CN110635902A - A chaotic key distribution system and method based on dispersion keying synchronization - Google Patents

Abstract

The invention belongs to the technical field of secure communication, specifically a chaotic key security distribution system and method based on dispersion keying synchronization, which solves the problems in the background technology. The system includes a first DFB laser 1, a first 1ⅹ2 optical fiber coupling 2, CFBG chirped fiber grating 3, the second 1ⅹ2 fiber coupler 4, A communication party and B communication party, the A communication party and B communication party both include a fiber optic circulator, an optical switch, a memory, and a first dispersion module , a second dispersion module, a photodetector, an analog-to-digital converter and a bit filter. When switching through the optical switch, the random sequence of dispersion feedback can be directly obtained, and the key distribution involved is not affected by the synchronization recovery time, which improves the key distribution rate; at the same time, the chaotic optical state of the first DFB laser is changed through dispersion feedback, The chaotic light directly emitted by the first DFB laser and the chaotic light after the dispersion feedback are not correlated with each other, and the security of key distribution is enhanced by using the non-linear characteristic.

Description

A chaotic key distribution system and method based on dispersion keying synchronization

technical field

The invention belongs to the technical field of secure communication and relates to key distribution, in particular to a chaotic key security distribution system and method based on dispersion keying synchronization.

Background technique

To ensure the security of secure communication systems, secure key distribution is crucial. Secure communication between two users in a cryptographic system relies on a secret key known only to both parties. Two users share the key through a secure key distribution scheme.

The security of existing key distribution schemes mainly has two forms: security based on computation and security based on information theory. For computation-based security, it requires the premise that the eavesdropper has limited computation power. For security based on information theory, it does not need to consider the computing power of the eavesdropper.

The basic principle of the calculation-based key distribution scheme is: the key distribution center KDC and each end user share a pair of unique master keys (transmitted in a physical way, such as U-shield). For each session between end users, a unique session key must be applied to the KDC, and the session key is transmitted through encryption with the master key shared with the KDC. Computation-based key distribution schemes use public and private keys to solve the problem of public key distribution. There are multiple DES, RSA algorithms, etc. The security of the public key and the private key depends on the complexity of the algorithm and the computing power of the eavesdropper. With the replacement speed of computer processors getting faster and faster, the processing speed of the processor As well as the continuous improvement of attack algorithms, the security of computing-based key distribution schemes will face great challenges.

Security key distribution based on information theory is realized by security key distribution based on physical principles. Security key distribution based on physical principles can be classified into the following categories:

1. Quantum key distribution: Quantum key distribution is an absolutely secure key distribution scheme that uses single photons as a communication carrier and encodes the key on the polarization state of the single photon. By comparing the phases of the two parties, the key agreement between the two communicating parties is realized. Since in quantum mechanics, there is no process that can accurately replicate an unknown quantum state, quantum key distribution is unconditionally secure. Due to the weak single-photon transmission power, it is difficult to achieve long-distance transmission, and the key transmission rate is only Mbit/s [Nature Photonics volume 10, pages 312–315 ,2016];

2. Key distribution based on fiber laser: The key distribution scheme based on fiber laser needs to set different reflectors at both ends of the fiber, and a narrow-band filter at each end of the fiber. When using different reflectors to generate laser As a private key, the user can use the power of the laser to judge the mirror selection of the other party. Since the two states of light are strictly symmetrical, eavesdroppers cannot distinguish them, so this scheme is a strictly physically secure key distribution scheme. The key distribution scheme based on fiber laser has achieved 500Km key distribution, and the key exchange rate is 100bit/s [Laser & Photonics Reviews, 8 (3): 436-442, 2014]. The key exchange rate of this scheme is limited by the way the key is generated. The laser needs to oscillate back and forth in the fiber multiple times to generate the first key, so the key generation rate is low;

3. Key distribution based on chaotic synchronization, key distribution driven by a broadband signal source with constant amplitude and random phase: The key distribution driven by a broadband signal source with constant amplitude and random phase uses a broadband signal with constant amplitude and random phase change The source drives multiple scramblers to achieve chaotic synchronization among the scramblers. The chaotic state of the scrambler can be changed by changing the phase parameter inside the scrambler. Key distribution is realized by selecting random number sequences with the same phase parameters. The key distribution driven by a broadband signal source based on constant amplitude and random phase has achieved a key distribution of 120Km and a key exchange rate of 182kbit/s [Physical Review Letters, 108 (7): 070602, 2012]. The security in this scheme depends on a constant-amplitude random-phase broadband signal source, whose rapid temporal variation cannot be fully detected by an eavesdropper using existing techniques.

