System and method for data transmission over arbitrary media using physical encryption

• US 8,315,387 B2
• Filed: 06/10/2009
• Issued: 11/20/2012
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: NuCrypt, LLC
• Original Assignee: NuCrypt, LLC
• Inventors: Kanter, Gregory S., Reily, Daniel
• Primary Examiner(s): Hoffman, Brandon
• Application Number:
  US12/482,267
• Publication Number:
  US 20100098252A1
• Time in Patent Office: 1,259 Days
• Field of Search: None
• US Class Current: 380/256
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/0852 Quantum cryptography transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03

Abstract

Apparatus and method for a secure communication network using AlphaEta quantum encryption is provided. A polarization insensitive optical receiver based on a 90 degrees hybrid coupler is used for the detection and digitization of optically encrypted signals. Once digitized, such signals can be decrypted, stored, or re-transmitted over arbitrary media such as using RF wireless means. Alternatively, the signal can be generated directly for transmission over RF wireless nodes. The system may include nodes for retransmitting the signal without decrypting it, allowing for secure communication among specific users.

Claims

1. A system for data transmission using a quantum encrypted signal, comprising:

an optical transmitter transmitting the quantum encrypted signal;

the signal is phase modulated according to an M-ary phase modulated format where the phase applied is determined by both a pseudo-random cryptographic algorithm working as a first extended key generator and the data to be transmitted;

a number of data bits transmitted per symbol is N, wherein N<

M;

a receiver which measures an incoming transmitted signal by making measurements at two or more different phase quadratures, digitizes the measurement using analog-to-digital converters, and estimates the phase applied at the transmitter using a digital signal processor (DSP).

2. The system of claim 1, wherein the receiver is a polarization insensitive optical receiver, comprising:

a circulator for receiving the incoming quantum encrypted signal and forwarding it to a 90 degrees hybrid coupler;

the 90 degrees hybrid coupler splitting the signal into two arms labeled as a first in-phase (I) and a first quadrature phase (Q) signals;

the first Q signal is delayed with respect to the first I signal by an integer number of one-half bit periods in a delay line;

a first and a second Faraday mirrors reflecting the first I and delayed Q signals back to the 90 degree hybrid coupler;

the delayed Q signal is additionally delayed with respect to the I signal in the delay line;

the 90 degree hybrid coupler outputting a second I and a second Q signals;

the second I passing the circulator;

a first and a second photodetectors detecting the second I and the second Q signals and outputting a first and a second electrical signals being digitized using the analog-to-digital converter;

the digital signal processor (DSP) processes the first and the second digital signals from the converter and determines a differential phase shift of the quantum encrypted signal;

the differential phase shift being indicative of the encoded data.

3. The system of claim 1, wherein

the quantum encrypted signal is AlphaEta signal;

the receiver further comprising

a second extended key generator to decrypt the encoded data from the applied phase shift;

the second extended key generator being complimentary to the first extended key generator located at the transmitter that is used to create the quantum encrypted signal.

4. The system of claim 1, wherein the quantum encrypted signal is a pulsed signal and wherein a portion of the incoming signal is separately detected to recover a clock.

5. The system of claim 4, wherein the clock is generated by feeding the incoming signal whose frequency is at the symbol rate into a linear feedback shift register to generate a non-return-to-zero signal which is subsequently transformed into a clock by a clock-and-data recovery circuit.

6. The system of claim 1, further comprising a signal regenerator after the DSP;

the regenerator regenerating the encrypted signal and a re-transmitter retransmitting a regenerated encrypted signal.

7. The system of claim 6, wherein the re-transmitting is over an arbitrary medium.

8. The system of claim 6, wherein the re-transmitting is in radio frequency (RF) range.

9. The system of claim 1, wherein the transmitted symbol rate is variable and the receiver uses an asymmetric I/Q demodulator with a tunable delay line in order to recover the I/Q information from the signals with different symbol rate.

10. The system of claim 1, wherein the transmitter and the receiver are moving with respect to each other;

a corresponding Doppler shift introduces a fast equivalent wavelength shift of the quantum encrypted signal; and

the effect of the wavelength shift on the determination of the differential phase is accounted for via the digital signal processing.

