Multiple security domain nondeducibility in cyber-physical systems

Cyber-physical Systems (CPS) present special problems for security. This dissertation examines the cyber security problem, the physical security problem, the security problems presented when cyber systems and physical systems are intertwined, and problems presented by the fact that CPS leak information simply by being observed. The issues presented by applying traditional cyber security to CPS are explored and some of the shortcomings of these models are noted. Specific models of a drive-by-wire\u27\u27 automobile connected to a road side assistance network, a Stuxnet type\u27\u27 attack, the smart grid, and others are presented in detail. The lack of good tools for CPS security is addressed in part by the introduction of a new model, Multiple Security Domains Nondeducibility over an Event System, or MSDND(ES). The drive-by-wire automobile is studied to show how MSDND(ES) is applied to a system that traditional security models do not describe well. The issue of human trust in inherently vulnerable CPS with embedded cyber monitors, is also explored. A Stuxnet type attack on a CPS is examined using both MSDND(ES) and Belief, Information acquisition, and Trust (BIT) logic to provide a clear and precise method to discuss issues of trust and belief in monitors and electronic reports. To show these techniques, the electrical smart grid as envisioned by the Future Renewable Electric Energy Delivery and Management Systems Center (FREEDM) project is also modeled. Areas that may lead to the development of additional tools are presented as possible future work to address the fact: CPS are different and require different models and tools to understand. --Abstract, page iii

Sécurité des réseaux et infrastructures critiques

Les infrastructures et réseaux critiques commencent à s'ouvrir vers des architectures, protocoles et applications vulnérables. Ainsi, non seulement il est question de sécuriser ces applications (e.g., contre les attaques potentielles), mais il faut également justifier notre confiance dans les mécanismes de sécurité déployés. Pour cela, nous présentons PolyOrBAC, un cadriciel basé sur le modèle de contrôle d'accès OrBAC, les mécanismes de services Web ainsi que les contrats électroniques. Ensuite, nous préconisons l'utilisation de la Programmation Logique par Contraintes (PLC) pour détecter et résoudre les conflits éventuels dans la politique de sécurité. Au niveau de la mise en œuvre, nous proposons le protocole Q-ESP, notre amélioration d'IPSec qui assure à la fois des besoins de sécurité et de QoS. Enfin, nous présentons nos modèles et résultats de test et d'évaluation d'outils de sécurité notamment les Systèmes de Détection d'Intrusions (IDS)

Guess my vote : a study of opacity and information flow in voting systems

With an overall theme of information flow, this thesis has two main strands. In the first part of the thesis, I review existing information flow properties, highlighting a recent definition known as opacity [25]. Intuitively, a predicate cP is opaque if for every run in which cP is true, there exists an indistinguishable run in which it is false, where a run can be regarded as a sequence of events. Hence, the observer is never able to establish the truth of cPo The predicate cP can be defined according to requirements of the system, giving opacity a great deal of flexibility and versatility. Opacity is then studied in relation to several well-known definitions for information flow. As will be shown, several of these properties can be cast as variations of opacity, while others have a relationship by implication with the opacity property [139]. This demonstrates the flexibility of opacity, at the same time establishing its distinct character. In the second part of the thesis, I investigate information flow in voting systems. Pret a Voter [36] is the main exemplar, and is compared to other schemes in the case study. I first analyse information flow in Pret a Voter and the FOO scheme [59], concentrating on the core protocols. The aim is to investigate the security requirements of each scheme, and the extent to which they can be captured using opacity. I then discuss a systems-based analysis of Pret a Voter [163], which adapts and extends an earlier analysis of the Chaum [35] and Neff [131]' [132]' [133] schemes in [92]. Although this analysis has identified several potential vulnerabilities, it cannot be regarded as systematic, and a more rigorous approach may be necessary. It is possible that a combination of the information flow and systems- based analyses might be the answer. The analysis of coercion-resistance, which is performed on Pret a Voter and the FOO scheme, may exemplify this more systematic approach. Receipt-freeness usually means that the voter is unable to construct a proof of her vote. Coercion-resistance is a stronger property in that it accounts for the possibility of interaction between the coercer and the voter during protocol execution. It appears that the opacity property is ideally suited to expressing the requirements for coercion-resistance in each scheme. A formal definition of receipt-freeness cast as a variation of opacity is proposed [138], together with suggestions on how it might be reinforced to capture coercion-resistance. In total, the thesis demonstrates the remarkable flexibility of opacity, both in expressing differing security requirements and as a tool for security analysis. This work lays the groundwork for future enhancement of the opacity framework.EThOS - Electronic Theses Online ServiceDSTL : EPSRCGBUnited Kingdo