A Security Attributes driven taxonomy of Wireless ...

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A Security Attributes driven taxonomy of Wireless Sensor Network Applications D. C. Jinwala, Dhiren Patel, K. S. Dasgupta

Abstract—The Wireless Sensor Networks (WSNs) have been observed to be applicable to a wide spectrum of applications in different areas, leading to pervasive and ubiquitous computing. But, due to the resource constrained nature of these devices, the satisfactory security services therein, pose a question mark. Theoretically, ensuring security in networks involves investigation of various attributes like encryption, entity authentication, message integrity, replay protection and the design of the mechanisms to do so. In WSNs, this investigation is compounded by the need for link layer security architecture, due to the multi-hopped nature of communication. Link layer security architecture may be implemented in the hardware or in the software, although obviously, the latter provides the flexibility much demanded on the experimental platforms. Although the existing software based link layer security frameworks like TinySec, SenSec, MiniSec and ZigBee do take the above mentioned security attributes into consideration; their design focuses merely on abstract applications, rather than focusing on the specific security needs of a particular application. We therefore, attempt here, to bring out the importance of attributes driven security. In the process, we present a broad taxonomy of WSN applications, keeping into account different security attributes demanded by these applications. We also show the impact this has, on judicious use of the WSN resources. Also, we undermine the need of security architecture, which is dynamically amenable to the security demands of the applications. Index Terms—Link Layer Security, Security Attributes, Security Mechanisms, Wireless Sensor Networks, Wireless Sensor Network Applications.

I. INTRODUCTION

D

riven by the ever increasing demands of sophistication in the application of technology in newer horizons, the technological milestones achieved in recent years in the areas of networking & wireless communications, micro electromechanical systems (MEMS), digital electronics and information security have increased the focus on the development & use of the small miniature devices, called sensor nodes deployed in thousands of numbers in the form of a Wireless Sensor Network (WSN) to work collaboratively. Manuscript received September 30, 2007 D. C. Jinwala is with the National Institute of Technology, Surat 395007, India; (e-mail: [email protected]). Dhiren Patel is with the National Institute of Technology, Surat 395007, India; (e-mail: [email protected]). K. S. Dasgupta is with the Indian Space Research Organization., Ahmedabad, India (e-mail: [email protected]).

The sensor nodes individually are miniature devices characterized by the low processing power, low memory, low bandwidth and low power source and integrating within a chip, various functional units like a CPU, a transceiver, a control unit and an appropriate sensing unit. Hence, as they are of any microcontroller based embedded device; the principal characteristics of the sensor nodes are (1) low cost, small packaging (2) low computational power & memory (3) low power consumption (4) low bandwidth (5) locally/remotely programmable and reprogrammable (6) higher I/O capabilities (7) easier integration with circuits (8) inherent suitability for cost, power & space starved applications and (9) meant for a special purpose usage [1]. Typical applications of the WSN range from environmental monitoring (e.g. monitoring temperature, rainfall, pressure etc, monitoring the stress and strain on a concrete structure, monitoring the salt concentration in concrete in buildings and bridges etc), factories (e.g. for measurement and monitoring of various parameters like oil levels, temperature etc), parks, sanctuaries (tracking the movement of an animal and the environmental conditions - while being attached to the collar of a hostile animal etc), banks, schools (tracking the movement of the humans), war zones, enemy camps (tracking the movement of the enemy without taking any evasive actions) etc. Being deployed in such varied environments, some of which may be hostile to their operation; the security issues in sensor networks are indeed critical. Security in WSNs is a challenge primarily due to the wireless nature of communication, energy constrained operation and deployment in typically critical and unattended environments and that too in a very large number [2][3]. At the same time, the conventional security protocols are not straightaway applicable in WSNs due to the (a) communication paradigm followed and (b) severe resource constraints that they face. The WSNs typically exhibit the communication paradigm which is data-centric multi-hop communication, wherein, after the data packet is routed towards the base station from its origin, the intermediate sensor nodes are also required to investigate & process the data in the packet, yielding on the fly in-network processing. This is unlike the conventional networks wherein, the intermediate nodes are merely required to investigate the header, in the incoming packet, to decide the further route of the packet. But, the implication of in-network processing is the fact that the end-to-end communication paradigm, exhibited by

