CONDITIONAL ACCESS SYSTEM AND METHOD FOR PREVENTION OF REPLAY ATTACKS

• US 20090316895A1
• Filed: 09/02/2009
• Published: 12/24/2009
• Est. Priority Date: 03/02/2000
• Status: Active Grant

• Current Assignee: TiVo Solutions Inc. (Adeia Inc.)
• Original Assignee: TiVo Inc. (Adeia Inc.)
• Inventors: Goodman, Andrew, Platt, David C., Zenchelsky, Daniel
• Granted Patent: US 8,036,382 B2
• Time in Patent Office: Days
• US Class Current: 380/210
• CPC Class Codes: H04L 2463/101 applying security measures for digital rights management data processing systems or methods, specially adapted for commerce, e.g. marketing, shopping, billing, auctions or e-commerce G06Q30/00
• CPC Class Codes: H04L 63/045 wherein the sending and receiving network entities apply hybrid encryption, i.e. combination of symmetric and asymmetric encryption cryptographic mechanisms or cryptographic arrangements using a plurality of keys or algorithms H04L9/14
• CPC Class Codes: H04L 63/10 for controlling access to devices or network resources
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/258 Client or end-user data management, e.g. managing client capabilities, user preferences or demographics, processing of multiple end-users preferences to derive collaborative data arrangements for services using the result on the distributing side of broadcast systems H04H60/66; profiles in network data switching protocols H04L67/30
• CPC Class Codes: H04N 21/25891 being end-user preferences retrieval of video data in a video database based on user preferences G06F16/739; arrangements for recognizing users' preferences H04H60/46; user profiles in network data switching protocols H04L67/306; processing of user preferences or user profiles in wireless networks H04W8/18
• CPC Class Codes: H04N 21/4126 The peripheral being portable, e.g. PDAs or mobile phones
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4367 Establishing a secure communication between the client and a peripheral device or smart card
• CPC Class Codes: H04N 21/4622 Retrieving content or additional data from different sources, e.g. from a broadcast channel and the Internet web site content organization and management for information retrieval from the Internet G06F16/958; transmission by internet of broadcast information H04H60/82; stock exchange data over packet-switching network H04L12/1804; push services including data channel over packet-switching network H04L12/1859
• CPC Class Codes: H04N 21/4623 Processing of entitlement messages, e.g. ECM [Entitlement Control Message] or EMM [Entitlement Management Message] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/47 End-user applications
• CPC Class Codes: H04N 21/4782 Web browsing , e.g. WebTV
• 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 21/816 involving special video data, e.g 3D video
• CPC Class Codes: H04N 21/84 Generation or processing of descriptive data, e.g. content descriptors systems specially adapted for using meta-information in broadcast systems H04H60/73
• CPC Class Codes: H04N 5/782 on tape
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/163 by receiver means only
• 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
• CPC Class Codes: H04N 7/17309 : Transmission or handling of upstream communications

Abstract

In a conditional access system, a headend transmits content to one or more receivers in encrypted transport streams. The system provides a multi-layer security architecture, rendering the system resistant to key replay attacks; if one layer is circumvented, subsequent layers remain intact. A first layer prevents unencrypted keys from being recorded by shielding the unencrypted keys from users and encrypting the path from the receiver'"'"'s conditional access module to the transport decryption module; a second layer prevents a key recorded on one receiver from being played back to the transport decryption module on a second receiver; a third layer prevents a user from decrypting transport streams without the encryption module by encrypting the stream a second time prior to being passed through any user-accessible memory or processor.

Event tables are transmitted with the transport stream, either unencrypted for immediate use or encrypted, to prevent unauthorized use.

Claims

1. A method, comprising:

creating, at a headend, an event table for a corresponding transport stream; and

transmitting the transport stream from the headend to at least one receiver among a plurality of receivers.

2. The method of claim 1, further comprising:

transmitting the event table along with the transport stream to the at least one receiver.

3. The method of claim 2, further comprising:

encrypting the event table prior to transmission.

4. The method of claim 1, further comprising:

encrypting the transport stream prior to transmission.

5. The method of claim 4, further comprising:

storing the encrypted transport stream transmitted from the headend at the at least one receiver; and

encrypting, at the at least one receiver, the transport stream so that a doubly encrypted transport stream is stored on a storage medium on or accessible to the receiver.

6. A conditional access system resistant to replay attacks, comprising:

a headend;

a plurality of receivers;

an event table creation subsystem, at the headend, that creates an event table for a corresponding transport stream; and

a transport stream transmission subsystem that transmits the transport stream from the headend to at least one receiver among the plurality of receivers.

7. The system of claim 6, further comprising:

an event table transmission subsystem that transmits the event table along with the transport stream to the at least one receiver.

8. The system of claim 7, further comprising:

an event table encryption subsystem that encrypts the event table prior to transmission.

9. The system of claim 6, further comprising:

a transport stream encryption subsystem that encrypts the transport stream prior to transmission.

10. The system of claim 9, further comprising:

a transport stream storage subsystem that stores the encrypted transport stream transmitted from the headend at the at least one receiver; and

a transport stream double encryption subsystem, at the at least one receiver, that encrypts the transport stream so that a doubly encrypted transport stream is stored on a storage medium on or accessible to the receiver.

11. A computer-readable medium carrying one or more sequences of instructions for a digital video recorder, which instructions, when executed by one or more processors, cause the one or more processors to perform a method, comprising:

creating, at a headend, an event table for a corresponding transport stream; and

transmitting the transport stream from the headend to at least one receiver among a plurality of receivers.

12. The computer-readable medium of claim 11, further comprising:

transmitting the event table along with the transport stream to the at least one receiver.

13. The computer-readable medium of claim 12, further comprising:

encrypting the event table prior to transmission.

14. The computer-readable medium of claim 11, further comprising:

encrypting the transport stream prior to transmission.

15. The computer-readable medium of claim 14, further comprising:

storing the encrypted transport stream transmitted from the headend at the at least one receiver; and

encrypting, at the at least one receiver, the transport stream so that a doubly encrypted transport stream is stored on a storage medium on or accessible to the receiver.