Adaptable Security in Wireless Sensor Networks by Using Reconfigurable ECC Hardware Coprocessors

Specific features of Wireless Sensor Networks (WSNs) like the open accessibility to nodes, or the easy observability of radio communications, lead to severe security challenges. The application of traditional security schemes on sensor nodes is limited due to the restricted computation capability, low-power availability, and the inherent low data rate. In order to avoid dependencies on a compromised level of security, a WSN node with a microcontroller and a Field Programmable Gate Array (FPGA) is used along this work to implement a state-of-the art solution based on ECC (Elliptic Curve Cryptography). In this paper it is described how the reconfiguration possibilities of the system can be used to adapt ECC parameters in order to increase or reduce the security level depending on the application scenario or the energy budget. Two setups have been created to compare the software- and hardware-supported approaches. According to the results, the FPGA-based ECC implementation requires three orders of magnitude less energy, compared with a low power microcontroller implementation, even considering the power consumption overhead introduced by the hardware reconfiguratio

Water isotopes in desiccating lichens

The stable isotopic composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in non-vascular, poikilohydric organisms such as lichens and bryophytes. To understand basic isotope exchange processes of non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrate with the isotopic composition of surrounding water vapour. A model was developed as a proof of concept that accounts for the specific water relations of these poikilohydric organisms. The approach incorporates first their variable thallus water potential and second a compartmentation of the thallus water into two isotopically distinct but connected water pools. Moreover, the results represent first steps towards the development of poikilohydric organisms as a recorder of ambient vapour isotopic composition

How to Keep Track of Your Network Configuration

In this paper we present extensions for the Ined network editor allowing us to discover the structure of an IP network automatically. The discovering algorithm is based on an active probing technique that fits well with our interactive editor. We have chosen a multithreaded approach to minimize response times which seems reasonable in fast networks but may fail when run over slow serial links. A set of utilities have been designed to lay out the discovered network based on additional information found in the Domain Name System. Introduction Maps showing the network configuration are very important documents for a variety of tasks. This motivated us to design and implement a domain specific editor called Ined that is specialized for drawing and maintaining network maps [7]. Ined provides all necessary editing features to draw and maintain network maps. Maps may be composed of node, network and link objects. Link objects represent connections between two node objects or a node and a n..

Load Balancing and Fault Tolerance in Workstation Clusters Migrating Groups of Communicating Processes

In the past, several process migration facilities for distributed systems have been developed. Due to the complex nature of the subject, all those facilities have limitations that make them usable for only limited classes of applications and environments. We discuss some of the usual limitations and possible solutions. Specifically, we focus on migration of groups of collaborating processes between Unix systems without kernel modifications, and from this we derive the design for a migration system. First experiences with our implementation show that we reach performance figures for the migration that are close to those of real distributed operating system

An Application Independent Network Editor

This paper presents an application independent network editor called Ined which can be used for network documentation tasks and as a graphical user interface for network management applications. We will discuss the requirements that motivated the design of Ined and we will introduce the interface which allows applications to use Ined as a graphical user interface. 1 Introduction The decentralization of computing resources has resulted in very complex networks which have become an increasingly important factor for the success of many enterprises. This is due to the fact that the likelihood and costs associated with faults or performance inefficiencies increase with the scale and complexity of a network. Planning and maintaining large scale complex networked systems requires a set of tools that assist network designers, operators and users. A central document is the network map, which describes the network structure and how nodes and subnetworks are connected. Such maps form the basis f..

Multiple Authentications With a Nonce-Based Protocol Using Generalized Timestamps

The Kerberos authentication service, a part of MIT's Project Athena, is based on the Needham and Schroeder protocol. Timestamps depending on reliable synchronized clocks are used to guarantee the freshness of messages. As an improvement, we present a nonce-based protocol offering the same features as Kerberos. We generate a ticket in an initial message exchange which includes a generalized timestamp. Checking this generalized timestamp is left to the principal who created it. Consequently we do not need synchronized clocks. Our protocol has the property of using a minimal number of messages to establish an authenticated session key. Keywords: Security, Authentication, Kerberos 1 Introduction In computer networks and distributed computing systems a mechanism is needed to provide secure communication. To trust the identity of each other, two principals must run a procedure resulting in mutual authentication. Key distribution protocols establish secret authenticated session keys using c..

Pomsets for message sequence charts

Message sequence charts (MSCs) are a standardised formalismfor the specification of the system’s communication behaviour that is widely used by industry. Various extensions to MSCs have recently been standardised by the ITU. This paper treats the extension of MSCs with structural operators that allow the hierarchical composition of MSCs. In particular, we propose a linear-time partial-order semantics for this extension that is based on the notion of partial-order multi-sets (pomsets, for short). We provide a compositional denotational semantics for hierarchical MSCs and show that well-known operations on pomsets correspond to the new composition operators in MSCs. The main benefit of our approach is that the semantics is conceptually rather straightforward, as opposed to the operational semantics for MSCs that is currently in the process of standardisation