A key distribution system and method for dynamic filtering of multimode lasers

Abstract

This invention belongs to the field of semiconductor device technology, specifically a key distribution system and method for dynamic filtering of multimode lasers. It includes a multimode laser, an isolator, a coupler, an Alice communication side, a Bob communication side, and a real-time digital oscilloscope. The Alice communication side includes a first adjustable attenuator, a first polarization controller, a first wavelength division multiplexer, a second wavelength division multiplexer, a first arbitrary waveform generator, and a first photodetector. The Bob communication side includes a second adjustable attenuator, a second polarization controller, a third wavelength division multiplexer, a fourth wavelength division multiplexer, a second arbitrary waveform generator, and a second photodetector. Both communicating parties use independent, random private keys to key the injected signal. Even if an eavesdropper obtains the private key transmitted over a public channel, they cannot crack the key information, thus increasing the security of key distribution. The open-loop structure of the DFB laser has a low synchronization recovery time, which can effectively improve the key distribution rate.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology and relates to key distribution technology, specifically a key distribution system and method for dynamic filtering of multimode lasers. Background Technology

[0002] Secure communications are a matter of vital importance to the well-being of people worldwide, and absolutely secure secure communications are a goal that human society has always pursued.

[0003] Shannon's "one-time pad" theory is an absolutely secure method of communication, which requires two conditions to be met in principle: (1) the ability to generate random keys at high speed; and (2) the ability to achieve high-speed and secure key distribution. Therefore, how to securely distribute high-speed random keys to both communicating parties is one of the key research contents for achieving absolutely secure communication.

[0004] Current key distribution schemes mainly include key distribution based on mathematical algorithms and physical layers.

[0005] Communication systems currently widely employ complex mathematical algorithms to generate random keys for encrypting information. These schemes primarily include symmetric and asymmetric encryption mechanisms. In symmetric encryption schemes, both communicating parties use the same seed and mathematical algorithm to generate a consistent random key, completing symmetric key distribution. In asymmetric encryption schemes, the sender encrypts the information using a private key and sends the corresponding public key to the receiver, who then obtains the corresponding private key, completing asymmetric key distribution. However, the security of mathematical algorithms relies heavily on their complexity and depends on the limited computational capabilities of the eavesdropper. Therefore, with the increase in computer processing speed and algorithm optimization, the security of this type of key distribution faces significant challenges. For example, the DES algorithm was cracked by RSA's supercomputer in 1999; the RSA algorithm was cracked by the Shor algorithm in 2015; and the AES-256 algorithm was cracked by a collision attack in 2017.

[0006] Physical layer-based key distribution mainly relies on the randomness of physical entropy sources. Typical schemes include quantum key distribution, key distribution based on ultra-long fiber lasers, key distribution based on fiber optic channel reciprocity, and key distribution based on chaotic synchronization.

[0007] Quantum key distribution (QKD) schemes are based on the principles of quantum uncertainty and no-cloning. Eavesdroppers cannot accurately obtain quantum state information, and the eavesdropping process inevitably interferes with legitimate communication and is thus detected. Therefore, QKD is unconditionally secure. However, the low detection efficiency of single-photon detectors and transmission losses limit the speed of long-distance QKD, making it difficult to meet the speed requirements of modern secure communication. For example, the fastest QKD rate in free space is only 20-400 bits / s (Nature Photonics, Vol. 11, No. 8, pp. 509-513, 2017).

[0008] In key distribution based on very long fiber lasers (VLS), the fiber optic communication paths of the two communicating parties constitute the resonant cavity of the fiber laser. Each party independently and randomly changes the center wavelength of the reflectors at the ends of the paths. When both parties select the same center wavelength, the fiber laser outputs a signal corresponding to that wavelength. When the selected center wavelengths differ, the center wavelengths of the output signals are all at the mean wavelength. Eavesdroppers cannot definitively determine the center wavelength settings from the signal characteristics, while legitimate communicating parties can use the laser output to infer the other party's selection based on their own reflector choices, thus achieving secure key exchange. However, in such schemes, the laser signal needs to be repeatedly transmitted multiple times along the communication path to achieve 1-bit key distribution, significantly limiting the key distribution rate. For example, in 2014, British scholar A. El-Taher achieved secure key distribution at a rate of 100 bits / s using a Raman fiber laser with a distance of 500 km (Laser Photonics Reviews, vol. 8, no. 3, pp. 436-442, 2014).

