通信安全是现代社会的一项重要需求。量子通信是一种实现安全通信的新型 独特方式，其安全性依赖于量子物理原理。有量子密钥分发和量子安全直接通信 两种模式，其中的量子密钥分发协议能够通过密钥协商实现合法通信方之间密钥 的安全共享，结合经典加密-解密信道来实现量子通信。量子安全直接通信能够在 无需提前分配密钥的情况下直接在量子信道中传输保密信息，从而实现量子通信。 量子安全直接通信协议提出之后，在理论协议发展的同时，实验也得到了长足的 发展，量子安全直接通信两步方案和单光子 DL04 协议的实验验证已经在光纤系 统与量子存储光学平台上实现，并且全功能的量子安全直接通信原理性样机也已 经完成。实际量子通信系统中，测量设备存在一定缺陷，其带来的安全漏洞将威胁 实际量子通信系统的安全性。量子安全直接通信在向实用化方向发展过程中，不 可避免地会遇到实际测量设备不完美性带来的安全威胁，相关问题亟待解决。 本论文针对实用化量子安全直接通信面临的实际测量设备缺陷造成的安全漏 洞问题，结合量子安全直接通信的特点，提出了测量设备无关量子安全直接通信 （MDI-QSDC）协议，解决了由于测量设备缺陷造成的安全漏洞。论文的主要创新 成果包括： 1. 提出了基于纠缠态的测量设备无关两步量子安全直接通信（MDI-TS）理论 协议，消除了所有和测量设备相关的漏洞与所有相关侧信道，增强了实用化量子 安全直接通信系统的安全性。协议由于使用了密集编码而具有较高的通信容量。 2. 完成了 MDI-QSDC 协议的安全性分析，针对基于纠缠的 MDI-TS 协议和基 于单光子的 MDI-DL04 协议，利用 Csiszár ? Körner 理论证明了两个协议的安全性， 并导出了协议的安全容量下界。MDI-QSDC 协议相较于量子安全直接通信协议牺 牲了部分安全容量换取实用化条件下的安全性，但其具有将量子安全直接通信通 信距离扩展至两倍的能力。 3. 提出了测量设备无关量子对话协议，利用 MDI-TS 协议的对称性对其进行 了推广，实现了无密钥的双向量子安全直接通信。此外，协议本身也可通过协商过 程生成密钥，利用密钥可实现通信双方的同时性消息解码。测量设备无关量子对 话协议赋予了实用化量子安全直接通信系统双向通信能力，增强了其组网灵活性。
Confidential communication is indispensable to modern society. Quantum communication provides a distinct new way for that, whose security is ensured by quantum principles. There are two kinds of manners in quantum communication, which are quantum key distribution and quantum secure direct communication (QSDC). The quantum key distribution can make two legal users share a key securely through the key agreement, and the quantum communication is completed by combining classical encryption-decryption channel. QSDC can transmit secure information directly in quantum channel without distributing secure key in advance, hence achieve the quantum communication. Along with the development of theoretical research, prove-of-principle experiments of entanglement based two-step QSDC and single photon based DL04 protocol have been achieved in the optical fiber system and quantum memory optical platform since the first QSDC protocol was proposed, and the full function QSDC prototype has also been completed. Measurement devices in the practical quantum communication system have defects that can lead to security loopholes, and threaten the security of practical quantum communication systems. In the practical application of QSDC, security threat from imperfect measurement devices is unavoidable, and demands prompt solutions. In order to solve the problem of security loopholes that originate from defects of measurement devices in the practical QSDC system, considering the features of QSDC, a measurement-device-independent quantum secure direct communication (MDI-QSDC) protocol is proposed in this thesis. It addresses the security vulnerabilities from defects of measurement devices. The major innovation achievements in this thesis including: 1. An entanglement based measurement-device-independent two-step quantum secure direct communication (MDI-TS) protocol is proposed, which eliminates all loopholes related to measurement devices and all relevant side channels. It strengthens the security of practical QSDC systems, and has a high communication capacity due to dense coding. 2. Security analysis of MDI-QSDC protocol is completed in this thesis. Utilizing Csiszár?Körner theory, security of two MDI-QSDC protocols, entanglement based MDITS protocol and single photon based MDI-DL04 protocol, is proven and the lower bound of secrecy capacity of each protocol is derived, respectively. Compared with QSDC, MDI-QSDC has a slight decrease in secrecy capacity at the price of enhancing the security. However, MDI-QSDC can double the transmission distance of QSDC. 3. An MDI quantum dialogue protocol is proposed in this thesis by generalizing MDI-TS protocol with its symmetry, and achieving a bidirectional QSDC without encryption. Besides, a key is also available through an agreement process in this protocol, and two legitimate users can decode messages simultaneously with that key. MDI quantum dialogue protocol enables bidirectional communication in practical QSDC systems, and enhances its flexibility in networking.