Among the existing key distribution technologies, quantum key distribution has strong security, but the key distribution rate is low; the calculation-based key distribution scheme has poor security; the security key distribution rate based on physical principles is high, but its security Still needs further improvement. It is necessary to invent a key distribution technology that can maintain the chaotic key distribution rate and improve its security. The invention is a key distribution technology based on chaotic delay coherent dynamic monitoring, and aims to improve the security of chaotic key distribution.

Contents of the invention

The purpose of the present invention is to solve the problems of low key distribution rate and poor security in the prior art, and provide a chaotic key distribution system and method based on dispersion monitoring synchronization.

The technical solution of the present invention to solve the technical problem provides a chaotic key distribution system based on dispersion keying synchronization, including the first DFB laser, the first 1ⅹ2 fiber coupler, the CFBG chirped fiber grating, and the second 1ⅹ2 fiber coupler , A communication party and B communication party; the output end of the first DFB laser is connected to the input end of the first 1ⅹ2 fiber coupler, and an output end of the first 1ⅹ2 fiber coupler is connected to the CFBG chirped fiber grating, The other output end is connected to the input end of the second 1ⅹ2 fiber optic coupler; the A communication party includes the A side optical fiber circulator, the A side optical switch and the A side memory, and the input end of the A side optical fiber circulator is connected to the second One output end of the 1ⅹ2 optical fiber coupler is connected, the reflection end of the A-side optical fiber circulator is connected to the A-side optical switch, and the A-side optical switch is also connected to the first A-side dispersion module and the second A-side dispersion module, The storage channel of the A side optical switch is connected to the input end of the A side memory, and the output end of the A side optical fiber circulator is connected with the A side photodetector, the A side analog-to-digital converter and the A side bit filter in sequence, The output end of the A side memory is connected to the A side bit filter; the B communication side includes the B side optical fiber circulator, the B side optical switch and the B side memory, and the input end of the B side optical fiber circulator is connected to the second The other output end of the 1ⅹ2 fiber optic coupler is connected, the reflection end of the B-side optical fiber circulator is connected to the B-side optical switch, and the B-side optical switch is also connected to the first B-side dispersion module and the second B-side dispersion module , the storage channel of the B-side optical switch is connected to the input end of the B-side memory, and the output end of the B-side optical fiber circulator is sequentially connected with a B-side photodetector, a B-side analog-to-digital converter, and a B-side bit filter , the output end of the B-side memory is connected to the B-side bit filter; a common channel is connected between the A-side memory and the B-side memory, and the dispersion of the first A-side dispersion module and the first B-side dispersion module The amount of dispersion is consistent, the second A-side dispersion module and the second B-side dispersion module have the same dispersion amount, and the A-side optical switch and B-side optical switch are both connected to the host computer.

Further, a second DFB laser is connected between the output end of the A-side optical fiber circulator and the input end of the A-side photodetector; the output end of the B-side optical fiber circulator is connected to the B-side photodetector A third DFB laser is connected between the input ends of the lasers. By adjusting the parameters of the second DFB laser and the third DFB laser, the security of the chaotic key distribution system based on dispersion keying synchronization can be effectively improved. After the second DFB laser and the third DFB laser are added, the key space of communication party A or communication party B can be increased, the difficulty of eavesdropping by eavesdroppers is increased, and the security of key distribution is improved.

The present invention also provides a chaotic key distribution method based on dispersion keying synchronization, comprising the following steps:

将第一DFB激光器产生的混沌激光注入至第一1ⅹ2光纤耦合器，经过CFBG啁啾光纤光栅反馈后从第一1ⅹ2光纤耦合器输出无时延特征的混沌光，所述无时延特征的混沌光经过第二1ⅹ2光纤耦合器等分成两路混沌光分别投入到A通信方和B通信方；

The chaotic laser generated by the first DFB laser is injected into the first 1ⅹ2 fiber coupler, and after being fed back by the CFBG chirped fiber grating, the chaotic light without delay characteristics is output from the first 1ⅹ2 fiber coupler. The light passes through the second 1ⅹ2 fiber coupler and is divided into two channels of chaotic light, which are respectively input to the A communication party and the B communication party;

