JP2010067001A - Information processor and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent content from being illegally obtained when the content is displayed on a screen. <P>SOLUTION: A controller stores the content in a storage device having a plurality of storage regions for displaying the content on the screen. An access control mechanism prohibits the content from being read from at least one of the plurality of storage regions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an information processing apparatus and an information processing apparatus control method, and more particularly to an information processing apparatus having a function of displaying content on a screen and a control method for the information processing apparatus. Hereinafter, “content” refers to content as data serving as a basis for displaying a predetermined image, video, or the like on a screen of a display device included in the information processing apparatus.

  Personal computers, mobile phones, game machines, and the like have a function of displaying digital contents distributed via a network, an auxiliary storage device such as a CD-ROM, etc. on a screen of a display device such as a CRT or a liquid crystal display.

Here, for example, Web content or digital content such as still images and moving images sold from a content provider via a network is subjected to encryption processing or the like for copyright protection. However, when displaying digital content on the screen of a display device, it is necessary to decrypt the content that has been subjected to the encryption processing and the like and then place it on the frame memory. At that time, it is assumed that the content that has been decoded and placed on the frame memory is illegally acquired by means of read access to the frame memory. On the other hand, if a function for prohibiting access to the frame memory is provided for the purpose of preventing unauthorized acquisition of content by such a method, access to the frame memory for content that is not subject to copyright protection is limited.
JP 2006-331011 A

  It is an object to provide a configuration that can prevent unauthorized acquisition of content to be protected when content is displayed on a screen in an information processing device.

  In the information processing apparatus, the control device stores the content in order to display the content on the screen, and the control device includes the storage device having a plurality of storage areas for the screen display control device to read and display the stored content on the screen. Is stored. The access control mechanism prohibits reading of content from at least one of the plurality of storage areas by the control device.

  In such an information processing apparatus, reading of content from the at least one storage area by the control device is prohibited. Therefore, if the content subject to copyright protection is stored in the at least one storage area, the content cannot be read by the control device, and unauthorized acquisition of the content is prevented.

  According to this information processing apparatus, at least one storage area of the plurality of storage areas for the screen display control apparatus to read and display the content stored and stored in order to display the content on the screen Reading by the control device is prohibited. Therefore, it is possible to prevent unauthorized acquisition of the content subject to copyright protection when the content is displayed on the screen.

  The information processing apparatus according to the embodiment is, for example, a personal computer, a mobile phone, a game machine, or the like. The information processing apparatus has a function of displaying digital contents distributed via a network or an auxiliary storage device such as a CD-ROM on the screen of a display device such as a CRT or a liquid crystal display device (hereinafter also referred to as LCD). Have.

  FIG. 1 is a block diagram for explaining a schematic configuration example of an information processing apparatus 1 according to the embodiment.

  In this information processing apparatus 1, a plurality (two in the example of FIG. 1) of frame memories 51 and 52 for storing contents to be displayed on the screen of the LCD 31 are arranged in each storage area of the main storage device 50. Yes. When displaying the content on the screen, the information processing apparatus 1 combines the data on the frame memories 51 and 52 and displays it on the screen.

  In the information processing apparatus 1, one of the plurality of frame memories 51 and 52 is a frame memory 52 for storing a copyright-protected content (hereinafter simply referred to as protected content) 22. The frame memory 52 for storing the protection target content 22 is hereinafter referred to as a protection target content display frame memory 52.

  The information processing apparatus 1 also includes an application interface 111 and a display driver 121 for accessing the protected content display frame memory 52. The application interface 111 and the display driver 121 are hereinafter referred to as a protection target content display application interface 111 and a protection target content display display driver 121, respectively.

  In the information processing apparatus 1, the frame memory 51 other than the protected content display frame memory 52 among the plurality of frame memories 51 and 52 is stored in the frame memory 51 for storing the content 21 that is not subject to copyright protection. It is said. Hereinafter, the content not subject to copyright protection is simply referred to as normal content 21. The frame memory 51 for storing the normal content 21 is hereinafter referred to as a normal content display frame memory 51.

  The information processing apparatus 1 includes an application interface 110 and a display driver 120 for accessing the normal content display frame memory 51. The application interface 110 and the display driver 120 are hereinafter referred to as a normal content display application interface 110 and a normal content display display driver 120, respectively.

  The information processing apparatus 1 has an access control mechanism 40, and the access control mechanism 40 has the following access restriction function.

