Contract-Based Blame Assignment by Trace Analysis

Fault diagnosis in networked systems has been an extensively studied field in systems engineering. Fault diagnosis generally includes the tasks of fault detection and isolation, and optionally recovery (FDIR). In this paper we further consider the blame assignment problem: given a system trace on which a system failure occurred and an identified set of faulty components, determine which subsets of faulty components are the culprits for the system failure. We provide formal definitions of the notion culprits and the blame assignment problem, under the assumptions that only one system trace is given and the system cannot be rerun. We show that the problem is equivalent to deciding the unsatisfiability of a set of logical constraints on component behaviors, and present the transformation from a blame assignment instance into an instance of unsatisfiability checking. We also apply the approach to a case study in the medical device interoperability scenario that has motivated our work

CIS400/401 Project Proposal Specification [Put your project title here]

The purpose of this document is three-fold. First, it describes the requirements of the project proposal. Second, it presents this information in a style your proposal should mimic. Third, by viewing the *.tex ‘code behind’, some basic LATEX technique can be learned. Do not feel compelled to completely follow our style – but do use it as a guide. Like this ‘report’, your proposal is expected to have an abstract. An abstract is a two-paragraph maximum executive summary of your work. It should briefly outline your problem statement and its (expected) contributions. 1

Process of designing robust, dependable, safe and secure software for medical devices: Point of care testing device as a case study

This article has been made available through the Brunel Open Access Publishing Fund.Copyright © 2013 Sivanesan Tulasidas et al. This paper presents a holistic methodology for the design of medical device software, which encompasses of a new way of eliciting requirements, system design process, security design guideline, cloud architecture design, combinatorial testing process and agile project management. The paper uses point of care diagnostics as a case study where the software and hardware must be robust, reliable to provide accurate diagnosis of diseases. As software and software intensive systems are becoming increasingly complex, the impact of failures can lead to significant property damage, or damage to the environment. Within the medical diagnostic device software domain such failures can result in misdiagnosis leading to clinical complications and in some cases death. Software faults can arise due to the interaction among the software, the hardware, third party software and the operating environment. Unanticipated environmental changes and latent coding errors lead to operation faults despite of the fact that usually a significant effort has been expended in the design, verification and validation of the software system. It is becoming increasingly more apparent that one needs to adopt different approaches, which will guarantee that a complex software system meets all safety, security, and reliability requirements, in addition to complying with standards such as IEC 62304. There are many initiatives taken to develop safety and security critical systems, at different development phases and in different contexts, ranging from infrastructure design to device design. Different approaches are implemented to design error free software for safety critical systems. By adopting the strategies and processes presented in this paper one can overcome the challenges in developing error free software for medical devices (or safety critical systems).Brunel Open Access Publishing Fund

Fault Ascription in Concurrent Systems

Fault diagnosis is becoming increasingly important and difficult with the growing pervasiveness and complexity of computer systems. We propose in this paper a general semantic framework for fault ascription, a precise form of fault diagnosis that relies on counterfactual analysis for identifying necessary and sufficient causes of faults in component-based systems. Our framework relies on configuration structures to handle concurrent systems, partial and distributed observations in a uniform way. It defines basic conditions for a counterfactual analysis of necessary and sufficient causes, and it presents a refined analysis that conforms to our basic conditions while avoiding various infelicities

Program Actions as Actual Causes: A Building Block for Accountability

Abstract-Protocols for tasks such as authentication, electronic voting, and secure multiparty computation ensure desirable security properties if agents follow their prescribed programs. However, if some agents deviate from their prescribed programs and a security property is violated, it is important to hold agents accountable by determining which deviations actually caused the violation. Motivated by these applications, we initiate a formal study of program actions as actual causes. Specifically, we define in an interacting program model what it means for a set of program actions to be an actual cause of a violation. We present a sound technique for establishing program actions as actual causes. We demonstrate the value of this formalism in two ways. First, we prove that violations of a specific class of safety properties always have an actual cause. Thus, our definition applies to relevant security properties. Second, we provide a cause analysis of a representative protocol designed to address weaknesses in the current public key certification infrastructure