所述A通信方中，将输入的混沌光注入A方光纤环形器并从反射端注入到A方光开关，所述A方光开关通过上位机控制，从而随机选择第一A方色散模块或第二A方色散模块进行光反馈，反馈光通过A方光纤环形器输出并依次通过A方光电探测器和A方模数转换器后产生A方随机数序列，再将A方随机数序列传输至A方比特滤波器中，所述A方光开关将上位机的随机切换状态作为A方私钥存储至A方存储器中；所述B通信方和A通信方的传输过程完全一致，A方存储器和B方存储器之间通过公共信道交换私钥，第一A方色散模块和第一B方色散模块的色散量一致故二者产生的随机数序列一致，第二A方色散模块和第二B方色散模块的色散量一致故二者产生的随机数序列同样一致；

In the communication party A, the input chaotic light is injected into the optical fiber circulator of the party A and injected into the optical switch of the party A from the reflection end, and the optical switch of the party A is controlled by the host computer, thereby randomly selecting the first dispersion module of the party A or The second A-side dispersion module performs optical feedback, and the feedback light is output through the A-side optical fiber circulator and then passes through the A-side photodetector and the A-side analog-to-digital converter in turn to generate the A-side random number sequence, and then transmit the A-side random number sequence In the bit filter of the A side, the A side optical switch stores the random switching state of the host computer as the A party’s private key in the A side’s memory; the transmission process of the B communication party and the A communication party is exactly the same, and the A party The private key is exchanged between the memory and the B-party memory through a public channel. The dispersion amount of the first A-party dispersion module and the first B-party dispersion module are consistent, so the random number sequences generated by the two are consistent. The second A-party dispersion module and the second The dispersion amount of the B-side dispersion module is the same, so the random number sequences generated by the two are also consistent;

所述A方存储器将B方私钥传输至A方比特滤波器，通过A方比特滤波器进行对比A、B双方的上位机的切换状态是否为一致，选取出切换状态一致时对应的A方随机数序列作为A方安全密钥；同理，所述B方存储器将A方私钥传输至B方比特滤波器，通过B方比特滤波器进行对比A、B双方的上位机的切换状态是否为一致，选取出切换状态一致时对应的B方随机数序列作为B方安全密钥，所述A方安全密钥和B方安全密钥保持一致。该方法在利用光开关切换时，能直接得到色散反馈的随机序列，涉及到的密钥分发不受同步恢复时间的影响，提高了密钥分发的速率；同时通过色散反馈改变第一DFB激光器的混沌光状态，使第一DFB激光器的混沌光与色散反馈之后的混沌光互不相关，利用了混沌光反馈和注入的非线性特性，增强了密钥分发的安全性。

The storage of party A transmits the private key of party B to the bit filter of party A, and compares whether the switching states of the upper computers of A and B are consistent through the bit filter of party A, and selects the corresponding party A when the switching states are consistent. The random number sequence is used as the security key of party A; in the same way, the storage of party B transmits the private key of party A to the bit filter of party B, and compares whether the switching status of the upper computers of both sides of A and B is checked by the bit filter of party B. For consistency, select the B-party random number sequence corresponding to the same switching state as the B-party security key, and the A-party security key and the B-party security key are consistent. This method can directly obtain the random sequence of dispersion feedback when the optical switch is used, and the key distribution involved is not affected by the synchronization recovery time, which improves the rate of key distribution; at the same time, the dispersion feedback changes the first DFB laser. The state of chaotic light makes the chaotic light of the first DFB laser irrelevant to the chaotic light after dispersion feedback, utilizes the nonlinear characteristics of chaotic light feedback and injection, and enhances the security of key distribution.

The method of the present invention first uses CFBG chirped fiber grating feedback to make the chaotic light output by the first 1ⅹ2 fiber coupler become chaotic light without delay characteristics, and then uses different dispersion modules to perform dispersion feedback on the chaotic light without time delay characteristics; Wherein the A communication party and the B communication party can make their feedback to obtain mutually uncorrelated chaotic light by adjusting the dispersion amount of the dispersion module, wherein in the present invention, the first A party dispersion module of the A communication party and the first B If the dispersion amount of the first party dispersion module is the same, the random number sequences generated by the first party A dispersion module and the first party B dispersion module are consistent; the second A party dispersion module of the A communication party and the second B party dispersion module of the B communication party If the amount of dispersion is the same, the random number sequence generated by the second A-party dispersion module and the second B-party dispersion module is consistent; in the systems of A communication party and B communication party, the random switching of different dispersion modules is selected through random switching of the host computer The state is used as the private key, and the communication parties use the public channel to exchange private keys, and compare and select the random number sequence corresponding to the same dispersion through the bit filter, and then perform bit filtering to obtain a consistent key, which is Party A security key or Party B security key.

