Abstract: A system of managing security in a cable modem. Rules are defined enabling a host migrated cable modem to maintain security at specified times. The security is maintained by writing encryption keys to a register only when they are detected as being received in an authorized way. When the decryption keys have been received in an unauthorized way, then they can be received, but not used for decryption purposes. The register in includes a write enable function which enables writing the keys associated with a specified service ID. The register also includes a key destruction function.