CN113612544B - Optical chaotic secret communication system with four-dimensional secret key space - Google Patents

Abstract

An optical chaotic secure communication system with a four-dimensional key space, the erbium-doped fiber amplifier at the transmitting end sends out an optical signal that passes through the first phase modulator, the first fiber Bragg grating, the second phase modulator, the first coupler, and the first Gires‑ The Tournois interferometer cascade group, the first adjustable delay line, the first photodetector and the first RF amplifier return to the second phase modulator; the first coupler sequentially passes through standard single-mode fiber, dispersion compensation fiber, and optical amplifier After that, it is connected to the second coupler at the receiving end. The second coupler passes through the second Gires‑Tournois interferometer cascade group, the second adjustable delay line, the second photodetector, and the second radio frequency amplifier in sequence, and then modulates the third phase with the third coupler. The first port of the third phase modulator is connected to the second coupler, the third port of the third phase modulator is connected to the third photodetector through the second fiber Bragg grating; the laser at the transmitting end is sequentially modulated by in-phase quadrature The device and the fourth photodetector are connected to the first phase modulator.

Description

Optical chaotic secure communication system with four-dimensional key space

technical field

The invention belongs to the technical field of optical information, in particular to an optical chaotic secure communication system with a four-dimensional key space.

Background technique

Chaos is a deterministic, quasi-random, bounded but non-convergent process that occurs in nonlinear systems. Applying the chaos phenomenon to the field of communication technology can realize the hardware encryption based on the physical layer, which has stronger security compared with the traditional secure communication system based on the digital encryption and decryption of the application layer. The optical chaotic system itself is easy to build and replicate, and the chaotic signal it generates is extremely sensitive to the initial conditions. In two identical optical chaotic systems, a small difference in input will cause a huge change in the results. Therefore, the same chaotic dynamics can be built at the transmitting end and the receiving end by using the easy duplication of the optical chaotic system to encrypt and decrypt information.

In the entire optical chaotic secure communication system, the key to confidentiality lies in the concealment of parameters at the transmitting end and a larger key space. The larger key space prevents the third party from accurately inferring the parameters of the transmitting end, which ensures the resistance of encrypted information. Interceptability makes it impossible for unauthorized persons to copy the chaotic dynamics of the transmitting end, effectively improving the confidentiality of information and ensuring the security of communication.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an optical chaotic secure communication system with a four-dimensional key space in order to solve the information confidentiality problem of the optical chaotic communication system.

To achieve the above object, the present invention adopts the following technical solutions:

An optical chaotic secure communication system with a four-dimensional key space includes a transmitting end and a receiving end; the transmitting end includes an erbium-doped fiber amplifier, and the erbium-doped fiber amplifier sends out a first optical signal through the first phase modulator, the first fiber Bragg grating, the first optical fiber The second phase modulator, the first coupler, the first cascade of Gires-Tournois interferometers, the first tunable delay line, the first photodetector and the first RF amplifier return to the second phase modulator; the first The coupler is connected to the second coupler at the receiving end through the standard single-mode fiber, the dispersion compensation fiber, and the optical amplifier in turn. The second coupler passes through the second Gires-Tournois interferometer cascade group, the second adjustable delay line, the second The second photodetector and the second RF amplifier are connected to the first port of the third phase modulator, the second port of the third phase modulator is connected to the second coupler, and the third port of the third phase modulator is connected to the second optical fiber The Bragg grating is connected to the third photodetector; the laser at the transmitting end is sequentially connected to the first phase modulator through the in-phase quadrature modulator and the fourth photodetector.

The second optical signal generated by the laser is modulated with the erbium-doped fiber amplifier in the first phase modulator after passing through the in-phase quadrature modulator and the fourth photodetector, and the modulated signal realizes phase-to-intensity in the first fiber Bragg grating The converted signal is modulated by the second phase modulator, and the modulated signal is divided into optical signal three and optical signal four through the first coupler. Optical signal three is fed into the channel for transmission, and optical signal four passes through the first coupler in turn. The cascaded group of Gires-Tournois interferometers, the first adjustable delay line, the first photodetector and the first radio frequency amplifier are then input to the second phase modulator. The optical signal 3 passes through the standard single-mode fiber, the dispersion compensation fiber, and the optical amplifier in turn, and then passes through the second coupler. The second coupler divides the optical signal into three parts, the optical signal 5 and the optical signal 6. The optical signal 5 passes through the second Gires-Tournois interference. After the instrument cascade group, the second adjustable delay line, the second photodetector, and the second radio frequency amplifier, it is modulated with the optical signal 6 in the third phase modulator and output, and the output optical signal passes through the second fiber Bragg grating and The third photodetector.

