JPH05233460A - File protection system - Google Patents

Abstract

PURPOSE:To encipher a file placed on an external device at all times by providing means which decipher the data of an enciphered file among memory mapped files by using an enciphering key when the data are transferred from the external storage to a main memory and enciphers the data by using the enciphering key when the data are put back to the external storage. CONSTITUTION:This system is equipped with a means which inputs the enciphering key from outside and records it as an enciphering key 13a in memory mapped file information 13, the deciphering means 15 which deciphers the data, block by block, by using the enciphering key 13a in the memory mapped file information 13 when the enciphered file data 10c are transferred from the disk 10 the main memory 12, and the enciphering means 16 which enciphers the file data on the main memory 12, block by block, by using the enciphering key 13a when the file data transferred to the main memory 12 are put back onto the disk 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file protection method suitable for application to an electronic computer system that handles files with high confidentiality and for preventing information leakage of files, and more particularly to a technique of memory mapped files. A file protection method that enables high-speed access and file protection of highly confidential file data at the same time by using.

[0002]

2. Description of the Related Art In recent years, an electronic computer system is indispensable for building a corporate information system, and there are more and more opportunities to hold important confidential information. Computer crimes such as hackers and viruses are increasing as social structure becomes more dependent on electronic computers. For this reason, there is a strong demand for information protection of highly confidential files. On the other hand, electronic computers are becoming more and more versatile, and the demand for high-speed processing never stops.

Therefore, memory mapped file technology, which enables high-speed file access by directly mapping a file onto an address space by taking advantage of the recent decrease in memory price, has been emphasized.

In order to protect a highly confidential file, it is necessary to encrypt the file, and in order to access the file at high speed, it is necessary to use the technique of the memory mapped file.

However, the encrypted file cannot be accessed directly by using the memory-mapped file technique, and the encrypted file is once decrypted on the external storage (on the disk). I had to create a file and access it using the technology of memory-mapped files. Therefore, after all, a highly confidential file exists on the disk in a non-encrypted form, which poses a problem of risk of information leakage.

[0006]

As described above, the conventional file protection method is incompatible with the technology of the memory-mapped file for accessing the file at high speed. It is difficult to apply it to the above technology, and after all, there is a problem that a highly confidential file exists on the disk in a non-encrypted form and is exposed to a risk of information leakage.

The present invention has been made in view of the above situation,
Protecting files and high-speed processing can be achieved at the same time by using the memory-mapped file technology to access files at high speed without making decrypted copies while keeping highly confidential files encrypted. The purpose is to provide a file protection method that can be performed.

[0008]

According to the file protection method of the present invention, a file on an external storage device is mapped onto the address space of a process, and a file is directly accessed from a program on a main memory. The means to identify whether the map target file to be mapped to is encrypted or not, and the encryption key is input from the outside when the map target file is encrypted by the same means, and the corresponding file is mapped. Means for holding the encryption key, and when the data of the encrypted file is transferred from the external storage device to the main memory, the stored encryption key is used to store the data. A means for decoding in a predetermined data amount unit set based on a data exchange unit between devices, for example, a block unit, and data of a file on the main memory When returned to the external storage device, using the encryption key the holding, characterized by comprising and means for encrypting the data in block units.

Further, the file protection system of the present invention maps a file on a remote computer connected by a network onto the address space of a process on the local computer, and makes it a memory-mapped file for direct access from the program. In the above, means for identifying whether or not the file to be mapped on the main memory is encrypted,
By inputting the encryption key when identifying that the file is encrypted by the same means, holding the encryption key while the corresponding file is mapped, and the data of the encrypted file is remotely After transferring from the electronic computer to the local electronic computer, means for decrypting the data in block units using the stored encryption key and means for returning the decrypted file data from the local electronic computer to the remote electronic computer At this time, a means for encrypting data in block units using the stored encryption key is provided.

[0010]

In the above structure, when the encrypted file is mapped on the main memory, the encryption key information is input from the outside and recorded as the encryption key in the memory mapped file information. After that, when transferring the encrypted file data from the external storage device to the main memory, the encrypted file data is decrypted in block units using the encryption key included in the memory-mapped file information. To do. or,
When returning the data of the file on the main memory to the external storage device, the data of the file is encrypted in block units using the encryption key. As a result, the file stored in the external storage device is always encrypted file data,
Therefore, it is possible to access files at high speed by using memory-mapped file technology without encrypting a highly confidential file and making a decrypted copy, enabling simultaneous protection of files and high-speed processing. Become.