Sec-04 the commonly used applications on the Internet is alone not suitable for the WSNs [4]. Along with the same, the use of the standard protocols which are meant for such an environment viz. SSH, SSL [5] or IPSec [6], in WSN environment is straightaway rejected. All the same, the security attributes like access control, message integrity, message confidentiality and replay protection cannot be achieved for free i.e. the techniques like encryption, decryption and the message authentication indeed involve performing additional operations over and above the message transmission and reception. In case of conventional networks, often for a common application, the support for security primitives is a case of an overkill; which though affects the performance but is affordable. The same set of proven protocols may not be affordable for the WSNs. For example, in case of the conventional networks, with the average network layer packet size of 576 bytes, addition of another 16-32 bytes, results into only 5.5% overhead in overall packet size; which although decreases the message throughput and increases latency; the performance degradation is marginal and is not noticeable, even in the applications where the security concerns are not too stringent [4]. On the other hand, in case of a standard tiny micro-threaded operating environment like TinyOS [7] employed in typical WSNs, with a 4MHz Atmel processor, 128KB of RAM, 128KB of program space and with 36 byte packets; an addition of 16-32 bytes would result into an overhead of around 50-100%, which cannot be tolerated [4]. At the same time, it is indeed true that the security demands of an application are largely derived from the operational paradigm followed and the execution environment required. Most of the existing research attempts at providing security architecture in WSN like SPINS [8], TinySec [4], SenSec [9], MiniSec [10] assume abstract applications and abstract security models of the WSN deployment; rarely focusing on the application specific threats and the countermeasures. It is indeed true that not all the applications require all the security attributes. Hence, the security parameters should be so chosen, as which are not overtly conservative, with respect to the applications and at the same time which can be justified with respect to the demands of the application. Any WSN security architecture design must take into account, the availability of resources and the overall performance also, while ensuring the necessary security. Hence, as a first exercise towards ensuring such a framework, this paper is an attempt to list out the common WSN applications, essential security attributes required therein and draw up taxonomy of WSN applications, depicting a clear mapping between the categories of the application versus the security attributes essential for the application. There has not been much related work discussing the research attempts at exploring models of attributes driven security, in the WSNs. To the best of our knowledge, [11] is a recent attempt which discusses an application driven perspective on WSN security. But essentially, it talks about the

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need for attribute driven security in light of two sample applications viz. Habitat Monitoring and Battlefield monitoring; without ever leveraging a detailed relationship between various applications and the security attributes. While Hill J et al in [12] is an attempt to describe the classes of WSN applications without ever emphasizing the security demands of the applications. The remaining paper is organized as follows: in Section II we describe the WSN platforms and the WSN application classes, in Section III, the desired security attributes in various applications are enlisted as well as summarized with taxonomy of the security attributes driven application classes and the paper concludes with the discussion of the future work aimed. II. TAXONOMY OF WSN APPLICATIONS A. Classes of WSN Platforms Hill J et al [12] focus on the operating characteristics of the sensor network nodes, subtly relating it to the operational requirements of the applications, suitable for various sensor node classes. Typically, four sensor platforms have been identified in it, elaborated further here. The WSN applications on one extreme could be highly specialized sensors with mini-motes, deployed in thousands of numbers to principally work as asset tags for tracking mobile assets or personnel, environmental parameter or for remote industrial measurements. The sensor nodes employed here have to be typically miniature smart-tag like devices, with limited battery resources, low processing power and bandwidth, highly integrated and designed to be inexpensive. Such motes would be aimed to be employed for years without any energy refurbishment, continually reporting its presence. The sensors in these sensor nodes are typically specialized to work with a particular platform only. At the level above, the sensor nodes could be of the form best represented by the Crossbow Berkeley Mica2 motes [13]. Having the resources including the memory, processing power, bandwidth and energy sources more than those in case of the specialized sensing nodes; these could be either deployed standalone or to work in collaboration with the specialized sensing nodes. These may be used for the applications which can be considered to be generic applications where the size, cost and the bandwidth required are not too critical; as also the applications do not demand specialized sensors. These are best suitable for the multi-hop communication required in WSNs, acting as the packet forwarders to the base station for the data packets passed on to them by the underlying specialized sensor nodes. Obviously, these sensors therefore are not suitable for those applications which require very high bandwidth – typically in the multimedia applications where video or audio data is required to be processed. The high performance sensors are like those represented by the Intel’s Imote2 [14] or Moteiv’s Tmote Sky [15] motes. These are based typically on relatively powerful processors like Intel’s PXA270 XScale processor, with 256 KB-32 MB RAM, 32-64 MB flash memory and the bandwidth to the tune

