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  • 1.
    Eldefrawy, Mohamed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Butun, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Pereira, Nuno
    Polytechnic of Porto (IPP), Porto, Portugal.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Formal security analysis of LoRaWAN2019In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 148, p. 328-339Article in journal (Refereed)
    Abstract [en]

    Recent Low Power Wide Area Networks (LPWAN) protocols are receiving increased attention from industry and academia to offer accessibility for Internet of Things (IoT) connected remote sensors and actuators. In this work, we present a formal study of LoRaWAN security, an increasingly popular technology, which defines the structure and operation of LPWAN networks based on the LoRa physical layer. There are previously known security vulnerabilities in LoRaWAN that lead to the proposal of several improvements, some already incorporated into the latest protocol specification. Our analysis of LoRaWAN security uses Scyther, a formal security analysis tool and focuses on the key exchange portion of versions 1.0 (released in 2015) and 1.1 (the latest, released in 2017). For version 1.0, which is still the most widely deployed version of LoRaWAN, we show that our formal model allowed to uncover weaknesses that can be related to previously reported vulnerabilities. Our model did not find weaknesses in the latest version of the protocol (v1.1), and we discuss what this means in practice for the security of LoRaWAN as well as important aspects of our model and tools employed that should be considered. The Scyther model developed provides realistic models for LoRaWAN v1.0 and v1.1 that can be used and extended to formally analyze, inspect, and explore the security features of the protocols. This, in turn, can clarify the methodology for achieving secrecy, integrity, and authentication for designers and developers interested in these LPWAN standards. We believe that our model and discussion of the protocols security properties are beneficial for both researchers and practitioners. To the best of our knowledge, this is the first work that presents a formal security analysis of LoRaWAN.

  • 2.
    Farag, Hossam
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Enabling Time- and Mission-Critical Applications in Industrial Wireless Sensor Networks2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nowadays, Wireless Sensor Networks (WSNs) have gained importance as aflexible, easier deployment/maintenance and cost-effective alternative to wired networks,e.g., Fieldbus and Wired-HART, in a wide-range of applications. Initially,WSNs were mostly designed for military and environmental monitoringapplications where energy efficiency is the main design goal. The nodes in the network were expected to have a long lifetime with minimum maintenance while providing best-effort data delivery which is acceptable in such scenarios. With recent advances in the industrial domain, WSNs have been subsequently extended to support industrial automation applications such as process automation and control scenarios. However, these emerging applications are characterized by stringent requirements regarding reliability and real-time communications that impose challenges in the design of Industrial Wireless Sensor Networks (IWSNs) to effectively support time- and mission-critical applications.

    Typically, time- and mission-critical applications support different traffic categories ranging from relaxed requirements, such as monitoring traffic to firm requirements, such as critical safety and emergency traffic. The critical traffic is mostly acyclic in nature and occasionally occurs at unpredictable time instants. Once it is generated, it must be delivered within strict deadlines. Exceeding the delay bound could lead to system instability, economic loss, or even endanger human life in the working area. The situation becomes even more challenging when an emergency event triggers multiple sensor nodes to transmit critical traffic to the controller simultaneously. The unpredictability of the arrival of such a type of traffic introduces difficulties with regard to making a suitable scheduling that guarantees data delivery within deadline bounds. Existing industrial standards and related research work have thus far not presented a satisfactory solution to the issue. Therefore, providing deterministic and timely delivery for critical traffic and its prioritization over regular traffic is a vital research topic.

    Motivated by the aforementioned challenges, this work aims to enable real-timecommunication for time- and mission-critical applications in IWSNs. In this context, improved Medium Access Control (MAC) protocols are proposed to enablea priority-based channel access that provides a timely delivery for acyclic critical traffic. The proposed framework starts with a stochastic modelling of the network delay performance under a priority-oriented transmission scheme, followed by two MAC approaches. The first approach proposes a random Clear Channel Assessment (CCA) mechanism to improve the transmission efficiency of acyclic control traffic that is generated occasionally as a result of observations of an established tendency, such as closed-loop supervisory traffic. A Discrete-Time Markov Chain (DTMC) model is provided to evaluate the performance of the proposed protocol analytically in terms of the expected delay and throughput. Numerical results show that the proposed random CCA mechanism improves the shared slots approach in WirelessHART in terms of delay and throughput along with better transmission reliability.