  That is, the access control mechanism 40 permits write access for writing among accesses by the CPU 10 (described later with reference to FIG. 2) to the protected content display frame memory 52. On the other hand, the access control mechanism 40 denies read access for reading out of accesses by the CPU 10 to the protected content display frame memory 52. Further, the access control mechanism 40 does not restrict the access by the CPU 10 to the normal content display frame memory 51, but permits both write access for writing and read access for reading.

  The access control function of the access control mechanism 40 has the following effects. That is, illegal protection of the protected content 22 displayed using the protected content display frame memory 52 among the digital contents being displayed on the screen using the frame memories 51 and 52 is prevented. . As a means for illegally copying, for example, a means for copying by a so-called screen capture function is assumed.

  When the protection target content 22 is displayed on the screen of the LCD 31 in the information processing apparatus 1, data of the content 22 is written from the content display application 100 into the protection target content display frame memory 52. When displaying the normal content 21 on the screen of the LCD 31, the data of the content 21 is written into the normal content display frame memory 51 from the content display application 100. The data 22 written to the protection target content display frame memory 52 is transferred to the LCD controller 30 and is combined with the data 21 on the normal content display frame memory 51 and displayed as an image 23 on the screen of the LCD 31.

  According to the information processing apparatus 1, the access control function 40 restricts the access of the CPU 10 to the protection target content display frame memory 52 as described above. As a result, read access to the protected content display frame memory 52 by a malicious application is prohibited, and unauthorized duplication by the screen capture function is prevented. Access to the normal content display frame memory 51 by the CPU 10 is not restricted by the access control mechanism 40. Therefore, the operation of the application that accesses the normal content display frame memory 51 is not limited.

  Hereinafter, the configuration of the information processing apparatus 1 according to the embodiment will be described in detail with reference to the drawings.

  FIG. 2 is a hardware block diagram of the information processing apparatus 1 of the above embodiment, and FIG. 3 is a diagram for explaining the programs and contents stored in the storage 20 in FIG.

  As shown in FIG. 2, the information processing apparatus 1 includes the CPU 10, storage 20, LCD 31, LCD controller 30, access control mechanism 40, main storage device 50, communication device 60, and auxiliary storage device 61.

  The CPU 10 is an arithmetic processing device that is the center of the information processing apparatus 1. The storage 20 is a storage device that stores data and programs, such as a hard disk device and a flash memory.

  As shown in FIG. 3, the storage 20 stores the content display application 100, the normal content display application interface 110, and the protection target content display application interface 111. The storage 20 further stores the normal content display display driver 120 and the protected content display driver 121. The storage 20 further stores a content acquisition application 130. Each application 100, 110, 111, 120, 121, 130 stored in the storage 20 is read from the storage 20 by the CPU 10 and expanded on the main storage device 50. Each application fulfills a predetermined function by being appropriately executed by the CPU 10. The storage 20 also stores the normal content 21 and the protection target content 22 displayed on the screen of the LCD 31 in the same manner.

  The main storage device 50 is a storage device for storing programs executed by the CPU 10 and data. In the main storage device 50, a normal content display frame memory 51 and a protection target content display frame memory 52 used for screen display on the screen of the LCD 31 are allocated to specific areas.

  The access control mechanism 40 is a firewall mechanism for the CPU 10 and has a function of monitoring access to the main storage device 50 by the CPU 10, the LCD controller 30, and the like. The access control mechanism 40 determines what hardware is to be accessed to the main storage device 50 (that is, the access source), what is its access type, and where is the area in the main storage device 50 to be accessed ( That is, access destination) is detected. Then, the access control mechanism 40 determines whether to permit the access based on the detection results. In the case of the present embodiment, the access control mechanism 40 denies the access only when the detection result matches all of the following three conditions i), ii), and iii), and permits the access otherwise. To do.

  i) The hardware to be accessed (that is, the access source) is the CPU 10.

  ii) The area (that is, the access destination) in the main storage device 50 to be accessed is the area of the protected content display frame memory 52.

  iii) The access type is read access for reading data.

  Therefore, for example, when the hardware to be accessed is the LCD controller 30 that displays a screen on the screen of the LCD 31, the access control mechanism 40 permits the access unconditionally.

  That is, the following access can be executed without any restriction by the access restriction function of the access control mechanism 40.

  i) Write access for writing data to the normal content display frame memory 51 by the CPU 10.

  ii) Write access for data writing to the protected content display frame memory 52 by the CPU 10.

  iii) Read access for reading data from the normal content display frame memory 51 by the LCD controller 30 (that is, reading for screen display on the screen of the LCD 31).

  iii) Read access for reading data from the protected content display frame memory 52 by the LCD controller 30 (that is, reading for screen display on the screen of the LCD 31).

  iv) Read access for reading data from the normal content display frame memory 51 by the CPU 10.

