In one embodiment, a mechanism for generating message sequence order numbers is disclosed. In one embodiment, a method includes generating a timestamp value, and calculating a message authentication code (MAC) using as inputs the timestamp value, public information of an intended recipient, and a shared secret key kept between a broadcaster and the intended recipient. In addition, the method includes extracting, according to a pre-determined process agreed to between the broadcaster and the intended recipient, a required number of bits that define a size of an initial sequence number from the MAC. Lastly, the method includes using the extracted result as the initial sequence number.