Patent ID: 8588417

Claim:
A method for retransmitting an encrypted broadcast-multicast frame comprising an encrypted frame body and a media access control (MAC) header including a retry subfield having a bit, the method comprising: making a modification to one or more fields within the MAC header of the encrypted broadcast-multicast frame, wherein the one or more fields before the modification are included in additional authentication data (AAD) used to generate an encryption key of the encrypted frame body, and wherein the one or more fields with the modification is indicative of a retransmission of the encrypted broadcast-multicast frame; and transmitting the encrypted broadcast-multicast frame with the modification to the field and the encrypted frame body; wherein the modification can be reversed by a station receiving the encrypted broadcast-multicast frame by recognizing that the modification in the one or more fields indicates that the encrypted broadcast-multicast frame with the modification is the retransmission of the encrypted broadcast-multicast frame, and wherein the station reconstructs the AAD of the original encrypted broadcast-multicast frame by reversing the modification and determines the encryption key of the encrypted frame body based on the reconstructed AAD.