Cybersecurity is of vital importance to industrial control systems (ICSs), such as ship automation, manufacturing, building, and energy automation systems. Many control applications require hard real-time channels, where the delay and jitter are in the levels of milliseconds or less. To the best of our knowledge, no encryption algorithm is fast enough for hard real-time channels of existing industrial fieldbuses and, therefore, made mission-critical applications vulnerable to cyberattacks, e.g., delay and data injection attacks. In this article, we propose a novel recursive watermark (RWM) algorithm for hard real-time control system data integrity validation. Using a watermark key, a transmitter applies watermark noise to hard real-time signals and sends through the unencrypted hard real-time channel. The same key is transferred to the receiver by the encrypted nonreal-time channel. With the same key, the receiver can detect if the data have been modified by the attackers and take action to prevent catastrophic damages. We provide analysis and methods to design proper watermark keys to ensure reliable attack detection. We use a ship propulsion control system for the simulation-based case study, where our algorithm smoothly shuts down the system after attacks. We also evaluated the algorithm speed on a Siemens S7-1500 programmable logic controller (PLC). This hardware experiment demonstrated that the RWM algorithm takes about 2.8 μs to add or validate the watermark noise on one sample data point. As a comparison, common cryptic hashing algorithms can hardly process a small data set under 100 ms. The proposed RWM is about 32 to 1375 times faster than the standard approaches.

中文翻译：

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一种增强硬实时工业控制系统网络弹性的递归水印方法


网络安全对于船舶自动化、制造、建筑和能源自动化系统等工业控制系统 (ICS) 至关重要。许多控制应用需要硬实时通道，其中延迟和抖动为毫秒级或更短。据我们所知，没有一种加密算法对于现有工业现场总线的硬实时通道来说足够快，因此，使得关键任务应用程序容易受到网络攻击，例如延迟和数据注入攻击。在本文中，我们提出了一种新颖的递归水印（RWM）算法，用于硬实时控制系统数据完整性验证。使用水印密钥，发射机将水印噪声应用于硬实时信号，并通过未加密的硬实时通道发送。相同的密钥通过加密的非实时通道传输到接收方。使用相同的密钥，接收者可以检测数据是否已被攻击者修改，并采取措施防止灾难性损害。我们提供分析和方法来设计适当的水印密钥，以确保可靠的攻击检测。我们使用船舶推进控制系统进行基于模拟的案例研究，我们的算法在受到攻击后顺利关闭系统。我们还评估了西门子 S7-1500 可编程逻辑控制器 (PLC) 上的算法速度。这一硬件实验表明，RWM 算法大约需要 2.8 μs 来在一个样本数据点上添加或验证水印噪声。相比之下，常见的加密哈希算法很难处理 100 毫秒以下的小数据集。所提出的 RWM 比标准方法快约 32 至 1375 倍。