    The second approach introduces a slot-stealing MAC protocol based on a dynamic deadline-aware scheduling to provide deterministic channel access in emergency and event-based situations, where multiple sensor nodes are triggered simultaneously to transmit time-critical data to the controller. The proposed protocol is evaluated mathematically to provide the worst-case delay bound for the time-critical traffic and the numerical results show that the proposed approach outperforms TDMA-based WSNs in terms of delay and channel utilization.

  • 3.
    Gebremichael, Teklay
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Lightweight Cryptographic Group Key Management Protocols for the Internet of Things2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of Things (IoT) is increasingly becoming an integral component of many applications in consumer, industrial and other areas. Notions such as smart industry, smart transport, and smart world are, in large part, enabled by IoT. At its core, the IoT is underpinned by a group of devices, such as sensors and actuators, working collaboratively to provide a required service. One of the important requirements most IoT applications are expected to satisfy is ensuring the security and privacy of users. Security is an umbrella term that encompasses notions such as confidentiality, integrity and privacy, that are typically achieved using cryptographic encryption techniques.

    A special form of communication common in many IoT applications is group communication, where there are two or more recipients of a given message. In or-der to encrypt a message broadcast to a group, it is required that the participating parties agree on a group key a priori. Establishing and managing a group key in IoT environments, where devices are resources-constrained and groups are dynamic, is a non-trivial problem. The problem presents unique challenges with regard to con-structing protocols from lightweight and secure primitives commensurate with the resource-constrained nature of devices and maintaining security as devices dynamically leave or join a group.

    This thesis presents lightweight group key management protocols proposed to address the aforementioned problem, in a widely adopted model of a generic IoT network consisting of a gateway with reasonable computational power and a set of resource-constrained nodes. The aim of the group key management protocols is to enable the gateway and the set of resource-constrained devices to establish and manage a group key, which is then used to encrypt group messages. The main problems the protocols attempt to solve are establishing a group key among participating IoT devices in a secure and computationally feasible manner; enabling additionor removal of a device to the group in a security preserving manner; and enabling generation of a group session key in an efficient manner without re-running the protocol from scratch. The main challenge in designing such protocols is ensuring that the computations that a given IoT device performs as part of participating in the protocol are computationally feasible during initial group establishment, group keyupdate, and adding or removing a node from the group.

    The work presented in this thesis shows that the challenge can be overcome by designing protocols from lightweight cryptographic primitives. Specifically, protocols that exploit the lightweight nature of crypto-systems based on elliptic curves and the perfect secrecy of the One Time Pad (OTP) are presented. The protocols are designed in such a way that a resource-constrained member node performs a constant number of computationally easy computations during all stages of the group key management process.

    To demonstrate that the protocols are practically feasible, implementation resultof one of the protocols is also presented, showing that the protocol outperforms similar state-of-the-art protocols with regard to energy consumption, execution time, memory usage and number of messages generated.

  • 4.
    Gebremichael, Teklay
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Lightweight IoT Group Key Establishment Scheme from the One Time PadManuscript (preprint) (Other academic)
    Abstract [en]

    Secure group communication in the Internet ofThings (IoT) entails the establishment and management of oneor more group keys to provide group security services such asconfidentiality of group messages. The main challenges in estab-lishing a group key consist in designing a group key establishmentscheme that is feasible for nodes with limited computationalcapabilities. In this paper, we propose a lightweight group keyestablishment scheme based on fast symmetric-key encryption.We show a mechanism for designing a lightweight and secure IoTgroup key establishment and management scheme whose securityis underpinned by the perfect secrecy provided by the One-time-pad. We then argue that the scheme is convenient for IoT groupapplications where nodes are resource-constrained. We prove thatour scheme is secure under a threat model where the attackerhas sufficiently large computational power. We also prove thatthe scheme provides desired group security properties such asconfidentiality, key secrecy and independent group session keysgeneration.

  • 5.
    Grimaldi, Simone
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Real-time Interference Identification via Supervised Learning: Embedding Coexistence Awareness in IoT Devices2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 835-850Article in journal (Refereed)
    Abstract [en]

    Energy sampling-based interference detection and identification (IDI) methods collide with the limitations of commercial off-the-shelf (COTS) IoT hardware. Moreover, long sensing times, complexity and inability to track concurrent interference strongly inhibit their applicability in most IoT deployments. Motivated by the increasing need for on-device IDI for wireless coexistence, we develop a lightweight and efficient method targeting interference identification already at the level of single interference bursts. Our method exploits real-time extraction of envelope and model-aided spectral features, specifically designed considering the physical properties of signals captured with COTS hardware. We adopt manifold supervised-learning (SL) classifiers ensuring suitable performance and complexity trade-off for IoT platforms with different computational capabilities. The proposed IDI method is capable of real-time identification of IEEE 802.11b/g/n, 802.15.4, 802.15.1 and Bluetooth Low Energy wireless standards, enabling isolation and extraction of standard-specific traffic statistics even in the case of heavy concurrent interference. We perform an experimental study in real environments with heterogeneous interference scenarios, showing 90%–97% burst identification accuracy. Meanwhile, the lightweight SL methods, running online on wireless sensor networks-COTS hardware, ensure sub-ms identification time and limited performance gap from machine-learning approaches.

