Secure conditional access port interface

Abstract

An apparatus and method thereof for providing a secure path for a digital signal in an intelligent transceiver such as a bi-directional set-top box. A digital signal (e.g., a broadcast signal or a signal received via a cable modem) is received by the intelligent transceiver at a front-end device (comprising, for example, a tuner). The digital signal is descrambled (if it is scrambled) and encrypted (if it is not encrypted) by a first functional block (e.g., an interface card or point of deployment) coupled to the front-end device. Coupled to the front-end device via the first functional block is a second functional block for processing (e.g., decoding) audio and/or visual content within the digital signal. Integrated into the second functional block is a decryption engine for decrypting encrypted signals. Signals from the front-end device are received via the first functional block by the decryption engine integral to the second functional block. There are no points between the first functional block and the decryption engine and between the decryption engine and the second functional block at which a descrambled and decrypted signal can be intercepted, thus providing a secure interface between the front-end device and the second functional block.

1 . A transceiver comprising: 
 a front-end unit for receiving a digital broadcast including; 
 a tuner;  
 a demodulator; and  
 a descrambling/encryption unit for descrambling the received digital broadcast and encrypting the descrambled digital broadcast;  
   an audio/video unit, including; 
 a demultiplexor for demultiplexing content;  
   a decryption engine for decrypting the encrypted digital broadcast; 
 wherein the decrypted digital broadcast is not externally accessible.  
   
   
   
       2 . The transceiver of  claim 1 , further comprising a point of deployment (POD), coupled to the front-end unit and the audio/video unit.  
   
   
       3 . The transceiver of  claim 2 , wherein the point of deployment stores a first key used by the descrambling/encryption unit to descramble the digital broadcast.  
   
   
       4 . The transceiver of  claim 3 , wherein the point of deployment stores a second key used by the descrambling/encryption unit to encrypt the digital broadcast.  
   
   
       5 . The transceiver of  claim 1 , further comprising a direct connection between the front-end unit and the decryption engine in the audio/video unit for securely transferring the encrypted digital broadcast.  
   
   
       6 . The transceiver of  claim 1 , wherein the audio/video unit further includes: 
 a first decoder, coupled to the demultiplexor, for decoding audio content contained in the decrypted digital broadcast; and    a second decoder, coupled to the demultiplexor, for decoding video content contained in the decrypted digital broadcast.    
   
   
       7 . The transceiver of  claim 6 , wherein the audio content is substantially compliant with a version of the AC3 format.  
   
   
       8 . The transceiver of  claim 6 , wherein the video content is substantially compliant with a version of the MPEG (moving picture experts group) format.  
   
   
       9 . The transceiver of  claim 1 , wherein the encrypted digital broadcast is encrypted using an encryption routine substantially compliant with DES ECB (data encryption standard electronic code book).  
   
   
       10 . The transceiver of  claim 1 , further comprising: 
 a processor coupled to the audio/video unit; and    a memory unit coupled to the processor.    
   
   
       11 . A transceiver comprising: 
 a point of deployment (POD) for descrambling a digital signal and encrypting the descrambled digital signal; and    a decryptor/encryptor for descrambling the digital signal from the POD and re-encrypting the digital signal,    an audio/video unit for decrypting the encrypted digital signal from the decryptor/encryptor and decoding the decrypted digital signal, wherein the decrypted digital signal is protected against external access and interception.    
   
   
       12 . The transceiver of  claim 11 , wherein the audio/video unit comprises an integrated circuit that includes a decryption engine and a functional block.  
   
   
       13 . The transceiver of  claim 11 , wherein the point of deployment further collects and transmits billing information related to the digital signal to a service provider.  
   
   
       14 . The transceiver of  claim 11 , further comprising a link for securely transmitting the encrypted digital signal from an encryption engine of the point of deployment to the decryption engine of the audio/video unit.  
   
   
       15 . The transceiver of  claim 11 , further comprising a front-end unit for receiving the digital signal.  
   
   
       16 . The transceiver of  claim 15 , wherein the digital signal is received from one or more systems consisting of a broadcast system, a satellite system, a cable system, a terrestrial line system, and a wireless transmission system.  
   
   
       17 . The transceiver of  claim 11 , further comprising a smart card, coupled to the point of deployment, for storing the billing information and a key used for descrambling the digital signal.  
   
   
       18 . A transceiver comprising: 
 a smart card for storing a key;    a descrambling unit, coupled to the smart card, for descrambling a digital media signal using the key;    an encryption engine, coupled to the descrambling unit, for encrypting the descrambled digital media signal;    an audio/video integrated circuit, coupled to the encryption unit comprising;    a decryption engine for decrypting the encrypted digital media signal; and    a functional block, coupled to the decryption engine, for processing the decrypted digital media signal.    
   
   
       19 . The transceiver of  claim 18 , further comprising a conditional access block comprising the descrambling unit and the encryption unit.  
   
