TRACE: A Centralized Trust and Competence-Based Energy-Efficient Routing Scheme for Wireless Sensor Networks Ayman Tajeddine, Ayman Kayssi, and Ali Chehab Department of Electrical and Computer Engineering American University of Beirut Beirut 1107 2020, Lebanon {ast03, ayman, chehab}@aub.edu.lb Abstract—We present TRACE as a centralized TRust And Competence-based Energy-efficient routing scheme to protect wireless sensor networks from various attacks and misbehaving nodes. TRACE identifies different types of "bad" nodes that can affect the correct routing operation and the reliability of the message delivery to the sink base station (BS). TRACE aids the routing protocol functionality and makes it more efficient and secure by using a centralized approach, where the more powerful and knowledgeable sink BS processes and validates the information received from the sensor nodes and calculates the maliciousness, competence, and cooperation levels of each node. The sink BS calculates two trust values for each node – namely Data Trust and Forwarding Trust and broadcasts a list of suspicious nodes in a Trust Report. TRACE accounts for the energy requirements of the severely-constrained network nodes by detecting and isolating the problematic nodes while eliminating the power-consuming reputation inquiries and computations required by each node in a distributed approach. We present energy calculations and simulations of TRACE and show its low energy consumption, correctness, and reliability. Keywords-component; Wireless Sensor Networks, Trust, Competence, Energy-Efficiency I. INTRODUCTION Sensor network technology has gained much attention in the past few years as it promises to improve data collection and statistical analysis [1]. However, with the severely-constrained sensor nodes, several security and energy concerns arise [2]. There are several methods to detect misbehaving nodes and provide secure routing while accounting for energy consumption and lengthening the network lifetime; among these are: reputation- and trust-based methods [3], location isolation [4], and behavior-based techniques [5]. In this paper, we present TRACE, an extension of our previous work [6], as a centralized trust and competence-based energy-efficient routing scheme to protect wireless sensor networks (WSN) from various attacks and misbehaving nodes. TRACE identifies different types of “bad” nodes that affect the correct routing operation and the reliability of the message delivery to the sink base station (BS) and hence decrease the network lifetime. Definition : A bad node is a malicious node sending false or illogical information, a non-cooperating node that does not reliably forward packets of other nodes, or an incompetent node that is unable to correctly deliver packets to the sink BS. TRACE aids the routing protocol functionality and makes it more efficient and secure by using a centralized approach, where the more powerful and knowledgeable sink BS processes and validates information received from the sensor nodes about the number of packets sent through their neighbors and the number of packets that were actually forwarded by their neighbors, and calculates the maliciousness, competence, and cooperation levels of each node. The sink BS calculates two trust values for each node – namely the Data Trust and Forwarding Trust and broadcasts, on a regular basis, a list of what the BS considers to be bad nodes in an authenticated Trust Report. The proposed approach provides trust and reliability while accounting for the severely-constrained sensor nodes batteries and preserving energy in the presence of misbehaving nodes by detecting and isolating them. TRACE eliminates the power-consuming reputation inquiries and computations required by a distributed approach; nodes are required to send minimal additional information, namely their next hop and two counters (s_counter and f_counter), showing the number of packets sent through and actually forwarded by this next hop, respectively. Moreover, each node uses a symmetric key with the sink BS to encrypt the additional messages together with a small integer hash and protect their confidentiality, thus preventing eavesdropping on the packets that contain the counters and next hop information and possibly tampering and changing the counter through the use of the hash. The rest of the paper is organized as follows: Section 2 surveys the previous work in the area of trust- and energy- aware techniques in wireless sensor networks. Section 3 presents our model, TRACE, with the corresponding definitions and parameters. The TRACE simulation results are presented in Section 4. Section 5 shows some energy calculations and the scheme benefits. Finally, Section 6 presents some conclusions and future work. 978-1-4577-9538-2/11/$26.00 ©2011 IEEE 953