CN111277337B - A Physical Layer Security Optical Fiber Communication System Based on Chaotic Phase Encryption - Google Patents

Abstract

The invention discloses a physical layer security optical fiber communication system based on chaotic phase encryption. The broadband random light source generated by the master laser is divided into two identical optical signals, which are respectively injected into the slave lasers on both sides of the communication, thereby generating synchronous chaotic signals. ; Then, the generated synchronous chaotic signal is used as the drive signal of the phase modulator, and the high-speed optical signal generated by the high-order modulation is encrypted and decrypted at the sending end and the receiving end.

Description

A Physical Layer Security Optical Fiber Communication System Based on Chaotic Phase Encryption

technical field

The invention belongs to the technical field of optical communication, and more particularly, relates to a physical layer security optical fiber communication system based on chaotic phase encryption.

Background technique

With the rise of the Internet era and the rapid development of information technology, people have higher and higher requirements for efficient and fast information transmission carriers and technologies. Optical fiber communication has become the dominant transmission technology of information network in the 21st century due to its advantages of large communication capacity, long transmission distance, good transmission quality and less crosstalk between signals. However, while optical fiber communication brings great convenience to people, its characteristics of openness and sharing also make information security problems increasingly serious. How to improve the security of optical fiber communication systems has become a hot research issue in the current academic circles.

With the development of optoelectronic technology and nonlinear dynamics theory, secure communication based on chaotic laser has attracted much attention due to its inherent security characteristics, and has become one of the new secure communication methods. Compared with the encryption technology at the traditional algorithm level, the chaotic laser security technology supports the encryption and decryption of information at the device and physical level, and directly guarantees the security of the information at the physical layer. External cavity semiconductor laser (ECSL) is the most commonly used light source to generate laser chaos. Due to the introduction of additional degrees of freedom, it will show rich dynamic characteristics, which has increasingly attracted extensive attention of scholars at home and abroad. Through reasonable selection of control parameters, ECSL can generate complex chaotic signals, which are widely used in important fields such as high-speed random number generator (RNG), secure communication, and reserve pool computing, and have broad application prospects.

However, after in-depth research, scholars have found that the chaotic laser generated by the external cavity semiconductor laser has safety defects. Due to the existence of the external cavity resonance, the autocorrelation curve of the generated chaotic signal has an obvious correlation peak at the external cavity period. This characteristic Known as the time-delay tag, the time-delay tag leaks the length of the outer cavity, so that the interceptor can use this key structural information to reconstruct the chaotic carrier signal, thereby deciphering the transmitted information and weakening the security of the communication system. On the other hand, the inherent relaxation oscillation of external cavity semiconductor lasers leads to the chaotic laser bandwidth of only several GHz. In chaotic optical communication, the chaotic laser acts as a carrier to hide the transmitted optical information, and the limited chaotic carrier bandwidth limits the transmission of chaotic optical communication. speed, making it difficult to be compatible with existing high-speed optical fiber communication systems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, provide a physical layer security optical fiber communication system based on chaotic phase encryption, realize effective encryption and decryption of high-speed and high-order modulated optical signals, and ensure that optical information is transmitted in the optical fiber link. security.

In order to achieve the above-mentioned purpose of the invention, a physical layer security optical fiber communication system based on chaotic phase encryption of the present invention is characterized in that, comprising: a transmitting end, a receiving end, and an optical fiber link connecting the transmitting end and the receiving end;

The sending end includes: master laser, slave laser 1, optical transmitter, fiber coupler FC1, polarization controller PC1, fiber isolator ISO1, adjustable optical attenuator VOA1, photodetector PD1, radio frequency amplifier RF1, encryption module and wavelength division multiplexer MUX;

Wherein, the main laser includes a continuous light laser CW1, an arbitrary waveform generator AWG, a radio frequency amplifier RF2 and a phase modulator PM1; the optical transmitter includes a CW light source, an IQ modulator and an arbitrary waveform generator AWG;

At the sending end, the arbitrary waveform generator AWG generates a Gaussian white noise signal, which is amplified by the radio frequency amplifier RF2 and then input to the phase modulator PM1 as the drive signal of PM1; when the optical signal output by CW1 is input to the phase modulator PM1, it is The modulated optical signal is output under the phase modulation of the driving signal, and then divided into two identical paths by the fiber coupler FC1. One of the optical signals passes through the adjustable optical attenuator VOA1 to adjust the optical power, and the optical isolator ISO1 controls the transmission direction and polarization. After the controller PC1 controls the polarization direction, it is injected into the slave laser SL1; the other channel is used as the optical signal output by the master laser;

