CIF: Small: Causal Secrecy-A Theoretical Basis for Secrecy of Signals

近几十年来，通信技术在日常生活、商业、政府、工业和社会互动中发挥了核心作用。技术不仅可以让世界各地的人们相互交流，还可以让机器自动互动-处理互联网搜索查询、管理仓库库存、预报恶劣天气、更新计算机软件，以及控制复杂的系统，如发电站网络。因此，对安全通信的需求也相应增加。目前，技术是围绕这样的概念设计的，即安全或私人通信信号必须对外部世界不可见，除非安全受到损害。这与好莱坞的绝密对话是通过一条“安全线路”进行的形象相吻合。然而，在机器相互传输重要信息信号的许多新兴应用中，成本较低的隐私类型就足够了-一种只会扭曲任何无意窃听者的信号视图，以至于他们无法使用信息扰乱系统的类型。这项研究涉及对信号保密性的数学分析。研究人员得出了保护信号通信的基本最低要求。本研究利用信息论为使用密钥和物理层安全的信号保密提供了理论基础。然而，这项工作在许多方面不同于以前的理论工作。一个关键的区别是，基于抽象或无形数学量的保密度量被省略了。取而代之的是，根据对手能够对从系统收集的信息做什么来评估保密性。这项研究是理论和广泛的，但结果的新颖性为应用密码学带来了新的见解。

Communication technologies have taken a central role in daily life, business, government, industry, and social interactions over recent decades. Technology is used not only to allow people to communicate with each other from across the world but to allow machines to interact automatically---processing internet search queries, managing warehouse inventory, forecasting severe weather, updating computer software, and controlling complex systems such as a network of electric power stations. The need for secure communication has increased accordingly. Currently, technology is designed around the concept that a secure or private communication signal must be invisible to the outside world unless the security is compromised. This matches the Hollywood image of a top-secret classified conversation taking place over a "secure line." However, in many emerging applications where machines transmit important information signals to each other, a less expensive type of privacy is adequate---one that simply distorts the view of the signal for any unintended eavesdroppers to the point where they cannot use the information to disrupt the system. This research involves a mathematical analysis of the secrecy of signals. The investigators derive fundamental minimum requirements to protect the communication of signals.This research uses information theory to provide a theoretical foundation for secrecy of signals, using secret keys and physical layer security. However, this work differs from previous theoretical work in a number of ways. One key difference is that metrics for secrecy based on abstract or intangible mathematical quantities are omitted. Instead, secrecy is evaluated based on what an adversary would be able to do with information gleaned from the system. This research is theoretical and broad, yet the novelty of the results bring new insights to applied cryptography.