  • 6.
    Karlsson, Karl-Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    New public management i arkivredovisning: Om Riksarkivets kommunikation kring verksamhetsbaserad arkivredovisning2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Uppsatsen är en kritisk diskursanalys av Riksarkivets kommunikation kring verksamhetsbaserad arkivredovisning utifrån informationen på riksarkivets hemsida, och med ett särskilt fokus på förekomsten av spår av New Public Management. Huvudmaterialet består av Riksarkivets FAQ, och som sidomaterial används även Riksarkivets allmänna föreskrifter.

    Utifrån analytiska begrepp som transitivitet, modalitet, intertextualitet med flera analyseras materialet för att komma fram till slutsatsen att Riksarkivets kommunikation inte innehåller några problematiska mängder spår av New Public Management, och uppsatsen skriver in sig i arkiv- och informationsvetenskapen genom att anknyta till det första steget som tas vid införande av verksamhetsbaserad arkivredovisning.

  • 7.
    Kim, Young-bin
    et al.
    KDDI Research, Inc., Saitama, Japan.
    Kang, Myung Gil
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Choi, Wan
    Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
    On-off Switched Interference Alignment for Diversity Multiplexing Tradeoff Improvement in the 2-User X-Network with Two Antennas2019In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 18, no 1, p. 546-558Article in journal (Refereed)
    Abstract [en]

    To improve diversity gain in an interference channel and hence to maximize diversity multiplexing tradeoff (DMT), we propose on-off switched interference alignment (IA) where IA is intermittently utilized by switching IA on/off. For on-off switching, either IA with symbol extension or IA with Alamouti coding is adopted in this paper. Deriving and analyzing DMT of the proposed schemes, we reveal that the intermittent utilization of IA with simultaneous non-unique decoding can improve DMT in the 2-user X-channel with two antennas. Both the proposed schemes are shown to achieve diversity gain of 4 and DoF per user of 4/3 . In particular, the on-off switched IA with Alamouti coding, to the best of our knowledge, surpasses any other existing schemes for the 2-user X-channel with two antennas and nearly approaches the ideal DMT. 

  • 8.
    Klett, Elisabeth
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Theory, regulation and practice in Swedish digital records appraisal2019In: Records Management Journal, ISSN 0956-5698, E-ISSN 1758-7689Article in journal (Refereed)
    Abstract [en]

    Purpose

    Digital records appraisal and aspects of archival values in theory, regularization and practice are explored. This paper aims to reflect upon the appraisal process, responsibility and norms for value creation in a digitalized environment. The research question was how do appraisal theory, normative rules and appraisal practice meet the aims of values in digital archives?

    Design/methodology/approach

    The study triangulated appraisal theory, normative values and participants’ views about archival values in appraisal practice in a Swedish setting. Content analysis were used to explore normative documents and interviews. Appraisal theories of the Swedish Nils Nilsson and the Canadian Terry Cook were interpreted. The result was related to theories on public values, the nature of responsibility and relations between the state and citizens.

    Findings

    The results show influences between theory, norms and practice. Changes in norms and practice do not follow the development of digitalization. Responsibility is focused on tasks, which exposes risks of accountability control and knowledge of appraisal grounds. The paper concludes that access requirements and user needs may prompt change in appraisal processes. In the light of digitalization, “primary and secondary value” are merely a matter of use and usability in a time and space (continuum) perspective.

    Research limitations/implications

    This study is based in Sweden where extensive right of access to public records and default preservation are norm.

    Originality/value

    The result shows how allocated responsibilities impinge on a re-active digital appraisal process.