The chaotic optical signal output by SL1 is divided into two channels by the fiber coupler FC2, one of which receives the injected optical signal of the main laser; the other optical signal is converted into a chaotic electrical signal by the photodetector PD1, and then amplified by the radio frequency amplifier RF1. , input to the encryption module as the drive signal of the phase modulator PM2;

The optical transmitter includes a continuous light laser CW2, an IQ modulator and an arbitrary waveform generator AWG;

The optical carrier generated by CW2 is input to the IQ modulator, and the IQ modulator receives the signal generated by the arbitrary waveform generator AWG, and performs I and Q modulation to generate a high-order modulation signal, which is input to the encryption module as the input optical signal of PM2 in the encryption module , and then, PM2 performs chaotic phase modulation under the driving signal, and outputs a modulated optical signal;

Finally, the optical signal output by the main laser and the modulated optical signal output by PM2 are multiplexed to the optical fiber link through the wavelength division multiplexer MUX;

The optical fiber link includes a single-mode optical fiber SMF, a dispersion-compensating optical fiber DCF, and an optical fiber amplifier EDFA;

In the optical fiber link, the optical signal is first transmitted through the single-mode fiber SMF, and then compensates the dispersion introduced by the optical fiber link through the dispersion compensation fiber DCF, and finally compensates the signal optical power attenuation caused by the optical fiber link through the optical fiber amplifier EDFA. end;

The receiving end includes: wavelength decomposition multiplexer DMUX, adjustable optical attenuator VOA2, optical fiber isolator ISO2, polarization controller PC2, optical fiber coupler FC3, adjustable optical fiber delay line DL, photodetector PD2, radio frequency amplifier RF3 , decryption module and optical receiver;

Wherein, the optical receiver further includes a polarization controller PC3, a coherent receiver and a local oscillator CW;

At the receiving end, the optical signal generated by the main laser at the transmitting end and the modulated optical signal output by PM2 are first separated by the wavelength demultiplexer DMUX; then, the optical signal generated by the main laser is passed through the adjustable optical attenuator VOA2 to adjust the optical power After the optical isolator ISO2 controls the transmission direction and the polarization controller PC2 controls the polarization direction, it is injected into the slave laser SL2; the modulated optical signal output by the PM2 is input into the decryption module;

The chaotic optical signal output from the laser SL2 is divided into two channels by the fiber coupler FC3, one of which receives the injected optical signal from the main laser; It is converted into a chaotic electrical signal, and finally the amplitude is amplified by the radio frequency amplifier RF3 and then input to the decryption module, and used as the drive signal of the phase modulator PM3 for phase decryption;

In the decryption module, the decryption module receives the modulated optical signal output by PM2 as an input signal, and then performs chaotic phase modulation under the action of the driving signal, and outputs the modulated optical signal to the optical receiver;

In the optical receiver, the modulated optical signal output by the decryption module controls the polarization direction through the polarization controller PC3, and then is input to the coherent receiver at the receiving end. The local oscillator CW provides the local oscillator optical signal for the coherent receiver, and finally recovered by the coherent receiver. out the original signal.

The purpose of the invention of the present invention is achieved in this way:

The invention is based on the physical layer security optical fiber communication system of chaotic phase encryption, by dividing the broadband random light source generated by the master laser into two identical optical signals, and injecting them into the slave lasers of both sides of the communication respectively, thereby generating synchronous chaotic signals; The synchronous chaotic signal of the phase modulator is used as the drive signal of the phase modulator, and the high-speed optical signal generated by the high-order modulation is encrypted and decrypted at the transmitting end and the receiving end.

At the same time, the physical layer security optical fiber communication system based on chaotic spectrum phase encryption also has the following beneficial effects:

(1), the physical layer encryption scheme designed by the present invention can effectively realize the encryption and decryption of the high-order modulation signal, and can realize the complete disturbance and correct recovery of the constellation diagram;

(2) The driving signals involved in encryption and decryption are generated locally by both parties of the communication, which ensures the security and privacy of the encryption and decryption modules;

(3) The encryption scheme proposed by the present invention is well compatible with the existing optical fiber communication system, supports encryption and decryption of signals of high speed and different modulation formats, and is suitable for different application scenarios of optical fiber communication.

Description of drawings

Fig. 1 is a kind of specific implementation structure diagram of the physical layer security optical fiber communication system based on chaotic phase encryption of the present invention;

Fig. 2 is the spectrogram after QPSK signal encryption, decryption;

FIG. 3 is a synchronization effect diagram of the chaotic drive signals generated by both communication parties.

