Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
2001-10-18
2004-12-21
Elmore, Reba I. (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C711S151000, C711S164000, C713S182000, C713S184000
Reexamination Certificate
active
06834333
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to data processing devices and data processing methods, and program providing media used therewith. In particular, the present invention relates to a data processing device and method in which content stored in a storage device is protected under high security management, and a program providing medium used therewith.
2. Description of the Related Art
With the rapid spread of the Internet in recent years and the spread of compact mobile players and portable game machines, the distribution of various types of software data (hereinafter referred to as “content”), such as music data, game programs, and image data, via a network such as the Internet or by storage media, such as digital versatile disks (DVDs), compact disks (CDs), and memory cards, is rapidly increasing. The distributed content is received via the network and is stored in a play-only device or a storage medium of a game machine which belongs to a user, or a memory card containing the content is loaded into the game machine, whereby content-playback processing or the execution of a program can be performed.
Content storage devices include a flash memory, which is commonly used. The flash memory is a form of electrically rewritable, non-volatile memory called an “electrically erasable, programmable read-only memory (EEPROM)”. The degree of integration of conventional EEPROMs is limited because the use of two transistors for one bit results in a large occupied area per bit. Conversely, in the flash memory, by using an all-bit batch erasure, one bit is implemented by one transistor. It is expected that flash memories will replace recording media such as magnetic disks and optical disks.
A type of memory card is also known in which the flash memory can be loaded/unloaded into/from a data recording/playback device. By using this memory card, a digital audio recorder/player in which a memory card is used instead of a conventional disk medium such as CD or MiniDisk (registered trademark) (MD) can be provided.
When such a content storage device using the flash memory is used in a personal computer, a playback unit, or the like, a file management system called a “file allocation table (FAT)” is generally used as an access information table. In the FAT system, after defining necessary files, the parameters required for the files are sequentially set from the first file. As a result, the file size can be set to be variable, and one or more management units (e.g., sectors or clusters) can constitute one file. Details related matters to the management units are written in the FAT. In the FAT system, the file structure can be easily formed regardless of the physical properties of the recording medium. Accordingly, the FAT system can be employed not only in floppy disks and hard disks but also in magneto-optical disks. The FAT system is employed in the above memory card.
Various content, such as music data, image data, or programs, are accessed based on the FAT from, for example, the above flash memory in response to a user's instruction from an information device which is used as a playback unit, a game machine, or a personal computer, or to a user's instruction via an input device connected to the information device. The content is played back by the information device or on a display and a speaker which are connected thereto.
In general, the distribution rights, etc., of much software content, such as game programs, music data, and image data, are possessed by the creators and sellers of the content. Accordingly, in the distribution of the contents, security limitation of usage is commonly employed in which unauthorized duplication, etc., is prevented by permitting only a registered user to use the content.
One technique enabling limitation of use by the user is encryption processing on the content to be distributed. Specifically, various encrypted contents, such as encrypted audio data, image data, and game programs, are distributed via, for example the Internet, and only a person who is identified as a registered user is supplied with a means for decrypting the distributed content, that is, a decryption key.
The encrypted data can be processed to form usable decrypted data (plaintext) by performing decryption processing based on predetermined processes. This method of data encryption and decryption which uses an encryption key for information encryption processing and a decryption key for decryption processing has been conventionally known.
By way of example, in a case in which a file system in the operating system of a personal computer manages files by independently reading a FAT stored as an access information table in recording media, the file system of the personal computer can freely rewrites the contents of the FAT.
Therefore, from recording media storing content managed by an access information table (FAT) in which a write-protected area is set, the access information table can be read and rewritten by the file system of the personal computer, so that data (content) in the recording media which is originally prevented from being rewritten can be rewritten. This causes a problem of insufficient content protection.
SUMMARY OF THE INVENTION
The present invention is made in view of the foregoing circumstances. It is an object of the present invention to provide a data processing device, a data storage device, and a data processing method in which the rewriting of data in recording media which is prevented from being rewritten is properly prevented, thus enhancing content protection. It is also an object of the present invention to provide a program providing medium used therewith.
To these ends, according to a first aspect of the present invention, there is provided a data processing device including a memory interface unit for accessing a data storage unit, and a control unit for controlling the memory interface unit. An access permission table which is stored in a data storage area in the data storage unit is set in the memory interface unit, and in response to an access command to access the data storage unit, which is issued by the control unit, the memory interface unit determines, by referring to the access permission table, whether or not to execute the access command, whereby processing which is set executable by the access permission table is only executed.
Preferably, the data storage area in the data storage unit is a flash memory having a plurality of blocks, each of which consists of a plurality of sectors which each have a predetermined data capacity, in the access permission table, permission information on block-unit data processing is set, and in accordance with the set permission information, the memory interface unit includes means for determines whether or not the block-unit data processing can be executed.
Preferably, only when a type of processing corresponding to the access command from the control unit is within a range of processing types which are set executable by the access permission table does the memory interface unit execute the type of processing, and sets a process-success flag in accordance with a success of the processing in the memory interface unit, and the control unit executes processing thereof on condition that the setting of the process-success flag in the memory interface unit is verified.
When the access command designates a data-file reading process, the control unit may execute a process in which the address of a data file to be read is selected from a file allocation table corresponding to the data storage area in the data storage unit and is transmitted to the memory interface unit, and after receiving the address of the data file, the memory interface unit may determine, by using the received address to refer to the access permission table, whether or not an address-assigned area having the address is a data-readable area, so that only when the address-assigned area is a data-readable area does the memory interface unit execute the data-file reading process.
When the access comma
Akishita Toru
Hayashi Shigekazu
Ishibashi Yoshihito
Ito Takeshi
Shirai Taizo
Elmore Reba I.
Frommer William S.
Frommer & Lawrence & Haug LLP
Smid Dennis M.
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