Authenticating Communications

The method of authenticating the source of a communication is disclosed. The method includes executing a clock for an operation period. The method also includes receiving a communication from a remote device at a communication time corresponding to a time interval of a plurality of time intervals sequentially covering the operation period. Each time interval has an associated authentication value. The communication includes a commitment value. The method also includes determining whether the commitment value matches the authentication value associated with the time interval corresponding to the communication time. The method also includes processing the communication when the commitment value matches the authentication value associated with the time interval corresponding to the communication time. The authentication value associated with the time interval corresponding to the communication time includes a hash digest of a hash function applied to the authentication value associated with a sequentially subsequent time interval.