[0009] In key distribution based on fiber optic channel reciprocity, the communicating parties share the same fiber optic link. The noise components introduced during the transmission of the optical signal are highly consistent, or certain parameters of the signal itself, such as signal amplitude, phase, and polarization state, are affected by the noise in the channel or the channel transmission characteristics, resulting in highly consistent random changes. The communicating parties can use the obtained highly correlated random signal as a physical entropy source, sample and quantize it to simultaneously extract a consistent random sequence from different locations as a shared key, thereby completing key distribution (Optics Express, Vol.21, No.20, pp.23756-23771, 2013; IEEE Photonics Technology Letters, Vol.30, No.8, pp.704-707, 2018; OpticsExpress, Vol.27, No.22, pp. 32096-32110, 2019). Subsequently, by adding a high-frequency perturbation device to the optical path, the limitation of the original bandwidth of the physical entropy source on the key generation rate was overcome, increasing the rate to Gbit / s (OpticsExpress, Vol.27, No.24, pp. 35761-33773, 2019; Journal of Lightwave Technology, Vol.39, No.6, pp.1595-1601, 2021; IEEE Photonics Technology Letters, Vol.33, No.6, pp.289-292, 2021; Optics Letters, Vol.46, No.23, pp.5910-5913, 2021). However, this scheme cannot maintain high reciprocity when transmitting over long distances of hundreds or even thousands of kilometers, and may even fail to complete the key distribution process.

[0010] Semiconductor lasers can generate broadband, high-amplitude, noise-like chaotic signals under external perturbations. Furthermore, two parameter-matched lasers can achieve chaotic synchronization under unidirectional injection, mutual coupling, and common signal driving conditions, thus generating highly correlated time series. In 2007, a scheme to generate random keys using chaotic signals as entropy sources was proposed, and in 2008, the first experimental realization of high-speed random key generation from chaotic laser signals was achieved. With the continuous advancement of research, it is now possible to generate random keys in real time at the Gbit / s level and offline at the Tbit / s level using chaotic lasers, a physical entropy source (Nature Photonics, Vol.2, No.12, pp.728-732, 2008; Optics Express, Vol.21, No.17, pp.20452-20462, 2013; IEEE Photonics Journal, Vol.9, No.2, pp. 7201412-1-7201412-13, 2017; Optics Letters, Vol.44, No.10, pp: 2446-2449, 2019).

[0011] Therefore, combining chaotic synchronization with the generation of random keys from chaotic signals holds promise for achieving key distribution based on chaotic synchronization. The communicating parties independently and randomly key their respective chaotic semiconductor lasers. When the keying conditions are the same, the resulting chaotic sequences are theoretically identical. Subsequently, both parties select the chaotic sequences with identical keying conditions as entropy sources, extract consistent random keys, and complete key distribution. Random keying of parameters adds physical layer security to this scheme. For example, in 2012, chaotic synchronization of semiconductor lasers was achieved using continuous light with fixed amplitude and random phase as the driving force, ultimately realizing key distribution at a rate of 64 kbit / s (Optics Express, Vol. 21, No. 15, pp.17869-17893, 2013). In 2017, this group achieved chaotic synchronization of photonic integrated semiconductor lasers using continuous light with fixed amplitude and random phase as the driving force, and ultimately achieved key distribution at a rate of 184 kbit / s (OpticsExpress, vol. 25, no. 21, pp. 26029-26044, 2017). However, semiconductor lasers experience synchronization recovery times of tens of nanoseconds during keying condition changes, i.e., switching between synchronization and desynchronization, which limits the key distribution rate of such schemes to the kbit / s range. Open-loop semiconductor lasers, on the other hand, have synchronization recovery times several orders of magnitude lower than open-loop structures (IEEE Journal of Quantum Electronics, Vol. 38, No. 9, pp. 197-1204, 2002), potentially increasing the key distribution rate by orders of magnitude.

[0012] In summary, existing key distribution schemes suffer from either poor security or low distribution rates. Therefore, it is necessary to invent a high-speed and secure key distribution technology to overcome the key security obstacle of high-speed key distribution in "one-time pad" absolutely secure communication. Summary of the Invention

[0013] To overcome the technical defects of existing key distribution schemes, such as poor security or low distribution rate, this invention provides a key distribution system and method for dynamic filtering of multimode lasers.

