Moonseong Kim

Efficient and anonymous two-factor user authentication in wireless sensor networks: achieving user anonymity with lightweight sensor computation.

A smart-card-based user authentication scheme for wireless sensor networks (hereafter referred to as a SCA-WSN scheme) is designed to ensure that only users who possess both a smart card and the corresponding password are allowed to gain access to sensor data and their transmissions. Despite many research efforts in recent years, it remains a challenging task to design an efficient SCA-WSN scheme that achieves user anonymity. The majority of published SCA-WSN schemes use only lightweight cryptographic techniques (rather than public-key cryptographic techniques) for the sake of efficiency, and have been demonstrated to suffer from the inability to provide user anonymity. Some schemes employ elliptic curve cryptography for better security but require sensors with strict resource constraints to perform computationally expensive scalar-point multiplications; despite the increased computational requirements, these schemes do not provide user anonymity. In this paper, we present a new SCA-WSN scheme that not only achieves user anonymity but also is efficient in terms of the computation loads for sensors. Our scheme employs elliptic curve cryptography but restricts its use only to anonymous user-to-gateway authentication, thereby allowing sensors to perform only lightweight cryptographic operations. Our scheme also enjoys provable security in a formal model extended from the widely accepted Bellare-Pointcheval-Rogaway (2000) model to capture the user anonymity property and various SCA-WSN specific attacks (e.g., stolen smart card attacks, node capture attacks, privileged insider attacks, and stolen verifier attacks).

Route Optimization in Nested NEMO: Classification, Evaluation, and Analysis from NEMO Fringe Stub Perspective

Mobile IP is the basic solution to providing host mobility, whereas network mobility (NEMO) refers to the concept of the collective mobility of a set of nodes. The NEMO basic support protocol has been proposed in IETF as a first solution to the problem of network mobility. The main limitation of this basic solution is that it forces triangular routing, i.e., packets are always forwarded through the home agent (HA), following a suboptimal path. This is because each sub-NEMO obtains a care of address (CoA) that belongs to the home prefix of its parent mobile router. Such a CoA is not topologically meaningful in the current location, since the parent mobile router could also be away from home, and hence, packets addressed to the CoA are forwarded through the HA of the parent NEMO. To solve this problem, various extended proposals, with differing approaches and goals, exist for route optimization (RO) in NEMO applications. Their influences on the RO performance have been evaluated by classifying the detailed operations performed within the nested NEMO network, and then each category is analyzed in detail. The modeling of the detailed RO operation is intended to quantify the tradeoffs between the different approaches in order to provide a basis for the selection decision. In particular, the proposed grouping of the different proposals, based on their address configuration strategy, clarifies their similarities and differences, and provides some useful insights into the various methods that have been developed. In conclusion, it is suggested that, when choosing a solution for deploying NEMO, the designer has to balance his choices between the different pros and cons, and the different cases of application that are derived in this paper.

MCBT: Multi-Hop Cluster Based Stable Backbone Trees for Data Collection and Dissemination in WSNs.

We propose a stable backbone tree construction algorithm using multi-hop clusters for wireless sensor networks (WSNs). The hierarchical cluster structure has advantages in data fusion and aggregation. Energy consumption can be decreased by managing nodes with cluster heads. Backbone nodes, which are responsible for performing and managing multi-hop communication, can reduce the communication overhead such as control traffic and minimize the number of active nodes. Previous backbone construction algorithms, such as Hierarchical Cluster-based Data Dissemination (HCDD) and Multicluster, Mobile, Multimedia radio network (MMM), consume energy quickly. They are designed without regard to appropriate factors such as residual energy and degree (the number of connections or edges to other nodes) of a node for WSNs. Thus, the network is quickly disconnected or has to reconstruct a backbone. We propose a distributed algorithm to create a stable backbone by selecting the nodes with higher energy or degree as the cluster heads. This increases the overall network lifetime. Moreover, the proposed method balances energy consumption by distributing the traffic load among nodes around the cluster head. In the simulation, the proposed scheme outperforms previous clustering schemes in terms of the average and the standard deviation of residual energy or degree of backbone nodes, the average residual energy of backbone nodes after disseminating the sensed data, and the network lifetime.

A Provably-Secure ECC-Based Authentication Scheme for Wireless Sensor Networks

A smart-card-based user authentication scheme for wireless sensor networks (in short, a SUA-WSN scheme) is designed to restrict access to the sensor data only to users who are in possession of both a smart card and the corresponding password. While a significant number of SUA-WSN schemes have been suggested in recent years, their intended security properties lack formal definitions and proofs in a widely-accepted model. One consequence is that SUA-WSN schemes insecure against various attacks have proliferated. In this paper, we devise a security model for the analysis of SUA-WSN schemes by extending the widely-accepted model of Bellare, Pointcheval and Rogaway (2000). Our model provides formal definitions of authenticated key exchange and user anonymity while capturing side-channel attacks, as well as other common attacks. We also propose a new SUA-WSN scheme based on elliptic curve cryptography (ECC), and prove its security properties in our extended model. To the best of our knowledge, our proposed scheme is the first SUA-WSN scheme that provably achieves both authenticated key exchange and user anonymity. Our scheme is also computationally competitive with other ECC-based (non-provably secure) schemes.

