Patent ID: 7653713

Claim:
A method of measuring round trip time (RTT), the method comprising: encrypting a first random number generated by a first device and transmitting the encrypted first random number to a second device; encrypting a second random number generated by the second device and transmitting the encrypted second random number to the first device; decrypting the encrypted second random number received at the first device; decrypting the encrypted first random number received at the second device; hashing the decrypted first random number to generate a hashed first random number; hashing the decrypted second random number to generate a hashed second random number; transmitting the hashed second random number from the first device to the second device; starting an RTT measurement when the hashed second random number is transmitted by the first device; receiving, at the second device, the hashed second random number transmitted from the first device; transmitting the hashed first random number from the second device to the first device, after the second device has received the hashed second random number; receiving, at the first device, the hashed first random number transmitted from the second device; and ending the RTT measurement when the hashed first random number is received by the first device.