As sensor networks edge closer towards wide-spread deployment, security issues become a central concern. So far, the main research focus has been on making sensor networks feasible and useful, and less emphasis was placed on security. We design a suite of security...

Key establishment in sensor networks is a challenging problem because asymmetric key cryptosystems are unsuitable for use in resource constrained sensor nodes, and also because the nodes could be physically compromised by an adversary. We present three new mechanisms for key establishment using the framework of pre-distributing a random set of keys to each node. First, in the q-composite keys scheme, we trade off the unlikeliness of a large-scale network attack in order to significantly strengthen random key predistribution’s strength against smaller-scale attacks. Second, in the multipath-reinforcement scheme, we show how to strengthen the security between any two nodes by leveraging the security of other links. Finally, we present the random-pairwise keys scheme, which perfectly preserves the secrecy of the rest of the network when any node is captured, and also enables node-to-node authentication and quorum-based revocation. 1 We gratefully acknowledge funding support for this research. This work was made possible in part by a gift from Bosch Research. This paper represents the opinions of the authors and does not necessarily represent the opinions or policies, either expressed or implied, of Bosch Research. Keywords: Sensor network, key distribution, random key predistribution, key establishment, node

To achieve security in wireless sensor networks, it is important to be able to encrypt messages sent among sensor nodes. Keys for encryption purposes must be agreed upon by communicating nodes. Due to resource constraints, achieving such key agreement in wireless sensor networks is non-trivial. Many key agreement schemes used in general networks, such as 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. Recently, a random key predistribution scheme and its improvements have been proposed.

Abstract — The establishment of shared cryptographic keys between communicating neighbor nodes in sensor networks is a challenging problem due to the unsuitability of asymmetric key cryptography for these resource-constrained platforms. A range of symmetric-key distribution protocols exist, but these protocols do not scale effectively to large sensor networks. For a given level of security, each protocol incurs a linearly increasing overhead in either communication cost per node or memory per node. We describe Peer Intermediaries for Key Establishment (PIKE), a class of key-establishment protocols that involves using one or more sensor nodes as a trusted intermediary to facilitate key establishment. We show that, unlike existing key-establishment protocols, both the communication and memory overheads of PIKE protocols scale sub-linearly (O ( √ n)) with the number of nodes in the network yet achieving higher security against node compromise than other protocols. I.

Abstract. In this paper we present a new class of attacks against RSA with low encrypting exponent. The attacks enable the recovery of plain-text messages from their ciphertexts and a known polynomial relation-ship among the messages, provided that the ciphertexts were created using the same RSA public key with low encrypting exponent. 1

To achieve security in wireless sensor networks, it is important to be able to encrypt messages sent among sensor nodes. Keys for encryption purposes must be agreed upon by communicating nodes. Due to resource constraints, achieving such key agreement in wireless sensor networks is non-trivial. Many key agreement schemes used in general networks, such as 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. Recently, a random key pre-distribution scheme and its improvements have been proposed. A common assumption made by these random key pre-distribution schemes is that no deployment knowledge is available. Noticing that in many practical scenarios, certain deployment knowledge may be available a priori, we propose a novel random key pre-distribution scheme that exploits deployment knowledge and avoids unnecessary key assignments. We show that the performance (including connectivity, memory usage, and network resilience against node capture) of sensor networks can be substantially improved with the use of our proposed scheme. The scheme and its detailed performance evaluation are presented in this paper. I.

This chapter reviews several key distribution and key establishment techniques for sensor networks. We briefly describe several well known key establishment schemes, and provide a more detailed discussion of our work on random key distribution in particular.

Wireless sensor networks are increasingly being used in applications where the communication between nodes needs to be protected from eavesdropping and tampering. Such protection is typically provided using techniques from symmetric key cryptography. The protocols in this domain suffer from one or more of the following problems ⎯ weak security guarantees if some nodes are compromised, lack of scalability, high energy overhead for key management, and increased end-to-end data latency. In this paper, we propose a protocol called SECOS that mitigates these problems in static sensor networks. SECOS divides the sensor field into control groups each with a control node. Data exchange between nodes within a control group happens through the mediation of the control head which provides the common key. The keys are refreshed periodically and the control nodes are changed periodically to enhance security. SECOS enhances the survivability of the network by handling compromise and failures of control nodes. It provides the guarantee that the communication between any two sensor nodes remains secure despite the compromise of any number of other nodes in the network. The experiments based on a simulation model show a seven time reduction in energy overhead and a 50 % reduction in latency compared to SPINS, which is one of the state-of-the-art protocols for key management in sensor networks.

. Mobile communication is more vulnerable to security attacks such as interception and unauthorized access than fixed network communication. To overcome these problems, many protocols have been proposed to provide a secure channel between a mobile station and a base station. However, the public-key based protocols are not fully utilized due to the poor computing power and the small battery capacity of a mobile station. In this paper, we propose some techniques accelerating public-key based key establishment protocols between a mobile station and a base station. The proposed techniques enable a mobile station to borrow computing power from a base station without revealing its secret information. The proposed schemes accelerate the previous protocols up to five times and reduce the amount of power consumption of a mobile station. The proposed schemes use SASC (Server-Aided Secret Computation) protocols that are used for smart cards. Our insight is that the unbalanced prope...

This thesis is dedicated to my parents ii ACKNOWLEDGMENTS Praises are due to Allah, the Almighty, who has bestowed upon me uncountable bounties without which this work would have never been accomplished. Then, I am obliged to express my sincere gratitude and appreciation to those individuals who advised and supported me throughout my work. First of all, I am indebted to my advisors, Professor Saurabh Bagchi and Professor Ness B. Shroff whose individual recommendations and guidance were the cure for several obstacles during preparation and planning as well as during writing this dissertation. As my graduate study advisors, their insights and comments have enriched my knowledge not only in this piece of work but also throughout my doctoral study. I am also thankful to my committee members, Professor Arif Ghafoor and Professor Mike Attalah for serving in my committee despite their full and busy schedule. I appreciate all their valuable comments and supportive attitudes.