when the encrypted file is browsed by a browser. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention encrypts and decrypts files from local server software to achieve file security.

With the spread of information networks, there is an increasing demand for the safety of files that users can access on the Internet.
In general, the file formats accessible on the Internet are HTML format, XML, PDF, etc., and are displayed by a web browser such as Microsoft Internet Explorer (IE) or Netscape. Can do.

When a user browses online, the network server provides a security means for encrypting or authenticating a file requiring security or data being transmitted to prevent a third party from peeping during browsing. As a result, the data cannot be illegally acquired by package interception or any host intrusion method, and even if the data is acquired, the contents of the plain code cannot be viewed by using various encryption means.
The file encryption technique is described in Non-Patent Document 1, and the basic theory of cryptography is described in Non-Patent Document 2.
Building secure software: how to avoid security problems the right way (John Viega, Gray McGraw) Applied Cryptography: Protocols, Algorithms, and Source Code in C (Bruce Schneier)

  However, browsers used by the local host generally provide a cache service in order to allow the user to browse at high speed. In the above-described method of browsing files in the online state, a file copy is left in the local host. Yes. For this reason, the connection with the original server is lost when browsing offline, and the security measure provided by the server is lost. Therefore, a third party can easily obtain a necessary security file from the copy access catalogue.

FIG. 1 is a diagram showing a structure for browsing a conventional network file.
In FIG. 1, the user is browsing the network file with the browser 19 installed in the computer 18. The browser 19 is a general web browser, and files are usually stored in some servers 13 connected to the Internet 15.
In addition, the server 13 is provided with a large-capacity storage medium storage database 11 such as a hard disk or an optical disk (for example, CD-ROM, DVD-ROM), for example, so as to provide download or online browsing to net users. Has been made.

In such a configuration, when a user browses a file in an offline state, the file must be downloaded to the storage medium 17 of the local computer. For this reason, the connection with the server 13 is lost when browsing offline, that is, there is no security measure provided by the server 13 in an online state.
In addition, when a user browses a file in an offline state via the server 13 connected to the Internet 15, it is necessary to browse the file after downloading the file in the database 11 to the system memory of the local computer.
In addition, a copy is usually copied into the cache memory, but since the cache memory is in a certain catalog on the hard disk in the local computer, it may be illegally obtained by a third party.

  As described above, in the conventional technology, when browsing a file offline, the security measures provided by the original server connected to the network (for example, Secure Socket Layer: SSL) are lost, and when browsing online, The copy where the local cache means remains also creates a security problem.

  The present invention has been made under the circumstances as described above, and can cope with not only the file format that can be browsed offline but also the encryption / decryption processing of other general-purpose files. An object of the present invention is to provide a file encryption / decryption method capable of establishing local file security.

  In order to solve the above-described problems, the file encryption / decryption method according to the present invention dynamically decrypts a file being browsed by a server program executed locally, and is provided with a security measure provided in a network server. Is to provide.

  That is, the file encryption / decryption method according to the present invention is a file encryption / decryption method for dynamically decrypting an encrypted file at the time of browsing, wherein the file is encrypted by encryption software; Generating a package file including local server software and the encrypted file; executing on the local host; deploying the package file; executing the local server software; resulting in a local server program And storing in the system memory of the local host, and when browsing the encrypted file in a browser, the local server program dynamically decrypts the file. .

Thus, in this method, before browsing the file encrypted by the encryption software, first, the local server software is executed to generate the local server program, and the program is stored in the system memory of the local host. To be made. When the encrypted file is opened by a browser for viewing, the file is dynamically decrypted by the local server program.
In other words, the encryption operation method of the encryption software and the decryption operation method of the local server software have a corresponding relationship, and the decryption processing for each file to be viewed can be realized offline, thereby achieving the purpose of local file security. be able to.
Further, this method can be applied not only to the means for encrypting / decrypting files to be browsed offline, but also to files of general-purpose formats other than the network browsing format.

  According to the present invention, when browsing a file encrypted by the encryption software, the local server program is first executed to store the local server program in the system memory of the local host. Since the encryption software and the encryption / decryption operation method of the local server program have a corresponding relationship, the file can be decrypted dynamically at the time of browsing, thereby achieving the purpose of local file security. Can do.

Embodiments according to the file encryption / decryption method of the present invention will be described below. First, a first embodiment will be described with reference to FIGS. FIG. 2 is a diagram showing a system configuration example for explaining the file encryption / decryption method of the present invention. FIG. 3 is a flowchart for explaining the processing steps of the file encryption / decryption method according to the first embodiment.
As shown in FIG. 2, a file 21 downloaded via the Internet or the like is stored in a storage medium 23 of a local host, for example, a disk, an optical disk, or various other storage media. The file 21 is encrypted with encryption software before being transmitted to the local host, and is converted into a package file (for example, an executable file).

In the package file, local server software 25 is packaged together with the file 21.
That is, the file 21 downloaded via the Internet or the like is encrypted by the encryption software, and then is combined with the local server software 25 into one package file and stored in the storage medium 23.
The local server software 25 has a local server program for performing decryption processing on the encrypted file, and corresponds to the encryption operation method of the encrypted software.
On the local host, the package file, that is, the archive file can be expanded, or can be taken out of the local host as a package file in that state.

