Patent ID: 7551915

Claim:
In a network in which a correspondent node sends packets to a home address of a mobile node and a home agent sends the packets to a care-of address of the mobile node, a method of authorizing the correspondent node to send future packets to the care-of address of the mobile node, the method comprising the steps of: generating an initiating-message authentication code by applying an initiating-message algorithm that hashes first input data, wherein the first input data includes an initiating-message key; sending a first initiating message, the first initiating message including a first test value and the initiating-message authentication code; sending a second initiating message, the second initiating message including a second test value; receiving a first responsive message, the first responsive message including the first test value, a first token, and a responsive-message authentication code; receiving a second responsive message, the second responsive message including the second test value and a second token; using a responsive-message key to validate the responsive-message authentication code; using the first and second tokens to generate an authorization-message authentication code; sending an authorization message that authorizes the correspondent node to send future packets to the care-of address of the mobile node, wherein the authorization message includes the authorization-message authentication code.