Abstract: A system and method are provided for preventing a cloned modem from completing the registration process with a communications network. A cable modem termination system (CMTS) compares the media access control (MAC) address of a modem attempting to register with the network with a list of cable modems that are currently registered. If the MAC address is already contained in the list, the CMTS examines communication characteristics associated with the modem to determine if the device attempting to register is a clone. Additionally, a network monitoring system may be used to monitor the MAC addresses contained in DHCP messages to determine if a modem is potentially a clone.

Abstract: An exemplary embodiment of a method (10) for authenticating software in a cable modem makes use of a secure key and certificate stored in flash memory. In this exemplary embodiment, the code employs a key to validate (16) a signature that is generated for each new build of the code. During build of the code, the code is digitally signed (12) using e.g., a Motorola RSA private key. The message digest and the signature are then stored at the end of code file itself (13). Each time the modem (52) reboots, the code can validate (16) that the image in flash has not been modified. This validation function (16) can be accomplished e.g., by calling an RSA Signature Verification function to confirm that the signature in the header equals the message digest signed by the manufacturer's private key or the manufacturer's CVC.