基于混沌同步公共信道特征的高速密钥安全分发探索

The essence of secure communication is to solve the difficulty of secure key distribution. With the enhancement of the computing capacity, the existing symmetric encryption and public-key encryption mechanisms based on algorithms are suffered from severe challenges. Quantum key distribution has made important progress, but it still needs to solve some difficulties such as transmission distances and generation rates.. In this project, we propose a high-speed key distribution scheme based on physical layer by combining the idea of key distribution utilizing related noise channel characteristics proposed by professor Csiszár et al. who won the Claude E. Shannon award and the advances in chaos synchronization. A zero-lag chaos synchronization is established between two external-cavity optical feedback chaotic semiconductor lasers which have similar structures and parameters, and the noise-like chaotic signals of the two lasers are highly related and have identical characteristics of noise channel. Then the shared keys can be extracted from the noise-like chaotic signals using the technology of photo-switch keying, and an error correction to the keys is implemented through information reconciliation. An eavesdropper cannot accurately record ultrafast relaxation oscillation with a bandwidth of dozens of GHz for chaotic laser, i.e., the bounded observability. This results in that the channel noise of eavesdropper is much larger than that of legitimate users. Consequently, the leakage of secret keys is limited, and the secure and high-speed key distribution with a long transmission distance can be achieved.. Our research will provide an idea of high-speed key distribution based on physical layer enriching the existing key distribution schemes.

保密通信的实质是解决密钥安全分发的难题。随着计算能力的不断提高，现在基于算法的对称密码体制和公钥密码体制均受到严峻挑战；量子密钥分发已取得重要进展，但还存在传输距离短、生成码率低等技术难题。.融合香农奖获得者Csiszár教授等人提出的利用具有相关性的噪声信道特征实现密钥分发的思想和混沌同步的研究进展，我们提出一种基于物理层的高速密钥分发方案：两个结构参数相近的外腔光反馈混沌半导体激光器之间实现零延时混沌同步，双方输出的类噪声混沌信号具有高度相关性及一致的噪声信道特征；利用光开关键控技术从类噪声混沌提取共享密钥，并通过信息协商对密钥进行纠错。由于窃听者无法准确记录混沌激光器带宽高达数十GHz的超快弛豫震荡，存在“观察局限”，致使其信道噪声远远高于合法用户的信道噪声，从而限制了密钥的泄漏，最终实现长距离的高速密钥安全分发。.本研究将提供一个基于物理层的高速密钥分发思路，丰富现有密钥分发方案。

“一次一密”是绝对安全的保密通信，它的实现需要（1）能够快速产生大量的随机密钥；（2）能够实现密钥的秘密分发。目前，高速密钥的产生已经取得重要进展，而安全的高速密钥分发则成为最后一个技术障碍。研究发现，半导体激光器在外部扰动下可产生宽带混沌激光，其输出光强具有大幅度随机起伏特征，可用于产生Gbps量级的高速物理密钥；此外，参数匹配的激光器可实现混沌同步，产生高度相似的混沌波形。因此，利用混沌激光作为物理熵源，并结合混沌同步，有望实现高速物理密钥分发。.我们按照原定计划开展研究，取得了预期成果。利用啁啾光纤光栅（CFBG）构建了外腔反馈混沌半导体激光器，产生了高复杂度的无周期混沌激光。以混沌激光为熵源，结合多位采样量化，提取了160Gbps高速随机密钥。利用CFBG反馈混沌半导体激光器共同驱动DFB激光器、宽带噪声源SLD共同驱动FP激光器实现了同步系数大于0.9的高质量混沌同步。基于CFBG反馈混沌半导体激光器共驱混沌同步，实验提取了2.5Gbps的相关随机数；基于CFBG色散键控混沌同步，理论验证了1.2Gbps的密钥分发；基于FP激光器模式键控混沌同步，实验实现了200km，0.75Gbps的点对点密钥分发。.项目执行过程中，发表期刊论文34篇、会议论文2篇；授权国家发明专利12件；获教育部技术发明二等奖1项、山西省技术发明一等奖1项、中国专利优秀奖1项、山西省优秀硕士学位论文奖1项，第二届全国光子技术论坛优秀口头报告奖1项；举办国内会议1次；参加学术会议44人次；培养博士研究生2人、硕士研究生11人。.本项目利用经典技术，探索出一种基于物理层的高速密钥安全分发的实现方案，为实现“一次一密”绝对安全的保密通信提供了基础，同时促进了混沌理论及应用研究的发展。