Patent ID: 7545768

Claim:
A method comprising: performing a generic authentication architecture bootstrapping procedure between a mobile terminal device and a bootstrapping server function resulting in said mobile terminal device and said bootstrapping server function each acquiring at least a bootstrapping transaction identifier associated with said mobile terminal device and a corresponding shared key; deriving with said mobile terminal device a network application function specific key based on at least said acquired shared key and an identifier of network application function; deriving with said mobile terminal device a message authentication code based on at least said derived network application function specific key; sending from said mobile terminal device to a home agent a request message for mobile internet protocol registration comprising said derived message authentication code and an identifier of said mobile terminal device; obtaining, based on said received identifier of said mobile terminal device, said network application function specific key with said home agent from one of said bootstrapping server function and said network application function; and authenticating said request message for mobile internet protocol registration with said home agent by verifying said message authentication code with said obtained network application function specific key.