Sensors and Actuators A 156 (2009) 394–405
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Sensors and Actuators A: Physical journal homepage: www.elsevier.com/locate/sna
On the implementation and evaluation of an elliptic curve based cryptosystem for Java enabled Wireless Sensor Networks David E. Boyle ∗ , Thomas Newe Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland
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Article history: Received 20 February 2009 Received in revised form 6 August 2009 Accepted 11 October 2009 Available online 20 October 2009 Keywords: Security Cryptography Elliptic Curve Cryptography Wireless Sensor Network Resource consumption Java
a b s t r a c t This paper considers the impact of the provision of security for a Java enabled wireless sensor networking platform. In 2007, Sun Microsystems, Inc. released a Java programmable platform; namely Sun Small Programmable Object Technology (Sun SPOT). Given the more intuitive application development environment, it is envisaged that real applications will emerge at a more rapid pace, and as such the importance of the provision of security remains to the fore. The only provision of security, to-date, is that of an industry standard TLS (Transport Layer Security) implementation at the Application Layer; rooted from an ECC (Elliptic Curve Cryptography) based public-key cryptosystem. This work demonstrates that the employment of TLS results in a reduction of 70% of network lifetime; a significant cost to provide security. Given this cost, alternative methods of securing a Sun SPOT based sensor network are considered, culminating in the specification of a cross-layer, hybrid security architecture. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Wireless Sensor Networks (WSNs) can be defined as groups of independent nodes, communicating wirelessly over limited frequency and bandwidth [1]. They have rapidly evolved over the past number of years, and their novelty lies in their reliance upon dense deployment and coordination to successfully execute their tasks. Distributed sensing in this manner allows for closer placement to the phenomena than could be achieved using a single sensor; especially when the exact location of a particular event is unknown or undeterminable [2]. Advances in Microelectromechanical Systems (MEMS) and communications technology have enabled the development of tiny, disposable, autonomous “computers”; referred to as motes or nodes, which connect wirelessly to form a WSN. These nodes typically combine a sensor, microcontroller, memory, radio transceiver and a battery. A popular example of such a device is the Crossbow “MICAz” [3]. This device consists of an 8-bit Atmega128 microcontroller, 4 kB of RAM, 512 kB of program memory, CC2420 radio transceiver and can accommodate the attachment of a sensor. Consistent with the majority of WSN motes available to-date, the MICAz is programmed in networked embedded systems C, or nesC [4], and is affected via the TinyOS operating system [5].
∗ Corresponding author. Tel.: +353 868397261. E-mail address:
[email protected] (D.E. Boyle). 0924-4247/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.sna.2009.10.012
Applications of WSNs are extremely diverse in range. Initially driven by military research, applications are limited only by what can be technologically sensed. Applications of WSNs have emerged in homeland security, military, medical, environmental, industrial, commercial and domestic areas [6]. As the range of application scenarios continues to expand and diversify, the importance of securing these systems remains paramount. Security requirements are dependent upon the sensitivity of the data sensed and disseminated throughout the WSN application. Considering an application in the medical field; it is necessary to ensure the confidentiality of physiological patient data, as is required by law, or any military application; the successful operation of which depends upon the security of the network. Concerns in relation to security, power management, control and routing, collaborative signal and information processing, and tasking and querying are all areas currently under research [7]. It is the combination of these concerns that has contributed to the inhibition of wider-spread deployment of WSNs to-date. It has been argued that the development platform employed todate for WSNs is inaccessible to many prospective implementers of the technology; citing a steep learning curve and difficult set-up and installation process based upon the Berkeley family of motes and the TinyOS operating system [8]. The reality of this sentiment is unproven, but has resulted (in combination with further advances in technology and forward-thinking) in the development of a powerful competitor. In 2007, Sun Microsystems, Inc. released a Java enabled WSN development platform: Sun Small Programmable Object Technol-
D.E. Boyle, T. Newe / Sensors and Actuators A 156 (2009) 394–405
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Table 1 MICAz and Sun SPOT hardware comparison.
MICAz Sun SPOT
Manufacturer
C
RAM
Program memory
Data memory
Radio
Range
OS
Crossbow Sun Microsystems
Atmel Atmega128L (8 MHz) ARM920T (180 MHz)
4 kB 512 kB
128 kB 4 MB
512 kB –
CC2420 CC2420
