3,202 research outputs found
A lightweight code analysis and its role in evaluation of a dependability case
A dependability case is an explicit, end-to-end argument, based on concrete evidence, that a system satisfies a critical property. We report on a case study constructing a dependability case for the control software of a medical device. The key novelty of our approach is a lightweight code analysis that generates a list of side conditions that correspond to assumptions to be discharged about the code and the environment in which it executes. This represents an unconventional trade-off between, at one extreme, more ambitious analyses that attempt to discharge all conditions automatically (but which cannot even in principle handle environmental assumptions), and at the other, flow- or context-insensitive analyses that require more user involvement. The results of the analysis suggested a variety of ways in which the dependability of the system might be improved.National Science Foundation (U.S.). (Deep and Scalable Analysis of Software) (Grant number 0541183)National Science Foundation (U.S.). Division of Computer and Network Systems (CRI: CRD – Development of Alloy Tools, Technology and Materials) (Grant number 0707612
ANCHOR: logically-centralized security for Software-Defined Networks
While the centralization of SDN brought advantages such as a faster pace of
innovation, it also disrupted some of the natural defenses of traditional
architectures against different threats. The literature on SDN has mostly been
concerned with the functional side, despite some specific works concerning
non-functional properties like 'security' or 'dependability'. Though addressing
the latter in an ad-hoc, piecemeal way, may work, it will most likely lead to
efficiency and effectiveness problems. We claim that the enforcement of
non-functional properties as a pillar of SDN robustness calls for a systemic
approach. As a general concept, we propose ANCHOR, a subsystem architecture
that promotes the logical centralization of non-functional properties. To show
the effectiveness of the concept, we focus on 'security' in this paper: we
identify the current security gaps in SDNs and we populate the architecture
middleware with the appropriate security mechanisms, in a global and consistent
manner. Essential security mechanisms provided by anchor include reliable
entropy and resilient pseudo-random generators, and protocols for secure
registration and association of SDN devices. We claim and justify in the paper
that centralizing such mechanisms is key for their effectiveness, by allowing
us to: define and enforce global policies for those properties; reduce the
complexity of controllers and forwarding devices; ensure higher levels of
robustness for critical services; foster interoperability of the non-functional
property enforcement mechanisms; and promote the security and resilience of the
architecture itself. We discuss design and implementation aspects, and we prove
and evaluate our algorithms and mechanisms, including the formalisation of the
main protocols and the verification of their core security properties using the
Tamarin prover.Comment: 42 pages, 4 figures, 3 tables, 5 algorithms, 139 reference
Toward a Dependability Case Language and Workflow for a Radiation Therapy System
We present a near-future research agenda for bringing a suite of modern programming-languages verification tools - specifically interactive theorem proving, solver-aided languages, and formally defined domain-specific languages - to the development of a specific safety-critical system, a radiotherapy medical device. We sketch how we believe recent programming-languages research advances can merge with existing best practices for safety-critical systems to increase system assurance and developer productivity. We motivate hypotheses central to our agenda: That we should start with a single specific system and that we need to integrate a variety of complementary verification and synthesis tools into system development
Modeling and Testing a Family of Surgical Robots: An Experience Report
Safety-critical applications often use dependability cases to validate that specified properties are invariant, or to demonstrate a counter example showing how that property might be violated. However, most dependability cases are written with a single product in mind. At the same time, software product lines (families of related software products) have been studied with the goal of modeling variability and commonality, and building family based techniques for both analysis and testing. However, there has been little work on building an end to end dependability case for a software product line (where a property is modeled, a counter example is found and then validated as a true positive via testing), and none that we know of in an emerging safety-critical domain, that of robotic surgery. In this paper, we study a family of surgical robots, that combine hardware and software, and are highly configurable, representing over 1300 unique robots. At the same time, they are considered safety-critical and should have associated dependability cases. We perform a case study to understand how we can bring together lightweight formal analysis, feature modeling, and testing to provide an end to end pipeline to find potential violations of important safety properties. In the process, we learned that there are some interesting and open challenges for the research community, which if solved will lead towards more dependable safety-critical cyber-physical systems
FRIENDS - A flexible architecture for implementing fault tolerant and secure distributed applications
FRIENDS is a software-based architecture for implementing fault-tolerant and, to some extent, secure applications. This architecture is composed of sub-systems and libraries of metaobjects. Transparency and separation of concerns is provided not only to the application programmer but also to the programmers implementing metaobjects for fault tolerance, secure communication and distribution. Common services required for implementing metaobjects are provided by the sub-systems. Metaobjects are implemented using object-oriented techniques and can be reused and customised according to the application needs, the operational environment and its related fault assumptions. Flexibility is increased by a recursive use of metaobjects. Examples and experiments are also described
Dependability Metrics : Research Workshop Proceedings
Justifying reliance in computer systems is based on some form of evidence about such systems. This in turn implies the existence of scientific techniques to derive such evidence from given systems or predict such evidence of systems. In a general sense, these techniques imply a form of measurement. The workshop Dependability Metrics'', which was held on November 10, 2008, at the University of Mannheim, dealt with all aspects of measuring dependability
Atomic-SDN: Is Synchronous Flooding the Solution to Software-Defined Networking in IoT?
The adoption of Software Defined Networking (SDN) within traditional networks
has provided operators the ability to manage diverse resources and easily
reconfigure networks as requirements change. Recent research has extended this
concept to IEEE 802.15.4 low-power wireless networks, which form a key
component of the Internet of Things (IoT). However, the multiple traffic
patterns necessary for SDN control makes it difficult to apply this approach to
these highly challenging environments. This paper presents Atomic-SDN, a highly
reliable and low-latency solution for SDN in low-power wireless. Atomic-SDN
introduces a novel Synchronous Flooding (SF) architecture capable of
dynamically configuring SF protocols to satisfy complex SDN control
requirements, and draws from the authors' previous experiences in the IEEE EWSN
Dependability Competition: where SF solutions have consistently outperformed
other entries. Using this approach, Atomic-SDN presents considerable
performance gains over other SDN implementations for low-power IoT networks. We
evaluate Atomic-SDN through simulation and experimentation, and show how
utilizing SF techniques provides latency and reliability guarantees to SDN
control operations as the local mesh scales. We compare Atomic-SDN against
other SDN implementations based on the IEEE 802.15.4 network stack, and
establish that Atomic-SDN improves SDN control by orders-of-magnitude across
latency, reliability, and energy-efficiency metrics
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