Further, in the communication party A, the feedback light first passes through the second DFB laser after being output by the optical fiber circulator of the A party, and the chaotic light output by the second DFB laser is then transmitted to the photodetector of the A party; in the B communication party After the feedback light is output by the B-side optical fiber circulator, it first passes through the third DFB laser, and the chaotic light output by the third DFB laser is then transmitted to the B-side photodetector. By adjusting the parameters of the second DFB laser and the third DFB laser, the security of the key distribution method can be enhanced. After adding the second DFB laser and the third DFB laser, the key space of A communication party or B communication party can be increased, the difficulty of eavesdropping is increased, and the security of key distribution is improved; at the same time, because the first DFB Due to the light injection of the laser, the bandwidth of the chaotic laser signal of the second DFB laser and the third DFB laser is enhanced, thereby greatly increasing the rate of key distribution.

The beneficial effect of the present invention is that: the chaotic key distribution system and method based on dispersion keying synchronization described in the present invention can directly obtain the random sequence of dispersion feedback when the optical switch is used to switch, and the key distribution involved is not subject to synchronization. The impact of recovery time improves the rate of key distribution; at the same time, the chaotic light state of the first DFB laser is changed through dispersion feedback, so that the chaotic light directly emitted by the first DFB laser is independent of the chaotic light after dispersion feedback. The nonlinear characteristics of chaotic optical feedback and injection enhance the security of key distribution. When the second DFB laser and the third DFB laser are added, by adjusting the parameters of the second DFB laser and the third DFB laser, the security of the key distribution method can be enhanced; at the same time, the A communication party or B communication can be increased. party’s key space, which increases the difficulty of eavesdroppers’ eavesdropping and improves the security of key distribution; the chaotic light output by the second DFB laser and the third DFB laser and the chaotic light directly emitted by the first DFB laser and the first DFB The chaotic light emitted by the laser after dispersion feedback is not correlated with each other, and due to the light injection of the first DFB laser, the bandwidth of the chaotic laser signal of the second DFB laser and the third DFB laser is enhanced, thereby greatly improving the density. The rate at which keys are distributed.

Description of drawings

FIG. 1 is a schematic structural diagram of a chaotic key distribution system based on dispersive keying synchronization according to the present invention.

Fig. 2 is a schematic structural diagram of a chaotic key distribution system based on dispersion keying synchronization according to the present invention (the second DFB laser and the third DFB laser are added).

In the figure: 1-the first DFB laser; 2-the first 1ⅹ2 fiber coupler; 3-CFBG chirped fiber grating; 4-the second 1ⅹ2 fiber coupler; 5a-A square fiber circulator; 5b-B square fiber ring 6a-A-side on-off keying; 6b-B-side on-off keying; 7a-First A-side dispersion module; 7b-Second A-side dispersion module; 8a-First B-side dispersion module; 8b-Second B Square dispersion module; 9a-A square memory; 9b-B square memory; 10a-second DFB laser; 10b-third DFB laser; 11a-A square photodetector; 11b-B square photodetector; 12a-A square Analog-to-digital converter; 12b-B square analog-to-digital converter; 13a-A square bit filter; 13b-B square bit filter; 14-common channel.

Detailed ways

In order to illustrate the embodiment of the present invention or the technical solution in the prior art more clearly, the technical solution of the present invention will be described in detail below. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

In the description of the present invention, the terms "first", "second", "third" and so on are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

Referring to accompanying drawings 1 and 2, a chaotic key distribution system and method based on dispersion keying synchronization provided by the present invention will now be described.

