Method and devices for secure measurements of time-based distance between two devices

摘要

In order to provide a secure measurement of Round Trip Time (RTT), the calculation of RTT and the authentication data are separated. A device A (212) sends a message (222) to device B (216) to start the method. Both devices generate (224; 226) a random number (Random_A, Random_B) and device A waits (228) for device B to finish. Device A sends (242) its random number to B, which answers (246) with its own random number, and device A calculates (250) the RTT. If the RTT is below a certain limit, device A then requires (252) authentication data, which is calculated (262) by device B and sent (264) to device A that verifies (266) the authentication data. The RTT can thus be securely calculated regardless of the calculating resources of device B. Alternate embodiments, a system and devices are also provided.