Patent ID: 7308575

Claim:
A method of maintaining additional security for communications between an upstream server and at least two downstream client modems on a shared communication media through use of a dynamic key generated by the particular client modems, the method comprising: A. the server receiving a scrambled upstream communication from a first client modem, wherein the upstream communication is a packet; B. the server unscrambling a scrambled packet containing a new key for the first client modem using a previous seed for the first client modem based on a previous key for the first client modem received in a previous upstream packet from the first client modem; C. the server storing information sufficient to create a new seed for the first client modern based on the new key for the first client modern based on the unscrambled contents of the upstream packet; D. the server scrambling at least a portion of the next downstream communication to a second client modem with scrambling based on a seed for the second client modem based on a key for the second client modem, where in the key for the second client modern is unrelated to the key for the first client modem, wherein the downstream communication is a subpacket; E. the server scrambling at least a portion of the next downstream subpacket to the first client modern with scrambling based on the new seed for the first client modern based on the new key for the first client modem; F. the first client modem receiving the next downstream subpacket scrambled for the first client modem; G. the first client modem unscrambling the scrambled portion of the next downstream subpacket scrambled for the first client modern with the new seed for the first client modern based on the new key for the first client modem; H. the first client modern creating a next upstream packet containing a next key for the first client modern; I. the first client modern storing information sufficient to create a next seed for the first client modem based on the next key for the first client modern; and J. the first client modem scrambling at least a portion of the next upstream packet using the new seed for the first client modem based on the previously communicated new key for the first client modem.