Method and apparatus for secure digital chaotic communication

• US 6,363,153 B1
• Filed: 11/09/1999
• Issued: 03/26/2002
• Est. Priority Date: 11/12/1998
• Status: Expired due to Term

• Current Assignee: University of New Hampshire
• Original Assignee: University of New Hampshire
• Inventors: Short, Kevin M., Parker, Andrew T.
• Primary Examiner(s): Hayes, Gail
• Assistant Examiner(s): Seal, James
• Application Number:
  US09/436,910
• Time in Patent Office: 868 Days
• Field of Search: 380/263
• US Class Current: 380/263
• CPC Class Codes: H04L 9/001 using chaotic signals
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner

Abstract

A method and apparatus that uses control of a chaotic system to produce secure digital chaotic communication. Controls are intermittently applied by a transmitter-encoder to a chaotic system to generate the 0 and 1 bits of a digital message. A new control/no control bit stream is thereby created in which a 0 indicates that no control was applied and a 1 indicates that a control was applied. The control/no control bit stream and a prepended synchronization bit stream are transmitted, using conventional transmission technologies, from the transmitter-encoder to an identical receiver-decoder. A chaotic system in the receiver-decoder is driven into synchrony and is subject to intermittent controls based on the control/no control bit stream, thereby causing it to generate the digital message.

Claims

1. A method for secure digital chaotic communication, said communication method comprising:

a) a method of encoding information, said encoding method comprising;

obtaining a message bit stream;

applying a series of intermittent controls to a first chaotic system to cause it to generate the message bit stream;

creating a control/no control bit stream that is based on the application of the intermittent controls; and

prepending a synchronization bit stream to the control/no control bit stream, to create a transmission bit stream from which the dynamics of the first chaotic system cannot be reconstructed;

b) transmitting the transmission bit stream;

c) a method of decoding information, said decoding method comprising;

obtaining the transmission bit stream;

extracting the synchronization bit stream from the transmission bit stream and applying the synchronization bit stream to a second chaotic system to cause it to synchronize with the first chaotic system;

extracting the control/no control bit stream from the transmission bit stream; and

applying intermittent controls, as indicated by the control/no control bit stream, to the second chaotic system causing it to generate the message bit stream.

2. The method for secure digital chaotic communication of claim 1, further comprising the steps of:

a) repeating one or more times the method of encoding information therein; and

b) repeating one or more times the method of decoding information therein.

3. The method for secure digital chaotic communication of claim 1 wherein the first chaotic system is defined by a set of differential equations.

4. The method for secure digital chaotic communication of claim 1 wherein the first chaotic system is defined by a mapping function.

5. The method for secure digital chaotic communication of claim 1 wherein the first chaotic system is defined by an electrical circuit.

6. The method for secure digital chaotic communication of claim 1 wherein the first chaotic system is defined by a configuration of optical devices.

7. A system for secure digital chaotic communication, said communication system comprising:

d) a system for encoding information, said encoding system comprising;

means for obtaining a message bit stream;

means for applying a series of intermittent controls to a first chaotic system to cause it to generate the message bit stream;

means for creating a control/no control bit stream that is based on the application of the intermittent controls; and

means for prepending a synchronization bit stream to the control/no control bit stream, to create a transmission bit stream;

e) system for transmitting the transmission bit stream, wherein no chaotic signals are transmitted;

f) system for decoding information, said decoding system comprising;

means for obtaining the transmission bit stream;

means for extracting the synchronization bit stream from the transmission bit stream and applying the synchronization bit stream to a second chaotic system to cause it to synchronize with the first chaotic system;

means for extracting the control/no control bit stream from the transmission bit stream; and

means for applying intermittent controls, as indicated by the control/no control bit stream, to the second chaotic system causing it to generate the message bit stream.

8. The system for secure digital chaotic communication of claim 7 wherein the first chaotic system is defined by a set of differential equations.

9. The system for secure digital chaotic communication of claim 7 wherein the first chaotic system is defined by a mapping function.

10. The system for secure digital chaotic communication of claim 7 wherein the first chaotic system is defined by an electrical circuit.

11. The system for secure digital chaotic communication of claim 7 wherein the first chaotic system is defined by a configuration of optical devices.

12. A system for secure digital chaotic communication, said communication system comprising:

a source of a message bit stream;

a transmitter-encoder to apply a series of intermittent controls to a first chaotic system to cause it to duplicate the message bit stream, to generate a control/no control bit stream that is based on the application of the intermittent controls and to prepend a synchronization bit stream to the control/no control bit stream;

the transmitter-encoder to transmit the control/no control bit stream and prepended synchronization bit stream, wherein the message bit stream is not transmitted;

a receiver-decoder to receive the control/no control bit stream and prepended synchronization bit stream; and

a second chaotic system, to which first the synchronization bit stream is applied and then the series of intermittent controls is applied to cause it to duplicate the message bit stream.