  • 9.
    Mahmood, Aamir
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Hossain, M. M. Aftab
    KTH Royal Institute of Technology, Sweden.
    Cavdar, Cicek
    KTH Royal Institute of Technology, Sweden.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Energy-Reliability Aware Link Optimization for Battery-Powered IoT Devices with Non-Ideal Power Amplifiers2019In: IEEE Internet of Things Journal, ISSN 2327-4662Article in journal (Refereed)
    Abstract [en]

    In this paper, we study cross-layer optimization of low-power wireless links for reliability-aware applications while considering both the constraints and the non-ideal characteristics of the hardware in Internet-of-things (IoT) devices. Specifically, we define an energy consumption (EC) model that captures the energy cost—of transceiver circuitry, power amplifier, packet error statistics, packet overhead, etc.—in delivering a useful data bit. We derive the EC models for an ideal and two realistic non-linear power amplifier models. To incorporate packet error statistics, we develop a simple, in the form of elementary functions, and accurate closed-form packet error rate (PER) approximation in Rayleigh block-fading. Using the EC models, we derive energy optimal yet reliability and hardware compliant conditions for limiting unconstrained optimal signal-to-noise ratio (SNR), and payload size. Together with these conditions, we develop a semi-analytic algorithm for resource-constrained IoT devices to jointly optimize parameters on physical (modulation size, SNR) and medium access control (payload size and the number of retransmissions) layers in relation to link distance. Our results show that despite reliability constraints, the common notion—higher-order M-ary modulations (MQAM) are energy optimal for short-range communication—prevails, and can provide up to 180% lifetime extension as compared to often used OQPSK modulation in IoT devices. However, the reliability constraints reduce both their range and the energy efficiency, while non-ideal traditional PA reduces the range further by 50% and diminishes the energy gains unless a better PA is used.

  • 10.
    Nikonowicz, Jakub
    et al.
    Poznań University of Technology, Poland.
    Mahmood, Aamir
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Sisinni, Emiliano
    University of Brescia, Italy.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Noise Power Estimators in ISM Radio Environments: Performance Comparison and Enhancement Using a Novel Samples Separation Technique2019In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 68, no 1, p. 105-115Article in journal (Refereed)
    Abstract [en]

    Noise power estimation is central to efficient radio resource allocation in modern wireless communication systems. In the literature, there exist many noise power estimation methods that can be classified based on underlying theoretical principle; the most common are spectral averaging, eigenvalues of sample covariance matrix, information theory, and statistical signal analysis. However, how these estimation methods compare against each other in terms of accuracy, stability, and complexity is not well studied, and the focus instead remains on the enhancement of individual methods. In this paper, we adopt a common simulation methodology to perform a detailed performance evaluation of the prominent estimation techniques. The basis of our comparison is the signal-to-noise ratio estimation in the simulated industrial, scientific and medical band transmission, while the reference noise signal is acquired from an industrial production plant using a software-defined radio platform, USRP-2932. In addition, we analyze the impact of different techniques for noise-samples' separation on the estimation process. As a response to defects in the existing techniques, we propose a novel noise-samples' separation algorithm based on the adaptation of rank-order filtering. Our analysis shows that the proposed solution, apart from its low complexity, has a very good root-mean-squared error of 0.5 dB and smaller than 0.1-dB resolution, thus  achieving a performance comparable with the methods exploiting information theory concepts.

  • 11.
    zadmirzaei, Majid
    et al.
    University of Guilan.
    Mohammadi Limaei, Solieman
    University of Guilan.
    Amirteimoori, Alireza
    Olsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Measuring the relative performance of forest management units: A chance-constrained DEA model in the presence of the non-discretionary factor2019In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037Article in journal (Refereed)
    Abstract [en]

    In this study, we develop a marginal chance-constrained data envelopment analysis model in the presence of non-discretionary inputs and hybrid outputs for the first time. We call it a stochastic non-discretionary DEA model (SND-DEA), and it is developed to measure and compare the relative efficiency of forest management units under different environmental management systems. Furthermore, we apply an output-oriented DEA technology to both deterministic and stochastic scenarios. The required data are collected from 24 forest management plans (as decision-making units and included four inputs and equal amount of outputs. The findings of this practical research show that the modified SND-DEA model in different probability levels give us apparently different results compared to the output from pure deterministic models. However, when we calculate the correlation measure, the probability levels give us a strong positive correlation between stochastic and deterministic models. Therefore, approximately 40% of the forest management plans based on the applied SND-DEA model should substantially increase their average efficiency score. As the major conclusion, our developed SND-DEA model is a suitable improvement over previous developed models to discriminate the efficiency and/or the inefficiency of decision-making units to hedge against risk and uncertainty in this type of forest management problems.

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