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

• US 20070192480A1
• Filed: 01/27/2006
• Published: 08/16/2007
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Bong-seon, Yoon, Young-sun, Han, Sung-hyu, Lee, Sun-nam, Lee, Jae-heung, Kim, Myung-sun
• Granted Patent: US 7,653,713 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways

Abstract

A method of measuring round trip time (RTT) and a proximity checking method using the same. The method of measuring RTT includes: transmitting a hashed second random number and starting the RTT measurement; and receiving a hashed first random number from a device that received the hashed second random number and ending the RTT measurement, thereby greatly reducing repetitive encryption and decryption operations in the proximity check using a repetitive RTT measurement.

Claims

1. A method of measuring round trip time (RTT), the method comprising:

transmitting a hashed second random number from a first device;

starting an RTT measurement when the hashed second random number is transmitted;

receiving a hashed first random number from a second device which received the hashed second random number; and

ending the RTT measurement when the hashed first random number is received.

2. The method of claim 1, wherein the hashed second random number is obtained by hashing a second random number;

wherein the RTT measurement is started by starting a timer for the RTT measurement; and

wherein the RTT measurement is ended by stopping the timer.

3. The method of claim 1, further comprising:

encrypting the first random number; and

transmitting the encrypted first random number,

wherein the hashed first random number is received based on the encrypted first random number.

4. The method of claim 1, further comprising:

receiving an encrypted second random number from the second device;

decrypting the encrypted second random number; and

hashing the decrypted second random number and thereby generating the hashed second random number.

5. The method of claim 1, further comprising:

authenticating the hashed first random number using a first random number; and

if the authentication of the hashed first random number is successful, determining that the RTT measurement is authentic.

6. The method of claim 5, wherein authenticating the hashed first random number comprises:

determining whether a hash value obtained by hashing the first random number is identical to the hashed first random number received from the second device;

if it is determined that the hash value obtained by hashing the first random number is identical to the hashed first random number received from the second device, transmitting a first authentication success message to the second device;

receiving a second authentication success message from the second device;

authenticating a value of the second authentication success message; and

if the second authentication success message is received, determining that the RTT measurement is authentic.

7. The method of claim 6, wherein a value of the first authentication success message is created by hashing a secret value which is created using the first random number.

8. A computer-readable storage medium comprising a computer program for executing a method of measuring RTT, the method comprising:

transmitting a hashed second random number from a first device;

starting an RTT measurement when the hashed second random number is transmitted;

receiving a hashed first random number from a second device which received the hashed second random number; and

ending the RTT measurement when the hashed first random number is received.

9. A proximity check method comprising:

transmitting a hashed second random number from a first device;

starting an RTT measurement when the hashed second random number is transmitted;

receiving a hashed first random number from a second device which received the hashed second random number;

ending the RTT measurement when the hashed first random number is received; and

checking the proximity of the first and the second devices based on the RTT measurement.

10. The proximity check method of claim 9, wherein checking the proximity of the first and the second devices comprises:

determining whether the RTT measurement is smaller than a critical RTT; and

if it is determined that the RTT measurement is smaller than the critical RTT, determining that the proximity check is successful.

11. The proximity check method of claim 10, wherein checking the proximity of the first and the second devices further comprises:

if it is determined that the RTT measurement is not smaller than the critical RTT, determining whether a present RTT measurement frequency is identical to a critical RTT measurement frequency; and

if it is determined that the present RTT measurement frequency is smaller than the critical RTT measurement frequency, transmitting a hashed fourth random number from the first device, and starting a second RTT measurement when the hashed fourth random number is transmitted.

12. The proximity check method of claim 9, wherein the hashed second random number is obtained by hashing and performing an XOR operation on a second random number and a present RTT measurement frequency,

wherein the RTT measurement is started by starting a timer for the RTT measurement, and

wherein the RTT measurement is ended by stopping the timer for the RTT measurement.

13. The method of claim 9, further comprising authenticating the hashed first random number using a first random number and the present RTT measurement frequency.

14. A computer-readable storage medium comprising a computer program for executing a proximity checking method, the method comprising:

transmitting a hashed second random number from a first device;

starting an RTT measurement when the hashed second random number is transmitted;

receiving a hashed first random number from a second device which received the hashed second random number;

ending the RTT measurement when the hashed first random number is received; and

checking the proximity of the first and the second devices based on the RTT measurement.

15. A method of supporting an RTT measurement, the method comprising:

receiving a hashed second random number which corresponds to a RTT measurement start; and

transmitting a hashed first random number, which corresponds to a RTT measurement end, to a first device which transmitted the hashed second random number.

16. The method of claim 15, further comprising encrypting a second random number and transmitting the encrypted second random number,

wherein the hashed second random number is received based on the encrypted second random number.

17. The method of claim 15, further comprising:

encrypting a first random number;

receiving the encrypted first random number from the first device;

decrypting the encrypted first random number,

hashing the decrypted first random number and thereby generating the hashed first random number.

18. A computer-readable storage medium comprising a computer program for executing a method of supporting an RTT measurement, the method comprising:

receiving a hashed second random number which corresponds to a RTT measurement start; and

transmitting a hashed first random number, which corresponds to a RTT measurement end, to a first device which transmitted the hashed second random number.

19. A method of measuring RTT, the method comprising:

generating a first random number at a first device;

generating a second random number at a second device;

securely exchanging the generated first and second random numbers between the first device and the second device;

transmitting a hashed first random number to measure the RTT from the first device to the second device; and

transmitting a hashed second random number to measure the RTT from the second device to the first device.