Sec-04 of 250-500 kbps. These are suitable, as mentioned earlier, for the video tracking and audio sensing applications e.g. tracking the vehicular movement for detection of the smoke emission or sending video streaming information in a Smart kindergarten or industrial equipment monitoring (vibration signatures/equipment health monitoring), water pipeline monitoring (pressure and water quality measurements) and structures monitoring (acceleration and displacement). A common characteristic of these applications is the generation of high bandwidth streaming data that needs to be efficiently buffered and transmitted over the radio. At the highest level, are the sensor nodes which act as gateways between the low-power mesh networks common in WSNs to the conventional networks. The representative gateway in this category is the Crossbow’s Stargate [16] based on Intel’s 400 MHz PXA225 processor with 64 MB RAM and 32 MB flash memory. These may be Web-enabled to act as the front-end processors for the WSNs. The processors used herein, are normally the embedded processors like Intel PXA225 processor OR Intel SA1111 StrongARM processor, with 32 MB flash memory, 32-64 MB RAM and a bandwidth of more than 500 KB. The operating system used is also a typical embedded operating system like VxWorks or Embedded Linux. B. Categories of WSN applications Various platforms of the WSNs described above may be suitable for specific applications. We now describe the categories of the typical applications of the WSN with respect to the one or more of the above platforms, based principally on the data rates required. At one extreme, there are applications which demand very high data rates typically ranging from data rates of few milliseconds to those in which only a few packets are transmitted per day. The sensor platforms used in these applications also vary from the specialized sensor platforms to the generic ones. The application category, principal requirements and some of the typical applications in each category are shown in Table I. III. SECURITY ATTRIBUTES AND APPLICATIONS Here in this section, are described the essential security attributes, expected for the applications enlisted above. The security attributes that a WSN should be equipped with can be viewed at two different levels. At the lower level, the security primitives consist of the essential cryptographic techniques, message integrity and the authentication whereas at the higher level, the secure routing, secure data aggregation, secure group management, and intrusion detection techniques make up the security primitives. A. Confidentiality, Integrity and Authentication Data encryption typically using the Symmetric Key Cryptography is used to achieve confidentiality of the messages. The typical application classes which need

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confidentiality are: (1) Military applications – wherein sensor nodes are placed at strategic locations amongst various enemy troops to collaborate and pass on vital information about the movement of the troops, I. TABLE

Sr No 1.

2.

3.

4.