  When the package file is expanded on the local host, the encrypted file 21 and local server software 25 are extracted. Then, the local server software 25 is executed. The local server software 25 generates a local server program in the system memory of the local host and stores it in the system memory as a resident program (daemon).

When the user 29 tries to open the encrypted file 21 via the browser 27, the browser 27 cooperates with the local server program, and the encrypted file 21 is decrypted in the local server program. The decrypted file 21 is opened by the browser 27 so that it can be viewed on the display.
Note that the function of the cache means of the local host is also stopped in order to avoid a copy remaining in the storage medium of the local host.

The file 21 is, for example, a web file format, for example, a network accessible format such as an HTML or XML file. The browser 27 is, for example, a web browser such as Microsoft Internet Explorer (IE) or Netscape.
In addition, when the file is encrypted with the encryption software, the file is encrypted based on the change value obtained with the password to be a package file. In the step of opening and expanding the package file, the file is opened only by correctly inputting the password.

Next, processing steps in the first embodiment will be described based on the flowchart of FIG.
Based on FIG. 3A, a process from encrypting the file 21 to storing it in the storage medium 23 will be described.
First, for example, a file 21 of a web file format such as HTML or XML is generated. Note that a general-purpose file, for example, a character file (* .txt), a PDF file, an image file (* .jpg, * .gif), or a character file on various set software (step) S31).
Next, the encryption software is executed, the user 29 sets a password, and the file 21 is encrypted according to the change value obtained by this password (step S32).
Then, a package file including the encrypted file 21 and the local server software 25 is generated (step S33).
By performing the encryption process based on the password and generating the package file in this way, it is necessary to input the password accurately when the package file is expanded, and security can be ensured.
The package file may be an executable file (* .exe) in the Windows environment, but is not limited to this.
Next, this package file is stored in the storage medium 23 (step S34), and the process of the encryption method is terminated. As described above, the package file may be copied and stored in the storage medium 23 of the local host, but may be directly transmitted to a user who needs to browse.

Next, the process of decrypting the encrypted file 21 will be described with reference to FIG. 3B.
First, in the local host, a package file including the encrypted file 21 and the local server software 25 is opened (step S35). In the step of opening the package file, authentication is performed by inputting a password set at the time of file encryption, and the package file is opened.
Then, the local server software 25 is generated (step S36), and a local server program is generated as a resident memory program in the system memory of the local host. The decryption operation method of the local server software 25 corresponds to the encryption operation method of the encryption software.
Also, in this step, the function of the cache means of the local host is stopped in order to avoid a copy remaining in the host storage medium.

And the browser 27 which is a web browser is opened (step S37). When the file format of the file 21 is not the web file format, the browser 27 is not limited to the web browser, and can be replaced with browsing software corresponding to the file format. That is, even in that case, the browser 27 as the browsing software and the local server program are linked.
Thereafter, when browsing the encrypted file 21, the browser 27 and the local server program cooperate with each other, and the file 21 is dynamically decrypted by the local server program.
For example, when viewing a file in the web file format, in order to ensure security, only the currently viewed contents are decrypted, and not all the files are decrypted simultaneously. For example, when the next page is entered by a hyperlink, the page is decrypted and the cache means of the local host is deactivated, so that no copy remains (step S38).
In this way, the decoding process is completed.

Next, a second embodiment will be described based on FIGS. FIG. 4 is a flowchart for explaining the processing steps of the file encryption / decryption method according to the second embodiment.
In the first embodiment, the package file includes the encrypted file 21 and the local server software 25. However, in the second embodiment, the local server software 25 is included. Is different from the first embodiment in that it is not included in the package file.
In this case, the local server software 25 is always stored in the storage medium of the local host. Only before opening the encrypted file 21, the local server software 25 is executed, and the local server program resides in the system memory. For this reason, when the file 21 is opened by the browser 27, the browser 27 and the local server program cooperate with each other so that the file 21 can be dynamically decrypted and browsed.

Next, processing steps in the second embodiment will be described based on the flowchart of FIG.
Based on FIG. 4A, a process until the file 21 is encrypted and stored in the storage medium will be described.
First, for example, a file 21 of a web file format such as HTML or XML is generated. Note that a general-purpose file, for example, a character file (* .txt), a PDF file, an image file (* .jpg, * .gif), or a character file on various set software (step) S41).
Next, the encryption software is executed, the user 29 sets a password, and the file 21 is encrypted according to the change value obtained by this password. Then, after encrypting the file 21, a package file is generated (step S42).
By performing the encryption process based on the password and generating the package file in this way, it is necessary to input the password accurately when the package file is expanded, and security can be ensured.
The package file does not need to be an executable file (* .exe) in the Windows environment, but may be a dedicated unique format, for example, a file of (* .pkg), but is not limited thereto. Is not to be done.
Next, the package file is stored in the storage medium (step S43), and the encryption process is terminated.

