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Method of measuring round trip time and proximity checking method using the same

  • US 7,653,713 B2
  • Filed: 01/27/2006
  • Issued: 01/26/2010
  • Est. Priority Date: 02/23/2005
  • Status: Expired due to Fees
First Claim
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1. 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.

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