Low level sequence as an anti-tamper Mechanism

• US 8,312,551 B2
• Filed: 02/15/2007
• Issued: 11/13/2012
• Est. Priority Date: 02/15/2007
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Chester, David B.
• Primary Examiner(s): Arani, Taghi
• Assistant Examiner(s): Plecha, Thaddeus
• Application Number:
  US11/675,120
• Publication Number:
  US 20080198832A1
• Time in Patent Office: 2,098 Days
• Field of Search: 370/343, 726/22, 726/26
• US Class Current: 726/26
• CPC Class Codes: H04J 1/02 Details
• CPC Class Codes: H04K 1/10 by using two signals transmitted simultaneously or successively
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32
• CPC Class Codes: H04L 63/18 using different networks or channels, e.g. using out of band channels cryptographic mechanisms or cryptographic arrangements for key distribution involving distinctive intermediate devices or communication paths H04L9/0827; cryptographic mechanisms or cryptographic arrangements for authentication using a plurality of channels H04L9/3215
• CPC Class Codes: H04W 12/106 Packet or message integrity

Abstract

A method is provided for tamper detection of a transmitted signal. The method is comprised of generating a first digital data signal having a first data rate. The method is also comprised of generating a second digital data signal having a second data rate. The method is further comprised of concurrently transmitting the first digital data signal at a first carrier frequency using a first modulation format and the second digital data signal at a second carrier frequency using a second modulation format. The method includes selecting the second carrier frequency and a bandwidth of the second digital data signal so that the second digital data signal is contained within a frequency spectrum defined by a bandwidth of the first digital data signal. The method also includes verifying an integrity of the first digital data signal at a remote receiver based on defection at the remote receiver of the second digital data signal. A system (100) is also provided for generating a tamper-protected transmitted signal.

Claims

1. A method for tamper detection of a transmitted signal, comprising:

generating a first digital data signal containing payload data and having a first data rate;

generating a second digital data signal containing an integrity code and having a second data rate;

concurrently transmitting said first digital data signal at a first carrier frequency using a first modulation format, and said second digital data signal at a second carrier frequency using a second modulation format;

selecting said second carrier frequency and a bandwidth of said second digital data signal so that said second digital data signal is contained within a frequency spectrum defined by a bandwidth of said first digital data signal;

tracking symbol timing of said first digital data signal;

using said tracked symbol timing to lock to said second digital data signal which has a symbol timing that is rationally related to and derived from said tracked symbol timing of said first digital data signal; and

verifying an integrity of said first digital data signal at a remote receiver based on detection at said remote receiver of said second digital data signal, wherein said verifying step comprises identifying said integrity code within said second digital data signal; and

responsive to said verifying step, automatically performing at said remote receiver actions including (1) notifying a user that tampering has occurred with respect to a composite signal comprising said first digital data signal and said second digital data signal, and (2) discarding said payload data contained in said first digital data signal.

2. The method according to claim 1, wherein said first digital data signal is combined with said second digital data signal prior to said transmission step.

3. The method according to claim 1, wherein said second digital data signal is transmitted at a second transmitter power level that is below a transmitted power level required to interfere with a demodulation level of said first digital data signal at said remote receiver.

4. The method according to claim 1, further comprising selecting a second transmitter power level, for transmitting said second digital data signal, that is at least one order of magnitude less than a first transmitter power level used for transmitting said first digital data signal.

5. The method according to claim 1, further comprising selecting said first data rate at least one order of magnitude higher as compared to said second data rate.

6. The method according to claim 1, wherein said integrity code is selected from a group consisting of pseudo-random number sequence, a chaotic sequence, and an encrypted number/symbol sequence.

7. The method according to claim 1, further comprising selecting said first modulation format to be different from said second modulation format.

8. The method according to claim 1, further comprising applying signal processing gain at said remote receiver to detect said second digital data signal contained within said bandwidth of said first digital data signal.

9. The method according to claim 8, wherein said applying said signal processing gain comprises using a signal integration time having a value that is at least one order of magnitude larger as compared to a value of said first data rate.

10. The method according to claim 1, further comprising filtering at said remote receiver a composite signal comprised of said first digital data signal and said second digital data signal to remove at least a portion of a frequency spectrum comprising said first digital data signal.

11. A system for generating a tamper-protected transmitted signal, comprising:

a first data generator configured for generating a first digital data signal containing payload data and has a first data rate;

a second data generator configured for generating a second digital data signal containing an integrity code and having a second data rate;

a transmitting device configured for concurrently transmitting said first digital data signal at a first carrier frequency using a first modulation format, and transmitting said second digital data signal at a second carrier frequency using a second modulation format, said second carrier frequency and a bandwidth of said second digital data signal contained within a frequency spectrum defined by a bandwidth of said first digital data signal; and

a remote receiving device comprising at least one signal processing circuit configured for

tracking symbol timing of said first digital data signal;

using said tracked symbol timing to lock to said second digital data signal which has a symbol timing that is rationally related to and derived from said tracked symbol timing of said first digital data signal; and

verifying an integrity of said first digital data signal based on the detection at said remote receiver of said integrity code in the second digital data signal; and

responsive to said verifying step, automatically performing at said remote receiver actions including (1) notifying a user that tampering has occurred with respect to a composite signal comprising said first digital data signal and said second digital data signal, and (2) discarding said payload data contained in said first digital data signal.

12. The system according to claim 11, wherein said transmitter transmits a composite signal which is comprised of said first digital data signal and said second digital data signal.

13. The system according to claim 11, wherein said transmitter is configured for transmitting said second digital data signal at a second transmitter power level that is below a transmitted power level required to interfere with a demodulation level of said first digital data signal at said remote receiver.

14. The system according to claim 11, wherein said second transmitter is configured for transmitting said second digital data signal at a second transmitter power level that is at least one order of magnitude less than a first transmitter power level used for transmitting said first digital data signal.

15. The system according to claim 11, wherein said first data rate is at least one order of magnitude higher as compared to said second data rate.

16. The system according to claim 11, wherein said integrity code is selected from a group consisting of a pseudo-random number sequence, a chaotic sequence, and an encrypted number/symbol sequence.

17. The system according to claim 11, wherein said first modulation format is different as compared to said second modulation format.

18. The system according to claim 11, wherein said remote receiver is configured to provide signal processing gain to detect said second digital data signal contained within said bandwidth of said first digital data signal.

19. The system according to claim 18, wherein said signal processing gain comprises an integrator circuit which utilizes an integration time having a value that is at least one order of magnitude larger as compared to a value of said first data rate.

20. The system according to claim 11, wherein said remote receiver further comprises a filter configured for filtering from a composite signal comprised of said first digital data signal and said second digital data signal at least a portion of a frequency spectrum comprising said first digital data signal.