Method and apparatus for secure communication between cryptographic systems using real time clock

• US 8,036,383 B2
• Filed: 04/15/2008
• Issued: 10/11/2011
• Est. Priority Date: 11/22/2007
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Dong Chan, Kim, Jae Heon, Han, Jae Woo, Park, Sang Woo
• Primary Examiner(s): BARRON JR, GILBERTO
• Application Number:
  US12/103,130
• Publication Number:
  US 20090138743A1
• Time in Patent Office: 1,274 Days
• Field of Search: 380/255, 380/264, 380/35, 380/277, 380/281, 380/282, 380/224, 380/44, 380/45, 713/171
• US Class Current: 380/255
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner

Abstract

Provided are a method and apparatus for secure communication between cryptographic systems using a Real Time Clock (RTC). The method and apparatus allow a transmitting cryptographic system to transfer partial RTC data and a receiving cryptographic system to restore entire RTC data, thereby minimizing data to be transferred between the cryptographic systems. The method includes: calculating a largest RTC deviation between a transmitting cryptographic system and a receiving cryptographic system; calculating the smallest number of bits of partial data on an RTC required for restoring entire data on the RTC on the basis of the calculated largest RTC deviation; calculating the partial RTC data on the basis of the calculated smallest number of bits of the partial RTC data; and transferring the calculated partial RTC data to the receiving cryptographic system.

Claims

1. A method for secure communication between cryptographic systems using a Real Time Counter (RTC), comprising:

calculating a largest RTC deviation between a transmitting cryptographic system and a receiving cryptographic system;

calculating the smallest number of bits of partial data on an RTC required for restoring entire data on the RTC on the basis of the calculated largest RTC deviation;

calculating the partial RTC data on the basis of the calculated smallest number of bits of the partial RTC data; and

transferring the calculated partial RTC data to the receiving cryptographic system.

2. The method of claim 1, further comprising:

restoring, at the receiving cryptographic system, the entire RTC data on the basis of the received partial RTC data.

3. The method of claim 1, wherein the calculating of the largest RTC deviation comprises calculating the largest RTC deviation according to lives of the transmitting and receiving cryptographic systems and an accuracy of the RTC.

4. The method of claim 1, wherein the smallest number “

n”

of bits of the partial RTC data is calculated by the following equation;

n=┌

log₂ T_d┐

+1,

wherein T_d denotes the largest RTC deviation between the transmitting cryptographic system and the receiving cryptographic system.

5. The method of claim 4, wherein the partial RTC data is calculated by the following equation:

T_A mod 2ⁿ,

wherein T_A denotes the RTC value of the transmitting cryptographic system, and n denotes the smallest number of bits of partial RTC data.

6. The method of claim 2, wherein the entire RTC data X renders |X−

T_B| be a smallest value and is calculated by the following equation;

X=T_A mod 2ⁿ+k2ⁿ,

wherein T_B denotes an RTC value of the receiving cryptographic system, and k is an integer.

7. An apparatus for secure communication between cryptographic systems using a Real Time Counter (RTC), comprising:

a largest RTC deviation calculator for calculating a largest RTC deviation between a transmitting cryptographic system and a receiving cryptographic system;

a partial RTC data calculator for calculating the smallest number of bits of partial data on an RTC required for restoring entire data on the RTC on the basis of the calculated largest RTC deviation;

a partial RTC data extractor for calculating the partial RTC data on the basis of the calculated smallest number of bits of the partial RTC data; and

a partial RTC data transmitter for transferring the calculated partial RTC data to the receiving cryptographic system.

8. The apparatus of claim 7, further comprising:

a partial RTC data receiver for receiving transferred partial RTC data; and

an entire RTC data restorer for restoring entire RTC data on the basis of the received partial RTC data.

9. The apparatus of claim 7, wherein the largest RTC deviation calculator calculates the largest RTC deviation according to lives of the transmitting and receiving cryptographic systems and an accuracy of the RTC.

10. The apparatus of claim 7, wherein the partial RTC data calculator calculates the smallest number “

n”

of bits of the partial RTC data using the following equation;

n=┌

log₂ T_d┐

+1,

wherein T_d denotes the largest RTC deviation between the transmitting cryptographic system and the receiving cryptographic system.

11. The apparatus of claim 10, wherein the partial RTC data extractor calculates the partial RTC data using the following equation:

T_A mod 2ⁿ,

wherein T_A denotes the RTC value of the transmitting cryptographic system, and n denotes the smallest number of bits of partial RTC data.

12. The apparatus of claim 8, wherein the entire RTC data restorer calculates the entire RTC data X rendering |X−

T_B| to be a smallest value using the following equation;

X=T_A mod 2ⁿ+k2ⁿ,

wherein T_B denotes an RTC value of the receiving cryptographic system, and k is an integer.