Verification of the source of program information in a conditional access system

• US 6,105,134 A
• Filed: 07/31/1998
• Issued: 08/15/2000
• Est. Priority Date: 04/03/1995
• Status: Expired due to Term

• Current Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Pinder, Howard G., Banker, Robert O., Akins, Glendon L. III, Palgon, Michael S.
• Primary Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US09/126,795
• Time in Patent Office: 746 Days
• Field of Search: 380/20, 380/239, 380/241, 380/279, 380/281, 380/283, 380/284, 713/168, 713/170, 713/171
• US Class Current: 713/170
• CPC Class Codes: H04L 63/04 for providing a confidential data exchange among entities communicating through data packet networks
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• 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 63/045 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 63/062 for key distribution, e.g. centrally by trusted party cryptographic mechanisms or cryptographic arrangements for key distribution involving a central third party H04L9/0819
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263
• CPC Class Codes: H04N 21/2265 Server identification by a unique number or address, e.g. serial number network arrangements, protocols or services for addressing or naming H04L61/00
• 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 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/4524 involving the geographical location of the client retrieval from the Internet by querying based on geographical locations G06F16/9537; systems specially adapted for using geographical information in broadcast systems H04H60/70; protocols in which the network application is adapted for the location of the user terminal in communication control or processing H04L67/52; services making use of the location of users or terminals in wireless networks H04W4/02; locating users or terminals in wireless networks H04W64/00
• 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 7/162 Authorising the user terminal, e.g. by paying; Registering the use of a subscription channel, e.g. billing
• 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

Abstract

A cable television system provides conditional access to services. The cable television system includes a headend from which service "instances", or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.

Claims

1. A method, in a cable television system comprising a programming source and a set top terminal, of verifying said programming source at said set top terminal, the method comprising the steps of

at said programming source,

providing said programming information, a control word, and a shared secret as inputs to a secure hash function;

using at least a portion of an output from said secure hash function as a source authentication;

encrypting said control word to generate an encrypted control word; and

transmitting said source authentication, said programming information, and said encrypted control word; and

at said receiver,

receiving said source authentication, said programming information, and said encrypted control word;

decrypting said encrypted control word to recover therefrom said control word;

providing said programming information, said control word, and said shared secret as inputs into said secure hash function;

using at least a portion of an output from said secure hash function as a receiver authentication; and

comparing said source authentication with said receiver authentication, the programming information and the control word being authentic when said source authentication and said receiver authentication are the same.

2. The method set forth in claim 1, wherein said control word is created by a pseudo random number generator.

3. The method set forth in claim 1, wherein said control word is created using a counter.

4. A head end transmitter for creating verifiable programming information that is transmitted within a cable television system, the head end transmitter comprising:

a control word generator for generating a control word;

a device for securely maintaining a shared secret;

a processor for performing a secure hash function having inputs of said control word, said shared secret, and said programming information, for creating a source authentication from at least a portion of an output from said secure hash function; and

a transmitter for transmitting said source authentication, said programming information, and said control word.

5. The head end transmitter of claim 4, further comprising:

an encryptor coupled to the processor and the transmitter for encrypting said control word prior to its transmission.

6. The head end transmitter set forth in claim 4, wherein said control word generator comprises a pseudo random number generator.

7. The head end transmitter set forth in claim 4, wherein said control word generator comprises a counter.

8. A cable television system for verifying the source of programming information, the cable television system comprising:

a programming source for providing inputs of a shared secret, a control word, and said programming information to a secure hash function, for receiving as an output thereof a source authentication, and for encrypting and transmitting said inputs and said source authentication;

a receiver for receiving said source authentication and said inputs, creating a receiver authentication from at least a portion of an output of a secure hash function having inputs of said shared secret, said control word, and said programming information, for comparing said source authentication with said receiver authentication, and for accepting the programming information as authentic when the two are the same; and

a transmission medium over which said transmission is broadcast from said programming source to said receiver.

9. The cable television system of claim 8, wherein:

the programming source further comprises an encryptor for encrypting said control word; and

the reciever further comprises a decryptor for decrypting said control word.

10. The cable television system set forth in claim 8, wherein said programming source comprises a pseudo random number generator for generating said control word.

11. The cable television system set forth in claim 8, wherein said programming source comprises a counter for generating said control word.

12. A method of verifying a source of information in a conditional access system with a source and a receiver, comprising the steps of:

using as inputs to a secure hash function system information, a control word, and a secret key, the secret key being shared by the source and the receiver and the control word being a key used in decrypting encrypted information and data transmitted over the conditional access system;

performing the secure hash function at the source and using at least a portion of the output of the secure hash function performed at the source as a source authenticator;

performing the secure hash function at the receiver and using at least a portion of the output of the secure hash function performed at the receiver as a receiver authenticator; and

comparing at the receiver the source authenticator and the receiver authenticator and verifying the source of information in the conditional access system as the source if the source authenticator and the receiver authenticator match.

13. The method of claim 12, further comprising the step of:

transmitting over the conditional access system the system information, the control word, and the source authenticator from the source to the receiver.

14. The method of claim 13, further comprising the steps of:

encrypting the control word at the source prior to the transmitting step; and

decrypting the control word at the receiver after the transmitting step.

15. The method of claim 12, wherein the secure hash function and the comparing of the source authenticator and the receiver authenticator performed at the receiver is performed in a secure element.

16. The method of claim 12, wherein the source is located in a headend of a cable television system.

17. The method of claim 12, wherein the receiver is a home communications terminal.