CIF: Small: Alignment for Secrecy: One-Time-Pads in the Air without Keys

在当今的通信网络中，大多数数据都是通过无线链路传输的，这特别容易受到窃听攻击。虽然目前可用的加密算法提供了有用的保护，以防止计算有限的窃听者，但对手不断增长的计算能力需要提供更强形式的安全保证的技术。信息论物理层安全提供了无条件的安全保证，即使面对计算无限的对手也是有效的。本研究的目标是推进信息论物理层安全，以解决由用户不当行为、用户利益冲突、缺乏完整的网络状态信息引起的实际问题；并设计出切实可行的代码。在信息论物理层安全技术在多用户无线信道中的应用中，对齐作为实现网络最大可能安全自由度的有力工具而出现。以安全为目的的最佳对齐可以被解释为一种无需显式交换密钥的空中一次性pad通信形式；安全性是从物理通道的随机性和用户的合作意愿中引导出来的。本研究的目标是开发技术，使这种安全对齐方案对用户不当行为和缺乏通道状态信息更加健壮；通过与极性编码的连接来开发明确的代码更实用；并且更广泛地适用于现代多天线节点无线网络。具体来说，本研究调查了以下情况：1)偏离用户，他们不遵循商定的最佳协议；2)打击利益冲突的帮助者和自私的使用者；3)使用多天线产生的矢量信道和相关的信道状态信息问题；4)利用极性码进行显式编码设计，并与极性对准和信号对准相关。

In today's communication networks, most data flow through wireless links which are particularly vulnerable to eavesdropping attacks. While currently available cryptographic algorithms provide useful protection against computationally limited eavesdroppers, the ever-increasing computational power of adversaries necessitates techniques that provide stronger forms of security guarantees. Information-theoretic physical layer security provides unconditional security guarantees that are valid even against computationally unlimited adversaries. The goal of this research is to advance information-theoretic physical layer security to address practical issues arising from user misbehavior, conflicting user interests, lack of complete network state information; and to devise practically implementable codes.In the application of information-theoretic physical layer security to multi-user wireless channels, alignment emerges as a powerful tool to achieve the maximum possible secure degrees of freedom for the network. Optimal alignment for the purposes of security may be interpreted as a form of one-time-pad communication in the air with no need for explicit exchange of keys; security is bootstrapped from the randomness in the physical channel and from the willingness of the users to cooperate. The goal of this research is to develop techniques to make such secure alignment schemes more robust to user misbehavior and to the lack of channel state information; more practical by making connections to polar coding to develop explicit codes; and more widely applicable to modern wireless networks with multi-antenna nodes. Specifically, this research investigates the cases of 1) deviating users who do not follow agreed-upon optimum protocols; 2) combating helpers and selfish users who have conflicting interests; 3) vector channels arising from use of multiple antennas and the associated channel state information issues; and 4) explicit code design using polar codes and relating polar alignment and signal alignment.