Detailed ways

The specific embodiments of the present invention are described below with reference to the accompanying drawings, so that those skilled in the art can better understand the present invention. It should be noted that, in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

Example

FIG. 1 is an architecture diagram of a specific implementation manner of a physical layer security optical fiber communication system based on chaotic phase encryption according to the present invention.

In this embodiment, as shown in FIG. 1 , a physical layer security optical fiber communication system based on chaotic phase encryption of the present invention includes: a sending end, a receiving end, and an optical fiber link connecting the sending end and the receiving end;

The sending end includes: master laser, slave laser SL1, optical transmitter, fiber coupler FC1, polarization controller PC1, fiber isolator ISO1, adjustable optical attenuator VOA1, photodetector PD1, radio frequency amplifier RF1, encryption module and wave demultiplexer MUX;

In the present embodiment, the distributed feedback semiconductor laser DFB is selected from the laser SL1; the signal sent by the optical transmitter is an arbitrary high-order modulated optical signal, such as quadrature phase keying QPSK, quadrature amplitude modulation QAM, etc.;

Among them, the main laser includes CW1, arbitrary waveform generator AWG, radio frequency amplifier RF2 and phase modulator PM1; the optical transmitter also includes CW light source, IQ modulator and arbitrary waveform generator AWG;

At the sending end, the arbitrary waveform generator AWG generates a Gaussian white noise signal, which is amplified by the radio frequency amplifier RF2 and then input to the phase modulator PM1 as the drive signal of PM1; when the optical signal output by CW1 is input to the phase modulator PM1, it is The modulated optical signal is output under the phase modulation of the driving signal, and then divided into two identical paths by the fiber coupler FC1. One of the optical signals passes through the adjustable optical attenuator VOA1 to adjust the optical power, and the optical isolator ISO1 controls the transmission direction and polarization. After the controller PC1 controls the polarization direction, it is injected into the slave laser SL1; the other channel is used as the optical signal output by the master laser;

The chaotic optical signal output by SL1 is divided into two channels by the fiber coupler FC2, one of which receives the injected optical signal of the main laser; the other optical signal is converted into a chaotic electrical signal by the photodetector PD1, and then amplified by the radio frequency amplifier RF1. , input to the encryption module as the drive signal of the phase modulator PM2;

Optical transmitter includes continuous light laser CW2, IQ modulator and arbitrary waveform generator AWG;

The IQ modulator simultaneously receives the signal generated by the arbitrary waveform generator AWG and the continuous optical signal generated by the continuous light laser CW2, and performs I and Q modulation to generate a high-order modulation signal, which is input to the encryption module as the input optical signal of PM2 in the encryption module , and then, PM2 performs chaotic phase modulation under the driving signal, and outputs a modulated optical signal;

Finally, the optical signal output by the main laser and the modulated optical signal output by PM2 are multiplexed to the optical fiber link through the wavelength division multiplexer MUX;

The fiber link includes single mode fiber SMF, dispersion compensation fiber DCF and fiber amplifier EDFA;

In the optical fiber link, the optical signal is first transmitted through the single-mode fiber SMF, and then compensates the dispersion introduced by the optical fiber link through the dispersion compensation fiber DCF, and finally compensates the signal optical power attenuation caused by the optical fiber link through the optical fiber amplifier EDFA. end;

The receiving end includes: wavelength decomposition multiplexer DMUX, adjustable optical attenuator VOA2, fiber isolator ISO2, polarization controller PC2, fiber coupler FC3, slave laser SL2, adjustable fiber delay line DL, photodetector PD2, radio frequency Amplifier RF3, decryption module and optical receiver; in this embodiment, PD2 and PD1 output signals have the same amplitude and opposite amplitude; slave laser SL2 also selects distributed feedback semiconductor laser DFB;

Among them, the optical receiver also includes a polarization controller PC3, a coherent receiver and a local oscillator CW3;

At the receiving end, the optical signal generated by the main laser at the transmitting end and the modulated optical signal output by PM2 are first separated by the wavelength demultiplexer DMUX; then, the optical signal generated by the main laser is passed through the adjustable optical attenuator VOA2 to adjust the optical power After the optical isolator ISO2 controls the transmission direction and the polarization controller PC2 controls the polarization direction, it is injected into the slave laser SL2; the modulated optical signal output by the PM2 is input into the decryption module;

The chaotic optical signal output from the laser SL2 is divided into two channels by the fiber coupler FC3, one of which receives the injected optical signal from the main laser; It is converted into a chaotic electrical signal, and finally the amplitude is amplified by the radio frequency amplifier RF3 and then input to the decryption module, and used as the drive signal of the phase modulator PM3 for phase decryption;

In the decryption module, the decryption module receives the modulated optical signal output by PM2 as an input signal, and then performs chaotic phase modulation under the action of the driving signal, and outputs the modulated optical signal to the optical receiver;

In the optical receiver, the modulated optical signal output by the decryption module controls the polarization direction through the polarization controller PC3, and then is input to the coherent receiver at the receiving end. The local oscillator CW3 provides the local oscillator optical signal for the coherent receiver, and is finally recovered by the coherent receiver. out the original signal.

