Designing Normative Theories for Ethical and Legal Reasoning: LogiKEy Framework, Methodology, and Tool Support

A framework and methodology---termed LogiKEy---for the design and engineering of ethical reasoners, normative theories and deontic logics is presented. The overall motivation is the development of suitable means for the control and governance of intelligent autonomous systems. LogiKEy's unifying formal framework is based on semantical embeddings of deontic logics, logic combinations and ethico-legal domain theories in expressive classic higher-order logic (HOL). This meta-logical approach enables the provision of powerful tool support in LogiKEy: off-the-shelf theorem provers and model finders for HOL are assisting the LogiKEy designer of ethical intelligent agents to flexibly experiment with underlying logics and their combinations, with ethico-legal domain theories, and with concrete examples---all at the same time. Continuous improvements of these off-the-shelf provers, without further ado, leverage the reasoning performance in LogiKEy. Case studies, in which the LogiKEy framework and methodology has been applied and tested, give evidence that HOL's undecidability often does not hinder efficient experimentation.Comment: 50 pages; 10 figure

A proof calculus for attack trees in Isabelle

Attack trees are an important modeling formalism to identify and quantify attacks on security and privacy. They are very useful as a tool to understand step by step the ways through a system graph that lead to the violation of security policies. In this paper, we present how attacks can be refined based on the violation of a policy. To that end we provide a formal definition of attack trees in Isabelle’s Higher Order Logic: a proof calculus that defines how to refine sequences of attack steps into a valid attack. We use a notion of Kripke semantics as formal foundation that then allows to express attack goals using branching time temporal logic CTL. We illustrate the use of the mechanized Isabelle framework on the example of a privacy attack to an IoT healthcare system

Isabelle Modelchecking for insider threats

The Isabelle Insider framework formalises the technique of social explanation for modeling and analysing Insider threats in infrastructures including physical and logical aspects. However, the abstract Isabelle models need some refinement to provide sufficient detail to explore attacks constructively and understand how the attacker proceeds. The introduction of mutable states into the model leads us to use the concepts of Modelchecking within Isabelle. Isabelle can simply accommodate classical CTL type Modelchecking. We integrate CTL Modelchecking into the Isabelle Insider framework. A running example of an IoT attack on privacy motivates the method throughout and illustrates how the enhanced framework fully supports realistic modeling and analysis of IoT Insiders

Isabelle Modelchecking for insider threats

The Isabelle Insider framework formalises the technique of social explanation for modeling and analysing Insider threats in infrastructures including physical and logical aspects. However, the abstract Isabelle models need some refinement to provide sufficient detail to explore attacks constructively and understand how the attacker proceeds. The introduction of mutable states into the model leads us to use the concepts of Modelchecking within Isabelle. Isabelle can simply accommodate classical CTL type Modelchecking. We integrate CTL Modelchecking into the Isabelle Insider framework. A running example of an IoT attack on privacy motivates the method throughout and illustrates how the enhanced framework fully supports realistic modeling and analysis of IoT Insiders

Isabelle Modelchecking for insider threats

The Isabelle Insider framework formalises the technique of social explanation for modeling and analysing Insider threats in infrastructures including physical and logical aspects. However, the abstract Isabelle models need some refinement to provide sufficient detail to explore attacks constructively and understand how the attacker proceeds. The introduction of mutable states into the model leads us to use the concepts of Modelchecking within Isabelle. Isabelle can simply accommodate classical CTL type Modelchecking. We integrate CTL Modelchecking into the Isabelle Insider framework. A running example of an IoT attack on privacy motivates the method throughout and illustrates how the enhanced framework fully supports realistic modeling and analysis of IoT Insiders

Formal modeling and analysis with humans in infrastructures for IoT health care systems

In this paper, we integrate previously developed formal methods to model infrastructure, actors, and policies of human centric infrastructures in order to analyze security and privacy properties. A fruitful approach for discovering attacks on human centric infrastructure models is invalidation of global policies. Invalidating global policies by a complete exploration of the state space can be realized by modelchecking. To counter the state explosion problem inherent in modelchecking, Higher Order Logic (HOL) supported by the interactive theorem prover Isabelle can be used to emulate modelchecking. In addition, the Isabelle Insider framework supports modeling and analysis of human centric infrastructures including attack trees. In this paper, we investigate how Isabelle modelchecking might help to improve detection of attack traces and re-finement of attack tree analysis. To this end, we use a case study from security and privacy of IoT devices in the health care sector as proposed in the CHIST-ERA project SUCCESS