Application Category

I

Frequency of packets High

Principal Tasks

High Volume Data in Monitoring, Environmental, Health, Object tracking, Military, Entertainment, Even detection Educational, Industrial Applications e.g. (a) PODS at Hawaii for near-real time observation rare species of plants including weather conditions [17] (b) SSIM application where a retina prosthesis chip consisting of one hundred micro-sensors are built and implanted within the human eye, allowing patients with no vision or limited vision to see at an acceptable level [18] (c) Monitoring of machine parameters [19] (d) Smart Kindergarten for monitoring Children behavior and movements with video streaming [20] High Volume Data in Monitoring, Low Environmental, Health, Object tracking, Military, Entertainment, Even detection Educational, Industrial Applications (a) Monitoring landfill and air quality (b) Water quality monitoring (c) Military applications for tracking (d) Monitoring of machine parameters (d) Smart Kindergarten for monitoring Children behavior and movements Moderate Volume Data in Monitoring, Low Environmental, Health, Object tracking, Military, Smart Even detection Classrooms (a) Modeling the behavior of the oceans and river estuaries as in CORIE [21] (b) Tracking movements of humans (c) Human Security systems Low Volume Data in Low-High Monitoring, Environmental Even detection Applications (a) Environmental monitoring as in Great Duck Island – to monitor the behavior of the birds [22] (b) Flood Detection (c) the use of sensors in monitoring the health of buildings, bridges and highways wherein the WSN is used to monitor stress, vibration, temperature, humidity etc. in civil infrastructures

(2) Health applications which consist of variations like telemonitoring of human physiological data, drug administration to the patients in hospitals, tracking and monitoring of doctors and patients inside a hospital etc.; Body Area Networks – wherein sensors are used to measure various human body parameters (3) Environment Control which consist of typically monitoring the health of the bridges, buildings and public places by analyzing the stress and the strain that they are exposed to, the salt concentration in the concrete, the corrosion of the reinforcement in the concrete structures, (4) Smart Home and Office systems – for tracking and monitoring the movement of humans. Note that the confidentiality of the data is not required in every application mentioned above whereas whether the

Sec-04 application category under consideration is military, health, environmental control or Smart office systems; integrity and authenticity of the data sensed and communicated as well as authentication of the entities participating in the network are always required. Even otherwise, any confidentiality without message integrity and entity authentication is anyway considered to be doubtful. To ensure message integrity, typically a message authentication code (MAC) is computed at the source and is verified at the intermediate hops/destination, using a keyed one-way hash function. The one-way hash function applied is publicly known and so the receiver can also, knowing the key used for generating MAC, compute the MAC to verify the integrity of the data packets. Nevertheless, computation and verification of MAC requires some bytes be allocated in the transmitted packet, containing the value of the MAC computed at the sender end. The number of bytes to be allocated very vitally becomes a critical design issue with respect to the used bandwidth. Having a high bandwidth transceiver also means increased probability of an attacker forging a MAC while on the other hand for the resource constrained nodes, a large packet size is not desirable. As for example, a 4-byte MAC is reasonable size for typically 40-60 bytes WSN packets, but can be considered to be safe from attacks? With a 4-byte MAC an adversary would have 1 chance in 232 attempts, to forge the MAC. Now, if the radio is operating at 19.2 kbps, as it is in case of CC1000 based MICA2 motes, one can send only about 40 forgery attempts per second, for the 68-bytes sized TinyOS/TinySec packets. Therefore, in order to make 231 tries, the adversary will need at least 621 days to be able to try forging the MAC. If we consider a mote class attacker, then this is simply not possible because the batteries of a mote can run only for 2 weeks when operated in such a mode where it has to continuously attempt sending the packets. But, if we assume the radio operating at 250 kbps, then using the same 68-bytes sized packets, would mean, adversary needs only 52 days of continuous packet transmission to forge the MAC. To solve the problem, the MAC for the high data rate applications, should not be limited to 4 bytes but should be increased. Thus, high data rate applications mentioned in Table I would demand more bytes to be allocated for MAC as they would naturally require higher bandwidth. B. Replay Protection Even when ensuring the attributes in (A) above, there is a need to prevent the adversary merely replaying the previous transmitted old packets. The message integrity and authentication are still preserved, thereby not enabling the recipient detect the lack of utility of the packets. The property of replay protection is vital for almost all the applications listed in (A). Typically, the attack is aimed merely at causing the recipient node unnecessarily waste its resources, especially the precious battery power. In the applications where the WSN is aimed to run for a long period of time

