Abstract:
An interactive information distribution system for providing secure distribution of video-on-demand content. The interactive information distribution system includes at least one programming source for storing at least one partially encrypted video program, and a distribution center including a remote server. The remote server stores the at least one partially encrypted video program received from the at least one programming source. The remote server also processes the partially encrypted video program corresponding to a subscriber requested video program to produce a fully encrypted video program. A subscriber-side distribution network, coupled to the distribution center, causes transmission of the fully encrypted video program to the requesting subscriber.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of commonly assigned U.S. patent application Ser. No. 09/850,231, filed on May 7, 2001, which is a continuation of commonly assigned U.S. patent application Ser. No. 09/267,800, filed on Mar. 12, 1999 (now U.S. Pat. No. 6,229,895) issued on May 8, 2001, both of which are incorporated herein by reference in their entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to the field of video distribution networks. In particular, this invention relates to secure video distribution networks.  
           [0004]    2. Description of the Background Art  
           [0005]    Security is an important issue for video distribution networks. For cable distribution networks, there are various portions or locations where security is of concern.  
           [0006]    A first portion where security is of concern is the primary distribution network. The primary distribution network is where video content is transferred from television studios to distribution centers. A second portion where security is of concern is the secondary distribution network. The secondary distribution network is where the video content is transmitted from a distribution center to subscriber stations.  
           [0007]    For video on-demand distribution networks, there is an additional point where security is of concern. That point is a remote server within a distribution center. Typically, such a remote server stores the video content before the video content is distributed to the subscriber stations.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a solution to the security issues presented above, especially with regards to security at a remote server. In accordance with a first aspect of the invention, an interactive information distribution system provides secure distribution of video-on-demand content. The interactive information distribution system includes at least one programming source for storing at least one partially encrypted video program, and a distribution center including a remote server.  
           [0009]    The remote server stores the at least one partially encrypted video program received from the at least one programming source. The remote server also processes the partially encrypted video program corresponding to a subscriber requested video program to produce a fully encrypted video program. A subscriber-side distribution network, coupled to the distribution center, causes transmission of the fully encrypted video program to the requesting subscriber. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a schematic diagram of a conventional cable distribution network.  
         [0011]    [0011]FIG. 2 is a flow chart depicting a conventional insecure process for distributing video content via a conventional cable distribution network.  
         [0012]    [0012]FIG. 3 is a flow chart depicting a conventional (somewhat) secure process for distributing video content via a conventional cable distribution network.  
         [0013]    [0013]FIG. 4 is a schematic diagram of a cable distribution network including a video on-demand source in accordance with a preferred embodiment of the present invention.  
         [0014]    [0014]FIG. 5A is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a first aspect of the present invention.  
         [0015]    [0015]FIG. 5B is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a second aspect of the present invention.  
         [0016]    [0016]FIG. 6 is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a third aspect of the present invention.  
         [0017]    [0017]FIG. 7 is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a fourth aspect of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    [0018]FIG. 1 is a schematic diagram of a conventional cable distribution network. The conventional cable distribution network typically includes one or more broadcast sources  102 , one or more premium broadcast sources  104 , one or more distribution centers  106 , one or more secondary distribution networks  108 , and a plurality of subscriber stations  110 .  
         [0019]    The broadcast source  102  may be, for example, a local television station. For instance, an affiliate station of a major network such as ABC, NBC, CBS, FOX, or UPN. The premium broadcast source  104  may be, for example, a premium channel such as HBO, Showtime, Cinemax, and so on. The sources  102  and  104  may be coupled via a primary distribution network to the distribution center  106 . The distribution center  106  may be, for example, a cable head-end. The distribution center  106  may be coupled via a secondary distribution network  108  to the subscriber stations  110 . The secondary distribution network  108  comprises may include, for example, various amplifiers, bridges, taps, and drop cables. Finally, the subscriber stations  110  may be, for example, set-top boxes and associated television equipment for viewing the video content by end users.  
         [0020]    [0020]FIG. 2 is a flow chart depicting a conventional insecure process for distributing video content via a conventional cable distribution network. First, a non-premium video signal is transported  202  from the broadcast source  102  to the distribution center  106 . At the distribution center  106 , the video signal is multiplexed  204  with other signals to generate a multiplexed signal. The multiplexed signal is then distributed  206  from the distribution center  106  via the secondary distribution network  108  to the subscriber stations  110 . At the subscriber stations  110 , the multiplexed signal is demultiplexed  208  to isolate the video signal, and then the video signal is displayed  210 , typically, on a television monitor.  
