Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Particular communication authentication technique
Reexamination Certificate
2000-04-24
2003-08-12
Barrón, Gilberto (Department: 2132)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Particular communication authentication technique
C713S192000, C713S193000
Reexamination Certificate
active
06606707
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a semiconductor memory card for storing digital contents, and a data reading apparatus for reading out the digital contents from the semiconductor memory card. More particularly, the present invention relates to a semiconductor memory card and a data reading apparatus suitable for copyright protection of digital contents.
(2) Description of the Prior Art
The multimedia network technology has developed to the extent that digital contents such as music contents are distributed via a communication network such as the Internet. This makes it possible to access a variety of music or the like provided from around the world at home. For example, a music content can be downloaded into personal computer (hereafter referred to as PC), then stored in a semiconductor memory card loaded into the PC. Also, the semiconductor memory card can be removed from the PC and can be loaded into a portable music player. This enables one to listen to the music while walking. The semiconductor memory cards are compact and lightweight cards containing a nonvolatile semiconductor memory (e.g., a flash memory) and having a large storage capacity.
In such a music distribution, the digital contents to be stored in the semiconductor memory card need to be encrypted beforehand using a key or the like to prevent unauthorized copying of the digital contents. Also, an arrangement is required so that file management software programs, many of which are standard equipment on commercial PCs, cannot copy the digital contents to other storage mediums.
In one possible method for preventing unauthorized copying, only dedicated software programs are allowed to access the semiconductor memory card. For example, when an authentication process between a PC and a semiconductor memory card has completed affirmatively, a PC is allowed to access the semiconductor memory card; and when the authentication process has not completed affirmatively due to the lack of a dedicated software program, the PC is not allowed to access the semiconductor memory card.
However, in the above method in which PCs should always have a dedicated software program to access the semiconductor memory card, free data exchange with users via the semiconductor memory card is not available. As a result, the above method loses a merit of conventional semiconductor memory cards, namely, a merit that file management software programs being standard equipment on commercial PCs can be used to access the semiconductor memory card.
Semiconductor memory cards that can only be accessed through dedicated software programs are superior as storage mediums for storing digital contents since such semiconductor memory cards function to protect copyright of the digital contents. However, the semiconductor memory cards have a problem that they cannot be used as auxiliary storage apparatuses in general-purpose computer systems.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a semiconductor memory card that can be used as a storage medium for storing digital contents and as a storage medium for storing general-purpose computer data (not an object of copyright protection), and to provide an apparatus for reading data from the storage medium.
The above object is fulfilled by a semiconductor memory card that can be used/removed in/from an electronic device, comprising: a rewritable nonvolatile memory; and a control circuit which controls accesses by the electronic device to an authentication area and a non-authentication area in the rewritable nonvolatile memory, wherein the control circuit includes: a non-authentication area access control unit which controls accesses by the electronic device to the non-authentication area; an authentication unit which performs an authentication process to check whether the electronic device is proper, and affirmatively authenticates the electronic device when the electronic device is proper; and an authentication area access control unit which permits the electronic device to access the authentication area only when the authentication unit affirmatively authenticates the electronic device.
With the above construction, the data being an object of copyright protection can be stored in the authentication area and other data can be stored in the non-authentication area, which makes it possible to achieve a semiconductor memory card which is capable of storing both digital contents to be copyright-protected and other data together.
In the above semiconductor memory card, the authentication unit may generate a key reflecting a result of the authentication process, and the authentication area access control unit decrypts an encrypted instruction using the key generated by the authentication unit, and controls accesses by the electronic device to the authentication area in accordance with the decrypted instruction, the encrypted instruction being sent from the electronic device.
With the above construction, even if the communication between the semiconductor memory card and in electronic device is tapped, the instruction to access the authentication area has been encrypted, reflecting the result of the preceding authentication. Accordingly, such a semiconductor memory card has a reliable function to protect an unauthorized access of the authentication area.
In the above semiconductor memory card, the authentication unit may perform a challenge-response type mutual authentication with the electronic device, and generates the key from challenge data and response data, the challenge data being sent to the electronic device to check whether the electronic device is proper, and the response data being generated to show the authentication unit is proper.
With the above construction, the key is shared by the semiconductor memory card and the electronic device only when both devices affirmatively authenticate each other. Furthermore, the key changes for each authentication. This enhances the security of the authentication area since the authentication area cannot be accessed without using the key.
In the above semiconductor memory card, the encrypted instruction sent from the electronic device may include a tag field and an address field, the tag field not having been encrypted and specifying a type of an access to the authentication area, the address field having been encrypted and specifying an address of an area to be accessed, wherein the authentication area access control unit decrypts the address field using the key, and controls accesses by the electronic device to the authentication area so that an access of the type specified in the tag field is made to the area indicated by the address in the decrypted address field.
With the above construction, only the address field of the instruction is encrypted. This facilitates the decryption and the decoding of the instruction by the semiconductor memory card which receives the instruction.
The above semiconductor memory card may further comprise: an identification data storage circuit which prestores identification data which is unique to the semiconductor memory card and enables the semiconductor memory card to be discriminated from other semiconductor memory cards, wherein the authentication unit performs a mutual authentication with the electronic device using the identification data stored in the identification data storage circuit, and generates the key from the identification data.
With the above construction, in the mutual authentication process, data unique to each semiconductor memory card is exchanged. This keeps a superior security level against unauthorized decoding of the mutual authentication.
The above semiconductor memory card may further comprise: an area resizing circuit which resizes the authentication area and the non-authentication area.
With the above construction, the semiconductor memory card can be used dynamically. That is, the semiconductor memory card can be used mainly as a recording medium for digital contents and can be used as an auxiliary storage ap
Hirota Teruto
Kozuka Masayuki
Minami Masataka
Tatebayashi Makoto
Yugawa Taihei
Barrón Gilberto
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
Zand Kambiz
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