Wireless sensor networks (WSNs) use small nodes with constrained capabilities to sense, collect, and disseminate information in many types of applications. As sensor networks become wide-spread, security issues become a central concern, especially in mission-critical tasks. In this paper, we identify the threats and vulnerabilities to WSNs and summarize the defense methods based on the networking protocol layer analysis first. Then we give a holistic overview of security issues. These issues are divided into seven categories: cryptography, key management, attack detections and preventions, secure routing, secure location security, secure data fusion, and other security issues. Along the way we analyze the advantages and disadvantages of current secure schemes in each category. In addition, we also summarize the techniques and methods used in these categories, and point out the open research issues and directions in each area.

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Sensor network security: a survey

A survey of communication/networking in Smart Grids

Recent advances in electronics and wireless communication technologies have enabled the development of large-scale wireless sensor networks that consist of many low-power, low-cost, and small-size sensor nodes. Sensor networks hold the promise of facilitating large-scale and real-time data processing in complex environments. Security is critical for many sensor network applications, such as military target tracking and security monitoring. To provide security and privacy to small sensor nodes is challenging, due to the limited capabilities of sensor nodes in terms of computation, communication, memory/storage, and energy supply. In this article we survey the state of the art in research on sensor network security.

Security in wireless sensor networks

Energy is a central concern in the deployment of wireless sensor networks. In this paper, we investigate the energy cost of cryptographic protocols, both from a communication and a computation point of view, based on practical measurements on the MICAz and TelosB sensors. We focus on the cost of two key agreement protocols: Kerberos and the elliptic curve Diffie-Hellman key exchange with authentication provided by the elliptic curve digital signature algorithm (ECDH-ECDSA). We find that, in our context, Kerberos is around one order of magnitude less costly than the ECDH-ECDSA key exchange and confirm that it should be preferred in situations where a trusted third party is available. We also observe that the power dedicated to communications can become a central concern when the nodes need to stay in listen mode, e.g. between the protocol rounds, even when reduced using a low power listening (LPL) protocol. Therefore, listening should be considered when assessing the cost of cryptographic protocols on sensor nodes.

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On the Energy Cost of Communication and Cryptography in Wireless Sensor Networks

The Internet of Things (IoT) will feature pervasive sensing and control capabilities via a massive deployment of machine-type communication (MTC) devices. The limited hardware, low-complexity, and severe energy constraints of MTC devices present unique communication and security challenges. As a result, robust physical-layer security methods that can supplement or even replace lightweight cryptographic protocols are appealing solutions. In this paper, we present an overview of low-complexity physical-layer security schemes that are suitable for the IoT. A local IoT deployment is modeled as a composition of multiple sensor and data subnetworks, with uplink communications from sensors to controllers, and downlink communications from controllers to actuators. The state of the art in physical-layer security for sensor networks is reviewed, followed by an overview of communication network security techniques. We then pinpoint the most energy-efficient and low-complexity security techniques that are best suited for IoT sensing applications. This is followed by a discussion of candidate low-complexity schemes for communication security, such as on–off switching and space-time block codes. The paper concludes by discussing open research issues and avenues for further work, especially the need for a theoretically well-founded and holistic approach for incorporating complexity constraints in physical-layer security designs.

Physical-Layer Security in the Internet of Things: Sensing and Communication Confidentiality Under Resource Constraints

In this paper we try to estimate the real influence of public key cryptography (PKC) to the lifetime of a sensor node in wireless sensor networks. We investigate four types of nodes; MICA2DOT, MICA2, MICAz and TelosB. For all these nodes we estimate the power consumption for most common RSA and ECC operations, i.e., signature generation and verification as well as key exchange mechanisms. We also estimate the power consumed by the transmission of their results. Our results show that the application of strong cryptography is feasible. Even for the most constrained node performing the ECC-160 signature once every 10 minutes increases the duty cycle only by about 0.5 per cent, i.e., the influence to the lifetime is not significant. Nevertheless, the public key cryptography shall be used with care.

How public key cryptography influences wireless sensor node lifetime

High-resolution net load forecasting for micro-neighbourhoods with high penetration of renewable energy sources

The advantage of a Wireless Sensor Network (WSN) compared to a centric approach is the distribution of sensing suites. However, in order for such a system of distributed resources to work in a reliable and effective way a smart cooperation between nodes is needed. In this paper we propose a middleware approach for a highly reliable data storage that helps to assure data availability despite the well known WSN resource problems and disappearing or inactive nodes by providing a reasonable data redundancy in the system. Such a solution helps to ease the design and optimization of the data exchange between nodes as well. Our solution is configurable in order to satisfy the needs of the application on top regarding performance/requirements trade-off. The options specify the quantity and quality of the data replication. Additional features like event mechanism that monitors the data and the possibility to issue database like queries increase the applicability of our middleware. In this paper we focus on the evaluation of its capabilities regarding reliability, the consistency of replicates and the costs of the data management. The simulation results for a reasonable set-up show that the CPU load caused by the data replication is low (below 3 percent) and the average inconsistency time is as small as about 0,06 seconds for a single hop and about 0,15 seconds for a two hops replication area. There is still room for improvements, but a clear definition of problems helps to find ways to cope with them in order to achieve the chosen goals.

tinyDSM: A highly reliable cooperative data storage for Wireless Sensor Networks

In this paper we discuss algorithms that allow the concealed data aggregation (CDA) in wireless sensor networks. We describe and evaluate three algorithms that were reported to suit to the WSN scenario. As result of the evaluation, where we emphasize the awareness to potential attack scenarios, we present a brief overview of strengths and weaknesses of the algorithms. Since no algorithm provides all desirable goals, we propose two approaches to cope with the problems. The first is the successive combination of two algorithms. It increases security, while the additional efforts can be minimized by carefully selected parameters. For the second approach we face specific weaknesses and engineer mechanisms that solve the particular issues. With the considered homomorphic message authentication code and a discussion of the id-issue we exemplary evaluate the two biggest issues of the very promising CMT algorithm. I. MOTIVATION

On Concealed Data Aggregation for WSNs

Public Key Cryptography (PKC), although very beneficial for key distribution, authentication and other related issues, was for a long time considered as too expensive for small, battery-powered and resource-constrained devices. In the recent years, first research groups started to cope with the challenges applying PKC in such environments. One of the results is that Elliptic Curve Cryptography (ECC) fits here perfectly, providing the level of security RSA does, but with much shorter keys. In this paper, we evaluate the power consumption induced by various PKC approaches including calculation and transmission costs. Our results clearly show that hardware accelerators significantly reduce the energy consumption and prolong lifetime of sensor nodes. Our solution for 163 bit ECC needs only 1.02 mm² cell area in a 0.25 µm technology and only 12.8 µWs per point multiplication. Due to its small size it can be manufactured for about 0.05 USD in mass production.

Krzysztof Piotrowski

Papers

How public key cryptography influences wireless sensor node lifetime

High-resolution net load forecasting for micro-neighbourhoods with high penetration of renewable energy sources

tinyDSM: A highly reliable cooperative data storage for Wireless Sensor Networks

On Concealed Data Aggregation for WSNs

Public key cryptography empowered smart dust is affordable