Next, a process of decrypting the encrypted file 21 will be described with reference to FIG. 4B.
First, the local server software 25 is executed on the local host (step S44). Then, a local server program is generated as a resident memory program in the system memory in the local host. The decryption operation method of the local server software 25 corresponds to the encryption operation method of the encryption software.
Further, in this step, the function of the cache means of the local host is stopped at the same time in order to avoid a copy remaining in the storage medium of the local host.

And the browser 27 which is a web browser is opened (step S45).
When browsing the file 21 via the browser 27 in the local host, or when browsing the package file of the file 21 by the browser 27, in the process of opening the package file, an operation of expanding and decrypting the archive file is performed. is necessary. At this time, it is opened by inputting an accurate password in the authentication process.
When the file format of the file 21 is not the web file format, the browser 27 is not limited to the web browser, and can be replaced with browsing software corresponding to the file format. That is, even in that case, the browser 27 as the browsing software and the local server program are linked.
Thereafter, when the encrypted file 21 is opened through the browser 27 (step S46), the browser 27 and the local server program cooperate with each other, and the file 21 is dynamically decrypted by the local server program (step S47). ).

It should be noted that when a file is dynamically decrypted by a local server program, for example, when viewing a file in the web file format, in order to ensure security, only the content currently being viewed is decrypted. There is no decryption at the same time. In addition, since the local host cache means stops functioning, no copy remains.
In this way, the decoding step of the second embodiment is completed.

  As described above, according to the embodiment of the present invention described above, it is possible to cope with not only the file format that can be browsed offline but also the encryption / decryption processing of other general-purpose files. A file encryption / decryption method capable of establishing security can be provided.

  The specific configurations disclosed in the first and second embodiments described above are merely preferred examples, and do not limit the scope of the claims of the present invention. Needless to say, structural changes in implementation of the contents and the like shown in the specification and drawings are included in the scope of the claims of the present invention.

It is a figure which shows the structure which browses the network file of a prior art. FIG. 2 is a diagram showing a system configuration example for explaining the file encryption / decryption method of the present invention. FIG. 3A is a flowchart for explaining the processing steps of the file encryption method according to the first embodiment. FIG. 3-B is a flowchart for explaining the processing steps of the file decryption method according to the first embodiment. FIG. 4-A is a flowchart for explaining the processing steps of the file encryption method according to the second embodiment. FIG. 4-B is a flowchart for explaining the processing steps of the file decryption method according to the second embodiment.

Explanation of symbols

11 Database 13 Server 15 Internet 17 Storage Medium 18 Computer 19 Browser 21 File 23 Storage Medium 25 Local Server Software / Program 27 Browser 29 User

Claims (15)

A file encryption / decryption method that dynamically decrypts an encrypted file when browsing,
Encrypting the file with encryption software;
Generating a package file including local server software and the encrypted file;
Executing on the local host and unpacking the package file;
Executing the local server software to generate a local server program and storing it in a system memory of the local host;
And a step of dynamically decrypting the file by the local server program when browsing the encrypted file in a browser.   2. The file encryption / decryption method according to claim 1, wherein the browser is a web browser.   3. The file encryption / decryption method according to claim 1, wherein the file is a file in a web file format.   The file encryption / decryption method according to any one of claims 1 to 3, wherein the package file is an executable file.   5. The process according to claim 1, wherein in the step of decrypting the encrypted file, the file designated through the browser is decrypted by the local server program. File encryption / decryption method.   6. The file encryption / decryption method according to claim 1, wherein the function of the cache unit of the local host is stopped in the step of generating the local server program.   7. The method of encrypting a file with the encrypted software, wherein an encryption operation method of the encrypted software corresponds to a decryption operation method of the local server software. The file encryption / decryption method according to the above.   The file encryption / decryption method according to any one of claims 1 to 7, wherein in the step of encrypting the file by the encryption software, the file is encrypted by a change value obtained by a password. A file encryption / decryption method that dynamically decrypts an encrypted file when browsing,
Encrypting the file with encryption software;
Generating a package file containing the encrypted file;
Storing the package file in a storage medium;
Executing local server software on the local host to generate a local server program;
Opening a browser linked to the local server program;
A file encryption method comprising: expanding the package file when the browser browses the encrypted file, and dynamically decrypting the encrypted file by the local server program. -Decoding / decoding method.   The file encryption / decryption method according to claim 9, wherein the browser is a web browser.   The file encryption / decryption method according to claim 9 or 10, wherein the file is a file in a web file format.   12. The process according to claim 9, wherein in the step of decrypting the encrypted file, the file designated via the browser is decrypted by the local server program. File encryption / decryption method.   13. The file encryption / decryption method according to claim 9, wherein the function of the cache unit of the local host is stopped in the step of generating the local server program.   14. The method according to claim 9, wherein in the step of encrypting the file by the encrypted software, an encryption operation method of the encrypted software corresponds to a decryption operation method of the local server software. A method for encrypting and decrypting a file by using the local server software described in the above.   15. The file encryption / decryption method according to claim 9, wherein in the step of encrypting the file by the encryption software, the file is encrypted by a change value obtained by a password.

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