[0014] This invention discloses a key distribution system for dynamic filtering of a multimode laser, comprising a multimode laser, an isolator, a coupler, an Alice communication side, a Bob communication side, and a real-time digital oscilloscope;

[0015] The broadband signal generated by the multimode laser is unidirectionally input to the coupler after passing through the isolator and then split into two paths, which are transmitted to Alice and Bob respectively.

[0016] The Alice communication unit includes a first adjustable attenuator, a first polarization controller, a first wavelength division multiplexer (WDM), a second WDM, a first arbitrary waveform generator, and a first photodetector. One output signal of the coupler is sequentially input to the first WDM after passing through the first adjustable attenuator and the first polarization controller. The first WDM filters the injected signal and splits it into two beams with different center wavelengths. One of the two beams with different center wavelengths is sequentially processed by a first intensity modulator and a first DFB laser before being input to the second WDM. The other beam is sequentially processed by a second intensity modulator and a second DFB laser before being input to the second WDM. The first intensity modulator and the second intensity modulator are controlled by the two inverted binary codes output from the first arbitrary waveform generator to perform on / off keying of the two beams with different center wavelengths. The output signals of the first DFB laser and the second DFB laser are processed by the second WDM and combined into a single laser signal, which is then input to the first photodetector.

[0017] The Bob communication unit includes a second adjustable attenuator, a second polarization controller, a third wavelength division multiplexer (WDM), a fourth WDM, a second arbitrary waveform generator, and a second photodetector. The other output signal of the coupler passes sequentially through the second adjustable attenuator and the second polarization controller before being input to the third WDM. The third WDM filters the injected signal and splits it into two beams with different center wavelengths. One of these beams passes sequentially through a third intensity modulator and a third DFB laser before being input to the fourth WDM, while the other passes sequentially through a fourth intensity modulator and a fourth DFB laser before being input to the fourth WDM. The third and fourth intensity modulators, under the control of two inverted binary codes output from the second arbitrary waveform generator, respectively, perform on / off keying on the two beams with different center wavelengths. The output signals of the third and fourth DFB lasers are processed by the fourth WDM and combined into a single laser signal, which is then input to the second photodetector.

[0018] The output signals of the first and second photodetectors are both input to a real-time digital oscilloscope for data acquisition.

[0019] Finally, the data acquired by the real-time digital oscilloscope from Alice and Bob's communication partners is transmitted to the computer. The private key information of both parties is compared, and the multi-path parallel consistent random key generated when the private keys are the same is selected to complete the key distribution.

[0020] This invention also discloses a key distribution method for dynamic filtering of multimode lasers, which is implemented based on the key distribution system for dynamic filtering of multimode lasers described in this invention. The key distribution protocol is as follows: when the private keys of Alice and Bob are the same, the center wavelength of the multimode laser filtering mode is the same as the center wavelength of the first DFB laser and the center wavelength of the third DFB laser with effective perturbation, both being λ1. At this time, the first DFB laser with center wavelength λ1 and the third DFB laser with center wavelength λ1 output laser signals, which are used as physical entropy sources, from which the sequence X0…X is extracted. n The random key; or the center wavelength of the multimode laser filter mode is the same as the center wavelength of the second DFB laser and the center wavelength of the fourth DFB laser with effective perturbation, and both are λ2. At this time, the second DFB laser with a center wavelength of λ2 and the fourth DFB laser with a center wavelength of λ2 output laser signals, which are used as physical entropy sources, and the sequence Y0…Y is extracted from them. n The random key is not generated when Alice and Bob's private keys are different. The center wavelength of the multimode laser filter mode is different from the center wavelength of the first and third DFB lasers with effective perturbation, or the center wavelength of the multimode laser filter mode is different from the center wavelength of the second and fourth DFB lasers with effective perturbation. Therefore, Alice and Bob are out of sync and cannot generate a random key.

