Patent ID: 8510561

Claim:
A method of computing a shared encryption key (k) for a group of n mobile devices, the group of n mobile devices comprising at least three mobile devices, wherein the method comprises, for an i-th mobile device of the group of n mobile devices: computing a public key (X i ) for the mobile device for transmission to at least one first other mobile device of the group of n mobile devices, wherein the public key (X i ) for the mobile device is a function of at least a private key (x i ) associated with the mobile device and of a shared password (π) known to all mobile devices of the group of n mobile devices; computing a public value (K i ) for the mobile device for transmission to each of all other mobile devices of the group of n mobile devices, wherein the public value (K i ) for the mobile device is a function of at least the private key (x i ) associated with the mobile device and of a public key of at least one second other mobile device of the group of n mobile devices; and using the public value (K 1 , . . . K i−1 , K i+1 , . . . K n ) of each of all other mobile devices of the group of n mobile devices to compute the shared encryption key (k) in accordance with a group key establishment protocol.