JP2017010209A - Storage device, data protection method, and data protection program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage device configured to improve processing speed for data protection, while ensuring safety, a data protection method, and a data protection program.SOLUTION: A storage device 1 includes: an exchange unit 11 which controls necessary data to exist in an access area as a result of exchange processing which exchanges multiple pieces of data between the access area and a storage area which is different from the access area; and an access unit 12 which accesses the whole of the access areas simultaneously, to acquire a data group including the necessary data. The exchange unit 11 executes exchange processing between an inside access area constituting an outside access area, and an inside storage area, after executing exchange processing between the outside access area and an outside storage area. The access unit 12 accesses the inside access area.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for protecting data stored in a storage device.

  Conventionally, when a computer executes an application, various types of data are expanded on a memory and accessed appropriately by the application. When these data are secret information that should be protected from a third party, a method for protecting the data by concealing the access pattern to the data is required.

  Non-Patent Document 1 proposes memory protection using Obvious RAM. However, since it is necessary to periodically rearrange all data in order to ensure safety, the overhead is large. On the other hand, for example, Patent Literature 1 and Non-Patent Literature 2 propose a method for reducing the load of data rearrangement processing by using access history and realizing high speed.

JP 2013-246678 A

Oded Goldrich and Rafir Ostrovsky, “Software protection and simulation on oblivious RAMs,” J. et al. ACM, 43 (3): 431-473, 1996. Yuto Nakano, Carlos Cid, Shinsaku Kimoto, and Yutaka Miyake, “Memory Access Pattern Protection for Resource-constrained Devices 2, CAD12.

  However, since overhead reduction and safety improvement are usually in a trade-off relationship, even with the above-described method, overhead reduction was not sufficient to ensure safety.

  An object of the present invention is to provide a storage device, a data protection method, and a data protection program capable of improving the processing speed for data protection while ensuring safety.

  The storage device according to the present invention is an exchange that controls so that necessary data exists in the access area as a result of an exchange process for exchanging a plurality of data between the access area and a storage area different from the access area. And an access unit that obtains a data group including the necessary data by accessing the entire access area at once, and the exchange unit exchanges the exchange between the outer access area and the outer storage area. After performing the processing, the exchange processing is performed between the inner access area and the inner storage area constituting the outer access area, and the access unit accesses the inner access area.

  The exchange unit stratifies the outer access area into the inner access area and the inner storage area over a plurality of hierarchies, and after repeating the exchange process by the number of the plural hierarchies, the access unit The innermost access area of the plurality of hierarchies may be accessed.

  The exchange unit stores a history of data moved from the access area to the storage area in the history area, and stores at least one piece of data moved from the storage area to the access area in the exchange process in the history area. You may select from the data that has been recorded.

  When the exchange unit performs the exchange process, if the necessary data is in the access area, the exchange unit randomly selects data from the storage area as data to be exchanged, and randomly selects data from the history area. May be selected.

  When the exchange unit performs the exchange process, if the necessary data is in the storage area and the history area, the exchange unit randomly selects data to be exchanged from the storage area together with the necessary data. May be selected.

  When the exchange unit performs the exchange process, if the necessary data is in the storage area and is not in the history area, the exchange unit randomly selects data to be exchanged from the history area together with the necessary data. May be selected.

  The data protection method according to the present invention is a data protection method using a storage device, and as a result of an exchange process for exchanging a plurality of data between an access area and a storage area different from the access area, the access area In the exchange step, the exchange step for controlling the necessary data to be present in the access area, and the access step for obtaining the data group including the necessary data by accessing the entire access area at once. After performing the exchange process between the outer access area and the outer storage area, the exchange process is performed between the inner access area and the inner storage area constituting the outer access area. In the access step, the inner access area Access to.

  A data protection program according to the present invention causes the storage device to execute the data protection method.

  According to the present invention, the processing speed for data protection can be improved while ensuring safety.

It is a figure which shows the function structure of the memory | storage device which concerns on embodiment. It is a figure which shows the structure of the storage area which concerns on embodiment. It is a flowchart which shows the data protection method which concerns on embodiment. It is a figure which shows the 1st pattern of the exchange process which concerns on embodiment. It is a figure which shows the 2nd pattern of the exchange process which concerns on embodiment. It is a figure which shows the 3rd pattern of the exchange process which concerns on embodiment. It is a figure which illustrates the mode of a data movement when the two-step exchange process which concerns on embodiment is performed. It is a figure which illustrates the mode of the movement of data when the one-step exchange process is performed.

Hereinafter, an example of an embodiment of the present invention will be described.
FIG. 1 is a diagram illustrating a functional configuration of the storage device 1 according to the present embodiment.

The storage device 1 includes an exchange unit 11 and an access unit 12.
As a result of exchange processing for exchanging a plurality of (for example, two) data between the access area and a storage area different from the access area, the exchange unit 11 has necessary data requested by the application in the access area. Control to do.
The access unit 12 accesses the entire access area at a time and acquires a data group including necessary data.

The storage device 1 rearranges the data stored in the storage area 10 by the function of each of these units, and then accesses (reads or writes) a plurality of data at a time to obtain an access pattern from a third party. Reduce data risk and protect data.
Next, a data protection method in the storage device 1 will be described in detail.