[0021] The key distribution system and method described in this invention avoids the limitation of synchronization recovery time in key distribution schemes based on chaotic synchronization, meeting the requirements of secure and high-speed key distribution for confidential communication. This invention employs open-loop structured first, second, third, and fourth DFB lasers as response lasers, achieving a synchronization recovery time on the order of ps, thus further improving the key distribution rate. Based on the fact that the center wavelengths of different modes of a multimode laser can correspond to the center wavelengths of different DFB lasers, and that the correlation between different modes of a multimode laser is very low, the multimode laser modes are filtered and injected into DFB lasers with corresponding center wavelengths to generate chaotic signals. Subsequently, the injected signals are keyed using a private key. When the private keys of both communicating parties are the same, the chaotic laser signals generated by DFB lasers with the same center wavelength can achieve synchronization; when the private keys of both parties are different, DFB lasers with different center wavelengths generate chaotic signals, making synchronization impossible.

[0022] Compared with existing technologies, the technical solution provided by this invention has the following technical advantages: First, the driving source of the multimode laser dynamic filtering key distribution system described in this invention is a multimode laser. Even if an eavesdropper obtains mode information from the public channel, the probability of the eavesdropper selecting the desired mode from dozens of modes and reconstructing synchronization is extremely low because the selection of the response laser is uniquely known to both communicating parties. This effectively enhances the security of key distribution. Furthermore, the key distribution system described in this invention can utilize more modes for random keying, increasing the complexity of the key distribution system and further enhancing its security. In addition, in the key distribution system described in this invention, both communicating parties use independent random private keys to key the injected signal. Even if an eavesdropper obtains the private key transmitted in the public channel, they cannot crack the key information, further increasing the security of key distribution. Second, the key distribution method described in this invention completes key distribution by comparing the private key information of both communicating parties and selecting consistent random keys generated when the private keys are the same. The open-loop DFB laser has a low synchronization recovery time, which can effectively improve the key distribution rate. In summary, the multimode laser dynamic filtering key distribution system described in this invention solves the problems of poor security and slow distribution rate of existing key distribution technologies, and provides a secure and high-speed key distribution scheme for absolutely secure confidential communication. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 This is a schematic diagram of the structure of a key distribution system for dynamic filtering of a multimode laser according to a certain embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the key distribution protocol described in a certain embodiment of the present invention.

[0027] In the diagram: 1. Multimode laser; 2. Isolator; 3. Coupler; 4a. First adjustable attenuator; 4b. Second adjustable attenuator; 5a. First polarization controller; 5b. Second polarization controller; 6a. First wavelength division multiplexer; 6b. Third wavelength division multiplexer; 7a. First intensity modulator; 7b. Third intensity modulator; 8a. Second intensity modulator; 8b. Fourth intensity modulator; 9a. First arbitrary waveform generator; 9b. Second arbitrary waveform generator; 10a. First DFB laser; 10b. Third DFB laser; 11a. Second DFB laser; 11b. Fourth DFB laser; 12a. Second wavelength division multiplexer; 12b. Fourth wavelength division multiplexer; 13a. First photodetector; 13b. Second photodetector; 14. Real-time digital oscilloscope. Detailed Implementation

[0028] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0029] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] In one embodiment, such as Figure 1 As shown, a key distribution system for dynamic filtering of a multimode laser is disclosed, including a multimode laser 1, an isolator 2, a coupler 3, an Alice communication side, a Bob communication side, and a real-time digital oscilloscope 14;

[0033] The broadband signal generated by the multimode laser 1 is input unidirectionally to the coupler 3 after passing through the isolator 2 and is then split into two paths and transmitted to Alice and Bob respectively.

[0034] The Alice communication unit includes a first adjustable attenuator 4a, a first polarization controller 5a, a first wavelength division multiplexer 6a, a second wavelength division multiplexer 12a, a first arbitrary waveform generator 9a, and a first photodetector 13a. One output signal of the coupler 3 is sequentially input to the first wavelength division multiplexer 6a via the first adjustable attenuator 4a and the first polarization controller 5a. The first wavelength division multiplexer 6a filters the injected signal and splits it into two beams with different center wavelengths. One of the two beams with different center wavelengths sequentially passes through a first intensity modulator 7a and a first DFB laser 10a. After processing, the signal is input to the second wavelength division multiplexer 12a. Another signal is processed by the second intensity modulator 8a and the second DFB laser 11a before being input to the second wavelength division multiplexer 12a. The first intensity modulator 7a and the second intensity modulator 8a control the two inverted binary codes output by the first arbitrary waveform generator 9a to switch the two signals with different center wavelengths. The output signals of the first DFB laser 10a and the second DFB laser 11a are processed by the second wavelength division multiplexer 12a and then combined into a single laser signal, which is input to the first photodetector 13a.

