Patent ID: 8165565

Claim:
A method of authentication in a communications network, the communications network comprising a home subscriber server, a first authentication entity, a first application entity and a user device, wherein a shared secret key is stored at the home subscriber server and the user device, and wherein the method comprises: (i) generating at the first authentication entity a first network session key based on the secret key stored at the home subscriber server and generating a first user session key based on the secret key stored at the user device, wherein the first network session key and the first user session key are the same; (ii) transmitting the first network session key from the first authentication entity to the first application entity; (iii) storing the first network session key at the first application entity and storing the first user session key at the user device; and (iv) determining at a second authentication entity, based on communications from the user device and the first application entity, whether the first network session key and the first user session key are the same, and if they are the same, then (v) generating a second network session key at the second authentication entity, wherein the second network session key is based on the first network session key stored at the first application entity, and generating a second user session key at the user device based on the first user session key stored at the user device, wherein the second network session key and the second user session key are the same.