An apparatus for transmitting N packets including a key mixing circuit to generate N groups of encryption seeds, each based upon a predetermined key, a transmitter address, and a predetermined start value for a packet number. A packet number circuit inserts a different one of N values for the packet number into each of the N packets. Each of the N values for the packet number is greater than, or equal to, the predetermined start value for the packet number. An encryption circuit encrypts each of the N packets using the one of the N groups of encryption seeds that was generated based on the value for the packet number in the respective one of the N packets. An output circuit sends the N packets. The encryption circuit generates each of the N groups of encryption seeds before an input circuit receives the respective one of the N packets.