A chaotic key distribution system based on dispersion keying synchronization, as shown in Figure 1, includes a first DFB laser 1, a first 1ⅹ2 fiber coupler 2, a CFBG chirped fiber grating 3, and a second 1ⅹ2 fiber coupler 4, A communication party and B communication party; the output end of the first DFB laser 1 is connected to the input end of the first 1ⅹ2 fiber coupler 2, and an output end of the first 1ⅹ2 fiber coupler 2 is connected to the CFBG chirped fiber Grating 3, another output end is connected to the input end of second 1ⅹ2 fiber optic coupler 4; Described A communication party comprises A side optical fiber circulator 5a, A side optical switch 6a and A side memory 9a, and described A side optical fiber ring The input end of the device 5a is connected to an output end of the second 1ⅹ2 optical fiber coupler 4, and the reflection end of the A side optical fiber circulator 5a is connected to the A side optical switch 6a, and the A side optical switch 6a is also connected to the first The A side dispersion module 7a and the second A side dispersion module 8a, the storage channel of the A side optical switch 6a is connected to the input end of the A side memory 9a, and the output end of the A side optical fiber circulator 5a is connected with the A side in turn. Photodetector 11a, A side analog-to-digital converter 12a and A side bit filter 13a, the output end of described A side memory 9a is connected to A side bit filter 13a; Described B communication side comprises B side optical fiber circulator 5b , B-side optical switch 6b and B-side memory 9b, the input end of the B-side optical fiber circulator 5b is connected to another output end of the second 1ⅹ2 fiber optic coupler 4, and the reflection end of the B-side optical fiber circulator 5b is connected To the B side optical switch 6b, the B side optical switch 6b is also connected with the first B side dispersion module 7b and the second B side dispersion module 8b, and the storage channel of the B side optical switch 6b is connected to the B side memory 9b Input end, the output end of described B side optical fiber circulator 5b is connected with B side photodetector 11b, B side analog-to-digital converter 12b and B side bit filter 13b in turn, and the output end of described B side memory 9b is connected to B-side bit filter 13b; a common channel 14 is connected between the A-side memory 9a and the B-side memory 9b, the first A-side dispersive module 7a is consistent with the first B-side dispersive module 7b, and the second A-side dispersive module 7b is consistent. The square dispersion module 8a is consistent with the second B-side dispersion module 8b, and the A-side optical switch 6a and the B-side optical switch 6b are both connected to the host computer.

Further, as a specific embodiment of a chaotic key distribution system based on dispersion keying synchronization in the present invention, the output end of the A-side optical fiber circulator 5a is connected to the input end of the A-side photodetector 11a A second DFB laser 10a is connected between them; a third DFB laser 10b is connected between the output end of the B-side fiber circulator 5b and the input end of the B-side photodetector 11b, the specific structure is shown in Figure 2 . After the second DFB laser 10a and the third DFB laser 10b are added, the key space of the communicating party A or the communicating party B can be increased, the difficulty of eavesdropping is increased, and the security of key distribution is improved.

A chaotic key distribution method based on dispersion keying synchronization, comprising the following steps:

将第一DFB激光器1产生的混沌激光注入至第一1ⅹ2光纤耦合器2，经过CFBG啁啾光纤光栅3反馈后从第一1ⅹ2光纤耦合器2输出无时延特征的混沌光，所述无时延特征的混沌光经过第二1ⅹ2光纤耦合器4等分成两路混沌光分别投入到A通信方和B通信方；

The chaotic laser light generated by the first DFB laser 1 is injected into the first 1ⅹ2 fiber coupler 2, and after being fed back by the CFBG chirped fiber grating 3, the chaotic light without delay characteristics is output from the first 1ⅹ2 fiber coupler 2. The chaotic light with extended characteristics is divided into two channels of chaotic light by the second 1ⅹ2 fiber coupler 4 and put into the A communication party and the B communication party respectively;

In the communication party A, the input chaotic light is injected into the optical fiber circulator 5a of the party A and injected into the optical switch 6a of the party A from the reflection end, and the optical switch 6a of the party A is controlled by the host computer, thereby randomly selecting the first party A The dispersion module 7a or the second A-side dispersion module 8a performs optical feedback, and the feedback light passes through the output of the A-side optical fiber circulator 5a and then passes through the A-side photodetector 11a and the A-side analog-to-digital converter 12a to generate the A-side random number sequence , and then transmit the A-side random number sequence to the A-side bit filter 13a, and the A-side optical switch 6a stores the random switching state of the upper computer as the A-side private key in the A-side memory 9a; It is completely consistent with the transmission process of the A communication party. The private key is exchanged through the public channel 14 between the A-party memory 9a and the B-party memory 9b. The dispersion quantities of the first A-party dispersion module 7a and the first B-party dispersion module 7b are consistent. The random number sequences produced by the former are consistent, and the dispersion quantities of the second A-side dispersion module 8a and the second B-side dispersion module 8b are consistent, so the random number sequences produced by the two are also consistent;