As a preferred solution, the cascade group of Gires-Tournois interferometers can be composed of Gires-Tournois interferometers with different cavity lengths and reflectivities, and the cascade groups of Gires-Tournois interferometers will produce different degrees of time delay for optical signals of different frequencies.

As a preferred solution, the parameters of the corresponding devices between the transmitting end and the receiving end are the same, that is, the parameters of the first phase modulator, the second phase modulator, and the third phase modulator are the same. The parameters of the first grating Bragg fiber and the second fiber Bragg grating are the same. The parameters of the first optical coupler and the second optical coupler are the same, and the parameters of the first Gires-Tournois interferometer cascade group and the second Gires-Tournois interferometer cascade group are the same. The parameters of the first adjustable delay line and the second adjustable delay line are the same. The parameters of the first photodetector, the second photodetector, the third photodetector, and the fourth photodetector are the same. The parameters of the first radio frequency amplifier and the second radio frequency amplifier are the same.

As a preferred solution, all couplers have a coupling coefficient of 0.5.

As a preferred solution, the wavelength of the signal generated by the laser is 1550 nm, the bandwidth of the ASE noise (first optical signal) generated by the erbium-doped fiber amplifier is 42 nm, and the center frequency is 193.4 Thz.

As a preferred solution, the receiving end directly outputs the restored plaintext information.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention has an optical chaotic communication system with a four-dimensional key space. The four-dimensional key space of the present invention is the cumulative dispersion degree of the fiber Bragg grating, the delay time of the adjustable delay line, the Gires-Tournois interferometer cascaded group delay curve and the Gires-Tournois interferometer cascaded group delay curve. -The number of cascades of Tournois interferometer cascade groups expands the key space, improves the confidentiality of information, and realizes double chaotic encryption of phase and intensity, which can be combined with more advanced modulation methods such as 16QAM to carry out information confidential transmission.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical chaotic secure communication system with a four-dimensional key space according to an embodiment of the present invention.

FIG. 2 is a chaotic bifurcation diagram of the feedback strength of the electro-optical delay feedback loop and the strength of the output signal at the transmitter in the optical chaotic secure communication system with a four-dimensional key space according to an embodiment of the present invention.

FIG. 3 is a chaotic bifurcation diagram of the feedback strength of the electro-optical delay feedback loop and the phase of the output signal at the transmitter in the optical chaotic secure communication system with a four-dimensional key space according to an embodiment of the present invention.

FIG. 4 is the chaotic attractor of the output signal x(t) of the transmitting end in the optical chaotic secure communication system with four-dimensional key space according to the embodiment of the present invention.

Detailed ways

In order to describe the embodiments of the present invention more clearly, the following will describe specific embodiments of the present invention with reference to the accompanying drawings. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained from these drawings without creative efforts, and obtain other implementations.

As shown in Figure 1, an optical chaotic secure communication system with a four-dimensional key space in an embodiment of the present invention includes a transmitter and a receiver, the transmitter is connected to the receiver, and the specific components include an erbium-doped fiber amplifier 1, a first phase modulation 2-1, the first grating Bragg fiber 3-1, the second phase modulator 2-2, the first optical coupler 4-1, the first Gires-Tournois interferometer cascade group 5-1, the first adjustable Delay line 6-1, first photodetector 7-1, first RF amplifier 8-1, laser 9, in-phase quadrature modulator 10, fourth photodetector 7-4, standard single-mode fiber 11, dispersion compensation Optical fiber 12, optical amplifier 13, second optical coupler 4-2, second Gires-Tournois interferometer cascade group 5-2, second adjustable delay line 6-2, second photodetector 7-2, Two radio frequency amplifiers 8-2, a third phase modulator 2-3, a second fiber Bragg grating 3-2, and a third photodetector 7-3.

The specific connection mode of the above-mentioned components is as follows: the port a1 of the erbium-doped fiber amplifier 1 at the transmitting end is connected to the first port b1 of the first phase modulator 2-1, and the third port b3 of the first phase modulator 2-1 is connected to the first port b3 of the first phase modulator 2-1. The first port c1 of a fiber Bragg grating 3-1 is connected, the second port c2 of the first fiber Bragg grating 3-1 is connected to the first port d1 of the second phase modulator 2-2, and the second phase modulator 2- 2 is connected to the first port e1 of the first optical coupler 4-1, and the second port e2 of the first optical coupler 4-1 is connected to the first Gires-Tournois interferometer cascade group 5-1. The first port f1 is connected, the second port f2 of the first Gires-Tournois interferometer cascade group 5-1 is connected to the first port g1 of the first adjustable delay line 6-1, and the first adjustable delay line 6-1 The second port g2 of the first photodetector 7-1 is connected to the first port h1 of the first photodetector 7-1, and the second port h2 of the first photodetector 7-1 is connected to the first port i1 of the first radio frequency amplifier 8-1. The second port i2 of a radio frequency amplifier 8-1 is connected to the third port d3 of the second phase modulator 2-2, and an electro-optical delay feedback loop is formed from the d2 port to the d3 port of the second phase modulator 2-2.

