Methods and systems for providing interference based physical-layer encryption

• US 8,477,937 B2
• Filed: 05/31/2011
• Issued: 07/02/2013
• Est. Priority Date: 04/07/2011
• Status: Active Grant

• Current Assignee: Comtech EF Data (Comtech Telecommunications Corporation)
• Original Assignee: Comtech EF Data (Comtech Telecommunications Corporation)
• Inventors: Akhavan-Toyserkani, Kasra, Ripple, Andrew, Beeler, Michael, Mamaril, Cris
• Primary Examiner(s): SIMITOSKI, MICHAEL J
• Application Number:
  US13/149,641
• Publication Number:
  US 20110228929A1
• Time in Patent Office: 763 Days
• Field of Search: 380/38, 380/204, 380/206, 380/221, 380/270, 370/342, 375/144, 375/145, 375/148, 375/346
• US Class Current: 380/206
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible

Abstract

A method for encrypting an information carrier comprising generating a sequence of data using a sequence generator, modulating, using a first modulator an output from the sequence generator such that an interference signal results, encoding the interference generator'"'"'s synchronization information using an encoder, modulating, using a second modulator, the encoded synchronization information such that a synchronization carrier signal results, spreading the synchronization carrier signal using a spreader such that a spread sub-carrier synchronization signal results, and combining the modulated information carrier signal, interference signal, and spread sub-carrier synchronization signal using a signal combiner such that a composite signal results, the interference signal having one or more signal characteristics that results in obfuscation of the information carrier signal when the information carrier signal and interference signal are combined.

Claims

1. A method for encrypting an information carrier signal comprising:

generating a sequence of data using a sequence generator;

modulating, using a first modulator an output from the sequence generator such that an interference signal results;

encoding synchronization information generated by the sequence generator using an encoder;

modulating, using a second modulator, the encoded synchronization information such that a synchronization carrier signal results;

spreading the synchronization carrier signal using a spreader such that a spread sub-carrier synchronization signal results; and

combining a modulated information carrier signal, the interference signal, and the spread sub-carrier synchronization signal using a signal combiner such that a composite signal results, the interference signal having one or more signal characteristics that results in obfuscation of the information carrier signal when the information carrier signal and interference signal are combined.

2. The method of claim 1, further comprising authenticating the information carried in the spread sub-carrier synchronization signal using an authentication device.

3. The method of claim 1, further comprising encrypting information carried in the spread sub-carrier synchronization signal using an encryption device.

4. The method of claim 1, further comprising providing forward error correction (FEC) to the spread sub-carrier synchronization signal using the encoder.

5. The method of claim 1, wherein the sub-carrier synchronization signal is modulated using one or more modulating devices.

6. The method of claim 1, wherein the spreading further comprises using spread spectrum techniques to reduce a power spectral density of the spread sub-carrier synchronization signal such that the power spectral density of the spread sub-carrier synchronization signal is lower than a power spectral density of the combined information carrier signal and interference signal.

7. The method of claim 1, further comprising determining a center frequency and occupied bandwidth of the information carrier signal using one or more Fourier transform techniques.

8. The method of claim 1, further comprising determining the power level of the information carrier signal using a power detector.

9. The method of claim 1, further comprising manually configuring one or more characteristics of the information carrier signal to specify a center frequency, occupied bandwidth, or power level of the information carrier signal.

10. The method of claim 1, further comprising up-converting the interference and sub-carrier synchronization signals prior to combining these signals with the information carrier signal.

11. The method of claim 1, wherein the combining of the signals occurs at baseband frequency.

12. A method of recovering encrypted information comprising:

receiving a composite carrier signal using a receiving device, the composite carrier signal comprising a previously combined information carrier signal, interference signal, and spread sub-carrier synchronization signal, wherein the interference signal has one or more signal characteristics that results in obfuscation of the information carrier signal by the interference signal in the composite signal;

despreading the spread sub-carrier synchronization signal using a despreader;

demodulating the despread sub-carrier synchronization signal using a demodulator;

decoding the demodulated despread sub-carrier synchronization signal using a decoder, resulting in extracted synchronization information from the sub-carrier synchronization signal;

synchronizing an interference generator using the extracted synchronization information such that the interference generator creates a replica of the interference signal contained in the received composite signal; and

cancelling the interference signal from the composite signal using a cancelling device that uses one or more cancellation techniques to obtain the information carrier signal.

13. The method of claim 12, further comprising splitting the composite carrier signal using a signal splitter.

14. The method of claim 12, wherein the despreading further comprises spread spectrum despreading.

15. The method of claim 12, further comprising decrypting information carried in the sub-carrier synchronization signal using a decryption device.