Further, in the file protection system of the present invention, a file on a remote computer connected by a network is mapped in the address space of a process on the local computer to directly access the file. It is also applied to the file mechanism. In this case, when the file to be mapped on the main memory of the local computer is encrypted, the data of the encrypted file is transferred from the remote computer to the local computer. After that, the above data is decrypted in block units using an encryption key inputted from the outside. Also, when returning the data of the file on the main memory of the local computer from the local computer to the remote computer, the data of the file is encrypted in block units using the above encryption key,
Return to the remote computer. Thus, the encrypted data is decrypted after being transferred via the network, and the decrypted data is encrypted before being transferred via the network. It is possible to prevent information leakage from data being transferred on the network. Further, only the encrypted file data is always stored in the file memory (external storage device) of the remote computer. Therefore, it is possible to access files at high speed by using the technology of memory-mapped files without encrypting the highly confidential files and making a decrypted copy. ..

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Here, the file 10a on the disk 10 serving as an external storage device is set to the address space 11a of the process 11.
11b is mapped. File 10a above
Is composed of file information 10b and file data 10c. In the file information 10b, encryption information 1 indicating whether or not the file data 10c is encrypted
0d is included.

The encrypted file is stored in the main memory 12
In the case of attempting to map to the upper side, the encryption key is input from the terminal device 11c, and the obtained encryption key information is recorded in the memory mapped file information 13 as the encryption key 13a.

As a terminal device for inputting the encryption key,
In addition to the user's terminal device, an operator console or the like can be considered. The encryption key can be input from a device other than the terminal device, and for example, the encryption key may be embedded in the program.

When the process 11 accesses the file mapped on the main memory 12 and transfers the encrypted file data 10c from the disk 10 to the main memory 12, the encrypted file data 10c is transferred. Encryption key 13a in the memory-mapped file information 13
Is used to decode in block units.

That is, the data of the file to be mapped in the main memory 12 is encrypted (indicates that the encrypted information 10d included in the file information 10b of the file to be mapped is encrypted in the file information 10b). When the encrypted file data 10c is transferred from the disk 10 to the main memory 12, the data is blocked by the decryption means 15 using the encryption key 13a in the memory-mapped file information 13. Decoded in units.

Conversely, from the disk 10 to the main memory 12
The decrypted data that had been transferred to
Also when returning to 0, the same data is encrypted in block units using the encryption key 13a.

That is, the file data decrypted by the decryption means 15 and transferred to the main memory 12 are stored in the disc 1
When returning to 0, the file data on the main memory 12 is encrypted by the encryption means 16 in block units using the encryption key 13a. FIG. 2 is a flow chart showing the flow of the mapping process for mapping the encrypted file on the main memory 12 in the embodiment shown in FIG.

In FIG. 2, A1 is a judgment step for checking whether or not the file to be mapped on the main memory 12 is encrypted. If it is determined that the data is encrypted, the processes of steps A2 and A3 are performed, and then the process of step A4 is performed. If not encrypted, steps A2 and A3 are not performed, but step A4 is performed.

A2 is a processing step for inputting the encryption key 13a, and A3 is a processing step for recording the input encryption key 13a in the memory-mapped file information 13. A4
Is a processing step for performing a normal memory-mapped file mapping process.

FIG. 3 is a process for moving the data of the encrypted file mapped on the main memory 12 from the disk 10 to the main memory 12 in the embodiment shown in FIG. 1 (page-in process of memory-mapped file). ) Is a flowchart showing the flow of FIG.

In FIG. 3, B1 is a step of moving the page of the file mapped on the main memory 12 from the disk 10 to the main memory 12. B2 is a judgment step for checking whether or not the data of the file mapped on the main memory 12 is encrypted.

If the data of the mapped file is encrypted, the process of step B3 is performed before the process of step B4. If the data of the mapped file is not encrypted, the process of step B3 is performed and the process of step B4 is performed.

B3 is a processing step of decrypting the data in the page to be transferred from the disk 10 to the main memory 12 by using the encryption key 13a, and B4 is a processing step of performing page-in processing of a normal memory-mapped file. ..

FIG. 4 is a process for returning the data of the encrypted file mapped on the main memory 12 from the main memory 12 to the disk 10 in the embodiment shown in FIG. 1 (page-out process of the memory-mapped file). 2) is a flowchart for explaining the flow of FIG. In FIG. 4, C1 is a processing step for checking whether or not the file mapped on the main memory 12 is the data of the file to be encrypted.

If it is the data of the file to be encrypted, the process of step C2 is performed and then step C
Processes C3 and C4 are performed. If the file data is not encrypted, the process of steps C3 and C4 is performed without performing the process of step C2.

