System and method for providing a secure environment for performing conditional access functions for a set top box

Abstract

A system and method are provided for decrypting a selected program. The system and method can receive at least one authorization message and at least one control message associated with a selected program. The system and method stores the at least one authorization message. The system and method transmits a first control signal if the at least one control message specifies a type of program that can be decrypted given the at least one authorization message and transmits a second control signal if the at least one control message specifies a type of program that can not be decrypted by the decryption device given the at least one authorization message.

What is claimed is:  
     
         1 . A secure processing system for a set top box, comprising: 
 a first system input for receiving at least one authorization message;    a second system input for receiving at least one control message associated with a selected program;    a system output for providing a system output signal;    a data storage device, the data storage device configured to store information associated with the at least one authorization message;    a processing unit configured to receive the at least one control message from the second system input, receive the at least one authorization message from the first system input, and store the information associated with the at least one authorization message in the data storage device, execute a first conditional access client applet, the first conditional access applet configured to cause the system output to transmit a first control signal if the at least one control message specifies a type of program that the set top box is authorized to decrypt given the information associated with the at least one authorization message, and to cause the system output to transmit a second control signal if the at least one control message specifies a type of program that can not be decrypted by the decryption device given the at least one authorization message.    
     
     
         2 . The secure processing system of  claim 1 , wherein the first control signal is adapted to cause a set top box to decrypt an encrypted signal and transmit a decrypted signal representing the selected program.  
     
     
         3 . The secure processing system of  claim 1 , wherein the second control signal is adapted to cause the set top box to transmit an encrypted signal representing the selected program.  
     
     
         4 . The secure processing system of  claim 1 , further comprising a third system input for receiving a service provider identifier.  
     
     
         5 . The secure processing system of  claim 4 , wherein if the service provider identifier received by the third system input is associated with a second conditional access applet, the central processing unit discontinues execution of the first conditional access applet and executes the second conditional access applet.  
     
     
         6 . The secure processing system of  claim 5 , wherein the second conditional access applet is configured to cause the system output to transmit a third control signal if the at least one control message specifies a type of program that can be decrypted by the decryption device given the at least one authorization message, and to cause the system output to transmit a fourth control signal if the at least one control message specifies a type of program that can not be decrypted by the decryption device given the at least one authorization message.  
     
     
         7 . The secure processing system of  claim 6 , wherein the third control signal is adapted to cause a set top box to decrypt an encrypted signal and transmit a decrypted signal representing the selected program.  
     
     
         8 . The secure processing system of  claim 6 , wherein the fourth control signal is adapted to cause the set top box to transmit an encrypted signal representing the selected program.  
     
     
         9 . The secure processing system of  claim 1 , wherein the data storage device is nonvolatile random access memory.  
     
     
         10 . A method for decrypting a selected program, comprising: 
 receiving at least one authorization message;    receiving at least one control message associated with a selected program;    storing information conveyed by the at least one authorization message;    transmitting a first control signal if the at least one control message specifies a type of program that can be decrypted given the at least one authorization message; and    transmitting a second control signal if the at least one control message specifies a type of program that can not be decrypted by the decryption device given the at least one authorization message.    
     
     
         11 . The method of  claim 10 , wherein in response to the first control signal, encrypted signal from a first service provider is decrypted and transmitted representing the selected program.  
     
     
         12 . The method of  claim 10 , wherein in response to the second control signal, an encrypted signal is transmitted representing the selected program.  
     
     
         13 . The method of  claim 10 , further comprising the step of receiving a service provider identifier.  
     
     
         14 . The method of  claim 13 , further comprising the step of transmitting a third control signal if the at least one control message specifies a type of program that can be decrypted given the at least one authorization message, and transmitting a fourth control signal if the at least one control message specifies a type of program that can not be decrypted given the at least one authorization message.  
     
     
         15 . The method of  claim 14 , wherein in response to the third control signal, an encrypted signal from a second service provider is decrypted and transmitted representing the selected program.  
     
     
         16 . The method of  claim 15 , wherein in response to the fourth control signal, an encrypted signal is transmitted representing the selected program.