16. The method of claim 12, further comprising authenticating information carried in the sub-carrier synchronization signal using an authentication device.

17. The method of claim 12, further comprising applying a frame parser to information carried in the sub-carrier synchronization signal.

18. The method of claim 12, further comprising generating a synchronized interference sequence using an interference sequence generator.

19. The method of claim 12, further comprising modulating the interference sequence using a modulator to generate a replica of the interference signal.

20. The method of claim 12, further comprising providing phase alignment between the replicated interference signal and the interference signal in the composite carrier signal using a memory device.

21. The method of claim 12, further comprising configuring a center frequency, occupied bandwidth, or power level of the interference carrier signal, information carrier signal, or composite carrier signal.

22. A system for encrypting an information carrier comprising:

a sequence generator configured to generate a sequence of data;

a first modulator configured to modulate an output from the sequence generator such that an interference signal results;

an encoder configured to encode synchronization information generated by the sequence generator;

a second modulator configured to modulate the encoded synchronization information such that a synchronization carrier signal results;

a spreader configured to spread the synchronization carrier signal such that a spread sub-carrier synchronization signal results; and

a combiner configured to combine a modulated information carrier signal, the interference signal, and the spread sub-carrier synchronization signal using a signal combiner such that a composite signal results, the interference signal having one or more signal characteristics that results in obfuscation of the information carrier signal when the information carrier signal and interference signal are combined.

23. The system of claim 22, further comprising an authentication device configured to authenticate the information carried in the spread sub-carrier synchronization signal.

24. The system of claim 22, further comprising an encryption device configured to encrypt information carried in the spread sub-carrier synchronization signal.

25. The system of claim 22, wherein the encoder is further configured to provide forward error correction (FEC) to the spread sub-carrier synchronization signal.

26. The system of claim 22, further comprising one or more modulating devices configured to modulate the sub-carrier synchronization signal.

27. The system of claim 23, wherein the spreader is further configured to use spread spectrum techniques to reduce a power spectral density of the spread sub-carrier synchronization signal such that the power spectral density of the spread sub-carrier synchronization signal is lower than a power spectral density of the combined information carrier signal and interference signal.

28. The system of claim 22, further comprising a processor configured to determine a center frequency and occupied bandwidth of the information carrier signal using one or more Fourier transform techniques.

29. The system of claim 22, further comprising a power detector configured to determine the power level of the information carrier signal.

30. The system of claim 22, further configured for manual configuration of one or more characteristics of the information carrier signal to specify a center frequency, occupied bandwidth, or power level of the information carrier signal.

31. The system of claim 22, further comprising an upconversion device configured to up-convert the interference and sub-carrier synchronization signals prior to combining these signals with the information carrier signal.

32. The system of claim 22, wherein the combiner is further configured to combine the signals at baseband frequency.

33. A system of recovering encrypted information comprising:

a receiving device configured to receive a composite carrier signal, the composite carrier signal comprising a previously combined information carrier signal, interference signal, and spread sub-carrier synchronization signal, wherein the interference signal has one or more signal characteristics that results in obfuscation of the information carrier signal by the interference signal in the composite signal;

a despreader configured to despread the spread sub-carrier synchronization signal;

a demodulator configured to demodulate the despread sub-carrier synchronization signal;

a decoder configured to decode the demodulated despread sub-carrier synchronization signal, resulting in extracted synchronization information from the sub-carrier synchronization signal;

an interference generator configured to be synchronized using the extracted synchronization information and create a replica of the interference signal contained in the received composite signal; and

a canceling device configured to cancel the interference signal from the composite signal using one or more cancellation techniques to obtain the information carrier signal.

34. The system of claim 33, further comprising a splitter configured to split the composite carrier signal.

35. The system of claim 33, wherein the despreader is further configured to use spread spectrum despreading.

36. The system of claim 33, further comprising a decryption device configured to decrypt information carried in the sub-carrier synchronization signal.

37. The system of claim 33, further comprising an authentication device configured to authenticate information carried in the sub-carrier synchronization signal.

38. The system of claim 33, further comprising a frame parser configured to frame parse information carried in the sub-carrier synchronization signal.

39. The system of claim 33, further comprising an interference sequence generator configured to generate a synchronized interference sequence.

40. The system of claim 33, further comprising a modulator configured to modulate the interference sequence to generate a replica of the interference signal.

41. The system of claim 33, further comprising a memory device configured to provide phase alignment between the replicated interference signal and the interference signal in the composite carrier.

42. The system of claim 33, further comprising a configuration device that allows configuration of a center frequency, occupied bandwidth, or power level of the interference carrier signal, information carrier signal, or composite carrier signal.