Importance

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Abstract

The specification relates to the encryption of data transmitted over a broadband multiple access bi-directional hybrid fiber/coax (HFC) network. The method supports downstream broadcast encryption from headend to cable modem, and also provides for encryption of transmissions from cable modems back to the headend. Although the present invention is described in relation to an HFC network, it is also equally applicable to a cellular wireless communications environment or any other digital broadcast medium. The invention is implemented in two subdivisions, a slow but secure software encrypting algorithm, and a fast but less secure hardware encrypting algorithm. The combination produces the security of the software subdivision, with the encrypting speed of the hardware subdivision. The encryption method and apparatus supports the various access and transmission modes, such as STM, ATM, and VL. The present invention utilizes a virtual random number generator at the individual cable modems to reduce cable modem hardware. The authentication and key generation process between headend and cable modem produces a mutually authenticated and mutually generated permanent key. The present invention features a cryptosync clock at the headend which is transmitted to individual cable modems as a broadcast clock, thus eliminating a need for a clock at each cable modem.

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First Claim