Patent ID: 7639802

Claim:
In a Mobile Node supporting Mobile IP, a method of generating an authentication key to be shared between the Mobile Node and a Foreign Agent to which the Mobile Node has roamed, comprising: dynamically generating a first key material at the Mobile Node supporting Mobile IP; transmitting the first key material by the Mobile Node to the Foreign Agent to enable the Foreign Agent to generate a Mobile-Foreign authentication key shared between the Mobile Node and the Foreign Agent; receiving a second key material by the Mobile Node from the Foreign Agent; and dynamically generating by the Mobile Node the Mobile-Foreign authentication key shared between the Mobile Node and the Foreign Agent from the second key material; wherein dynamically generating the first key material includes computing the value of X=(g x )mod n, wherein x is a random integer, wherein X is the first key material, and both g and n are Diffie-Hellman group parameters that are universally known to the Mobile Node, Foreign Agent, and Home Agent; and wherein dynamically generating the Mobile-Foreign authentication key shared between the Mobile Node and the Foreign Agent includes computing the value k=(Y x ) mod n, wherein Y is the second key material received from the Foreign Agent, wherein k is the Mobile-Foreign authentication key.