  Therefore, the access restriction function of the access control mechanism 40 does not restrict the operation of the LCD controller 30 reading the data of the normal content 21 from the normal content display frame memory 51 and displaying the screen on the LCD 31 based on the data. . Similarly, the access restriction function of the access control mechanism 40 restricts the operation in which the LCD controller 30 reads the data of the protection target content 22 from the protection target content display frame memory 52 and displays the screen on the LCD 31 based on the data. Never happen. Further, the so-called screen capture operation performed by the CPU 10 by reading the data of the normal content 21 from the normal content display frame memory 51 is not limited. However, the so-called screen capture operation in which the CPU 10 reads out the data of the protection target content 22 from the protection target content display frame memory 52 is prohibited. Accordingly, the screen display of the protection target content 22 by the LCD controller 30 is executed as usual, but unauthorized acquisition by screen capture of the protection target content 22 is prevented. Moreover, the legitimate use by the screen capture of the normal content 21 that is not protected can be executed without any problem.

As the access control mechanism 40 having such an access restriction function, an apparatus that provides a function of performing access control to hardware, such as M-Shield manufactured by Texas Instruments, Inc., can be applied. Details of the apparatus can be obtained from the following URL (as of June 2008), for example.
i) Overview of M-Shield:
http://focus.ti.com/general/docs/wtbu/wtbugencontent.tsp?templateId=6123&navigationId=12316&contentId=4629
-"Secure access / restriction" of "M-Shield Hardware Security Technology"
to all chip peripherals and memories "
ii) M-Shield white paper:
http://focus.ti.com/pdfs/wtbu/ti_mshield_whitepaper.pdf
-"MMI peripherals" in "Secure chip-interconnect and Secure DMA" on p.5
such as keyboard, LCD, fingerprint sensor "
iii) OMAP35xx Peripherals Overview:
http://focus.ti.com/lit/ug/sprufn0/sprufn0.pdf
-"5. SDRAM Controller Subsystem" security firewall
iv) OMAP35xx Technical Reference Manual
http://focus.ti.com/lit/ug/spruf98a/spruf98a.pdf
-5.4.3 L3 Security and Firewalls
-5.9.3 L4 Security and Firewalls

Returning to the description of FIG. 2, the LCD controller 30 is an LSI that provides a function of controlling screen display on the screen of the LCD 31. The LCD controller 30 has a function of displaying the data written in the normal content display frame memory 51 and the protected content display frame memory 52 on the screen of the LCD 31. More specifically, the LCD controller 30 has a function of superimposing and displaying image data by an overlay function provided by, for example, OMAP manufactured by Texas Instruments. That is, for example, as described above with reference to FIG. 1, the image 23 in which the normal content 21 and the protection target content 22 are combined and superimposed on each other is displayed on the screen of the LCD 31 by the overlay function of the LCD controller 30. Details of this OMAP can be obtained from, for example, the following URL (as of June 2008).

OMAP35xx Applications Processor Display Interface Subsystem
http://focus.ti.com/lit/ug/sprufa4/sprufa4.pdf
-1.4.2.2 Graphics Pipeline
-1.4.2.4 Overlay Support

  Returning to the description of FIG. 2, the network device 60 is a device that is connected to the network 70 and transmits and receives data. The information processing apparatus 1 can acquire content from outside through the network 70 by the function of the network device 60.

  The auxiliary storage device 61 is a device (for example, a CD-ROM) having a function of actually reading and writing data with respect to an electronic medium (that is, a computer-readable recording medium) 71 having a function of holding data, such as a CD-ROM. ROM drive). By using the auxiliary storage device 61, the information processing apparatus 1 can acquire content from the outside through the electronic medium 71.

  The flow of the content acquisition process performed by the information processing apparatus 1 configured as described above will be described with reference to FIG.

  In step S <b> 1, the content acquisition application 130 acquires content from the network 70 using the network device 60 in accordance with, for example, an operation input by the user. Alternatively, the content acquisition application 130 acquires content from the electronic medium 71 using the auxiliary storage device 61 in response to, for example, an operation input by the user.

  At this time, the content acquisition application 130 determines whether the content acquired in this way corresponds to the protection target content 22 or the normal content 21. As a result of the determination, if the content corresponds to the protection target content 22 (YES in step S2), the content acquisition application 130 stores the content as the protection target content 22 in the storage 20 (step S4). On the other hand, if it is determined that the content corresponds to the normal content 21 (NO in step S2), the content acquisition application 130 stores the content as the normal content 21 in the storage 20 (step S3).

