Patent ID: 8509438

Claim:
A node of a wireless communications network, the node being remote from a master node of the wireless communications network, the master node and the node communicating via the wireless communications network, the node comprising: a wireless communications interface for communicating via the wireless communications network; a primary key for encrypting and decrypting messages in accordance with a symmetric key encryption algorithm; a secondary key for encrypting and decrypting messages in accordance with the symmetric key encryption algorithm; and a processor that operates to: receive an encrypted message from the master node via the wireless communications interface; attempt to decrypt the received encrypted message using the primary key; if the attempt to decrypt the received encrypted message using the primary key fails, attempt to decrypt the received encrypted message using the secondary key; and if the attempt to decrypt the received encrypted message using the secondary key fails, receive a command transmitted by a source local to the node to change the secondary key; change the secondary key in response to the command; and use the changed secondary key to perform encrypted communications with the master node via the wireless communications interface to obtain a new primary key from the master node, wherein the processor locally generates the primary key based at least in part on a combination of a primary seed value and an identifier that uniquely identifies the node on the wireless communications network, and wherein the processor locally generates the secondary key based at least in part on a combination of a secondary seed value and the identifier that uniquely identifies the node on the wireless communications network, and wherein the primary seed value and the secondary seed value are stored locally within a memory of the node.