         [0021]    [0021]FIG. 3 is a flow chart depicting a conventional (somewhat) secure process for distributing video content via a conventional cable distribution network. First, a premium video signal is encrypted  302  to generate an encrypted signal. The encrypted signal is transported  304  from the premium broadcast source  104  to the distribution center  106 .  
         [0022]    At the distribution center  106 , the video signal is decrypted  306  to regenerate the premium video signal. The premium video signal is then scrambled  308  and multiplexed  310  with other signals to generate a multiplexed signal. The multiplexed signal is then distributed  312  from the distribution center  106  via the secondary distribution network  108  to the subscriber stations  110 .  
         [0023]    At the subscriber stations  110 , the multiplexed signal is demultiplexed  314  to isolate the scrambled video signal, the scrambled video signal is unscrambled  316 , and then the video signal is displayed  318 , typically, on a television monitor connected to a set-top box. The process in FIG. 3 is a typical conventional process for delivering premium video using scrambling. Other conventional processes also exist.  
         [0024]    [0024]FIG. 4 is a schematic diagram of a cable distribution network including a video on-demand source in accordance with a preferred embodiment of the present invention. In addition to the components of the conventional cable distribution network shown in FIG. 1, the cable distribution network shown in FIG. 4 includes a video on-demand source  402  and a remote server  404 . The video on-demand source  402  may house, for example, a collection of video programs such as, for example, movies. As shown in FIG. 4, the remote server  404  may be located within the distribution center  106 . The remote server  404  may include, for example, a parallel processing computer configured to be a video server, a disk drive array to store video data, and a video session manager to provide session control of the video data flowing to and from the video server.  
         [0025]    [0025]FIG. 5A is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a first aspect of the present invention. The process depicted in FIG. 5A may be called a store, decrypt, and re-encrypt process.  
         [0026]    First, a video program is encrypted  502  by a video on-demand source  402  to generate an encrypted program in a first encrypted form. The encrypted program is transported  504  via a primary distribution network from the video on-demand source  402  to a remote server  404  within a distribution center  106 . The encrypted program is then stored  506  in the remote server  404 .  
         [0027]    Subsequently, when the remote server  404  receives  508  a request for transmission of the video program from a subscriber station  110 , the remote server  404  responds by first decrypting  510  the video program from the first encrypted form. A first key is may be used to accomplish such decryption  510 , and such key may have been received from the video on-demand source  402  via a communication channel that is separate from the one used to transmit the video program. After the video program is decrypted  510 , the remote server  404  re-encrypts  512  the video program into a second encrypted form using a second key.  
         [0028]    The second key may be a public key of a public key encryption system. Such a public key encryption system uses two different key: a public key to encrypt data and a private key to decrypt data. In that case, decryption would be accomplished using a corresponding private key of the public key encryption system. Examples of such a public key encryption system is encryption under the PGP (Pretty Good Privacy) system or under the RSA (Rivest, Shamir, and Adleman) system. Alternatively, the second key may be a private key of a private key encryption system. Such a private key encryption system uses a single private key to encrypt and decrypt data. Examples of such a private key encryption system is encryption under the Data Encryption Standard (DES) or under triple-DES which involves applying DES three times to enhance security. The private key(s) itself may be transmitted from the remote server  404  to the subscriber station  110  while encrypted in a third encrypted form.  
         [0029]    After the video program is re-encrypted  512 , the re-encrypted program in the second encrypted form (and the second key if necessary) is multiplexed  514  with other signals to generate a multiplexed signal. The multiplexed signal is then distributed  516  via the secondary distribution network  108  to the subscriber stations  110 .  
         [0030]    At the subscriber stations  110 , the multiplexed signal is demultiplexed  518  to isolate the re-encrypted program in the second encrypted form (and the second key if necessary), the re-encrypted program is decrypted  520  from the second encrypted form to generate the unencrypted video program, and then the video program is displayed  522 , typically, on a television monitor connected to set-top box.  
         [0031]    [0031]FIG. 5B is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a second aspect of the present invention. The process depicted in FIG. 5B may be called a decrypt, re-encrypt, and store process. In comparison with the process in FIG. 5A, the process in FIG. 5B decrypts  510  and re-encrypts  512  the video program before the video program is stored  506  in the remote server  404 .  
         [0032]    First, a video program is encrypted  502  by a video on-demand source  402  to generate an encrypted program in a first encrypted form. The encrypted program is transported  504  via a primary distribution network from the video on-demand source  402  to a remote server  404  within a distribution center  106 . At this point, the remote server  510  decrypts  510  the video program from the first encrypted form. A first key is may be used to accomplish such decryption  510 , and such key may have been received from the video on-demand source  402  via a communication channel that is separate from the one used to transmit the video program. After the video program is decrypted  510 , the remote server  404  re-encrypts  512  the video program into a second encrypted form using a second key. After the decryption  510  and re-encryption  512 , the re-encrypted program is then stored  506  in the remote server  404 .  