  Here, for example, when the information indicating whether or not the content corresponds to the protection target is added to the acquired content in the form of a header or the like, the determination in step S2 is performed based on the information. . As another example, an operation input to the information processing apparatus 1 by the user is obtained, and the above determination is performed according to the content of the input.

  In addition, as a method of storing the content as the protection target content 22 or the normal content 21 in steps S3 and S4, the following method can be considered. That is, for example, a method of separately providing table information or the like on the storage 20 can be considered. In this method, table information or the like is provided for associating the identification information of each stored content with information indicating whether or not the content corresponds to a protection target. As another method, when information indicating whether or not the content corresponds to the protection target is added in the form of the header or the like, the header or the like is stored as it is added to the content. A method is also conceivable.

  Next, the flow of the screen display processing operation executed by the information processing apparatus 1 will be described with reference to FIG.

  In step S21, the content display application 100 acquires content used for screen display from the storage 20. Specifically, for example, upon receiving an operation input from the user to the information processing apparatus 1, the application 100 displays a content list on the screen of the LCD 31. When the user performs a selection input operation, the application 100 acquires content related to the selection according to the operation. In this example, it is assumed that both the protection target content 22 and the normal content 21 are selected and acquired.

  At that time, the content display application 100 determines whether the acquired content is the protection target content 22 or the normal content 21 in step S22. As a determination method in this case, when the table information or the like is provided, a method of determining by referring to the table information or the like can be considered. In addition, when the header or the like is added to each content and stored, a method of determining by referring to the header or the like can be considered.

  As a result of the determination, if the content is the protection target content 22 (YES in step S22), the process proceeds to the protection target content display application interface 111 in step S26. In step S27, the protection target content display application interface 111 requests the protection target content display display driver 121 to perform a drawing process. In step S 28, the protection target content display display driver 121 receives the drawing processing request from the protection target content display application interface 111, and the protection content display frame memory 52 receives the drawing processing request specified by the drawing processing request. Make a request to write content.

  On the other hand, in the case of the normal content 21 that does not require copyright protection (NO in step S22), the process is transferred to the normal content display application interface 110 in step S23. In step S24, the normal content display application interface 110 makes a drawing process request to the normal content display driver 120. In step S25, the normal content display display driver 120 receives the drawing processing request from the normal content display application interface 110, and writes the content specified in the drawing processing request into the normal content display frame memory 51. Make a request for.

  In this way, the protection target content display driver 121 makes a request for writing the protection target content 22 to the protection target content display frame memory 52 in the main storage device 50 (step S28). Similarly, the normal content display driver 120 makes a request for writing the normal content 21 to the normal content display frame memory 51 in the main storage device 50 (step S25). Here, such write processing to the main storage device 50 is monitored by the access control mechanism 40, and the access source, access destination, and access type of the write processing are determined (step S29). If the access source is the CPU 10 as a result of the determination (YES in step S30), the process proceeds to step S31. When the access destination is the protection target content display frame memory 52 (protection target content display frame memory in step S31), the process proceeds to step S32. If the access type is read access (read access in step S32), the access control mechanism 40 rejects the access (step S33).

  On the other hand, if the result of the determination is that the access source is other than the CPU 10, for example, the LCD controller 30 (NO in step S30), the process proceeds to step S34. If the access destination is the normal content display frame memory 51 in step S31 (normal content display frame memory in step S31), the process proceeds to step S34. If the access type is write access in step 32 (write access), the process proceeds to step S34.

  Here, the operation in which the protection target content display display driver 121 writes the protection target content 22 in the protection target content display frame memory 52 in step S28 is actually a write operation by the CPU 10. That is, the CPU 10 writes the protection target content 22 in the protection target content display frame memory 52 by executing the program as the protection target content display driver 121. Therefore, in this case, the determination result of step S30 is YES, and the process proceeds to step S31. In this case, since the access destination is the protected content display frame memory 52, the process proceeds to step S32. In this case, since the access type is write access, the process proceeds to step S34.

  On the other hand, the operation in which the normal content display driver 120 writes the normal content 21 in the normal content display frame memory 51 in step S25 is actually a write operation by the CPU 10. That is, the normal content 21 is written in the normal content display frame memory 51 by the CPU 10 executing the program as the normal content display display driver 120. Therefore, also in this case, the determination result of step S30 is YES, and the process proceeds to step S31. In this case, since the access destination is the normal content display frame memory 51, the process proceeds to step S34.

