Content playback system, content playback method, content playback requesting apparatus, and temporary playback apparatus

• US 20010034714A1
• Filed: 02/21/2001
• Published: 10/25/2001
• Est. Priority Date: 02/23/2000
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kurihara, Ken, Terao, Hajimu
• Granted Patent: US 7,251,330 B2
• Time in Patent Office: Days
• US Class Current: 705/57
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 2221/2137 Time limited access, e.g. to a computer or data
• CPC Class Codes: H04L 63/0442 wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

In order to share content possessed by each user among a plurality of users who hold a token of encrypted content, a content playback system includes a playback requesting apparatus which holds a token and which requests the playback of the encrypted content, and a temporary playback apparatus for performing the playback of the encrypted content in response to a playback request of the content. The temporary playback apparatus transmits a token sending request in a form in which an identifier of the content and a digital signature are attached. The playback requesting apparatus sends back the token to the temporary playback apparatus only when the authentication procedure for a digital signature is successful.

Claims

1. A content playback system for playing back encrypted content which can be decrypted by a token, said content playback system comprising:

playback requesting means which holds a token and which requests playback of the encrypted content; and

temporary playback means for requesting sending of a token to said playback requesting means in response to the content playback request and for performing playback of the encrypted content by using the token.

2. A content playback system according to

claim 1

, wherein said playback requesting means and said temporary playback means can be connected to each other by short-distance wireless data communication.

3. A content playback system according to

claim 1

, wherein said playback requesting means holds one or more encrypted content and a token for each encrypted content, and transfers the held encrypted content to said temporary playback means.

4. A content playback system according to

claim 1

, wherein said temporary playback means comprises means for receiving and storing the encrypted content from one or more playback requesting means.

5. A content playback system according to

claim 1

, wherein said temporary playback means transmits a request for sending a token in a form in which an identifier of content for which playback has been requested and a digital signature are attached, and said playback requesting means sends back the token to said temporary playback means only when an authentication procedure for the digital signature is successful.

6. A content playback system according to

claim 5

, wherein said temporary playback means has a public key and a secret key of a public key cryptosystem, the public key of said temporary playback means is contained in said digital signature, and said playback requesting means encrypts the token by the public key of said temporary playback means and sends it back.

7. A content playback system according to

claim 1

, wherein said playback requesting means and/or said temporary playback means are mounted on a circuit package having a tamper-resistant characteristic.

8. A content playback system according to

claim 1

, wherein said playback requesting means and said temporary playback means can be connected to each other by short-distance wireless data communication, and a plurality of said playback requesting means are present within an area in which communication is possible by the short-distance wireless data communication, and said temporary playback means broadcasts a token sending request.

9. A content playback method for playing back encrypted content which can be decrypted by a token in a system comprising a playback requesting apparatus which holds a token and which requests the playback of encrypted content, and a temporary playback apparatus for performing playback of the encrypted content in response to the content playback request, said content playback method comprising:

a step (a) in which said playback requesting apparatus transmits a content playback request with an attached content identifier;

a step (b) in which said temporary playback apparatus transmits a token in a form in which an identifier of content for which playback has been requested and a digital signature are attached;

a step (c) in which said playback requesting apparatus sends back the token to said temporary playback apparatus only when an authentication procedure for the digital signature is successful; and

a step (d) in which said temporary playback apparatus plays back the content for which playback has been requested by using the received token.

10. A content playback method according to

claim 9

, wherein said playback requesting apparatus and said temporary playback apparatus can be connected to each other by short-distance wireless data communication.

11. A content playback method according to

claim 9

, wherein said playback requesting apparatus holds one or more encrypted content and a token for each encrypted content, said content playback method further comprising:

a step (a)′

in which said playback requesting apparatus transfers the encrypted content in advance to said temporary playback apparatus; and

a step (a)″

in which said temporary playback apparatus stores the encrypted content.

12. A content playback method according to

claim 9

, wherein said temporary playback apparatus has a public key and a secret key of a public key cryptosystem, the public key of said temporary playback apparatus is contained in said digital signature which is transmitted in said step (b), and said playback requesting apparatus encrypts the token by the public key of said temporary playback apparatus and sends it back in said step (c).

13. A content playback method according to

claim 9

, wherein said playback requesting means and/or said temporary playback means are mounted on a circuit package having a tamper-resistant characteristic.

14. A content playback method according to

claim 9

, wherein said playback requesting apparatus and said temporary playback apparatus can be connected to each other by short-distance wireless data communication, and a plurality of said playback requesting apparatus is present within an area in which communication is possible by the short-distance wireless data communication, and said temporary playback apparatus broadcasts a token sending request in said step (b).

15. A playback requesting apparatus for requesting the playback of encrypted content which can be decrypted by a token, said playback requesting apparatus comprising:

token holding means for holding a token;

content storage means for storing encrypted content;

interfacing means for exchanging data with an external apparatus; and

control means for controlling the operation of the apparatus.

16. A playback requesting apparatus according to

claim 15

, wherein said control means sends back the token only when an authentication procedure for the digital signature is successful, in response to receiving the token sending request with a digital signature via said interfacing means.

17. A playback requesting apparatus according to

claim 16

, wherein the public key of the token sending requesting source is contained in said digital signature, and said control means sends back the token encrypted using the public key to the requesting source.

18. A temporary playback apparatus for temporarily playing back encrypted content which can be decrypted by a token, said temporary playback apparatus comprising:

signature holding means for holding a digital signature;

secret key holding means for holding the secret key of the apparatus itself;

content storage means for storing encrypted content;

interfacing means for exchanging data with an external apparatus;

content playback means for playing back content which is converted to plain text; and

control means for controlling the operation of the apparatus.

19. A temporary playback apparatus according to

claim 18

, wherein the digital signature held by said signature holding means contains at least the public key of the temporary playback apparatus, and a specific character string for an authentication procedure.

20. A temporary playback apparatus according to

claim 18

, wherein said control means transmits a token sending request with a digital signature, which requests the sending of a token corresponding to the requested content, in response to receiving a content playback request via said interfacing means.

21. A temporary playback apparatus according to

claim 20

, wherein said control means causes the playback of the content to be performed by using the token in response to receiving the sending back of the token for the token sending request.

22. A temporary playback apparatus according to

claim 18

, further comprising token holding means for holding the token only temporarily.