Stealth communication method

• US 20050228659A1
• Filed: 04/06/2004
• Published: 10/13/2005
• Est. Priority Date: 04/06/2004
• Status: Abandoned Application

• Current Assignee: Vlad Mitlin
• Original Assignee: Vlad Mitlin
• Inventors: Mitlin, Vlad
• Application Number:
  US10/817,869
• Publication Number:
  US 20050228659A1
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal

Abstract

In accordance with the present invention, there is provided a stealth communication method for transmitting a proprietary message using an information-bearing noise having an internal structure associated with the message. The spectral properties of the information-bearing noise are indistinguishable from those of the noise in the communication channel. This information-bearing noise can be combined with a non-random decoy signal.

Claims

1. A method for proprietary data transmission comprising:

means for transmitting a message over a communication channel between a transmitting station and a receiving station using a smart noise;

wherein said smart noise has an internal structure associated with said message.

2. The method of claim 1 wherein said means comprises:

generating at least two components of said smart noise at said transmitting station;

merging said components into the smart noise at the transmitting station; and

retrieving said message from the smart noise at said receiving station.

3. The method of claim 2, further comprising:

measuring the spectrum of the channel noise.

4. The method of claim 2, further comprising:

measuring an average power of the channel noise;

wherein said channel noise is an additive white noise characterized by said power.

5. The method of claim 2 wherein said generating comprises:

employing a time series having a similar spectrum as that of the channel noise;

determining current values of said components by applying predefined functions to said time series; and

said functions comprise an equality of at least two first statistical momenta of said components.

6. The method of claim 2, further comprising a similarity of the spectra of said smart noise and of the channel noise.

7. The method of claim 6 wherein said similarity is proportionality with a predefined coefficient.

8. The method of claim 5 wherein said functions are determined as follows:

output=(current input+input delayed by one sample)/2 and

output=(current input−

input delayed by one sample)/2.

9. The method of claim 2 wherein said merging comprises:

extracting blocks of data of a predefined length, each from one said component at a time;

the order of switching between the components is determined by a current symbol in said message; and

said smart noise is a sequence of blocks of data extracted.

10. The method of claim 2 wherein said retrieving comprises:

applying a set of filters to said smart noise; and

each of said filters is associated to one of said components.

11. The method of claim 10 wherein said filters are the functions determined in accordance with claim 8.

12. The method of claim 11, further comprising:

applying a correlator to the output of each of said filters.

13. The method of claim 12, further comprising:

applying at least one averager to the output of each of said correlators;

wherein the number of samples in the window of said averager and the number of samples in one symbol of said message are mutually prime.

14. The method of claim 2, further comprising:

generating at least one decoy signal; and

complementing said smart noise with said decoy signal.

15. The method of claim 14 wherein the spectrum of the channel noise is noticeably different from that of said smart noise complemented with said decoy signal.

16. The method of claim 14, further comprising:

choosing the frequency of said decoy signal.

17. The method of claim 16 wherein said smart noise consists of two components;

and

said frequency is the central frequency of the spectral window used for transmission.

18. The method of claim 16 wherein said smart noise consists of a plurality of components;

spectra of said components are predominantly localized in adjacent sections of the spectral window used for transmission; and

said frequency is at the boundary of two said adjacent sections of said spectral window.