Implementation of Secure Key Management Techniques in Wireless Sensor Networks

Creating a secure wireless sensor network involves authenticating and encrypting messages that are sent throughout the network. The communicating nodes must agree on secret keys in order to be able to encrypt packets. Sensor networks do not have many resources and so, achieving such key agreements is a difficult matter. Many key agreement schemes like Diffie-Hellman and public-key based schemes are not suitable for wireless sensor networks. Pre-distribution of secret keys for all pairs of nodes is not viable due to the large amount of memory used when the network size is large. We propose a novel key management system that works with the random key pre-distribution scheme where deployment knowledge is unknown. We show that our system saves users from spending substantial resources when deploying networks. We also test the new system’s memory usage, and security issues. The system and its performance evaluation are presented in this thesis

A Secure Behavior Modification Sensor System for Physical Activity Improvement

Today, advances in wireless sensor networks are making it possible to capture large amounts of information about a person and their interaction within their home environment. However, what is missing is how to ensure the security of the collected data and its use to alter human behavior for positive benefit. In this research, exploration was conducted involving the infrastructure and intelligence aspects of a wireless sensor network through a Behavior Modification Sensor System. First was to understand how a secure wireless sensor network could be established through the symmetric distribution of keys (the securing of the infrastructure), and it involves the mathematical analysis of a novel key pre-distribution scheme. Second explores via field testing the intelligence level of the system. This was meant to support the generation of persuasive messages built from the integration of a person\u27s physiological and living pattern data in persuading physical activity behavior change associated with daily walking steps. This system was used by an elderly female in a three-month study. Findings regarding the infrastructure or the novel key pre-distribution scheme in comparison to three popular key distribution methods indicates that it offers greater network resiliency to security threats (i.e., 1/2^32 times lower), better memory utilization (i.e., 53.9% less), but higher energy consumption (i.e., 2% higher) than its comparison group. Findings from the intelligence level of the research posit that using a person\u27s physiological and living pattern data may allow for more information rich and stronger persuasive messages. Findings indicate that the study participant was able to change and improve her average daily walking steps by 61% over a pre-treatment period. As the study participant increased her physical activity, changes in her living pattern were also observed (e.g., time spent watching television decreased while time spent engaged in walking increased by an average of 15 minutes per day). Reinforcement of these findings were noted between a pre and post-study survey that indicated the study participant moved from a contemplation stage of change where physical activity engagement was intended but not acted upon to an action stage of change where physical activity engagement dominated the new behavior

Active security mechanisms for wireless sensor networks and energy optimization for passive security routing

Wireless sensor networks consisting of numerous tiny low power autonomous sensor nodes provide us with the remarkable ability to remotely view and interact with the previously unobservable physical world. However, incorporating computation intensive security measures in sensor networks with limited resources is a challenging research issue. The objective of our thesis is to explore different security aspects of sensor networks and provide novel solutions for significant problems. We classify security mechanisms into two categories - active category and passive category. The problem of providing a secure communication infrastructure among randomly deployed sensor nodes requires active security measurements. Key pre-distribution is a well-known technique in this class. We propose a novel 2-Phase technique for key pre-distribution based on a combination of inherited and random key assignments from the given key pool to individual sensor nodes. We develop an analytical framework for measuring security-performance tradeoffs of different key distribution schemes. Using rigorous mathematical analysis and detailed simulation, we show that the proposed scheme outperforms the existing solution in every performance aspect. Secure data aggregation in wireless sensor networks is another challenging problem requiring active measures. We address the problem of stealthy attack where a compromised node sends wrong/fictitious data as a reply to a query. We propose a novel probabilistic accuracy model which enables an aggregator to compute accuracy of each sensor reading by exploiting spatial correlation among data values. We also propose some novel, energy efficient statistical methods to enable a user accept the correct value with a high probability. Increasing network lifetime is a passive security mechanism which enables many security mechanisms to work more efficiently. We define length-energy-constrained optimality criteria for energy-optimized routes that impose uniform energy distribution across the network, thus preventing expedited network partition. We propose three different distributed, nearly-stateless and energy efficient routing protocols that dynamically find optimal routes and balance energy consumption across the network. We show that global energy information acquired through this process utilized in conjunction with energy depletion control in the sensornet ensures a significant improvement in terms of network lifetime

Using combined keying materials for key distribution in wireless sensor networks

In this paper, we propose a probabilistic key predistribution scheme for wireless sensor networks that increases connectivity of the basic scheme while keeping sizes of keyring and key pool fixed. We introduce the concept of XORed key, which is the bitwise XOR of two regular (a.k.a. single) keys. Sensor nodes are preloaded with a mixture of single and XORed keys. Nodes establish secure links by using shared XORed keys whenever possible. If node pairs do not have any shared XORed or single keys, they transfer keys from their secure neighbors in a couple of ways, and use them to match with their XORed keys. In this way, the probability of securing links, i.e. local connectivity, increases. The decision of which key is to be transferred from which node is given based on local information at the hand of the nodes. We aim to control the resilience of the network against node capture attacks by using XORed keys since an attacker has to know either both single key operands or the XORed key itself. Simulations show that our scheme is up to 50% more connected as compared to basic scheme. Also it has better resilience performance at the beginning of a node capture attack. When it starts to deteriorate, the difference between the resilience of our proposed scheme and basic scheme is not greater than 5%