FIG. 2 is a diagram illustrating a configuration of the storage area 10 to be controlled by the storage device 1 according to the present embodiment.
The storage area 10 is divided into an outer access area A1 and an outer storage area B1, and an outer history area C1 is further provided. Necessary data requested by the application exists in either the outer access area A1 or the outer storage area B1 at the time of the request.
Here, the outer history area C1 is an area for storing a history of data moved from the outer access area A1 to the outer storage area B1 by an exchange process described later.

The outer access area A1 is divided into an inner access area A2 and an inner storage area B2, and an inner history area C2 is further provided.
The inner history area C2 is an area for storing a history of data moved from the inner access area A2 to the inner storage area B2 by an exchange process described later.

The history area (C1 or C2) stores a pointer to actual data, that is, the address of the storage area (B1 or B2) where the actual data is stored. The access area (A1 or A2) may also be configured to store a pointer to the storage area (B1 or B2).
The history area (C1 or C2) may be an area in which a finite number of histories are stored, and is deleted in order from the oldest data.

  Here, the inner access area A2 may be further divided into an inner access area and a storage area, and similarly, the hierarchization for dividing the outer access area A1 into the inner access area A2 and the inner storage area B2 is divided into n layers. You may go over. In this case, the exchange unit 11 sequentially repeats the exchange process from the outside by the number (n) of layers, and the access unit 12 accesses the innermost access area.

  In this embodiment, in order to simplify the description, the storage area 10 is assumed to have a two-layer structure. That is, the exchange unit 11 performs the exchange process between the outer access area A1 and the outer storage area B1, and then performs the exchange process between the inner access area A2 and the inner storage area B2. Thereafter, the access unit 12 accesses the entire inner access area A2.

FIG. 3 is a flowchart showing a data protection method in the storage device 1 according to the present embodiment.
In step S1, the exchange unit 11 performs an exchange process between the outer access area A1 and the outer storage area B1, and exchanges data so that necessary data exists in the outer access area A1.

  In step S2, the exchange unit 11 performs an exchange process between the inner access area A2 and the inner storage area B2, and exchanges data so that necessary data exists in the inner access area A2.

  In step S3, the access unit 12 accesses the inner access area A2 and acquires a data group including necessary data.

  The exchange process is divided into the following three patterns depending on in which area the necessary data exists. Note that the exchange process targets the access area (A1 or A2), the storage area (B1 or B2), and the history area (C1 or C2) in the same hierarchy. A, a storage area B, and a history area C.

(1) The necessary data is in the access area A.
(2) The necessary data is in the storage area B and in the history area C.
(3) The necessary data is in the storage area B and not in the history area C.

  The exchange unit 11 selects at least one of data to be moved from the storage area B to the access area A from the data stored in the history area C in each pattern of the exchange process. In the present embodiment, the exchange unit 11 moves two data including the data stored in the history area C from the storage area B to the access area A, and instead of these, two data are transferred from the access area A to the storage area B. Move data.

FIG. 4 is a diagram showing a first pattern of exchange processing according to the present embodiment.
When the necessary data X is in the access area A, the exchange unit 11 randomly selects the data Y from the storage area B and the data Z from the history area C as data to be exchanged.

FIG. 5 is a diagram showing a second pattern of the exchange processing according to the present embodiment.
When the necessary data X is in the storage area B and in the history area C, the exchange unit 11 randomly selects data Y from the storage area B together with the necessary data X as data to be exchanged.

FIG. 6 is a diagram showing a third pattern of exchange processing according to the present embodiment.
When the necessary data X is in the storage area B and not in the history area C, the exchange unit 11 randomly selects data Z from the history area C together with the necessary data X as data to be exchanged.

  Note that the exchange unit 11 performs control so that two data moving from the storage area B to the access area A do not overlap in each pattern of the exchange process. Further, two pieces of data to be moved from the access area A to the storage area B may be selected at random except for necessary data.

  When such an exchange process is performed in two stages, after the data is exchanged between the outer access area A1 and the outer storage area B1 by each pattern in the first exchange process, the necessary data is exchanged by the second exchange process. Depending on the location, data is further exchanged in each pattern.

FIG. 7 is a diagram illustrating a state of data movement when the two-stage exchange process according to the present embodiment is performed.
For example, when the necessary data a is in the outer storage area B1, the necessary data a is moved to the inner storage area B2 or the inner access area A2 in the outer access area A1 together with the other data x by the first exchange process.

When the necessary data a moves to the inner storage area B2 (a), the necessary data a moves again to the inner access area A2 together with other data y by the second exchange process.
On the other hand, when the necessary data a moves to the inner access area A2 (b), the necessary data a is not moved by the second exchange process, and other data y and z move to the inner access area A2. .

  Thus, the necessary data a in the outer storage area B1 may move to the inner access area A2 via the inner storage area B2, or may move directly to the inner access area A2. The necessary data a may exist in the outer access area A1 before the exchange process. In particular, when the necessary data a is frequently accessed, there is a high possibility that the necessary data a remains in the inner access area A2 or the outer access area A1 than other data.