   
       20 . The transceiver of  claim 18 , further comprising a front-end unit comprising: 
 a tuner, coupled to the descrambling unit, for receiving the digital media signal    the descrambling unit; and    the encryption engine.    
   
   
       21 . The transceiver of  claim 18 , further comprising a link between the encryption engine and the audio/video integrated circuit for securely transmitting the encrypted digital media signal from the encryption engine to the decryption engine.  
   
   
       22 . The transceiver of  claim 18 , wherein the function block comprises: 
 a first decoder for decoding audio content in the decrypted digital media signal; and    a second decoder for decoding video content contained in the decrypted digital media signal.    
   
   
       23 . The transceiver of  claim 18 , wherein a point for intercepting the digital signal in the clear between the descrambling unit and the function block in not present.  
   
   
       24 . The transceiver of  claim 18 , wherein the smart card further stores billing information.  
   
   
       25 . A receiver comprising: 
 a front-end unit including; 
 a network interface for receiving content;  
 a unit containing a descrambler for removing network-level security and a re-scrambler for applying receiver-level security to the content;  
   an audio/video unit, including; 
 a second descrambler for removing the applied receiver-level security; and  
 a decoder to decompress the content.  
   
   
   
       26 . The receiver of  claim 25 , where the network interface is a tuner.  
   
   
       27 . The receiver of  claim 26 , where the network interface also includes a demodulator to demodulate a stream of the content.  
   
   
       28 . The receiver of  claim 25 , where the network interface is a connection to the Internet.  
   
   
       29 . The receiver of  claim 28 , where the connection is Ethernet.  
   
   
       30 . The receiver of  claim 25 , where the descrambler that removes network-level security descrambles a stream of the content from a conditional access module that is coupled to the front-end unit.  
   
   
       31 . The receiver of  claim 25 , where the descrambler that removes network-level security receives a clear stream of the content from a conditional access module that is coupled to the front-end unit.  
   
   
       32 . The receiver of  claim 31 , where the conditional access module is a Point of Deployment (POD) module.  
   
   
       33 . The receiver of  claim 25 , where the descrambler that removes network-level security receives keys from a smart card coupled to the front-end unit.  
   
   
       34 . The receiver of  claim 25 , further comprising a direct connection between the re-scrambler in the front-end unit and the second descrambler in the audio/video unit for securely transferring the receiver-level security protected steam of the content.  
   
   
       35 . A receiver comprising: 
 a conditional access module for descrambling a digital signal and for re-scrambling the descrambled digital signal to produce a copy protected digital signal; and    an audio/video unit for descrambling the copy protected digital signal to produce a digital signal in the clear and decoding digital signal in the clear, wherein the digital signal in the clear is protected against external access and interception.    
   
   
       36 . The receiver of  claim 35 , wherein the conditional access module is a Point of Deployment module.  
   
   
       37 . The receiver of  claim 35 , wherein the audio/video unit comprises an integrated circuit that includes a descrambler engine and a functional block.  
   
   
       38 . The receiver of  claim 37 , further comprising a link for securely transmitting the copy protected digital signal from the conditional access module to the descrambler engine of the audio/video unit.  
   
   
       39 . The receiver of  claim 35 , further comprising a front-end unit for receiving the digital signal.  
   
   
       40 . The receiver of  claim 39 , wherein the digital signal is received from one or more systems consisting of a broadcast system, a satellite system, a cable system, a terrestrial system, and a wireless transmission system.  
   
   
       41 . The receiver of  claim 39 , wherein the front-end unit comprises a connection to the Internet.  
   
   
       42 . The receiver of  claim 35 , further comprising a smart card, coupled to the conditional access module, for storing the billing information and a key used for descrambling the digital signal.  
   
   
       43 . A receiver comprising: 
 a smart card for storing a key;    a first descrambling engine, coupled to the smart card, for descrambling a digital media signal using the key;    a scrambler engine, coupled to the descrambling unit, for re-scrambling the descrambled digital media signal for copy protection within the receiver;    an audio/video integrated circuit, coupled to the scrambler engine comprising; 
 a second descrambler engine for descrambling the copy protected digital media signal; and  
 a functional block, coupled to the second descrambler engine, for processing the descrambled copy protected digital media signal.  
   
   
   
       44 . The receiver of  claim 43 , further comprising a Point of Deployment comprising: 
 the first descrambling engine; and    the scrambler engine.    
   
   
       45 . The receiver of  claim 43 , further comprising a front-end unit comprising: 
 the first descrambling engine;    the scrambler engine; and    a tuner, coupled to the first descrambling engine, for receiving the digital media signal.    
   
   
       46 . The receiver of  claim 43 , further comprising a link between the scrambler engine and the audio/video integrated circuit for securely transmitting the copy protected digital media signal from the scrambler engine to the second descrambler engine.  
   
   
       47 . The receiver of  claim 43 , wherein a point for intercepting the digital signal in the clear between the first descrambling engine and the function block in not present.