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without the batteries being replenished - like in Great Duck Island application [22], the replay protection along with message integrity and entity authentication become the vital properties and not the confidentiality of the data. C. Secure Localization The sensor nodes used at either the specialized level or at the generic levels - typically rely on increased collaboration amongst each other. The locations of the sensor nodes which are deployed in an adhoc manner without being pre-decided before the deployment, rely very much on the collaboration and voting, to convey the location information, the location of their neighbors and so on. The sensor nodes in WSNs are often identified by the attribute oriented query e.g. “all the sensor nodes which sense a temperature value of t” in a typical temperature monitoring application. In such a scenario, adversaries may feign falsely as neighbors of a particular node or falsely project wrong location information of a particular node to the other nodes. Hence, ensuring secure localization is of prime importance in almost all the applications discussed before. But secure localization assume even more importance in the environmental applications e.g. sensing flow of water across a river bed, sensing the depth of water, sensing environmental parameters, fire/smoke detection, target tracking, asset detection, enemy troops movement, movement of human being, monitoring health of the bridges and buildings etc. D. Secure Routing The multihop nature of the WSNs, demands that the messages would be routed through many other sensor nodes in a multi-hopped manner and hence, each sensor node has to act also as a routing element apart from sensing and data processing. The routing algorithms applicable to other networks, cannot be directly used here due to the characteristic differences between the general networks and the WSNs. Some of the routing algorithms which have been proposed for the WSNs currently are the flat network routing protocols like Sensor Protocols for Information via Negotiation, the Directed Diffusion, the Rumor routing, the Minimum Cost Forwarding Algorithm, the hierarchical routing algorithms like the LEACH protocol, the Power Efficient Gathering in Sensor Information Systems, the Sensor Aggregates Routing, the Geographic and Energy Aware routing etc [23]. But, most of these algorithms do not take security into account at any step of their design. In fact routing protocols like directed diffusion and geographic routing actually assume a trusted environment to work properly. The fact that sensor networks are less mobile, exhibit different traffic pattern, follow attribute based data search, do not have a global addressing scheme due to large number of nodes deployed and their designs are application specific, make them characteristically different from the adhoc networks to apply even the secure routing algorithms proven for the adhoc networks. Since the network layer is most prone to the adversary attacks, security should be inherently built into the routing protocols designed for the

Sec-04 WSNs. A secure routing protocol is the one in which the legitimate sensor nodes are able to communicate correctly in presence of adversarial activities. The routing protocol should also provide the inherent and primary expectations viz. all the nodes in the sensor network must be reachable, the node coverage must be high, the algorithm should be fault tolerant and should scale up with any additional number of nodes dynamically added to the network; while ensuring that it works with in the bounds of the low storage and low energy resources. Most of the attacks against the routing protocols can be prevented by using the link layer encryption and authentication. But, the link layer security mechanisms using a globally shared key are completely ineffective in presence of insider attacks or subverted nodes [23]. Secure routing therefore is vital for again all the applications discussed earlier. E. Secure Data Aggregation The end-to-end security mechanisms employed by the conventional networks including the Internet are tolerable and sufficient because the intermediate routers therein, are required to inspect only the message headers, not the message data. The end-to-end security alone is obviously not feasible in WSNs; primarily due to its multi-hop nature of communication with necessity for in-network processing as mentioned before. In sensor networks, it is essential that the data aggregation (also referred to as data fusion) takes place wherein, the data sensed from different sensor nodes forming one group, is collected and aggregated by an aggregator node and then only a single packet is transmitted upstream to either the base station or further aggregating nodes; in order to save energy by not sending the duplicates. The aggregation may take some other form of processing involving passive participation too, wherein a sensor overhearing a packet sent by a close neighbor, does not forward it to the base station deliberately in order to eliminate the duplicates. The principle advantages of aggregation are: (a) considerable reduction in the amount of data packets communicated to the base station and (b) increased battery life due to reduction in the communication (c) improved scalability. But the aggregation also opens further avenues for the attacker. For, by merely capturing the aggregating node, the attack can be virtually carried out on all those nodes which relay the packets sensed by them to the aggregator node. Hence, secure aggregation is an essential security attribute in those WSN applications which are communication oriented. Typically, the applications in which large amounts of data are sensed and communicated frequently by a large population of distributed sensors – like in many environmental control applications and Military applications, secure aggregation is vital whereas, for the sensor nodes acting as the gateway nodes at highest level, secure aggregation is not required.