The output port u1 of the laser 9 is connected to the first port v1 of the in-phase quadrature modulator 10, the second port v2 of the in-phase quadrature modulator 10 is connected to the first port w1 of the fourth photodetector 7-4, and the fourth photoelectric The second port w2 of the detector 7-4 is connected to the second port b2 of the first phase modulator 2-1.

The third port e3 of the first optical coupler 4-1 is connected to the first port j1 of the standard single-mode fiber 11, the second port j2 of the standard single-mode fiber 11 is connected to the first port k1 of the dispersion compensation fiber 12, and the dispersion compensation The second port k2 of the optical fiber 12 is connected to the first port l1 of the optical amplifier 13, the second port l2 of the optical amplifier 13 is connected to the first port m1 of the second optical coupler 4-2, and the second optical coupler 4-2 The second port m2 of the second Gires-Tournois interferometer cascade group 5-2 is connected to the first port n1 of the second Gires-Tournois interferometer cascade group 5-2, and the second port n2 of the second Gires-Tournois interferometer cascade group 5-2 is connected to the second adjustable delay The first port o1 of the line 6-2 is connected, the second port o2 of the second adjustable delay line 6-2 is connected to the first port p1 of the second photodetector 7-2, and the second photodetector 7-2 The second port p2 is connected to the first port q1 of the second radio frequency amplifier 8-2, the second port q2 of the second radio frequency amplifier 8-2 is connected to the first port r1 of the third phase modulator 2-3, and the third phase The second port r2 of the modulator 2-3 is connected to the third port m3 of the second optical coupler 4-2, the third port r3 of the third phase modulator 2-3 and the third port r3 of the second fiber Bragg grating 3-2. A port s1 is connected, the second port s2 of the second fiber Bragg grating 3-2 is connected to the first port t1 of the third photodetector 7-3, and the second port t2 of the third photodetector 7-3 outputs the restored information.

The optical chaotic secure communication system with a four-dimensional key space disclosed in this embodiment, the principle of encrypting information and expanding the key space is as follows: using the ASE noise generated by the erbium-doped fiber amplifier as a random sequence to phase-modulate the plaintext information, The plaintext information is encrypted on the phase, and the phase-encrypted signal is sent into the fiber Bragg grating to convert the phase encryption into intensity encryption, and provide the first-dimensional key—the cumulative dispersion degree of the fiber Bragg grating. Then, the intensity-encrypted signal enters the electro-optical delay feedback loop with Gires-Tournois interferometer cascade group to realize phase encryption. The complexity of the parameters of the chaotic system is enhanced, and finally the phase and intensity of the plaintext information are double encrypted. In this system, the chaotic carrier can effectively hide the delay curve information of the cascaded Gires-Tournois interferometer group, and the delay information curve prevents the parameters of the chaotic system from being easily deciphered, thus jointly constructing a robust security Communication Systems. The time delay generated by the adjustable delay line in the electro-optical delay feedback loop, the time delay curve of the Gires-Tournois interferometer and the number of cascades of the Gires-Tournois interferometer respectively provide a three-dimensional key, which further expands the key space and enhances the The complexity of the parameters of the chaotic system improves the security of the chaotic communication system.

The process of using the optical chaotic communication system with the four-dimensional key space of the present embodiment to realize communication is as follows:

1. Use the ASE noise generated by the erbium-doped fiber amplifier as a random entropy source to phase-encrypt the 16QAM information output by the in-phase quadrature modulator, and pass the encrypted information through the fiber Bragg grating to realize the conversion from phase encryption to intensity encryption, and obtain intensity encryption. waveform.

2. The intensity encrypted waveform enters the electro-optical time delay feedback loop, generates time delay through the cascade group of Gires-Tournois interferometers and adjustable delay line, turns into an electrical signal through the photoelectric detector, and is amplified by the RF amplifier and fed back to the phase modulator , encrypt the phase information of the plaintext in the feedback loop, and expand the key space to four dimensions.

