Patent ID: 8855305

Claim:
A system, to provide protected digital content, comprising: at least one processor and control logic which, when used by the at least one processor, results in the system performing operations comprising: determining a first receiver, coupled to the system, satisfies a predetermined maximum round trip time (RTT) for a pair of messages communicated between the system and the first receiver; and determining a second receiver, coupled to the system, satisfies the RTT for a second pair of messages communicated between the first receiver and the second receiver; determining a first value based on data from the system and data from the first receiver, and obtaining, from the first receiver, a second value based on the data from the system and the data from the first receiver; wherein the system is physically upstream to the first receiver, the first receiver is physically upstream to the second receiver, and determining the first receiver satisfies the RTT is based on (a) transmitting a first message to the first receiver, and (b) obtaining a first response to the first message, within a first time period, indicating the first receiver is ready for proximity testing.