C2 is a processing step of encrypting the data in the page returned from the main memory 12 to the disk 10 by using the encryption key 13a, and C3 returns the page of the file mapped on the main memory 12 to the disk 10. It is a step. C4 is a processing step for performing page-out processing of a normal memory-mapped file.

In the embodiment shown in FIGS. 1 to 4,
When mapping an encrypted file on the disk 10 onto the main memory 12, an encryption key is input from the terminal device 11c, and the input encryption key information is stored in the memory-mapped file information 13 as the encryption key 13a. To record as.

That is, in the mapping process for mapping the encrypted file on the main memory 12 at this time, it is checked whether or not the file to be mapped on the main memory 12 is encrypted (step A1 in FIG. 2). ..

At this time, the encrypted information 10d included in the file information 10b of the file to be mapped on the main memory 12
Indicates whether or not the corresponding file information 10b is encrypted.

Here, when the data of the file to be mapped on the main memory 12 is encrypted, the encryption key information input in the process of inputting the encryption key is used as the encryption key 13a in the memory-mapped file information 13. After recording (steps A2 and A3 in FIG. 2), a normal memory-mapped file mapping process is performed (step A4 in FIG. 2).

Further, when the data of the file to be mapped on the main memory 12 is not encrypted, the above-mentioned encryption key processing (steps A2 and A3 in FIG. 2) is not performed, and a normal memory-mapped file mapping is performed. Processing is performed (step A4 in FIG. 2).

When the process 11 accesses the file mapped on the main memory by the above mapping process and transfers the data of the file from the disk 10 to the main memory 12, if the corresponding file data 10c is encrypted, The encrypted file data 10c is decrypted using the encryption key 13a in the memory mapped file information 13.

That is, when the file data on the disk 10 is transferred to the main memory 12, it is judged whether or not the data of the file read from the disk 10 is encrypted (step B1 in FIG. 3).

Here, when the data of the file mapped on the main memory is encrypted, the encrypted file data 10c is transferred from the disk 10 to the main memory 12.
When moving up, the data is
It is decrypted in block units using the encryption key 13a in the memory-mapped file information 13 (steps B2 and B in FIG. 3).
3), the page-in process of the memory-mapped file is performed through the decryption process (step B in FIG. 3).
4).

Next, even when the decrypted data transferred from the disk 10 to the main memory 12 is returned to the disk 10, the decrypted data is the encryption key 13a.
Is encrypted using.

That is, when the file data in the main memory 12 is returned to the disk 10, it is judged whether or not the file mapped in the main memory 12 is the data of the file to be encrypted (step C1 in FIG. 4). ).

Here, when the data is the data of the file to be encrypted, the data in the page returned from the main memory 12 to the disk 10 is encrypted by the encryption means 16 using the encryption key 13a (step C2 in FIG. 4). C3), the page-out process of the memory-mapped file is performed through the encryption process (step C4 in FIG. 4).

By such processing control of the file, the encrypted file is not decrypted on the disk 10, and therefore, a method such as a "Trojan horse" (true data cannot be seen as a file (Hidden state)
As a result, even if the file itself is stolen due to an illegal copy or the like, it is possible to prevent leakage of confidential information unless the encryption key is stolen.

When the page-in / page-out process of the file mapped on the main memory 12 occurs frequently, the overhead of encryption / decryption of the file data increases, but in recent years, since the memory price has decreased, Using large amounts of memory eliminates this problem. FIG. 5 is a block diagram showing another embodiment of the present invention.

Here, the file 20a stored in the disk 20 on the remote node 28 is converted into the portion 21 of the address space 21a of the process 21 on the local node 27.
The example which maps to b is shown. At this time, the file 20a is assumed to be composed of file information 20b and file data 20c. The file information 20b includes the encrypted information 20d and the file data 20c.
Indicates whether or not is encrypted.

When an encrypted file is to be mapped onto the memory 22, the terminal 21c is requested to provide an encryption key, and the obtained encryption key information is encrypted in the memory-mapped file information 23. It is recorded as the key 23a.
Reference numeral 29 is a network for the local node 27 and the remote node 28 to communicate with each other.

The process 21 accesses the file mapped on the memory 22, and the encrypted file data is transmitted via the network 29 to the remote node 2.
8 disk 20 to local node 27 memory 22
When the file data 20c is transferred to the local node 27, the file data 20c is sent to the local node 27 via the network 29 and then decrypted by the decryption means 25 in block units using the encryption key 23a.

On the contrary, the remote node 28
When the data that has been transferred from the disk 20 of FIG. 2 to the memory 22 of the local node 27 is returned to the disk 20 of the remote node 28 via the network 29, the file data is transferred to the remote node 28 via the network 29. At the time of sending, the encryption means 26 re-encrypts in block units using the encryption key 23a.

