Program

The track provides a forum for scientists and engineers in academia and industry to present and discuss their latest research findings on selected topics in dependable, adaptive and trustworthy distributed systems and services. The topics of particular interest include, but are not limited to:

Accepted Papers

• ICE - Self-Configuration of Information Processing in Heterogeneous Agent Teams
  Stefan Niemczyk, Stephan Opfer, Nugroho Fredivianus and Kurt Geihs

  Teams of agents, solving complex tasks in dynamic environments, require high-quality information about the current situation. One way of achieving high-quality information is reliable information processing, that is suitable for the application domain. However, the characteristics of some domains such as disaster scenarios are partially unknown at design-time. Therefore, specifying information processing at design-time becomes nearly impossible and leads to unreliable information. We tackle this problem with the ICE middleware which supports adaptive information processing for teams of autonomous agents. It provides a decentralized self-configuration and dynamic integration of information sources. A configuration is created with respect to required information, available sources, and resource constraints. Our evaluation shows that ICE is sufficiently efficient to be operated in highly dynamic domains.

• Performance trade-offs on a secure multi-party relational database
  Rogério Pontes, Mário Pinto, Manuel Barbosa, Ricardo Vilaça, Miguel Matos and Rui Oliveira

  The privacy of information is an increasing concern of software applications users. This concern was caused by attacks to cloud services over the last few years, that have leaked confidential information such as passwords, emails and even private pictures. Once the information is leaked, the users and software applications are powerless to contain the spread of information and its misuse. With databases as a central component of applications that store almost all of their data, they are one of the most common targets of attacks. However, typical deployments of databases do not leverage security mechanisms to stop attacks and do not apply cryptographic schemes to protect data. This issue has been tackled by multiple secure databases that provide trade-offs between security, query capabilities and performance. Despite providing stronger security guarantees, the proposed solutions still entrust their data to a single entity that can be corrupted or hacked. Secret sharing can solve this problem by dividing data in multiple secrets and storing each secret at a different location. The division is done in such a way that if one location is hacked, no information can be leaked. Depending on the protocols used to divide data, functions can be computed over this data through secure protocols that do not disclose information or actually know which values are being calculated. We propose a SQL database prototype capable of offering a trade-off between security and query latency by using a different secure protocol. An evaluation of the protocols is also performed, showing that our most relaxed protocol has an improvement of 5% on the query latency time over the original protocol.

• Deconstructing Source Location Privacy-aware Routing Protocols
  Arshad Jhumka and Matthew Bradbury

  Source location privacy (SLP) is becoming an important property for a large class of security-critical wireless sensor network applications such as monitoring and tracking. Much of the previous work on SLP have focused on the development of various protocols to enhance the level of SLP imparted to the network, under various attacker models and other conditions. Others works have focused on analysing the level of SLP being imparted by a specific protocol. In this paper, we focus on deconstructing routing-based SLP protocols to enable a better understanding of their structure. We argue that the SLP-aware routing protocols can be classified into two main categories, namely (i) spatial and (ii) temporal. Based on this, we show that there are three important components, namely (i) decoy selection, (ii) use and routing of control messages and (iii) use and routing of decoy messages. The decoy selection technique imparts the spatial or temporal property of SLP-aware routing. We show the viability of the framework through the construction of well-known SLP-aware routing protocols using the identified components.

• Choreographing Cyber-Physical Distributed Control Systems for the Energy Sector
  Hugo A. López and Kai Heussen

  Energy Systems are facing a significant change in the way their management and control is conceived. With the introduction of distributed and renewable energy based resources, a shift to a more distributed operation paradigm is emerging, overturning the conventional top-down design and operation principles. This shift creates a demand for distributed control systems (DCS) to facilitate a more adaptive and efficient operation of power networks. One key challenge here is to ensure the required reliability of distributed control systems. Whereas proven strategies exist for reliable control for coordination of physical actions, with increasing distribution of such control, the reliability and degradation properties in response to communications issues become more important. We build on the notion of Quality Choreographies, a formal model for the development of failure-aware distributed systems, and discuss how quality choreographies respond to the needs presented by DCS. We demonstrate their applicability by modelling the Bully Algorithm, one of the de-facto election algorithms used in coordination of DCS.

• Evidence-Based Security Configurations for Cloud Datastores
  Frank Pallas, David Bermbach, Steffen Müller and Stefan Tai

  Cloud systems offer a diversity of security mechanisms with potentially complex configuration options. So far, security engineering has focused on achievable security levels, but not on the costs associated with a specific security mechanism and its configuration. Through a series of experiments with a variety of cloud datastores conducted over the last years, we gained substantial knowledge on how one desired quality like security can have a significant impact on other system qualities like performance. In this paper, we report on select findings related to security-performance trade-offs for three prominent cloud datastores, focusing on data in transit encryption, and propose a simple, structured approach for making trade-off decisions based on factual evidence gained through experimentation. Our approach allows to rationally reason about security trade-offs.

• Automatic Generation of Policies to Support Elastic Scaling in Cloud Environments
  Richard Gil Martinez, Antonia Lopes and Luis Rodrigues

  The problem of elastic scaling of resources in the cloud have been studied extensively due to its practical relevance. Planning strategic reconfiguration actions to guide the system to an acceptable state is a hard task, as the number of possible configurations options grows. Decision-making can be supported by expert-derived policies. However, even experts may fail to anticipate conditions that may arise at run-time and, hence, expert's know-how could be complemented with the use of intelligent tools. Automated planning presents itself as a promising solution to complex decision-making, when finding strategic plans over a multidimensional space is required. In this paper, we address the challenges of using automated planning for the generation of high-level policies, namely: representing the adaptation problem using a standard planning language, making proper use of planning tools to generate and select adequate adaptation plans, and incorporating mechanisms to scan the space of initial system conditions to feed the planner.

• Handling Bitcoin Conflicts Through a Glimpse of Structure
  Thibaut Lajoie-Mazenc, Romaric Ludinard and Emmanuelle Anceaume

  Double spending and blockchain forks are two main issues that the Bitcoin crypto-system is confronted with. The former refers to an adversary's ability to use the very same coin more than once while the latter reflects the occurrence of transient inconsistencies in the history of the blockchain distributed data structure. We present a new approach to tackle these issues: it consists in adding some local synchronization constraints on Bitcoin's validation operations, and in making these constraints independent from the native blockchain protocol. Synchronization constraints are handled by nodes which are randomly and dynamically chosen in the Bitcoin system. We show that with such an approach, content of the blockchain is consistent with all validated transactions and blocks which guarantees the absence of both double-spending attacks and blockchain forks.

Accepted Posters

Track Program Co-Chairs

Important Dates