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Thus, now having looked separately at the typical WSN platforms, the categories of the WSN applications and the types of security attributes desired, we now present an attributes driven taxonomy of the WSN applications, in Table II. Table II lists out the principle groups of security attributes and maps the same to the applications which demand the appropriate security in each group. It also lists the design criteria with respect to the selection of the MAC size i.e. whether 4-bytes or 8-bytes MAC is needed. IV. CONCLUSION From the taxonomy described in Table II, it is clear that there is considerable gap between the security demands of different applications. Currently, there are no security solutions, offering WSN security adaptable with the demands of the applications. For example, the TinySec link layer security architecture offers a MAC of 4 bytes cannot be emphasizes on the efficiency of implementation with reasonable security; but it won’t be suitable for applications demanding stringent security. Hence, a successful attempt has been made in the paper to bring forth the need for a security attributes driven (configurable) architecture for the Wireless Sensor Networks. As part of the future work it is aimed to propose an attribute driven model for security in WSNs. REFERENCES [1] [2]

[3]

[4]

[5] [6] [7]

[8]

[9] [10]

[11]

[12]

[13] [14] [15]

I F Akyildiz, W Su, Y Sankarasubramaniam, E Cayirci; “Wireless Sensor Networks: A Survey”, Computer Networks, 38(4), March 2002 V Raghunathan, C Schurgers, Park S, Srivastava M B; “Energy Aware Wireless Microsensor Networks”; IEEE Signal Processing Magazine, Vol 19, Issue 2, March 2002. Adrain Perrig, John Stankovic, David Wagner; “Security in Wirless Sensor Networks”; Communications of the ACM, CACM’04, Vol 47, No 6, 2004 Chris Karlof, Naveen Sastry, David Wagner; “TinySec: Link Layer Encryption for Tiny Devices”, ACM Conference on Embedded Networked Sensor Systems, 2004, Ohio. Secure Socket Layer - http://www.openssl.org Requests for Comments viz. RFC 2401, RFC 2402, RFC 2406, RFC 2408 http://www.ietf.org/rfc/rfc240n.txt Jason Hill, Robert Szewczyk, Alec Woo, Seth Hollar, David Culler, Kristofer Pister; “System Architecture Directions for Networked Sensors”; ASPLOS, 2000 A Perrig, R Szewczyk, V Wen, D Cullar, J D Tygar; “SPINS: Security Protocols for Sensor Networks”; Proceedings of the 7th International Conference on Mobile Computing and Networking, July 2001 Tieyan Li, Hongjun Wu, Xinkai Wang, Feng Bao; “SenSec Design, I2R Sensor Network Flagship Project”; Technical Report TR v1.0 Mark Luk, GhitaMezzour, Adrian Perrig, Virgil Gligor; “MiniSec: A Secure Sensor Network Communication Architecture”; ACM International Conference on Information Processing in Sensor Networks; April 2007 Eric Sabbah, Adnan Majeed, Kyong-Don Kang, Ke Liu, Nael AbuGhazaleh; “An Application-Driven Perspective on Wireless Sensor ACM International Workshop on Network Security”, 2nd QoS and Security for Wireless and Mobile Networks, 2006 Jason Hill, Mike Horton, Raplh Kling, L Krishnamurthy; “The Platforms Enabling Wireless Sensor Networks”; Communications of ACM, CACM’04, June 04. Crossbow Berkeley Mica2 motes - http://www.xbow.com/Products/ Intel’s Imote - http://www.xbow.com/Products/ Moteiv’s Tmote Sky – http://www.moteiv.com

