Patent ID: 8195949

Claim:
A computer-implemented method, comprising: generating, by a computing machine, a timestamp value; calculating, by the computing machine, a first message authentication code (MAC) using the timestamp value, public information of a recipient of a sequences of messages, and a shared secret key; extracting, by the computing machine, according to a process agreed to between the computing machine and the recipient, a number of bits from the first MAC equal to a size of an initial sequence number of the sequence of messages; using, by the computing machine, the extracted bits as an applied initial sequence number for the sequence of messages; calculating, by the computing machine, a second MAC using the timestamp value, the applied initial sequence number, and the shared secret key; and sending, by the computing machine, a message of the sequence of messages and the second MAC together to the recipient, the message further comprising the timestamp value and the number of bits extracted from the first MAC.