11. A system for multiple-channel signal transmission, comprising:

a plurality of optical differential phase-modulated signal transmitters of different wavelengths;

wherein each channel'"'"'s phase modulation can be either traditional or quantum encrypted,

a receiver having a single asymmetric I/Q demodulator for detecting the differential phase of the signals;

wherein an in-phase I and a quadrature Q outputs are followed by a wavelength division multiplexer to separate each channels I and Q signals;

a series of photodetectors measuring each I/Q signal followed by analog-to-digital converters digitizing the signal,

a DSP unambiguously determining the differential phase and subsequently the data applied to each channel.

12. The system of claim 11, wherein the channels can have a plurality of symbol rates;

and a different asymmetric I/Q demodulator is used for each symbol rate;

wherein an asymmetric delay of the I/Q demodulator is chosen to demodulate the desired symbol rate.

13. The system of claim 11, wherein the channel signals are with different symbol rates;

the channels are separated out at the receiver prior to the I and Q signal detection by a wavelength selective filter.

14. The system of claim 11, wherein the transmitted symbol rate is variable and the receiver uses an asymmetric I/Q demodulator with a tunable delay line in order to recover the I/Q information from the channel signals with different symbol rate.

15. A system for data transmitting using an encrypted signal, comprising:

a transmitter transmitting the encrypted signal wherein the encrypted signal has an M-ary format and the data is an N-ary format with N<

M, the M-ary symbol is chosen based on the output of a pseudo-random cryptographic algorithm working as an extended key generator and the data to be transmitted;

at least a first node which receives, measures and retransmits the received encrypted signal; and

a receiver which measures the incoming encrypted signal and decrypts it using a cryptographic algorithm.

16. The system of claim 15, further comprising

the encrypted signal having an unencrypted header or a header traditionally encrypted with information allowing the first node to determine a source and a destination of a signal packet.

17. The system of claim 16, wherein

the node switching an AlphaEta frame by converting an M-ary portion of the packet to a longer binary packet and then switching it using conventional switching technology and subsequently re-converting it into AlphaEta frames before retransmission.

18. The system of claim 16, wherein

the frame header being modified by the node according to an underlying protocol without disturbing an AlphaEta encrypted portion of the packet.

19. The system of claim 15, wherein

the node retransmits the signal without inspecting a header or modifying any portion of a packet.

20. The system of claim 15, wherein

the first node switches AlphaEta frames by converting an M-ary portion of the packet to a longer binary packet which is subsequently switched into a traditional network being compatible with binary frames but not with M-ary AlphaEta frames, a resulting binary packet is transferred through the traditional network until it reaches a second node being compatible with M-ary AlphaEta frames, the second node re-converts the encrypted signal back to the M-ary AlphaEta format for sending through an AlphaEta-capable network.

21. The system of claim 15, wherein

the first node switches AlphaEta frames by converting an M-ary portion of the packet to a longer binary packet which is subsequently switched into a traditional network being compatible with binary frames but not with M-ary AlphaEta frames, a resulting binary packet is transferred through the traditional network until it reaches the receiver which subsequently decrypts the binary packet into an unencrypted message.

22. The system of claim 15, wherein

the encrypted data frames use an AlphaEta protocol over a network that is capable of sending the frames through the node using a key hierarchy where two or more keys are used to encrypt the data, one being an AlphaEta key, which can transform symbols from binary to M'"'"'ary format, another being a standard encryption key which is only distributed to nodes that are authorized to access a secret data itself, where the first node converts the M-ary AlphaEta signal into a binary traditionally encrypted signal for the purpose of processing the frames but then re-encrypts the frames into AlphaEta format upon re-transmission, and wherein the receiver decrypts both the AlphaEta and standard encryption in order to gain access to the secret data.

23. The system of claim 22, wherein encrypted data frames use the AlphaEta protocol over a network that is capable of sending the frames through the node using a key hierarchy where various keys are used to encrypt the data, at least one being an AlphaEta key which is shared with a next node required to process the frame and one standard key which is only shared with parties that are authorized to have access to the secret message, whereas the next processing node can decrypt the AlphaEta frames into encrypted binary frames for processing and subsequently re-encrypts into the AlphaEta format using a key that it shares with the next node that must process the frame, whereas such a procedure is repeated until the receiver receives the frame, and where the receiver can use the standard key to access the secret data itself.