Multipath Energy-Aware Routing Protocol in Wireless Sensor Networks

In this paper, we present an energy efficient, scalable, and distributed node disjoint multipath routing algorithm for wireless sensor networks (WSNs). The proposed algorithm, the multipath energy-aware routing protocol (MERP), adjusts traffic flows via a novel load balancing scheme. The MERP has a higher average node energy efficiency, lower control overhead, and a shorter average delay than those of well-known previous works. Moreover, since MERP takes into consideration network reliability, it is useful for delivering data in unreliable environments.

On Efficient Core Selection for Reducing Multicast Delay Variation under Delay Constraints

With the proliferation of multimedia group applications, the construction of multicast trees satisfying the Quality of Service (QoS) requirements is becoming a problem of the prime importance. An essential factor of these real-time application is to optimize the Delay- and delay Variation-Bounded Multicast Tree (DVBMT) problem. This problem is to satisfy the minimum delay variation and the end-to-end delay within an upper bound. The DVBMT problem is known as NP-complete problem. The representative algorithms for the problem are DVMA, DDVCA, and so on. In this paper, we show that the proposed algorithm outperforms any other algorithm. The efficiency of our algorithm is verified through the performance evaluation and the enhancement is up to about 13.5% in terms of the multicast delay variation. The time complexity of our algorithm is O(mn 2 ) which is comparable to well known DDVCA.

Security Weaknesses in Harn-Lin and Dutta-Barua Protocols for Group Key Establishment

Key establishment protocols are fundamental for establishing secure communication channels over public insecure networks. Security must be given the topmost priority in the design of a key establishment protocol. In this work, we provide a security analysis on two recent key establishment protocols: Harn and Lin’s group key transfer protocol and Dutta and Barua’s group key agreement protocol. Our analysis shows that both the Harn-Lin protocol and the Dutta-Barua protocol have a flaw in their design and can be easily attacked. The attack we mount on the Harn-Lin protocol is a replay attack whereby a malicious user can obtain the long-term secrets of any other users. The Dutta-Barua protocol is vulnerable to an unknown key-share attack. For each of the two protocols, we present how to eliminate their security vulnerabilities. We also improve Dutta and Barua’s proof of security to make it valid against unknown key share attacks.

An Energy-Aware Multipath Routing Algorithm in Wireless Sensor Networks

One of the major challenges facing the design of a routing protocol for Wireless Sensor Networks (WSNs) is to find the most reliable path between the source and sink node. Furthermore, a routing protocol for WSN should be well aware of sensor limitations. In this paper, we present an energy efficient, scalable, and distributed node disjoint multipath routing algorithm. The proposed algorithm, the Energy-aware Multipath Routing Algorithm (EMRA), adjusts traffic flows via a novel load balancing scheme. EMRA has a higher average node energy efficiency, lower control overhead, and a shorter average delay than those of well-known previous works. Moreover, since EMRA takes into consideration network reliability, it is useful for delivering data in unreliable environments.

On QoS multicast routing algorithms using k-minimum Steiner trees

In this paper, we study how to obtain Steiner trees appropriately for efficient multicast routing. We first introduce a scheme for generating a new weighted multicast parameter by efficiently combining two independent measures: cost and delay. We call our proposal the Weighted Parameter for Multicast Trees (WPMT) algorithm. The WPMT can be adjusted by the weight @w@?[0,1]. For instance, if @w approaches 0, then the delay of the multicast tree may be relatively lower than the delay of other trees that are obtained as @w approaches 1. Otherwise, as the weight approaches 1 then the cost of the obtained tree may be relatively lower compared with other trees. A case study shows how to find an appropriate Steiner tree for each @w. The simulation results show that the use of the proposed WPMT produces results similar to the k-minimum Steiner tree algorithm. The WPMT can be applied to several existing multicast problems as we describe. We also propose several multicast algorithms using the WPMT in order to solve well-known multicast problems, and compare the proposed algorithms-based the WPMT with representative algorithms for the well-known problems.

On enabling cooperative communication and diversity combination in IEEE 802.15.4 wireless networks using off-the-shelf sensor motes

This paper presents the ‘Generalized Poor Man’s SIMO System’ (gPMSS) which combines two approaches, cooperative communication and diversity combination, to reduce packet losses over links in wireless sensor networks. The proposed gPMSS is distinct from previous cooperative communication architectures in wireless sensor networks which rely on a relay channel, and also distinct from implementations in 802.11 networks that require a wired infrastructure or hardware changes for cooperation. gPMSS foregoes the need for any changes to mote hardware and it works within the current IEEE 802.15.4 standard. We describe the gPMSS protocol that governs the cooperation between receivers. Three variants are evaluated including selection diversity, equal gain and maximal ratio combining. First, we demonstrate gPMSS on bit error traces in a fully reproducible manner. This is followed by an implementation of gPMSS in C# on the .NET Micro Framework edition of the recently released Imote2 mote platform. We demonstrate by means of experiments an increase in the packet reception rate from 22–30% to 73–76%, a relative increase of 150–245%. We also analyzed the power consumed by the transmitter per delivered packet and observe a reduction of up to 68%. We also take into account the retry limit of the IEEE 802.15.4 protocol and demonstrate that gPMSS is able to provide 99% packet delivery at the protocol’s default retry parameters against 65–75% without it.