Figure 2 is a spectrum diagram of the encrypted and decrypted QPSK signal.

In this embodiment, back-to-back transmission and 50km transmission experiments are respectively adopted, wherein the first row is the back-to-back transmission experiment constellation diagram and the second row is the 50km transmission experiment constellation diagram, wherein, Figure 2(a), (d) are the original QPSK signals. Constellation diagram; Figures 2(b) and (c) are the constellation diagrams of encrypted signals; Figures 2(c) and (f) are the constellation diagrams of the decrypted QPSK signal at the receiving end. It can be seen that, compared with the original QPSK signal, after the chaotic phase encryption proposed by this scheme, the phase of the constellation diagram is completely disturbed, and each constellation point cannot be distinguished, thus ensuring the security of signal transmission in the link. After calculation, the bit error rate of the eavesdropper is close to 0.5. For the legitimate receiver, after the corresponding chaotic phase decryption, the QPSK signal can be correctly recovered, and each constellation point can be clearly distinguished, and the corresponding bit error rate is lower than 3×10 ^-5 , so it is verified that the scheme is effective. feasibility.

FIG. 3 is a synchronization effect diagram of the chaotic drive signals generated by both communication parties.

In this example, we verify the secure transmission of a signal with a bit rate of 25Gbps and a modulation format of QPSK over a 50km fiber link. As shown in Fig. 3, Fig. 3(a) is the time domain waveform diagram of the output signal of the main laser; Fig. 3(b) is the time domain waveform diagram of the output signal of the transmitting end SL1; Fig. 3(c) is the output signal of the receiving end SL2 The time domain waveform diagram of the signal; Figure 3(d) is the cross-correlation diagram of the output signal of the main laser and the output signal of the transmitter SL1; Figure 3(e) is the cross-correlation diagram between the output signals of SL1 and SL2 on both sides of the communication.

We adopt the cross-correlation coefficient (CC) to quantify the correlation between its output signals. On the one hand, there is a high correlation between the chaotic signals generated by the sender and the receiver SL. Here we use the commonly used cross-correlation coefficient (CC) to quantify the synchronization performance [N.Jiang,A.K.Zhao, C. P. Xue, J.M. Tang, and K. Qiu, “Physical secure optical communication based on private chaoticspectral phase encryption/decryption,” Opt. Lett. 44(7), 1536–1539 (2019)], the closer the CC value is to 1 synchronization performance The better, usually when the CC value exceeds 0.9, the signal synchronization is achieved. The cross-correlation coefficient of the signal produced by this scheme is as high as 0.95, so the high correlation ensures the correct demodulation of the signal. On the other hand, there is no correlation between the common injection signal generated by the main laser DL and the chaotic signal generated by both communication parties (CC<0.1). Since only the broadband random optical signal output by the DL will be transmitted in the public link, it is guaranteed that The local SLs of both communicating parties generate privacy for the security of chaotic signals.

Although the illustrative specific embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, As long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the inventive concept are included in the protection list.

Claims (4)

1. A physical layer secret optical fiber communication system based on chaos phase encryption is characterized by comprising: the system comprises a sending end, a receiving end and an optical fiber link for connecting the sending end and the receiving end;

the transmitting end comprises: the system comprises a master laser, a slave laser 1, an optical transmitter, a fiber coupler FC1, a polarization controller PC1, a fiber isolator ISO1, a variable optical attenuator VOA1, a photoelectric detector PD1, a radio frequency amplifier RF1, an encryption module and a wavelength division multiplexer MUX;

wherein the master laser comprises a continuous light laser CW1, an arbitrary waveform generator AWG, a radio frequency amplifier RF2 and a phase modulator PM 1; the optical transmitter comprises a CW light source, an IQ modulator and an AWG;