Thus, the encrypted data is
Decrypted after transfer via network 29,
Further, since the decrypted data is encrypted before being transferred via the network 29, it is possible to prevent information leakage from the data transferred on the network 29.

[0046]

As described in detail above, according to the file protection system of the present invention, a file in an external storage device is mapped in the address space of a process, and a file is directly accessed from a program in a memory-mapped file. ,
A means to identify whether the map target file to be mapped on the main memory is encrypted, and an encryption key is input from the outside when the map target file is identified to be encrypted by the same means. While the files are being mapped
A means for holding the encryption key, and when the data of the encrypted file is transferred from the external storage device to the main memory, the stored encryption key is used to transfer the data to a predetermined data transfer unit (for example, a block). Means to decrypt in units),
When the data of the file on the main memory is returned to the external storage device, the encryption key is held and the data is encrypted in block units. Highly encrypted files remain encrypted,
Memory-mapped file technology can be used for fast access without making a decrypted copy, and file protection and high-speed processing can be realized at the same time.

According to the file protection system of the present invention,
A file on a remote computer connected by a network is mapped on the address space of a process on a local computer, and in a memory-mapped file that is accessed directly from a program, the file mapped on the main memory is encrypted. And a means for inputting an encryption key when the file is encrypted by the same means and holding the encryption key while the corresponding file is mapped. , Means for decrypting the data of the encrypted file from the remote computer to the local computer and then decrypting the data in block units using the retained encryption key, and the decrypted data of the file When you transfer the data from the local computer to the remote computer, you can use the encryption key held above to copy the data. By was provided to become a configuration and means for encrypting using the clock unit, the data being encrypted is decoded after transferring via the network,
Moreover, since the decrypted data is encrypted before being transferred via the network, it is possible to prevent information leakage from the data being transferred on the network. Also, since only the encrypted file data is always stored in the file memory (external storage device) of the remote computer, a decrypted copy is made with the highly confidential file encrypted. Without using the memory-mapped file technology, high-speed access can be achieved, and file protection and high-speed processing can be realized at the same time.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining a process of mapping an encrypted file on a memory in the embodiment of FIG.

FIG. 3 is a flowchart for explaining a process of moving data in an encryption target file mapped on a memory from a disk to a memory in the embodiment of FIG.

FIG. 4 is a flowchart for explaining a process of returning the data in the encrypted file mapped on the memory from the memory to the disk in the embodiment of FIG.

FIG. 5 is a block diagram showing the configuration of another embodiment of the present invention.

[Explanation of symbols]

10 ... Disk, 10a ... File, 10b ... File information, 10c ... File data, 10d ... Encryption information,
11 ... Process, 11a ... Address space, 11b ... File mapping portion, 11c ... Terminal device, 12 ...
Memory, 13 ... Memory mapped file information, 13a ...
Encryption key, 14 ... encryption key input means, 15 ... decryption means, 1
6 ... Encryption means, 20 ... Disk, 20a ... File,
20b ... file information, 20c ... file data, 20
d ... Encrypted information, 21 ... Process, 21a ... Address space, 21b ... File mapping portion, 21c ...
Terminal device, 22 ... Memory, 23 ... Memory mapped file information, 23a ... Encryption key, 24 ... Encryption key input means, 25
Decryption means, 26 encryption means, 27 local node, 28 remote node, 29 network.

Claims (2)

[Claims] 1. In a memory-mapped file in which a file in an external storage device is mapped in the address space of a process and a program directly accesses the file, is the map target file to be mapped in the main storage encrypted? An encryption key is input from the outside when a means for identifying whether or not the file to be mapped is encrypted is identified by the means, and the encryption key is held while the corresponding file is mapped. Means, means for decrypting the data of the encrypted file from the external storage device to the main memory by using the held encryption key, and data of the file on the main memory. A file protection system, characterized in that it has means for encrypting the same data using the encryption key stored therein when returning to the external storage device. 2. A memory-mapped file in which a file on a remote computer connected by a network is mapped in the address space of a process on a local computer, and the file is directly accessed from a program. Means to identify whether or not the file is encrypted, and when the same means identifies that the file to be mapped is encrypted, the encryption key is input from the outside and the corresponding file is A means for holding the encryption key while it is being mapped, and transferring the data of the encrypted file from the remote computer to the local computer, and then decrypting the data using the held encryption key. And the same data when returning the data of the decrypted file from the local computer to the remote computer. File protection method characterized by comprising comprises a means for encrypting using the encryption key that is the holding of data.