3. After decryption through the electro-optical delay feedback loop and fiber Bragg grating with the same parameters at the receiving end, it is converted into an electrical signal output by a photodetector, and the output is the transmitted plaintext information.

The invention realizes the four-dimensional key space, expands the key space, improves the confidentiality of information, and realizes the double chaotic encryption of phase and intensity, and can be combined with a more advanced modulation mode such as 16QAM to carry out the confidential transmission of information .

The above are the preferred embodiments of the present invention and do not limit the protection scope of the present invention. For those of ordinary skill in the art, based on the research ideas provided by the present invention, there will be improvements in specific design schemes, and these changes It should also be regarded as the protection scope of the present invention.

Claims (10)

1. An optical chaotic secure communication system with a four-dimensional key space, comprising a transmitting end and a receiving end, wherein the transmitting end comprises an erbium-doped fiber amplifier (1), and the erbium-doped fiber amplifier (1) sends out a first optical signal Pass through the first phase modulator (2-1), the first fiber Bragg grating (3-1), the second phase modulator (2-2), the first coupler (4-1), the first Gires-Tournois The interferometer cascade group (5-1), the first adjustable delay line (6-1), the first photodetector (7-1) and the first radio frequency amplifier (8-1) return to the second phase modulation device (2-2); the ASE noise generated by the erbium-doped fiber amplifier (1) is used as a random sequence to phase-modulate the plaintext information, and the plaintext information is encrypted in phase; The first coupler (4-1) is connected to the second coupler (4-2) at the receiving end after passing through the standard single-mode fiber (11), the dispersion compensation fiber (12), and the optical amplifier (13) in sequence, and the second coupler (4-2) Pass through the second Gires-Tournois interferometer cascade group (5-2), the second adjustable delay line (6-2), the second photodetector (7-2), and the second radio frequency amplifier in sequence (8-2) is then connected to the first port of the third phase modulator (2-3), the second port of the third phase modulator (2-3) is connected to the second coupler (4-2), and the third The third port of the phase modulator (2-3) is connected to the third photodetector (7-3) through the second fiber Bragg grating (3-2); The laser (9) at the transmitting end is connected to the first phase modulator (2-1) through the in-phase quadrature modulator (10) and the fourth photodetector (7-4) in sequence. 2. the optical chaos secret communication system with four-dimensional key space according to claim 1, is characterized in that, the first Gires-Tournois interferometer cascade group is made up of the Gires-Tournois interferometers of different cavity lengths, reflectivity, A cascade of Gires-Tournois interferometers will produce different degrees of time delay for optical signals of different frequencies; and/or, the second cascade of Gires-Tournois interferometers consists of Gires-Tournois interferometers with different cavity lengths and reflectivities Composed of, the cascaded group of second Gires-Tournois interferometers will produce different degrees of time delay for optical signals of different frequencies. 3 . The optical chaotic secure communication system with a four-dimensional key space according to claim 1 , wherein the parameters of the first phase modulator, the second phase modulator and the third phase modulator are the same. 4 . 4 . The optical chaotic secure communication system with a four-dimensional key space according to claim 1 , wherein the parameters of the first grating Bragg fiber and the second fiber Bragg grating are the same. 5 . 5. The optical chaotic secure communication system with four-dimensional key space according to claim 1 or 2, wherein the parameters of the first optical coupler and the second optical coupler are the same; and/or, the first Gires-Tournois The parameters of the interferometer cascade group and the second Gires-Tournois interferometer cascade group are the same. 6 . The optical chaotic secure communication system with a four-dimensional key space according to claim 1 , wherein the parameters of the first adjustable delay line and the second adjustable delay line are the same. 7 . 7. The optical chaotic secure communication system with four-dimensional key space according to claim 1, wherein the parameters of the first photodetector, the second photodetector, the third photodetector, and the fourth photodetector are the same ; and/or the parameters of the first radio frequency amplifier and the second radio frequency amplifier are the same. 8 . The optical chaotic secure communication system with a four-dimensional key space according to claim 1 , wherein the coupling coefficients of the first optical coupler and the second optical coupler are both 0.5. 9 . 9 . The optical chaotic secure communication system with a four-dimensional key space according to claim 8 , wherein the wavelength of the signal generated by the laser is 1550 nm. 10 . 10. The optical chaotic secure communication system with a four-dimensional key space according to any one of claims 1-4, 6-9, wherein the bandwidth of the ASE noise generated by the erbium-doped fiber amplifier is 42 nm, and the center frequency is 193.4 Thz.

Images