  As described above, in this example, in step S21, both the protection target content 22 and the normal content 21 are selected and acquired. Accordingly, in step S34, the access control mechanism 40 writes the protection target content 22 and the normal content 21 in the protection target content display frame memory 52 and the normal content display frame memory 51, respectively.

  In step S35, the LCD controller 30 synthesizes the protection target content 22 and the normal content 21 thus written in the protection target content display frame memory 52 and the normal content display frame memory 51 (see FIG. 1). ). Then, the image 23 synthesized in this way is displayed on the LCD 31 (step S36).

  In this way, in step S35, the content written in the protection target content display frame memory 52 and the normal content display frame memory 51 is synthesized by the LCD controller 30. Therefore, the LCD controller 30 performs an operation of reading the contents 22 and 21 written in the protection target content display frame memory 52 and the normal content display frame memory 51. This read operation involves access to the main storage device 50 including the protection target content display frame memory 52 and the normal content display frame memory 51. Therefore, the access control mechanism 40 monitors the read operation in the same manner as in steps S30, S31, and S32. However, in this case, since the access source is not the CPU 10 but the LCD controller 30, the determination result in step S 30 is NO, and the read operation can be freely executed without any restriction by the access control mechanism 40.

It is a block diagram for demonstrating schematic structure of the information processing apparatus by an Example. It is a hardware block diagram of the information processing apparatus by an Example. FIG. 3 is a diagram for explaining a program and content stored in a storage in FIG. 2. It is a flowchart which shows the flow of operation | movement of the content acquisition process of the information processing apparatus by an Example. It is a flowchart which shows the flow of operation | movement of the content display process of the information processing apparatus by an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Information processing apparatus 21 Normal content 22 Content to be protected 23 Composite image data 30 LCD controller 31 LCD
40 Access Control Mechanism 50 Main Storage Device 51 Normal Content Display Frame Memory 52 Protection Target Content Display Frame Memory 100 Content Display Application 110 Normal Content Display Application 111 Protection Target Content Display Application 120 Normal Content Display Display Driver 121 Protection Target Display driver for content display

Claims (6)

A storage device having a plurality of storage areas for storing content to be displayed on the screen;
A control device for writing the content to the storage device or reading from the storage device;
A screen display control device for reading out the content stored in the storage device and displaying the content on the display device;
An information processing apparatus comprising: an access control mechanism that prohibits reading of the content by the control apparatus for at least a first storage area of the plurality of storage areas. 2. The information processing according to claim 1, wherein each of the plurality of storage areas includes a frame memory, and the screen display control device displays the content stored in each of the frame memories in a superimposed manner on a screen. apparatus. A first application interface for making a request for displaying the content on a screen;
A first display driver that receives the request from the first application interface and makes a request to write the content to the first storage area;
A second application interface for making a request for displaying the content on the screen;
A second display driver that receives the request from the second application interface and issues a write request to the second storage area other than the first storage area among the plurality of storage areas. Have
The access control mechanism detects an access request from the control device to the first and second storage areas, and permits the access request when the access request is an access request by the second display driver. The access request is permitted even when it is a write request by the first display driver, but is rejected when the access request is a read request by the first display driver. The information processing apparatus according to claim 1 or 2. A control method for an information processing apparatus, comprising: a control device; a screen display control device; and a storage device having a plurality of storage areas for the screen display control device to read and display the stored content on the screen. There,
Storing the content in the storage device by the control device;
A step of a screen display control device reading out the content stored in the storage device and displaying the content on the display device;
A method for controlling an information processing apparatus, comprising: an access control mechanism prohibiting reading of content by the control apparatus for at least a first storage area of the plurality of storage areas. 5. The information processing apparatus according to claim 4, wherein each of the plurality of storage areas includes a frame memory, and the screen display control apparatus displays the content stored in each of the frame memories in a superimposed manner on the screen. Control method. A first screen display request stage for making a request for displaying content on the screen;
A first write request step for receiving a request for writing the content to the first storage area in response to the request from the first screen display request step;
A second screen display request stage for making a request to display content on the screen;
In response to the request from the second screen display request stage, a second write request stage for requesting writing of the content to a second storage area other than the first storage area among the plurality of storage areas. When,
The access control mechanism detects an access request from the control device to the first and second storage areas, and permits the access request when the access request is the write request in the second write request stage. If the access request is the write request in the first write request stage, this is permitted, but if the access request is a request for reading content from the first storage area, 6. The information processing apparatus control method according to claim 4, further comprising a step of rejecting the information processing apparatus.

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