Device for sending or receiving a signal encrypted using deterministic chaos

• US 6,704,420 B1
• Filed: 06/01/1999
• Issued: 03/09/2004
• Est. Priority Date: 06/02/1998
• Status: Expired due to Fees

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Merolla, Jean-Marc, Langer, Laurent, Goedgebuer, Jean-Pierre
• Primary Examiner(s): Barrón, Gilberto
• Assistant Examiner(s): Zand, Kambiz
• Application Number:
  US09/323,742
• Time in Patent Office: 1,743 Days
• Field of Search: 380/263
• US Class Current: 380/263
• CPC Class Codes: H04B 10/85 Protection from unauthorised access, e.g. eavesdrop protection
• CPC Class Codes: H04L 2209/80 Wireless
• CPC Class Codes: H04L 9/001 using chaotic signals

Abstract

Device for sending an encrypted signal, including:

a source (1) for generating said signal and means (2) for intensity modulating the signal,

a feedback loop which includes delay line means and non-linear means,

characterized in that the feedback loop includes:

an interferometer (5) to which is applied an electric current that corresponds to the delayed generated signal and an auxiliary source of constant intensity that feeds the interferometer optically, the output signal of the interferometer being a non-linear function of the output signal of the delay line means,

a photodiode (7) which converts the luminous power at the output of the interferometer to a modulation current, and

a summing circuit (8) which adds the message to be encrypted to the modulation current at the output of said photodiode, the output signal of the summing circuit controlling modulator means.

Claims

1. Device for sending an encrypted signal, including:

a source (1) for generating said signal and means (2) for producing chaotic modulation of a luminous intensity of the signal,

a feedback loop which includes delay line means and non-linear means,

characterized in that the feedback loop includes;

an interferometer (5) to which is applied an electric current that corresponds to the delayed generated signal and an auxiliary source of constant intensity that feeds the interferometer optically, the output signal of the interferometer being a non-linear function of the output signal of the delay line means,

a photodiode (7) which converts the luminous power at the output of the interferometer to a modulation current, and

a summing circuit (8) which adds the message to be encrypted to the modulation current at the output of said photodiode, the output signal of the summing circuit controlling modulator means.

2. Device according to claim 1, characterized in that the source (1) for generating the signal is an optical source, said device including a photodiode which converts the generated signal into an electrical signal and means for injecting the electrical signal into the input of the delay line means.

3. Device according to claim 2, characterized in that the modulation means are internal to the source emitting the optical signal.

4. Device according to claim 2, characterized in that the modulator means are external to the source emitting the optical signal.

5. Device according to claim 1, characterized in that the source for generating the signal is a radio frequency source.

9. Device according to any one of the preceding claims, characterized in that the interferometer (5) is of the Mach-Zehnder type.

10. Device according to claim 9, characterized in that the Mach-Zehnder interferometer (5) is integrated on lithium niobate, gallium arsenide or silicon.

6. Device for receiving an encrypted signal, including:

means (9) for receiving said signal;

a feedback loop which includes delay line means and non-linear means,

characterized in that the feedback loop includes;

an interferometer (11) to which is applied a current that corresponds to the delayed received signal and an auxiliary source of constant intensity which feeds the interferometer optically, the interferometer output signal being a non-linear function of the output signal of the delay line means,

a first photodiode (13) which converts the luminous power at the interferometer output into a current,

a second photodiode to produce the base chaotic modulation of a luminous intensity of said signal based on the interferometer output, and

a subtractor circuit (14) which applies the subtraction operation to the received signal and to the output of said second photodiode, the output signal of the subtractor circuit being the demodulated signal.

7. Device according to claim 6, characterized in that the encrypted signal is an optical signal and the receiver means comprise a photodiode (9) that converts the luminous power of the encrypted signal into an electrical signal.

8. Device according to claim 6, characteized in that the encrypted signal is a radio frequency signal and the receiver means include a receive antenna.