  Therefore, the movement pattern of the necessary data a is diversified by a plurality of exchange processes. As a result, even if the data movement by the first exchange process (broken line) and the data movement by the second exchange process (solid line) are analyzed, for example, the continuous movement as shown in FIG. The occurrence frequency decreases, and the risk that the necessary data a is specified by a third party is reduced.

FIG. 8 is a diagram exemplifying how data is moved when one-stage exchange processing is performed for comparison with the present embodiment.
Since the size of the access area A is very small compared to the size of the storage area B, in many cases, the necessary data a is moved from the storage area B to the access area A by an exchange process.
Therefore, there is a possibility that the attacker can specify the necessary data a by analyzing this data movement with higher probability than analyzing the entire access area A.

  On the other hand, in the present embodiment, the necessary data a often moves to the inner access area A2 by the first exchange process (broken line) as shown in FIG. 7B, and the second exchange process (solid line). ) Does not always move. Therefore, the risk that the necessary data a is specified by the data movement analysis is reduced.

  According to the present embodiment, the storage device 1 performs an exchange process between the outer access area A1 and the outer storage area B1, and then performs an exchange process between the inner access area A2 and the inner storage area B2. As a result, the storage device 1 can reduce the possibility of specifying necessary data when accessing the entire inner access area A2 as compared with the case of performing one-stage exchange processing on the inner access area A2. As a result, safety can be improved without increasing the size of the inner access area A2, and further, the processing speed can be improved as compared with increasing the size of the inner access area A2.

  In addition, the storage device 1 can stratify the outer access area A1 into the inner access area A2 and the inner storage area B2 over a plurality of hierarchies, thereby ensuring the safety and ensuring the innermost area. The processing speed for data protection can be improved by reducing the size of the access area.

The storage device 1 also provides history areas C1 and C2, and controls to select data to be moved in the exchange process from the history areas C1 and C2. Therefore, the storage device 1 can improve the safety by suppressing the bias of data to be moved.
Specifically, when the necessary data is in the access area A, the storage device 1 randomly selects data to be moved from the storage area B and the history area C, and when the necessary data is in the storage area B, Depending on whether or not it is in the history area C, data to be moved is randomly selected from the storage area B or the history area C. Thereby, the storage device 1 can easily select data to be moved and execute data protection processing at high speed.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to embodiment mentioned above. Further, the effects described in the present embodiment are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the present embodiment.

  The data protection method by the storage device 1 is realized by software. When realized by software, a program constituting the software is installed in the information processing apparatus (storage device 1). These programs may be recorded on a removable medium such as a CD-ROM and distributed to the user, or may be distributed by being downloaded to the user's computer via a network. Furthermore, these programs may be provided to the user's computer (storage device 1) as a Web service via a network without being downloaded.

DESCRIPTION OF SYMBOLS 1 Storage device 10 Storage area 11 Exchange part 12 Access part A1 Outer access area A2 Inner access area B1 Outer storage area B2 Inner storage area C1 Outer history area C2 Inner history area

Claims (8)

As a result of an exchange process for exchanging a plurality of data between an access area and a storage area different from the access area, an exchange unit for controlling the necessary data to exist in the access area;
An access unit that accesses the entire access area at a time to obtain a data group including the necessary data, and
The exchange unit performs the exchange process between the inner access area and the inner storage area constituting the outer access area after performing the exchange process between the outer access area and the outer storage area,
The access unit is a storage device that accesses the inner access area. The exchange unit performs stratification that divides the outer access area into the inner access area and the inner storage area over a plurality of hierarchies, and repeats the exchange process by the number of the plural hierarchies,
The storage device according to claim 1, wherein the access unit accesses an innermost access area of the plurality of hierarchies. The exchange unit is
A history of data moved from the access area to the storage area is stored in the history area,
The storage device according to claim 1 or 2, wherein at least one of data to be moved from the storage area to the access area in the exchange process is selected from data stored in the history area.   When the exchange unit performs the exchange process, if the necessary data is in the access area, the exchange unit randomly selects data from the storage area as data to be exchanged, and randomly selects data from the history area. The storage device according to claim 3, wherein the storage device is selected.   When the exchange unit performs the exchange process, if the necessary data is in the storage area and the history area, the exchange unit randomly selects data to be exchanged from the storage area together with the necessary data. The storage device according to claim 3, wherein the storage device is selected.   When the exchange unit performs the exchange process, if the necessary data is in the storage area and is not in the history area, the exchange unit randomly selects data to be exchanged from the history area together with the necessary data. The storage device according to claim 3, wherein the storage device is selected. A data protection method using a storage device,
As a result of the exchange process for exchanging a plurality of data between the access area and a storage area different from the access area, an exchange step for controlling the necessary data to exist in the access area;
Performing an access step of accessing the entire access area at a time to obtain a data group including the necessary data;
In the exchange step, after performing the exchange process between the outer access area and the outer storage area, the exchange process is performed between the inner access area and the inner storage area constituting the outer access area,
A data protection method for accessing the inner access area in the access step.   A data protection program for causing the storage device to execute the data protection method according to claim 7.

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