Method and devices for reproducing encrypted content and approving reproduction

• US 8,321,660 B2
• Filed: 03/17/2008
• Issued: 11/27/2012
• Est. Priority Date: 07/02/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ju, Hak-soo, Kim, Myung-sun, Moon, Ji-young
• Primary Examiner(s): Chea, Philip
• Assistant Examiner(s): Gao, Shu Chun
• Application Number:
  US12/049,609
• Publication Number:
  US 20090013172A1
• Time in Patent Office: 1,716 Days
• Field of Search: 713/153, 713/193, 713/150, 713/189, 380/277, 726/4, 705/52
• US Class Current: 713/150
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00195 using a device identifier associated with the player or recorder, e.g. serial numbers of playback apparatuses or MAC addresses
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00246 wherein the key is obtained from a local device, e.g. device key initially stored by the player or by the recorder
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04N 2005/91342 the copy protection signal being an authentication signal
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

A reproduction method capable of immediately revoking a leaked device key by dividing the device key into a first partial key and a second partial key is provided. The reproduction method includes the operations of receiving encrypted content to be reproduced, requesting a token for decrypting the received content from an external device containing a first partial key of a device via a network, receiving the requested token from the external device, and decrypting the received token by using a second partial key contained in the device, thereby preventing content encrypted and distributed before revocation of an illegally copied device from being reproduced, and minimizing damage due to key leakage.

Claims

1. A method of reproducing an encrypted content in a device connected to a network, the method comprising:

receiving the encrypted content to be reproduced;

requesting a token for decrypting the received content from an external device containing a first partial key of the device via the network;

receiving the requested token from the external device; and

decrypting the received token by using a second partial key contained in the device,

wherein if it is determined that the device has been revoked, receipt of the token fails,

wherein a device key is divided to create the first partial key and the second partial key,

wherein the requesting the token further comprises transmitting an identification (ID) of the device and the encrypted content, and

wherein the token comprises a mediate decryption value of the transmitted encrypted content calculated based on the first partial key of the device corresponding to the transmitted ID.

2. The method of claim 1, further comprising determining whether the device corresponding to the transmitted ID has been revoked, and if it is determined that the device has been revoked, receipt of the token fails.

11. The method according to claim 1, wherein the token comprises a partial decryption value calculated using the first partial key contained in the external device and the second partial key contained in the device.

3. A method of approving reproduction of an encrypted content by a security mediated module connected to a network, the method comprising:

receiving a request for a token for decrypting the encrypted content from a device;

generating the token based on a partial key of the device, according to the received request, wherein the partial key is contained in the security mediated module; and

transmitting the generated token to the device via the network,

wherein if it is determined that the device has been revoked, a request for the token is rejected,

wherein a device key is divided to create the partial key,

wherein the receiving the request for the token further comprises receiving an identification (ID) of the device and the encrypted content, and

wherein the token comprises a mediate decryption value of the received encrypted content calculated by using a partial key of the device corresponding to the received ID.

4. The method of claim 3, further comprising determining whether the device corresponding to the received ID has been revoked, and if it is determined that the device has been revoked, a request for the token is rejected.

5. A reproduction device reproducing an encrypted content and being connected to a network, the reproduction device comprising:

an input unit which receives the encrypted content to be reproduced;

a token processing unit which requests a token for decrypting the received content from an external device containing a first partial key of the reproduction device via the network, and receives the requested token;

a decryption unit which decrypts the token received by the token processing unit, based on a second partial key contained in the reproduction device; and

an output unit which reproduces the decrypted content,

wherein if the reproduction device has been revoked, the token processing unit fails to receive the token,

wherein a device key is divided to create the first partial key and the second partial key,

wherein the token processing unit transmits an identification (ID) of the reproduction device and the encrypted content to the external device,

wherein the token comprises a mediate decryption value of the transmitted encrypted content calculated based on the first partial key of the reproduction device corresponding to the transmitted ID.

6. The method of claim 5, wherein if the reproduction device corresponding to the transmitted ID has been revoked, the token processing unit fails to receive the token.

7. An approval device approving reproduction of an encrypted content and being connected to a network, the approval device comprising:

a token interface which receives a request for a token for decrypting the encrypted content from a reproduction device, and transmits the requested token; and

a token generation unit which generates the requested token based on a partial key of the reproduction device, according to the received request, wherein the partial key is contained in the approval device,

wherein if the reproduction device has been revoked, the token generation unit rejects generation of the requested token,

wherein a device key is divided to create the partial key,

wherein the token interface receives an identification (ID) of the reproduction device and the encrypted content,

wherein the token comprises a mediate decryption value of the received encrypted content calculated based on a partial key of the reproduction device corresponding to the received ID.

8. The method of claim 7, further comprising a revocation checking unit which contains a revocation list of the reproduction device corresponding to the received ID, and if the reproduction device has been revoked, the token generation unit rejects generation of the requested token.

9. A non-transitory computer readable recording medium having recorded thereon a program for executing a method of reproducing an encrypted content in a device connected to a network, the method comprising:

receiving encrypted content to be reproduced;

requesting a token for decrypting the received content from an external device containing a first partial key of the device via the network;

receiving the requested token from the external device; and

decrypting the received token by using a second partial key contained in the device,

wherein if it is determined that the device has been revoked, receipt of the token fails,

wherein a device key is divided to create the first partial key and the second partial key,

wherein the requesting the token further comprises transmitting an identification (ID) of the device and the encrypted content, and

wherein the token comprises a mediate decryption value of the transmitted encrypted content calculated based on the first partial key of the device corresponding to the transmitted ID.

10. A non-transitory computer readable recording medium having recorded thereon a program for executing a method of approving reproduction of an encrypted content by a security mediated module connected to a network, the method comprising:

receiving a request for a token for decrypting the encrypted content from a device;

generating the token based on a partial key of the device, according to the received request, wherein the partial key is contained in the security mediated module; and

transmitting the generated token to the device via the network,

wherein if it is determined that the device has been revoked, a request for the token is rejected,

wherein a device key is divided to create the partial key,

wherein the receiving the request for the token further comprises receiving an identification (ID) of the device and the encrypted content, and

wherein the token comprises a mediate decryption value of the transmitted encrypted content calculated based on the first partial key of the device corresponding to the transmitted ID.