所述A方存储器9a将B方私钥传输至A方比特滤波器13a，通过A方比特滤波器13a进行对比A、B双方的上位机的切换状态是否为一致，选取出切换状态一致时对应的A方随机数序列作为A方安全密钥；同理，所述B方存储器9b将A方私钥传输至B方比特滤波器13b，通过B方比特滤波器13b进行对比A、B双方的上位机的切换状态是否为一致，选取出切换状态一致时对应的B方随机数序列作为B方安全密钥，所述A方安全密钥和B方安全密钥保持一致。

The A-party memory 9a transmits the B-party private key to the A-side bit filter 13a, and compares whether the switching states of the upper computers of A and B are consistent through the A-side bit filter 13a, and selects the corresponding state when the switching states are consistent. Party A’s random number sequence is used as the security key of Party A; similarly, the memory 9b of Party B transmits the private key of Party A to the bit filter 13b of Party B, and compares the two sides of A and B through the bit filter 13b of Party B. Whether the switching state of the upper computer is consistent, select the B-party random number sequence corresponding to the consistent switching state as the B-party security key, and the A-party security key and the B-party security key are consistent.

The method of the present invention first utilizes the CFBG chirped fiber grating 3 feedback to make the chaotic light output by the first 1ⅹ2 fiber coupler 2 become chaotic light without delay characteristics, and then use different dispersion modules to disperse the chaotic light without time delay characteristics Feedback; where the communication party A and the communication party B can make their feedback obtain uncorrelated chaotic light by adjusting the dispersion amount of the dispersion module, wherein in the present invention, the first A-party dispersion module 7a of the A communication party and the B communication party’s The dispersion amount of the first B-party dispersion module 7b is consistent, then the random number sequence produced by the first A-party dispersion module 7a and the first B-party dispersion module 7b is consistent; the second A-party dispersion module 8a of the A communication party and the B communication party The dispersion amount of the second B-party dispersion module 8b is the same, then the random number sequences generated by the second A-party dispersion module 8a and the second B-party dispersion module 8b are consistent; The machine random switching selects the random switching state of different dispersion modules as the private key, and the two parties use the public channel 14 to exchange the private key, and select the corresponding random number sequence when the dispersion is the same through bit filter comparison, and then perform bit filtering to obtain A consistent key, where the consistent key is the security key of party A or the security key of party B.

Further, as a specific embodiment of a chaotic key distribution method based on dispersion keying synchronization in the present invention, in communication party A, after the feedback light is output by the optical fiber circulator 5a of party A, it first passes through the second DFB Laser 10a, the chaotic light output by the second DFB laser 10a is then transmitted to the A-side photodetector 11a; in the B-communication side, the feedback light first passes through the third DFB laser 10b after being output by the B-side optical fiber circulator 5b, The chaotic light output by the third DFB laser 10b is transmitted to the B-side photodetector 12a.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and can also be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art. Variations.

Claims (4)

1. A chaotic key distribution system based on dispersion keying synchronization, comprising a first DFB laser (1), a first 1 x 2 fiber coupler (2), a CFBG chirped fiber grating (3), a second 1 x 2 fiber coupler (4), an a communication party and a B communication party; the output end of the first DFB laser (1) is connected to the input end of a first 1 x 2 fiber coupler (2), one output end of the first 1 x 2 fiber coupler (2) is connected to the CFBG chirped fiber grating (3), and the other output end is connected to the input end of a second 1 x 2 fiber coupler (4); the A communication party comprises an A-party optical fiber circulator (5 a), an A-party optical switch (6 a) and an A-party memory (9 a), the input end of the a-square optical fiber circulator (5 a) is connected to one output end of a second 1 x 2 optical fiber coupler (4), the reflection end of the A-side optical fiber circulator (5 a) is connected to an A-side optical switch (6 a), the A-side optical switch (6 a) is also connected with a first A-side dispersion module (7 a) and a second A-side dispersion module (8 a), the storage channel of the A-side optical switch (6 a) is connected to the input of an A-side memory (9 a), the output end of the A-side optical fiber circulator (5 a) is sequentially connected with an A-side photoelectric detector (11 a), an A-side analog-digital converter (12 a) and an A-side bit filter (13 a), the output of the A-side memory (9 a) is connected to an A-side bit filter (13 a); the B communication party comprises a B-party optical fiber circulator (5B), a B-party optical switch (6B) and a B-party memory (9B), the input end of the B-side optical fiber circulator (5B) is connected to the other output end of the second 1 x 2 optical fiber coupler (4), the reflection end of the B-side optical fiber circulator (5B) is connected to a B-side optical switch (6B), the B-side optical switch (6B) is also connected with a first B-side dispersion module (7B) and a second B-side dispersion module (8B), the storage channel of the B-side optical switch (6B) is connected to the input end of a B-side memory (9B), the output end of the B-side optical fiber circulator (5B) is sequentially connected with a B-side photoelectric detector (11B), a B-side analog-digital converter (12B) and a B-side bit filter (13B), the output end of the B-side memory (9B) is connected to a B-side bit filter (13B); a public channel (14) is connected between the A-side memory (9 a) and the B-side memory (9B), the dispersion quantities of the first A-side dispersion module (7 a) and the first B-side dispersion module (7B) are consistent, the dispersion quantities of the second A-side dispersion module (8 a) and the second B-side dispersion module (8B) are consistent, and the A-side optical switch (6 a) and the B-side optical switch (6B) are both connected to an upper computer.

