Systems and Methods for Providing Opportunistic Security for Physical Communication Channels

• US 20100128877A1
• Filed: 09/18/2007
• Published: 05/27/2010
• Est. Priority Date: 09/18/2006
• Status: Active Grant

• Current Assignee: Cambridge Enterprises Limited, Universidade D.O. Porto, Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Cambridge Enterprises Limited, Universidade D.O. Porto, Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Barros, Joao Francisco Cordeiro de Oliveira, Bloch, Matthieu Ratislav, Rodrigues, Miguel Raul Dias, McLaughlin, Steven William
• Granted Patent: US 8,213,616 B2
• Time in Patent Office: Days
• US Class Current: 380/268
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible

Abstract

Systems and methods of providing opportunistic security for physical communication channels are disclosed. One disclosed method is for opportunistic secure communication on a main channel between a sender device and a receiver device when an eavesdropper device is listening on an eavesdropper channel. This example method includes transmitting, in a first time period in which signal quality on the main channel is better than signal quality on the eavesdropper channel, symbols that are randomly selected from a set of symbols. The method also includes transmitting, in a second time period in which signal quality on the main channel is not better than signal quality on the eavesdropper channel, coding information associated with the randomly selected symbols. The method also includes reconciling the randomly selected symbols using the coding information.

Claims

1. A method for opportunistic secure communication on a main channel between a sender device and a receiver device when an eavesdropper device is listening on an eavesdropper channel, the method comprising:

transmitting, in a first time period in which signal quality on the main channel is better than signal quality on the eavesdropper channel, symbols that are randomly selected from a set of symbols;

transmitting, in a second time period in which signal quality on the main channel is not better than signal quality on the eavesdropper channel, coding information associated with the randomly selected symbols; and

reconciling the randomly selected symbols using the coding information.

2. The method of claim 1, further comprising:

generating the coding information for transmission in the second time period with a multilevel code.

3. The method of claim 1, further comprising:

generating the coding information for transmission in the second time period with a low-density parity-check (LDPC) code.

4. The method of claim 1, further comprising:

mapping the randomly selected symbols to a bit sequence; and

generating the coding information for transmission in the second time period from the bit sequence.

5. The method of claim 1, wherein reconciling the randomly selected symbols using the coding information produces a reconciled bit sequence, the method further comprising:

applying a universal hash function to the reconciled bit sequence to distill a secure key.

7. The system of claim 1, further comprising:

means for generating the coding information for transmission in the second time period with a multilevel code.

8. The system of claim 1, further comprising:

means for generating the coding information for transmission in the second time period with a low-density parity-check (LDPC) code.

9. The system of claim 1, further comprising:

means for mapping the randomly selected symbols to a bit sequence; and

means for generating the coding information for transmission in the second time period from the bit sequence.

10. The system of claim 1, wherein the means for reconciling the randomly selected symbols using the coding information produces a reconciled bit sequence, the system further comprising:

means for applying a universal hash function to the reconciled bit sequence to distill a secure key.

6. A system of opportunistic secure communication on a main channel between a sender device and a receiver device when an eavesdropper device is listening on an eavesdropper channel, the system comprising:

means for transmitting, in a first time period in which signal quality on the main channel is better than signal quality on the eavesdropper channel, symbols that are randomly selected from a set of symbols;

means for transmitting, in a second time period in which signal quality on the main channel is not better than signal quality on the eavesdropper channel, coding information associated with the randomly selected symbols; and

means for reconciling the randomly selected symbols using the coding information.

11. A method for opportunistic secure communication on a main channel between a sender device and a receiver device when an eavesdropper device is listening on an eavesdropper channel, the method comprising:

transmitting, in a first time period, symbols that are randomly selected from a set of symbols;

transmitting, in a second time period, coding information associated with the randomly selected symbols; and

reconciling the randomly selected symbols using the coding information, wherein the first and second time periods are distinguished by relative signal quality on the main channel and on the eavesdropper channel.

12. The method of claim 11, further comprising:

generating the coding information for transmission in the second time period with a multilevel code.

13. The method of claim 11, further comprising:

generating the coding information for transmission in the second time period with a low-density parity-check (LDPC) code.

14. The method of claim 11, further comprising:

mapping the randomly selected symbols to a bit sequence; and

generating the coding information for transmission in the second time period from the bit sequence.

15. The method of claim 11, wherein reconciling the randomly selected symbols using the coding information produces a reconciled bit sequence, the method further comprising:

applying a universal hash function to the reconciled bit sequence to distill a secure key.

19. The method of claim 11, wherein reconciling the randomly selected symbols using the coding information produces a reconciled bit sequence, the method further comprising:

applying a universal hash function to the reconciled bit sequence to distill a secure key.

16. A system for opportunistic secure communication on a main channel between a sender device and a receiver device when an eavesdropper device is listening on an eavesdropper channel, the system comprising:

a physical layer component configured to distill a key from symbols and coding information that are presented on the main channel during two different time periods, the two different time periods distinguished by relative signal quality on the main channel and on the eavesdropper channel; and

a higher-than-physical-layer component configured to encrypt a message using the distilled key.

17. The system of claim 16, wherein the two different time periods comprise a first and a second time period, and the physical layer component is further configured to:

transmitting, in the first time period, symbols that are randomly selected from a set of symbols;

transmitting, in the second time period, coding information associated with the randomly selected symbols; and

reconciling the randomly selected symbols using the coding information.

18. The system of claim 16, wherein the physical layer component is further configured to:

generating the coding information with a low-density parity-check (LDPC) code.

20. The system of claim 16, wherein the higher-than-physical layer component is further configured to request the physical layer component to distill the key.

21. A system for opportunistic secure communication on a main channel between a sender device and a receiver device when an eavesdropper device is listening on an eavesdropper channel, the system comprising:

a physical layer component configured to generate a first key in a first generation period and to generate a second key during a second generation period; and

a higher-than-physical-layer component configured to encrypt in a first encryption period with the first key and to encrypt in a second encryption period with the second key,

wherein the physical layer component is further configured to generate each of the first and the second keys from symbols and coding information that are presented on the main channel during two different sub-periods contained within the respective generation periods, the two different sub-periods distinguished by relative signal quality on the main channel and on the eavesdropper channel.

22. The system of claim 21, wherein the higher-than-physical layer component is further configured to request the physical layer component to generate the first key.

23. The system of claim 21, wherein the higher-than-physical layer component is further configured to request the physical layer component to generate the first key, wherein frequency of the request is based on characteristics of the main channel.

24. The system of claim 21, wherein the physical layer component is further configured to generate the first key without a request from the higher-than-layer physical component.

25. The system of claim 21, wherein the two different sub-periods comprise a first and a second sub-period, and the physical layer component is further configured to:

transmit, in the first sub-period, symbols that are randomly selected from a set of symbols;

transmit, in the second sub-period, coding information associated with the randomly selected symbols; and

reconcile the randomly selected symbols using the coding information.