at a sending end, an arbitrary waveform generator AWG generates a Gaussian white noise signal, and the Gaussian white noise signal is amplified by a radio frequency amplifier RF2 and then is input to a phase modulator PM1 to serve as a driving signal of PM 1; when an optical signal output by CW1 is input to a phase modulator PM1, a modulated optical signal is output under the phase modulation effect of a drive signal, and is divided into two identical paths by an optical fiber coupler FC1, wherein one path of optical signal is sequentially subjected to optical power adjustment by an adjustable optical attenuator VOA1, transmission direction control by an optical isolator ISO1 and polarization direction control by a polarization controller PC1, and then is injected into a slave laser SL 1; the other path is used as an optical signal output by the main laser;

the chaotic light signal output by the SL1 is divided into two paths through an optical fiber coupler FC2, wherein one path receives the injection light signal of the main laser; the other path of optical signal is converted into a chaotic electric signal through a photoelectric detector PD1, is subjected to amplitude amplification through a radio frequency amplifier RF1 and is input into an encryption module to serve as a driving signal of a phase modulator PM 2;

the optical transmitter comprises a continuous optical laser CW2, an IQ modulator and an arbitrary waveform generator AWG;

an optical carrier output by CW2 is input to an IQ modulator, the IQ modulator receives a signal generated by an AWG (arrayed waveguide grating) of an arbitrary waveform generator, modulates the signal by I, Q to generate a high-order modulation signal, inputs the high-order modulation signal to an encryption module to serve as an input optical signal of PM2 in the encryption module, and then carries out chaotic phase modulation on PM2 under a driving signal to output a modulated optical signal;

finally, the optical signal output by the main laser and the modulated optical signal output by the PM2 are multiplexed to the optical fiber link through the wavelength division Multiplexer (MUX);

the optical fiber link comprises a single mode fiber SMF, a dispersion compensation fiber DCF and a fiber amplifier EDFA;

in the optical fiber link, optical signals are transmitted through a single mode fiber SMF, then chromatic dispersion introduced by the optical fiber link is compensated through a chromatic dispersion compensation fiber DCF, finally signal optical power attenuation caused by the optical fiber link is compensated through an optical fiber amplifier EDFA, and the signals are input to a receiving end;

the receiving end includes: the device comprises a wavelength division demultiplexer DMUX, an adjustable optical attenuator VOA2, a fiber isolator ISO2, a polarization controller PC2, an optical fiber coupler FC3, an adjustable optical fiber delay line DL, a photodetector PD2, a radio frequency amplifier RF3, a decryption module and an optical receiver;

the optical receiver comprises a polarization controller PC3, a coherent receiver and a local oscillator CW 3;

at a receiving end, firstly, an optical signal generated by a main laser at a sending end and a modulated optical signal output by PM2 are separated by a wavelength division demultiplexer DMUX; then, the optical signal generated by the master laser is injected into the slave laser SL2 after the optical power is adjusted by the variable optical attenuator VOA2 and the transmission direction is controlled by the optical isolator ISO2 and the polarization direction is controlled by the polarization controller PC 2; inputting the modulated optical signal output by the PM2 to a decryption module;

the chaotic light signal output from the laser SL2 is divided into two paths through an optical fiber coupler FC3, wherein one path receives the injection light signal of the main laser; the other path of optical signal is subjected to delay processing through an adjustable optical fiber delay line DL, then is converted into a chaotic electric signal through a photoelectric detector PD2, is subjected to amplitude amplification through a radio frequency amplifier RF3, is input into a decryption module, and is used as a driving signal of a phase modulator PM3 for phase decryption;

in the decryption module, the decryption module receives the modulated optical signal output by the PM2 and takes the modulated optical signal as an input signal, and then chaotic phase modulation is carried out under the action of a driving signal to output the modulated optical signal to an optical receiver;

in the optical receiver, the modulated optical signal output by the decryption module is input to a coherent receiver at a receiving end after the polarization direction is controlled by a polarization controller PC3, the local oscillator CW3 provides a local oscillator optical signal for the coherent receiver, and finally the original signal is recovered by the coherent receiver.

2. The chaotic phase encryption-based physical layer privacy fiber optic communication system of claim 1, wherein the PD2 and the PD1 output signals have the same amplitude and opposite amplitudes.

3. The physical layer privacy-preserving fiber optic communication system based on chaotic phase encryption as claimed in claim 1, wherein the slave lasers SL1 and SL2 are distributed feedback semiconductor lasers DFB.

4. The physical layer privacy-preserving fiber optic communication system based on chaotic phase encryption as claimed in claim 1, wherein the signal transmitted by the optical transmitter is any high-order modulated optical signal.

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