【作者】 周敏；

【导师】 王云才；

【作者基本信息】 广东工业大学 ， 通信工程（专业学位）， 2023， 硕士

【摘要】 香农的“一次一密”保密通信方案要求合法的通信双方在每次进行信息传输时都使用新产生的随机密钥对信息进行加密和解密处理,生成的密钥序列长度要大于信息的长度,且不会重复使用。因此,如何实现安全高速的密钥分发是当前保密通信面临的关键问题。半导体激光器在受到外部反馈或注入的影响时,会产生复杂而随机的混沌信号（此时的半导体激光器称为混沌激光器）,两个相同的混沌激光器在弱耦合下可实现混沌同步,利用混沌同步可实现密钥分发。但是,在现有的基于混沌同步的密钥分发方案中,研究者多利用注入锁定来实现同步,这样,外部的驱动信号和混沌激光器的输出混沌信号存在着的强相关,窃听者可以从公共信道直接量化驱动信息获取部分密钥,从而降低密钥分发的安全性。同时,受限于激光器的弛豫振荡频率,混沌信号带宽较低,导致生成的密钥速率不能满足高速保密通信的需要。本文的具体工作如下:（1）提出了一种基于非线性模块增强共驱混沌同步密钥分发系统安全性的方案。通过引入非线性硬件变换模块,对响应激光器的输出进行非线性变换,降低驱动与响应信号之间的相关性,进而保障密钥分发的安全性,并以马赫-曾德尔干涉仪（MZI）作为非线性变换模块为例进行了实验验证。利用MZI的延迟干涉效应实现对同步激光器输出信号的非线性变换,将驱动和响应信号的相关性从0.49降低至0.15。通过对MZI输出的时序波形进行模数变换和双阈值量化,实现了100 km的光纤传输,速率为0.23Gbit/s,误码率低于3.8×10^-3的密钥分发。实验结果证明:在基于混沌同步的密钥分发方案中,引入非线性变换模块可以有效防止非法用户直接量化驱动信号窃取密钥,避免信息的泄露,实现合法用户的安全密钥分发。（2）提出了基于混沌自载波延时相位调制产生宽带混沌,实现高速密钥分发的方案。利用VPI photonics仿真软件建立混沌自载波延时相位调制模型进行仿真,对比分析了混沌带宽展宽前后的混沌特征,通过分析系统的可调参数,产生了有效带宽为19.77GHz的混沌信号,并搭建了实验系统,实验实现0.93的高质量混沌同步,为提高密钥的分发速率提供一种可能。更多还原

【Abstract】 In Shannon’s“one-time pad”theory,a secure communication system demands that legitimate users encrypt and decrypt information with freshly generated random keys.The length of the generated key sequence ought to surpass the length of the information,and it should not be used repeatedly.Hence,a major challenge for secure communication system is how to accomplish secure and high-speed key distribution.Semiconductor lasers are excellent as a light source for key distribution and may generate complex and random chaotic signals when influenced by outside feedback or injection.It’s attainable to get synchronization between two identical chaotic lasers with weak coupling.However,there is a strong correlation between the driving signal and the chaotic output signal under the strong laser injection condition.Finally,this weakens the security of key distribution because eavesdroppers can directly quantify the driving source from the public channel to obtain a part of the key.At the same time,the current chaotic bandwidth is low due to the laser’s relaxation oscillation frequency,which leads to a key generation rate that is insufficient for the existing optical communication system.This thesis offers a resolution to these issues by offering experimental verification,namely the following work:(1)In this thesis,we propose and experimentally demonstrate a secure key distribution scheme based on a nonlinear transformation module to enhance the protection efficiency of chaos synchronization-based secure key distribution.After being driven by the broadband optical noise signals,the response lasers between transceivers will enter the state of common-signal-induced synchronization and then generate two chaotic signals injected into the respective Mach-Zehnder interferometer(MZI),and successively,the nonlinear transformation module.Thereinto,the chaotic signal is subjected to a nonlinear delayed interference by the MZI to eliminate the residual correlation in intensity between the driving and response signal.Finally,it reduced the correlation between driving and response signals from 0.49 to 0.15.Therefore,the correlation between the above two signals is reduced and the security of key distribution can be greatly improved.Subsequently,after the accomplishment of high-quality chaos synchronization,the final keys were generated by sampling and quantizing the chaotic waveforms from MZI utilizing the dual-threshold method.A proof experiment for secure key distribution at the rate of 0.23 Gb/s through100-km fiber transmission is implemented.The experimental results prove that the introduction of the nonlinear transform module in the chaos synchronization-based key distribution scheme can effectively prevent illegal users from stealing keys by directly quantizing the drive signal,avoiding information leakage and realizing secure key distribution for legitimate users.(2)We propose a scheme based on chaos self-carrier delayed-phase modulation to generate broadband chaos as an entropy source for high-speed key distribution.To simulate chaos self-carrier delayed-phase modulation model,we employ the commercial optical simulation software VPI photonics and compare and analyze the chaos characteristics.With an effective bandwidth of 19.77 GHz,high-quality chaotic synchronization is achieved by looking into the system’s adjustable parameters.Additionally,based on the simulation,a basic experimental verification system is established,resulting in a high-quality chaotic synchronization of 0.93 and providing the potential to increase the key distribution rate.更多还原