Patent ID: 7234062
Filing Date: 2007-06-19
Classification: H04L

Abstract:
1. In an appliance communication network, a method for authenticating appliance messages, the method comprising: maintaining at an appliance communication center a first shared message counter that counts messages communicated between the appliance communication center and a first appliance, the first shared message counter shared between the communication center and the first appliance; maintaining at the appliance communication center a second shared message counter that counts messages communicated between the appliance communication center and a second appliance, the second shared message counter provides a count separate from a count provided by the first shared message counter; generating a first authentication word by applying an appliance message, a shared authentication keying variable K shared between the appliance communication center and the first appliance, and the first shared message counter, as stored in the communication center, to an authentication algorithm; transmitting the appliance message and the first authentication word as an authenticated message to the first appliance; receiving the authenticated message at the first appliance; applying a third shared message counter, the shared authentication keying variable, as stored in the first appliance, and the appliance message to the authentication algorithm to generate the second authentication word; comparing the first authentication word and the second authentication word to determine authenticity of the authenticated message; installing a master keying variable within the first appliance and the appliance communication center; and changing, within the first appliance, the shared authentication keying variable by applying the shared authentication keying variable and the master keying variable to the authentication algorithm to generate a new shared authentication keying variable.