Preventing entitlement management message (EMM) filter attacks

• US 20070180231A1
• Filed: 01/31/2006
• Published: 08/02/2007
• Est. Priority Date: 01/31/2006
• Status: Abandoned Application

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Widevine Technologies Incorporated (Alphabet Inc.)
• Inventors: Morten, Glenn, Hiar, Edward
• Application Number:
  US11/344,321
• Publication Number:
  US 20070180231A1
• Time in Patent Office: Days
• US Class Current: 713/158
• CPC Class Codes: H04N 21/2585 Generation of a revocation list, e.g. of client devices involved in piracy acts
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/63345 by transmitting keys key distribution for secret or secure communication H04L9/08; network support of key management H04L63/06
• CPC Class Codes: H04N 21/6583 Acknowledgement
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

A system, apparatus, and method are directed towards preventing entitlement/rights filter attacks in a conditional access to secure content over a network. An EMM that is configured to revoke access to selected content may be sent to a user, when a content provider, or the like, determines that access to the selected content is to be revoked for that user. A server may monitor for an acknowledgment of the revocation. If, after a predetermined time, a valid acknowledgement is not received by the server, the server may send another revocation EMM and again monitor for an acknowledgement response. If, after a predetermined number of retry attempts, a valid acknowledgement is not received, the server may send an alert message, investigate for possible network or device failures, change of encryption keys such as the CW, change a service key, or the like, for future content delivery to the user.

Claims

1. A network device for managing access to content over a network, comprising:

a transceiver for receiving and sending information over the network;

a processor in communication with the display and the transceiver; and

a memory in communication with the processor and for use in storing data and machine instructions that causes the processor to perform a plurality of actions, including;

sending a revocation message over the network to revoke access to the content;

if the network device fails to receive a valid acknowledgement message within a time period, then performing at least one retry attempt comprising sending another revocation message; and

if after the at least one retry attempt the network device fails to receive the valid acknowledgement message within at least another time period, performing a revocation failure action.

2. The network device of claim 1, wherein an acknowledgement message is determined to be valid based on at least one of a nonce within the message, or a digital signature.

3. The network device of claim 1, wherein the revocation failure action further comprises performing at least one of changing an encryption/decryption key associated with the secure content, a service key, or performing a network failure detection analysis.

4. The network device of claim 1, wherein the time period and the at least one other time period are different.

5. The network device of claim 1, wherein at least one of the time period or the at least one other time period is based on a network characteristic.

6. The network device of claim 1, the actions further comprising:

performing at least two retry attempts.

7. The network device of claim 1, wherein the revocation message further comprises at least one of an Entitlement Management Message (EMM) or an Access Control List (ACL).

8. A system usable in managing access to content, comprising:

a content access component that is operative to perform actions, comprising;

sending a revocation message to revoke access to content;

if the content access component fails to receive a valid acknowledgement message within a time period, then performing at least one retry attempt comprising sending another revocation message; and

if after the at least one retry attempt the content access component fails to receive the valid acknowledgement message within at least another time period, sending a failure alert message; and

an alert component that is operative to perform actions, comprising;

receiving the failure alert message; and

in response, performing at least one revocation failure action.

9. The system of claim 8, wherein the revocation messages and the acknowledgement message are communicated using different mechanisms including at least one of a high-speed network link, a portable content storage device, or a low-speed network link.

10. The system of claim 8, wherein the failure alert message is sent to the alert component using at least one of email message, a Simple Network Management Protocol (SNMP) message, or a Common Management Information Protocol (CMIP) signal

11. The system of claim 8, wherein the actions of the alert component further comprising storing the failure alert message to enable at least one of a trend analysis to be performed, a legal action to be performed, a network failure analysis to be performed, or an analysis to determine if the failure alert message is due to a hacker attack.

12. The system of claim 8, wherein the at least one revocation failure action further comprises analyzing for a network failure between the system and a client device from which the valid acknowledgement message is to be received.

13. The system of claim 8, the at least one revocation failure action further comprises changing at least one access key associated with the content.

14. The system of claim 8, wherein the alert component and the content access component reside within a same network device.

15. The system of claim 8, wherein the content is provided to a client device using MPEG format.

16. The system of claim 8, wherein the revocation message further comprises at least one of an Entitlement Management Message (EMM), or an Access Control List (ACL) that is configured to invalidate a digital certificate.

17. A method usable in managing access to content, comprising:

sending a revocation message to revoke access to the content by a client device;

if a valid acknowledgement message is un-received within a time period, then performing at least one retry attempt comprising sending another revocation message; and

if after the at least one retry attempt the valid acknowledgement message is un-received within at least another time period, performing a revocation failure action.

18. The method of claim 17, wherein the revocation message is prevented from being received by the client device by a filtering mechanism.

19. The method of claim 17, wherein the client device employs a virtual smart card in part to manage access to the content.

20. The method of claim 17, wherein an acknowledgement message is determined to be valid based on at least one of a nonce associated with the message, or a digital signature.

21. The method of claim 17, wherein the revocation failure action further comprises performing at least one of changing an encryption/decryption key associated with the secure content, a service key, or performing a network failure detection analysis.

22. The method of claim 17, wherein the time period and the at least one other time period are different.

23. A modulated data signal configured to include program instructions for performing the method of claim 17.

24. The method of claim 17, wherein sending the revocation message further comprises sending the revocation message using at least one of a network mechanism or a portable content storage device.

25. The method of claim 17, further comprising:

sending the content to the client device using at least one of a portable content storage device or a network.

26. An apparatus for managing content encryption over a network, comprising:

a transceiver to receive input data over the network; and

means for sending a revocation message over the network to revoke access to the content;

means for providing at least one revocation retry attempt that includes sending another revocation message, if a valid acknowledgment is un-received within a time period; and

means for performing a revocation failure action based on failure to the valid acknowledgement message within at least another time period.