Sec-04 [16] Crossbow Stgargate - http://www.xbow.com/Products [17] PODS, A Remote Ecological Micro-sensor Network Project, http://www.pods.hawaii.edu [18] L. Schwiebert, S. K. S. Gupta, and J. Weinmann, “Research challenges in wireless networks of biomedical sensors”; Proc. 7th ACM International Conference on Mobile Computing and Networking (MobiCom ’01), Rome, Italy, July 2001. [19] H.O.Marcy, J. R. Agre, C. Chien, L. P. Clare, N. Romanov, and A. Twarowski, “Wireless sensor networks for area monitoring and integrated vehicle health management applications”; Proc. AIAA Guidance, Navigation, and Control Conference and Exhibit, Portland, Ore, USA, 1999, Collection of Technical Papers. [20] M. B. Srivastava, R. R. Muntz, and M. Potkonjak, “Smart kindergarten: sensor-based wireless networks for smart developmental problem-

solving enviroments”; Proc. 7th ACM International Conference on Mobile Computing and Networking (MobiCom ’01), Rome, Italy, July 2001. [21] CORIE website, http://www.ccalmr.ogi.edu/CORIE [22] A. Mainwaring, J. Polastre, R. Szewczyk, D. Culler, and J. Anderson, “Wireless sensor networks for habitat monitoring”; Proc. International Workshop on Wireless Sensor Networks and Applications (WSNA ’02), Atlanta, Ga, USA, September 2002 [23] Chris Karlof, David Wagner; “Secure Routing in Wireless Sensor Networks: Attacks and Counter Measures”, Proceedings of the 1st IEEE International Workshop on Sensor Network Protocols and Applications, May 2004

I. TABLE II

Sr No 1.

6

Essential Security Attributes

Application Category

Example Applications

Remarks

Environmental monitoring, Health with high volume data, high frequency

3.

-do-

4.

-do-

5.

6.

Data Encryption, Entity Authentication, Message Integrity, Replay Protection, Secure Routing, Secure Data Aggregation -do-

Environmental Monitoring Applications with Moderate Volume Data Environmental Monitoring Applications with Low Volume Data Smart Office/Home applications with high volume data, high frequency

e.g. (a) PODS at Hawaii [17] (b) SSIM application [18] (c) Monitoring of machine parameters [19] (a) Monitoring landfill and air quality (b) Water quality monitoring (c) Monitoring of machine parameters (a) Modeling the behavior of the oceans and river estuaries as in CORIE [21] (a) Great Duck Island – to monitor the behavior of the birds [22] (b) Flood Detection e.g. Smart Kindergarten [20], Smart Office/Home Applications (with video streaming)

Link layer security mechanisms, MAC of 48 bytes

2.

Entity Authentication, Message Integrity, Replay Protection, Secure Routing, Secure Data Aggregation -do-

7.

-do-

8.

-do-

Environmental Monitoring Applications, Structural with high volume data, low frequency

Military, Personal with high volume data, low frequency

Environmental Monitoring Applications with Moderate Volume Data Environmental Monitoring Applications with Low Volume Data

(a) Military for tracking objects (b) Smart Kindergarten for tracking Children movements (c) Smart Office/Home Applications (without video streaming) (a) Tracking movements of humans (b) Human Security systems (c) the use of sensors in monitoring the health of buildings, bridges and highways wherein the WSN is used to monitor stress, vibration, temperature, humidity etc. in civil infrastructures

Link layer security mechanisms, MAC of 4 bytes Link layer security mechanisms, MAC of 4 bytes Link layer security mechanisms, MAC of 4 bytes Link layer security mechanisms, MAC of 48 bytes

Link layer security mechanisms, MAC of 4 bytes

Link layer security mechanisms, MAC of 4 bytes Link layer security mechanisms, MAC of 4 bytes