[0035] The Bob communication unit includes a second adjustable attenuator 4b, a second polarization controller 5b, a third wavelength division multiplexer 6b, a fourth wavelength division multiplexer 12b, a second arbitrary waveform generator 9b, and a second photodetector 13b. The other output signal of coupler 3 is sequentially input to the third wavelength division multiplexer 6b via the second adjustable attenuator 4b and the second polarization controller 5b. The third wavelength division multiplexer 6b filters the injected signal and splits it into two beams with different center wavelengths. One of these two beams sequentially passes through a third intensity modulator 7b and a third DFB laser 10b. After processing, the signal is input to the fourth wavelength division multiplexer 12b. Another signal is processed by the fourth intensity modulator 8b and the fourth DFB laser 11b before being input to the fourth wavelength division multiplexer 12b. The third intensity modulator 7b and the fourth intensity modulator 8b control the two inverted binary codes output by the second arbitrary waveform generator 9b to switch the two signals with different center wavelengths. The output signals of the third DFB laser 10b and the fourth DFB laser 11b are processed by the fourth wavelength division multiplexer 12b and then combined into a single laser signal, which is input to the second photodetector 13b.

[0036] The output signals of the first photodetector 13a and the second photodetector 13b are both input to the real-time digital oscilloscope 14 for data acquisition.

[0037] Finally, the data acquired by the real-time digital oscilloscope 14 from Alice and Bob's communication parties is transmitted to the computer. The private key information of the two parties is compared, and the multi-path parallel consistent random key generated when the private keys are the same is selected to complete the key distribution.

[0038] In one embodiment, such as Figure 2 As shown, a key distribution method for dynamic filtering of multimode lasers is also disclosed, which is implemented based on the key distribution system for dynamic filtering of multimode lasers described in this invention. The key distribution protocol is as follows: when the private keys of Alice and Bob are the same, the center wavelength of the filtering mode of multimode laser 1 is the same as the center wavelength of the first DFB laser 10a and the center wavelength of the third DFB laser 10b with effective perturbation, and both are λ1. At this time, the first DFB laser 10a with a center wavelength of λ1 and the third DFB laser 10b with a center wavelength of λ1 output laser signals, which are used as physical entropy sources, from which the sequence X0…X is extracted. n The random key; or the center wavelength of the multimode laser 1 filter mode is the same as the center wavelength of the second DFB laser 11a and the center wavelength of the fourth DFB laser 11b with effective perturbation, and both are λ2. At this time, the second DFB laser 11a with a center wavelength of λ2 and the fourth DFB laser 11b with a center wavelength of λ2 output laser signals, which are used as physical entropy sources, and the sequence Y0…Y is extracted from them. n The random key is not generated when Alice and Bob's private keys are different. The center wavelength of the multimode laser 1 filter mode is different from the center wavelength of the first DFB laser 10a and the center wavelength of the third DFB laser 10b with effective perturbation, or the center wavelength of the multimode laser 1 filter mode is different from the center wavelength of the second DFB laser 11a and the center wavelength of the fourth DFB laser 11b with effective perturbation. Therefore, Alice and Bob are out of sync and cannot generate a random key.

