Method and apparatus for limiting number of times contents can be accessed using hash chain

• US 20050256910A1
• Filed: 01/07/2005
• Published: 11/17/2005
• Est. Priority Date: 01/08/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Nam, Su-hyun, Lee, Sun-nam, Lee, Jae-heung, Jang, Yong-jin, Kim, Myung-sun
• Granted Patent: US 7,788,728 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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]

Abstract

A method and apparatus are provided for simply and securely limiting a number of times that contents can be accessed using a hash chain. The apparatus limiting a number of times contents are accessed by a user terminal includes a hash chain generator receiving information indicating selected contents by the user terminal and information indicating how many times (n) the user terminal has authority to access the selected contents and generating a hash chain including n hash values derived from a seed value, and a contents access manager deleting the hash values one by one from the hash chain whenever the user terminal accesses the selected contents such that the number of times the contents can be accessed by the user terminal is decreased by the number of deleted hash values.

Claims

1. An apparatus limiting a number of times contents are accessed by a user terminal, the apparatus comprising:

a hash chain generator which receives information indicating selected contents by the user terminal and information indicating a number of times n the user terminal has authority to access the selected contents and generates a first hash chain comprising n hash values derived from a seed value; and

a contents access manager which deletes the hash values one by one from the hash chain when the user terminal accesses the selected contents such that the number of times n the user terminal has authority to access the selected contents is decreased by a number of deleted hash values.

2. The apparatus of claim 1, wherein the hash chain generator generates the seed value randomly and transmits the generated seed value to the user terminal such that the user terminal can generate a second hash chain identical to the first hash chain generated by the hash chain generator based on the seed value.

3. The apparatus of claim 1, wherein the seed value is received from the user terminal.

4. The apparatus of claim 1, wherein the contents access manager encrypts the selected contents using one of the hash values of the first hash chain and transmits encrypted contents to the user terminal, thereby allowing the user terminal to access the contents, and the hash value used for encryption is deleted from the hash chain.

5. The apparatus of claim 4, wherein the contents access manager encrypts the selected contents using a hash value corresponding to a total number of times that the contents have been accessed, transmits the encrypted contents to the user terminal when the hash value corresponding to the total number of times that the selected contents have been accessed is received from the user terminal, and points a pointer of the first hash chain to a hash value corresponding to a next number of times the selected contents have been accessed.

6. A method of limiting a number of times contents are accessed, the method comprising:

receiving information indicating selected contents by a user terminal and information indicating a number of times n the user terminal has authority to access the selected contents; and

generating a hash chain comprising n hash values derived from a seed value.

7. The method of claim 6, wherein the seed value is received from the user terminal requesting access to the contents.

8. The method of claim 6, wherein the seed value is generated by a server allowing access to the contents.

9. A computer readable recording medium executing a method of limiting a number of times contents are accessed, the method comprising:

receiving information indicating selected contents by a user terminal and information indicating a number of times n the user terminal has authority to access the selected contents; and

generating a hash chain comprising n hash values derived from a seed value.

10. The recording medium of claim 9, wherein the seed value is received from the user terminal requesting access to the contents.

11. The claim 9, wherein the seed value is generated by a server allowing access to the contents.

12. A method of limiting a number of times contents are accessed by a contents requester having authority to access the contents n times, the method comprising:

preparing a hash chain with respect to the contents, the hash chain comprising n hash values derived from a seed value; and

deleting a hash value from the hash chain when the contents requester accesses the contents such that a total number of hash values deleted equals a number of times that the contents have been accessed by the contents requester.

13. The method of claim 12, wherein the deleting the hash value from the hash chain comprises:

encrypting the contents using one of the hash values of the hash chain and transmitting encrypted contents to the contents requester, thereby allowing the contents requester to access the contents, and

deleting the hash value used for encryption is deleted from the hash chain.

14. The method of claim 13, wherein the encrypting the contents using one of the hash values of the hash chain and transmitting the encrypted contents to the contents requester comprises:

encrypting the contents using a hash value corresponding to the total number of times that the contents have been accessed and transmitting the encrypted contents to the contents requester when receiving the hash value corresponding to the total number of times that the contents have been accessed from the contents requester; and

pointing a pointer of the hash chain to a hash value corresponding to a next number of times that the contents have been accessed.

15. A computer readable recording medium on which a program executing a method of limiting a number of times contents are accessed by a contents requester having authority to access the contents n times has been recorded, the method comprising:

preparing a hash chain with respect to the contents, the hash chain comprising n hash values derived from a seed value; and

deleting a hash value from the hash chain when the contents requester accesses the contents such that a total number of hash values deleted equals the number of times that the contents have been accessed by the contents requester.

16. The recording medium of claim 15, wherein the deleting the hash value from the hash chain comprises:

encrypting the contents using one of the hash values of the hash chain and transmitting encrypted contents to the contents requester, thereby allowing the contents requester to access the contents, and

deleting the hash value used for encryption from the hash chain.

17. The recording medium of claim 16, wherein the encrypting the contents using one of the hash values of the hash chain and transmitting the encrypted contents to the contents requester comprises:

encrypting the contents using a hash value corresponding to the total number of times that the contents have been accessed and transmitting the encrypted contents to the contents requester when receiving the hash value corresponding to the total number of times that the contents have been accessed from the contents requester; and

pointing a pointer of the hash chain to a hash value corresponding to a next number of times that the contents have been accessed.

18. An apparatus having authority to access contents n times, the apparatus comprising:

a hash chain generator which generates a hash chain comprising n hash values derived from a seed value;

a hash chain manager which transmits to a contents supplier a hash value corresponding to a total number of times that the contents have been accessed; and

a contents decrypter which decrypts encrypted contents received from the contents supplier using the hash value corresponding to the total number of times that the contents have been accessed.

19. The apparatus of claim 18, wherein the hash chain manager deletes the hash value corresponding to the total number of times that the contents have been accessed from the hash chain.

20. The apparatus of claim 18, wherein the seed value is received from the contents supplier.

21. A computer readable recording medium on which a program executing a method of limiting a number of times contents are accessed by a contents requester having authority to access the contents n times is recorded, the method comprising:

generating a first hash chain comprising n hash values derived from a seed value;

transmitting to the contents supplying server a hash value corresponding to a total number of times that the contents have been accessed;

receiving encrypted contents using the hash value corresponding to the total number of times that the contents have been accessed from the contents supplying server; and

decrypting the encrypted contents encrypted using the hash value corresponding to the total number of times that the contents have been accessed.

22. The recording medium of claim 21, wherein the generating the first hash chain comprising n hash values derived from a seed value comprises generating the seed value randomly and transmitting the generated seed value to the contents supplying server such that the contents supplying server can generate a second hash chain identical to the first hash chain generated by the hash chain generator based on the seed value.

23. The recording medium of claim 21, wherein the seed value is received from the contents supplying server.

24. The recording medium of claim 21, wherein the method further comprises:

deleting the hash value corresponding to the total number of times that the contents have been accessed from the hash chain after completing the decrypting the encrypted contents; and

pointing a pointer of the hash chain to a hash value corresponding to a next number of times that the contents have been accessed.