CyPhyCrypt: Advanced Crypto for New and Next-Generation Cyber-Physical Systems

我们被越来越多的网络物理系统（CPS）所包围，例如电子收费、交通管理系统、智能家居或智能电网。这种演变为用户和整个社会带来了许多好处，但也带来了系统安全和用户隐私方面的严重风险。正如已经公开的许多攻击所证明的那样，例如，针对智能计量或电子运输支付的攻击，保护CPS是一项非平凡的任务。此外，用户的隐私往往被忽视，这可能会对欧洲广泛接受此类系统造成重大障碍。有趣的是，理论密码学的世界提供了一个大型的高级协议工具箱（除了单纯的加密和签名算法），其特性对于保护下一代CPS非常有吸引力。不幸的是，这些协议在应用于CPS上下文中有几个缺点，例如效率低或缺少功能，从而阻止了现成的使用。尽管如此，由于强大且可证明的安全性和隐私保证，从高级加密构建CPS安全解决方案似乎非常有吸引力。我们相信，至少在一定程度上，通过仔细地重新设计、扩展和组合这些构建块，这是可能的。事实上，我们在这一领域的第一个成果，即基于匿名凭证和电子现金建立高效的过境支付系统，支持了这一假设。因此，该项目的主要目标是开发一个适合保护CPS的高级加密组件工具箱。为此，我们将举例研究两类重要的CPS的技术和非技术要求，即参与式传感（PPS）和车辆-2-电网（V2G），其中我们的主要重点是PPS方案。在此基础上，将评估有前途的高级加密协议实例（如匿名凭证、电子现金、声誉和公平交换协议）的适用性。这将导致（重新）设计特定的组件，以满足特殊的要求。一个重要的目标是开发这些高级协议的更轻量级的实例，以便它们变得实用，以及具有增强功能的组件（例如，保护隐私的数据挖掘功能）。作为另一个重要的贡献，基于我们的工具箱将组成一个完整的PPS概念验证安全方案，从而显示其适用性。除了构建之外，还包括对该组合的安全性证明，其在移动目标平台和后端上的安全高效实现，以及小规模原型的建立。为了应对这些挑战，需要纯密码学和应用密码学的跨学科努力。相比之下，大多数先前的工作处理孤立的CPS安全方面，使用启发式安全技术或基本加密，并且缺乏正式的安全证明。

We are surrounded by an ever-growing number of cyber-physical systems (CPS), such as electronic toll collection, traffic management systems, smart homes or the smart grid. This evolution offers many benefits for users and the society at large, but also comes with serious risks with respect to system security and user privacy. As demonstrated by the numerous attacks that have become public, e.g., targeting smart metering or electronic transportation payments, securing CPS is a non-trivial task. Also, the privacy of users is often neglected, which can impose a major roadblock for the broad acceptance of such systems in Europe.Interestingly, the world of theoretical cryptography offers a large toolbox of advanced protocols (besides mere encryption and signature algorithms) with features that are extremely attractive for protecting next-generation CPS. Unfortunately, these protocols have several shortcomings when applied ina CPS context, such as poor efficiency or missing functionality, preventing an off-the-shelf use. Nevertheless, it seems highly attractive to build CPS security solutions from advanced crypto due to the strong and provable security and privacy guarantees. We believe that this is possible, at least to a certain extent, by carefully re-designing, extending, and composing these building blocks. Indeed, our first results in this field, where we build efficient transit payment systems based on anonymous credentials and electronic cash, support this hypothesis.Hence, the main goal of this project is to develop a toolbox of advanced crypto components suitable for securing CPS. To this end, we will exemplarily study the technical and non-technical requirements of two important classes of CPS, namely Participatory Sensing (PPS) and Vehicle-2-Grid (V2G), where our main focus will be the PPS scenario. Based on this, the suitability of promising instances of advanced crypto protocols such as anonymous credentials, e-cash, reputation, and fair-exchange protocols will be assessed. This will lead to the (re-)design of particular components with the goal to match special requirements. One important goal will be the development of more lightweight instances of these advanced protocols so that they become practical, as well as components with enhanced functionality (e.g., privacy-preserving datamining capabilities). As another important contribution, a complete proof-of-concept security scheme for PPS will be composed based on our toolbox, thereby showing its suitability. Besides the construction, this includes a proof of security for the composition, its secure and efficient implementation on the mobile target platforms and the backend, and the setup of a small-scale prototype. To cope with these challenges requires an interdisciplinary effort of pure and applied cryptography. In contrast, most previous work dealt with isolated CPS security aspects, uses heuristic security techniques or basic crypto, and lacks formal security proofs.