Rajan Shankaran

Security for cluster based ad hoc networks

A mobile ad hoc network is a short-lived cooperative collection of mobile nodes that communicate with each other without the services of a fixed infrastructure. Each host acts as a specialised router to relay information to other nodes. Near-Term Digital Radio (NTDR) networks, which follow the cluster based design principles, are designed specifically for use in ad hoc networks. A major challenge in the design of these networks is their vulnerability to security attacks. In this paper, we describe the security threats and propose security services to counteract these threats in cluster-based NTDR ad hoc networks. We describe secure schemes for a mobile node to initiate, join and leave a cluster. We also discuss the secure end-to-end communication and group key management related issues for NTDR networks.

A trust management architecture for hierarchical wireless sensor networks

Security and trust are fundamental challenges when it comes to the deployment of large wireless sensor networks. In this paper, we propose a novel hierarchical trust management scheme that minimizes communication and storage overheads. Our scheme takes into account direct and indirect (group) trust in trust evaluation as well as the energy associated with sensor nodes in service selection. It also considers the dynamic aspect of trust by introducing a trust varying function which could give greater weight to the most recently obtained trust values in the trust calculation. The proposed framework can be extended to such dynamic mobile inter-cluster wireless sensor network environments.

Multiple ECG Fiducial Points-Based Random Binary Sequence Generation for Securing Wireless Body Area Networks

Generating random binary sequences (BSes) is a fundamental requirement in cryptography. A BS is a sequence of

Context-Aware Trust Management for Peer-to-Peer Mobile Ad-Hoc Networks

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Encryption for Implantable Medical Devices Using Modified One-Time Pads

bits, and each bit has a value of 0 or 1. For securing sensors within wireless body area networks (WBANs), electrocardiogram (ECG)-based BS generation methods have been widely investigated in which interpulse intervals (IPIs) from each heartbeat cycle are processed to produce BSes. Using these IPI-based methods to generate a 128-bit BS in real time normally takes around half a minute. In order to improve the time efficiency of such methods, this paper presents an ECG multiple fiducial-points based binary sequence generation (MFBSG) algorithm. The technique of discrete wavelet transforms is employed to detect arrival time of these fiducial points, such as P, Q, R, S, and T peaks. Time intervals between them, including RR, RQ, RS, RP, and RT intervals, are then calculated based on this arrival time, and are used as ECG features to generate random BSes with low latency. According to our analysis on real ECG data, these ECG feature values exhibit the property of randomness and, thus, can be utilized to generate random BSes. Compared with the schemes that solely rely on IPIs to generate BSes, this MFBSG algorithm uses five feature values from one heart beat cycle, and can be up to five times faster than the solely IPI-based methods. So, it achieves a design goal of low latency. According to our analysis, the complexity of the algorithm is comparable to that of fast Fourier transforms. These randomly generated ECG BSes can be used as security keys for encryption or authentication in a WBAN system.

Ideas and Challenges for Securing Wireless Implantable Medical Devices: A Review

Mobile Ad hoc Networks (MANETs) are self-organizing and adaptive, and securing such networks is non-trivial. Most security schemes suggested for MANETs tend to build upon some fundamental assumptions regarding the trustworthiness of the participating hosts and the underlying networking systems without presenting any definite scheme for trust establishment. If MANET is to achieve the same level of acceptance as traditional wired and wireless network, then a formal specification of trust and a framework for trust management must become an intrinsic part of its infrastructure. The goal of this paper is to highlight issues relating to trust in MANETs and describe a context-aware, reputation-based approach for establishing trust that assesses the trustworthiness of the participating nodes in a dynamic and uncertain MANET environment.

A Dynamic Trust Establishment and Management Framework for Wireless Sensor Networks

We present an electrocardiogram (ECG)-based data encryption (EDE) scheme for implantable medical devices (IMDs). IMDs, including pacemakers and cardiac defibrillators, perform therapeutic or even life-saving functions and store sensitive data; therefore, it is important to prevent adversaries from having access to them. The EDE is designed with the ability to provide information-theoretically unbreakable encryption where two well-known techniques of classic one-time pads (OTPs) and error correcting codes are combined to achieve a cryptographic primitive for IMDs. Unlike other ECG-based key agreement schemes where ECG features are used to facilitate a key distribution, in the EDE scheme, random binary strings generated from ECG signals are directly used as keys for encryption. OTP keys are generated by the IMD and the programmer, respectively, before each encryption attempt; thus, the EDE does not require a cryptographic infrastructure to support a key distribution, storage, revocation, and refreshment. Protected by the EDE, IMDs could not be accessed by adversaries; however, medical personnel can have access to them by measuring real-time ECG data in emergencies. Therefore, the EDE design achieves a balance of high security and high accessibility for the IMD. Our data and security analysis shows that the EDE is a viable scheme for protecting IMDs.

A Dynamic Authentication Scheme for Hierarchical Wireless Sensor Networks

Implantable medical devices (IMDs) are normally used for monitoring and treating various medical conditions. These days, wireless modules have become an intrinsic part of many modern IMDs. So, doctors can use device programmers wirelessly to configure parameters in the IMDs. However, such a wireless technology exposes the IMDs to security attacks. In this paper, we analyze potential threats faced by the IMDs and discuss security solutions proposed in the existing literature to counter these threats. Securing an IMD involves three design tradeoffs that require a careful consideration. The first one is security versus accessibility in an emergency situation. We compare the IMD security schemes in the literature in terms of their merits and disadvantages. The second one is the tradeoff between the security schemes for supporting emergency access and those for supporting normal check-up access to the IMDs. This normal check-up access to the IMDs should avoid extra resource consumptions, which is different from the requirement in the emergency access. The third one is between the requirements of strong security and limited resources. The IMD, as a tiny wireless device used for medical purposes, has very limited resources when compared with a generic wireless sensor device/node. We analyze various schemes that aim to conserve the underlying resources of an IMD and also counter battery denial of service attacks from different perspectives. Based on the literature review, we analyze general concerns in the IMD security design from the system engineering point of view, and discuss possible future research directions.

A non-key based security scheme supporting emergency treatment of wireless implants

In this paper, we present a trust establishment and management framework for hierarchical wireless sensor networks. The wireless sensor network architecture we consider consists of a collection of sensor nodes, cluster heads and a base station arranged hierarchically. The framework encompasses schemes for establishing and managing trust between these different entities. We demonstrate that the proposed framework helps to minimize the memory, computation and communication overheads involved in trust management in wireless sensor networks. Our framework takes into account direct and indirect (group) trust in trust evaluation as well as the energy associated with sensor nodes in service selection. It also considers the dynamic aspect of trust by introducing a trust varying function which could be adjusted to give greater weight to the most recently obtained trust values in the trust calculation. The architecture also has the ability to deal with the inter-cluster movement of sensor nodes using a combination of certificate based trust and behaviour based trust.

Truthful Channel Sharing for Self Coexistence of Overlapping Medical Body Area Networks.

Sensor networks offer economically viable solutions for a wide variety of monitoring applications. In surveillance of critical infrastructure such as airports by sensor networks, security becomes a major concern. To resist against malicious attacks, secure communication between severely resource-constrained sensor nodes is necessary while maintaining scalability and flexibility to topology changes. A robust security solution for such networks must facilitate authentication of sensor nodes and the establishment of secret keys among nodes In this paper, we propose a decentralized authentication and key management framework for hierarchical ad hoc sensor networks. This scheme is light weight and energy aware and reduces the communication overhead.