         [0033]    Note that step  506  in FIG. 5B differs from step  506  in FIG. 5A in that step  506  in FIG. 5B involves storing the video program in the second encrypted form while step  506  in FIG. 5A involves storing the video program in the first encrypted form.  
         [0034]    Subsequently, when the remote server  404  receives  508  a request for transmission of the video program from a subscriber station  110 , the remote server  404  responds by multiplexing  514  the re-encrypted program in the second encrypted form (and the second key if necessary) with other signals to generate a multiplexed signal. The multiplexed signal is then distributed  516  via the secondary distribution network  108  to the requesting subscriber station  110 .  
         [0035]    At the subscriber stations  110 , the multiplexed signal is demultiplexed  518  to isolate the re-encrypted program in the second encrypted form (and the second key if necessary), the re-encrypted program is decrypted  520  from the second encrypted form to generate the unencrypted video program, and then the video program is displayed  522 , typically, on a television monitor connected to set-top box.  
         [0036]    [0036]FIG. 6 is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a third aspect of the present invention. The process depicted in FIG. 6 may be called a pass-through process.  
         [0037]    First, a video program is encrypted  602  by a video on-demand source  402  to generate an encrypted program in a first encrypted form. The encrypted program is transported  604  via a primary distribution network from the video on-demand source  402  to a remote server  404  within a distribution center  106 . A key to decrypt the encrypted program may also be transported from the source  402  to the server  404 . The encrypted program is then stored  606  in the remote server  404 .  
         [0038]    The key may be a public key of a public key encryption system. Such a public key encryption system uses two different key: a public key to encrypt data and a private key to decrypt data. In that case, decryption would be accomplished using a corresponding private key of the public key encryption system. Examples of such a public key encryption system is encryption under the PGP (Pretty Good Privacy) system or under the RSA (Rivest, Shamir, and Adleman) system. Alternatively, the key may be a private key of a private key encryption system. Such a private key encryption system uses a single private key to encrypt and decrypt data. Examples of such a private key encryption system is encryption under the Data Encryption Standard (DES) or under triple-DES which involves applying DES three times to enhance security. The private key(s) itself may be transmitted from the source  402  to the server  404  while encrypted in a second encrypted form. Alternatively, the private key(s) may be transported from the source  402  to the server  404  via a communication channel which is separate from the communication channel used to transport the video program from the source  402  to the server  404 .  
         [0039]    Subsequently, when the remote server  404  receives  608  a request for transmission of the video program from a subscriber station  110 , the remote server  404  responds by multiplexing  610  the encrypted program in the first encrypted form (and the key if necessary) with other signals to generate a multiplexed signal. The multiplexed signal is then distributed  612  via the secondary distribution network  108  to the requesting subscriber station  110 .  
         [0040]    At the subscriber stations  110 , the multiplexed signal is demultiplexed  614  to isolate the encrypted program in the first encrypted form (and the key if necessary), the encrypted program is decrypted  616  from the first encrypted form to generate the unencrypted video program, and then the video program is displayed  618 , typically, on a television monitor connected to set-top box.  
         [0041]    [0041]FIG. 7 is a flow chart depicting a secure process for distributing video on-demand content via a cable distribution network in accordance with a fourth aspect of the present invention. The process depicted in FIG. 7 may be called a multiple-layer encryption process. In comparison with the process in FIG. 6, the process in FIG. 7 pre-encrypts  702  the video program at the source  402 , completes encryption  704  of the video program at the remote server  404 , and fully decrypts  706  the video program at the subscriber station  110 .  
         [0042]    The pre-encryption step  702  may be implemented by applying a single DES encryption or a double DES encryption. If the pre-encryption step  702  uses a single DES encryption, then the completion of encryption step  704  may be implemented by applying a double DES encryption to achieve triple-DES encryption. Similarly, if the pre-encryption step  702  uses a double DES encryption, then the completion of encryption step  704  may be implemented by applying a single DES encryption to achieve triple-DES encryption. In either case, the video program is transported from the remote server  404  to the subscriber station  110  while under triple-DES encryption. As long as the subscriber station has the three keys required, it will be able to fully decrypt  706  the triple-DES encryption to obtain the unencrypted video program.  
         [0043]    It is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of one application of the principles of the invention. For example, while the present invention is described in application to video on-demand, it also has some application in broadcast video. Numerous additional modifications may be made to the methods and apparatus described without departing from the true spirit of the invention.