2. The chaotic key distribution system based on dispersion keying synchronization according to claim 1, wherein a second DFB laser (10 a) is connected between the output end of the a-side optical fiber circulator (5 a) and the input end of the a-side photodetector (11 a); and a third DFB laser (10B) is connected between the output end of the B-side optical fiber circulator (5B) and the input end of the B-side photoelectric detector (11B).

3. A chaotic key distribution method based on dispersion keying synchronization, which is implemented by the system of claim 1, and comprises the following steps:

the chaotic laser generated by the first DFB laser (1) is injected into the first 1 x 2 optical fiber coupler (2), the chaotic light without the time delay characteristic is output from the first 1 x 2 optical fiber coupler (2) after being fed back by the CFBG chirped fiber grating (3), and the chaotic light without the time delay characteristic is equally divided into two paths of chaotic light by the second 1 x 2 optical fiber coupler (4) and is respectively thrown into the communication party A and the communication party B;

in the A communication party, input chaotic light is injected into an A-party optical fiber circulator (5 a) and is injected into an A-party optical switch (6 a) from a reflection end, the A-party optical switch (6 a) is controlled by an upper computer, so that a first A-party dispersion module (7 a) or a second A-party dispersion module (8 a) is randomly selected for optical feedback, feedback light is output through the A-party optical fiber circulator (5 a) and generates an A-party random number sequence after sequentially passing through an A-party photoelectric detector (11 a) and an A-party analog-to-digital converter (12 a), the A-party random number sequence is transmitted into an A-party bit filter (13 a), and the A-party optical switch (6 a) stores the random switching state of the upper computer into an A-party memory (9 a) as an A-party private key; the transmission process of the B communication party and the A communication party is completeThe private keys are exchanged between the A-side memory (9 a) and the B-side memory (9B) through a public channel (14), the dispersion quantities of the first A-side dispersion module (7 a) and the first B-side dispersion module (7B) are consistent, so that the random number sequences generated by the first A-side dispersion module and the first B-side dispersion module are consistent, and the dispersion quantities of the second A-side dispersion module (8 a) and the second B-side dispersion module (8B) are consistent, so that the random number sequences generated by the first A-side dispersion module and the second B-side dispersion module are the same;

the A-party memory (9 a) transmits the B-party private key to an A-party bit filter (13 a), compares A, B the switching states of the upper computers of the two parties to be consistent through the A-party bit filter (13 a), and selects a corresponding A-party random number sequence as an A-party security key when the switching states are consistent; similarly, the B-party memory (9B) transmits the A-party private key to a B-party bit filter (13B), compares A, B the switching states of the upper computers of the two parties to be consistent through the B-party bit filter (13B), selects the corresponding B-party random number sequence when the switching states are consistent as a B-party security key, and the A-party security key and the B-party security key are kept consistent.

4. The method according to claim 3, wherein in the communication party A, the feedback light passes through the second DFB laser (10 a) after being output by the optical fiber circulator (5 a) of the party A, and the chaotic light output by the second DFB laser (10 a) is transmitted to the photodetector (11 a) of the party A; in the communication party B, feedback light passes through a third DFB laser (10B) after being output by the optical fiber circulator (5B) of the party B, and chaotic light output by the third DFB laser (10B) is transmitted to a photoelectric detector (12 a) of the party B.

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