Abstract: A control system provides secure transmission of programs, including at least one of video, audio, and data, between a service provider and a customer's set top unit over a digital network. Program bearing data packets are received in a first network protocol over a first data link and removed from the first network protocol. Packets representing a particular program requested by a customer having a set top unit are selected. Conditional access is provided to the selected program. In particular, program bearing packets are encrypted according to a first encryption algorithm using a first key, which is then encrypted according to a second encryption algorithm using a second key. The first keys are transported in packets to the customer's set top units along with the program packets. A public key cryptographic technique encrypts the second key such that the public key used in the encryption corresponds to the private key of the customer's set top unit.

Abstract: Methods and apparatus are described for ensuring that programs comprising at least one of video, audio, and data that are requested by a customer from a service provider (SP) via an interactive information services system, which transmits the requested programs in program bearing packets to a set top unit (STU) associated with the customer, are accessible by only authorized customers. The apparatus is positioned between the SP and the STU and comprises: means for receiving the program beating packets in a first network protocol from a first data link and removing the packets from the first network protocol; means for adding conditional access to the program bearing packets; and, means for re-encapsulating the program bearing packets in a second network protocol and outputting the program bearing packets over a second data link.

Abstract: A control system provides secure transmission of programs, including at least one of video, audio, and data, between a service provider and a customer's set top unit over a digital network. Program bearing data packets are recieved in a first network protocol over a first data link and removed from the first network protocol. Packets representing a particular program requested by a customer having a set top unit are selected. Conditional access is provided to the selected program. In particular, program bearing packets are encrypted according to a first encryption algorithm using a first key, which is then encrypted according to a second encryption algorithm using a second key. The first keys are transported in packets to the customer's set top units along with the program packets. A public key cryptographic technique encrypts the second key such that the public key used in the encryption corresponds to the private key of the customer's set top unit.