Patent ID: 8160254

Claim:
A method for updating a group traffic encryption key (GTEK) for a group traffic service in a wireless portable Internet system, the method comprising: a) determining, at a base station, whether a lifetime of a current group key encryption key (GKEK) used for encrypting a current GTEK expires within a lifetime of the current GTEK; b) when the lifetime of the current GKEK does expire within the lifetime of the current GTEK, generating, at the base station, a next GTEK and a next GKEK to be used for encrypting the next GTEK within the lifetime of the current GTEK and transmitting the next GTEK and the next GKEK to a subscriber station; and c) when the lifetime of the current GKEK does not expire within the lifetime of the current GTEK, generating, at the base station, a next GTEK within the lifetime of the current GTEK and transmitting the next GTEK to the subscriber station, wherein the next GTEK is encrypted by using the current GKEK.