[0039] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A key distribution system for dynamic filtering of a multimode laser, characterized in that, It includes a multimode laser (1), an isolator (2), a coupler (3), an Alice communication unit, a Bob communication unit, and a real-time digital oscilloscope (14). The broadband signal generated by the multimode laser (1) is unidirectionally input to the coupler (3) through the isolator (2) and then split into two paths to be transmitted to Alice and Bob respectively. The Alice communication unit includes a first adjustable attenuator (4a), a first polarization controller (5a), a first wavelength division multiplexer (6a), a second wavelength division multiplexer (12a), a first arbitrary waveform generator (9a), and a first photodetector (13a). One output signal of the coupler (3) is sequentially input to the first wavelength division multiplexer (6a) via the first adjustable attenuator (4a) and the first polarization controller (5a). The first wavelength division multiplexer (6a) filters the injected signal and splits it into two beams with different center wavelengths. One of the two beams with different center wavelengths sequentially passes through a first intensity modulator (7a) and a first DFB laser (10a). a) After processing, the signal is input to the second wavelength division multiplexer (12a). The other signal is processed by the second intensity modulator (8a) and the second DFB laser (11a) and then input to the second wavelength division multiplexer (12a). The first intensity modulator (7a) and the second intensity modulator (8a) control the two inverted binary codes output by the first arbitrary waveform generator (9a) to control the two signals with different center wavelengths. The output signals of the first DFB laser (10a) and the second DFB laser (11a) are combined into a single laser signal after being processed by the second wavelength division multiplexer (12a) and input to the first photodetector (13a). The Bob communication unit includes a second adjustable attenuator (4b), a second polarization controller (5b), a third wavelength division multiplexer (6b), a fourth wavelength division multiplexer (12b), a second arbitrary waveform generator (9b), and a second photodetector (13b). The other output signal of the coupler (3) is sequentially input to the third wavelength division multiplexer (6b) through the second adjustable attenuator (4b) and the second polarization controller (5b). The third wavelength division multiplexer (6b) filters the injected signal and splits it into two beams with different center wavelengths. One of the two beams with different center wavelengths sequentially passes through the third intensity modulator (7b) and the third DFB laser (10b). After processing, the signal is input to the fourth wavelength division multiplexer (12b). Another signal is processed by the fourth intensity modulator (8b) and the fourth DFB laser (11b) before being input to the fourth wavelength division multiplexer (12b). The third intensity modulator (7b) and the fourth intensity modulator (8b) control the two inverted binary codes output by the second arbitrary waveform generator (9b) to turn on and off the two signals with different center wavelengths. The output signals of the third DFB laser (10b) and the fourth DFB laser (11b) are processed by the fourth wavelength division multiplexer (12b) and combined into a single laser signal, which is then input to the second photodetector (13b). The output signals of the first photodetector (13a) and the second photodetector (13b) are both input to a real-time digital oscilloscope (14) for data acquisition. Finally, the data collected by the real-time digital oscilloscope (14) from Alice and Bob are transmitted to the computer. The private key information of the two parties is compared. When the private keys are the same, the center wavelength of the multimode laser (1) filter mode is the same as the center wavelength of the first DFB laser (10a) and the center wavelength of the third DFB laser (10b) with effective perturbation, or the center wavelength of the multimode laser (1) filter mode is the same as the center wavelength of the second DFB laser (11a) and the center wavelength of the fourth DFB laser (11b) with effective perturbation, and the corresponding multi-path parallel consistent random key is generated to complete the key distribution.

2. A key distribution method for dynamic filtering of a multimode laser, characterized in that, This is implemented based on a key distribution system for dynamic filtering of a multimode laser as described in claim 1. The key distribution protocol is as follows: when the private keys of Alice and Bob are the same, the center wavelength of the filtering mode of the multimode laser (1) is the same as the center wavelength of the first DFB laser (10a) and the center wavelength of the third DFB laser (10b) with effective perturbation, and both are λ1. At this time, the first DFB laser (10a) with a center wavelength of λ1 and the third DFB laser (10b) with a center wavelength of λ1 output laser signals, which are used as physical entropy sources, and the sequence X0…X is extracted from them. n The random key; or the center wavelength of the multimode laser (1) filter mode is the same as the center wavelength of the second DFB laser (11a) and the center wavelength of the fourth DFB laser (11b) with effective perturbation, and both are λ2. At this time, the second DFB laser (11a) with a center wavelength of λ2 and the fourth DFB laser (11b) with a center wavelength of λ2 output laser signals, which are used as physical entropy sources, and the sequence Y0…Y is extracted from them. n The random key; when Alice and Bob have different private keys, the center wavelength of the multimode laser (1) filter mode is different from the center wavelength of the first DFB laser (10a) and the center wavelength of the third DFB laser (10b) with effective perturbation, or the center wavelength of the multimode laser (1) filter mode is different from the center wavelength of the second DFB laser (11a) and the center wavelength of the fourth DFB laser (11b) with effective perturbation. Therefore, Alice and Bob are out of sync and cannot generate a random key.

Images