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

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.