24. The system of claim 22, wherein the transmission or re-transmission of a packet is of a protocol that requires an acknowledgement frame and wherein the following node can send an acknowledgement frame back based on its own frame processing as well based on acknowledgement frames received from other nodes which process the binary frame.

25. A system of data transmission using an encrypted signal, wherein an AlphaEta-style encryption is implemented in a radio-frequency communications and a local noise source generates noise which is added to an M'"'"'ary transmission symbol, where the M'"'"'ary symbol is determined both from a pseudo-random cryptographic algorithm and the data to be transmitted, and wherein the M'"'"'ary symbol contains N bits of information on the data, and where N<

M.

26. The system of claim 25, wherein the radio-frequency communications uses an orthogonal frequency division modulation format and a plurality of sub-carriers are transformed into the M'"'"'ary symbol by an encryption process.

27. The system of claim 26 wherein a pad of suitable length is inserted in the packet of the encrypted signal, the pad ensures that the M'"'"'ary encrypted signaling can start at the beginning of an orthogonal frequency division multiplexed symbol.

28. The system of claim 25, wherein the radio communications is implemented in a software defined radio.

29. A method for data transmission of quantum encrypted signals, comprising:

sending at least a first quantum encrypted signal;

the signal is phase modulated according to an M-ary phase modulated format where the phase applied is determined by both a pseudo-random cryptographic algorithm working as a first extended key generator and the data to be transmitted;

a number of data bits transmitted per symbol is N₁, wherein N₁<

M;

receiving the first transmitted signal by a receiver having a delay line corresponding to the symbol duration,

measuring two or more different phase quadratures,

digitizing measured signals, and

estimating the phase using a digital signal processing, and recovering information from the transmitted data.

30. The method of claim 29, wherein the encrypted signal uses AlphaEta encryption.

31. The method of claim 30, further comprising:

switching an AlphaEta frame at a node by converting the M-ary portion of the packet to a longer binary packet and then switching it using conventional switching technology; and

subsequently re-converting it into AlphaEta frames before retransmission.

32. The method of claim 31, further comprising:

the first quantum encrypted signal being encrypted using a key hierarchy where two or more keys are used to encrypt the data, one being an AlphaEta key, which can transform symbols from binary to M'"'"'ary format, another being a standard encryption key which is only distributed to nodes that are authorized to access a secret data itself, and

converts the M-ary AlphaEta signal into a binary traditionally encrypted signal in the nodes;

processing the frames;

but then

re-encrypting the frames into AlphaEta format upon re-transmission, and

decrypting both the AlphaEta and standard encryption at the receiver in order to gain access to the secret data.

33. The method of claim 29, further comprising:

sending a second quantum encrypted signal;

the second signal is phase modulated according to an M-ary phase modulated format where the phase applied is determined by both a pseudo-random cryptographic algorithm working as a first extended key generator and the data to be transmitted;

a number of data bits transmitted per symbol is N₂≠

N₁, wherein N₂<

M;

adjusting the delay line in the receiver for receiving the second transmitted signal;

measuring two or more different phase quadratures of the second signal,

digitizing measured signals, and

estimating the second phase using a digital signal processing, and recovering information from the transmitted data in the second signal.

34. A method of data transmission using an encrypted signal, comprising:

sending a radio-frequency signal using an AlphaEta-style encryption;

the signal uses an orthogonal frequency division modulation format and a plurality of sub-carriers are transformed into an M'"'"'ary symbol by an encryption process;

generating a local noise signal and adding it to the M'"'"'ary transmission symbol, where the M'"'"'ary symbol is determined both from a pseudo-random cryptographic algorithm and the data to be transmitted, and wherein the M'"'"'ary symbol contains N bits of information on the data, and where N<

M;

receiving the transmitted encrypted signal, decrypting the signal by transforming the plurality of sub-carriers from M'"'"'ary to N'"'"'ary using the output of a matched pseudo-random cryptographic algorithm, and recovering data.