Sanjeev Setia

LEAP+: Efficient security mechanisms for large-scale distributed sensor networks

We describe LEAP+ (Localized Encryption and Authentication Protocol), a key management protocol for sensor networks that is designed to support in-network processing, while at the same time restricting the security impact of a node compromise to the immediate network neighborhood of the compromised node. The design of the protocol is motivated by the observation that different types of messages exchanged between sensor nodes have different security requirements, and that a single keying mechanism is not suitable for meeting these different security requirements. LEAP+ supports the establishment of four types of keys for each sensor node: an individual key shared with the base station, a pairwise key shared with another sensor node, a cluster key shared with multiple neighboring nodes, and a global key shared by all the nodes in the network. LEAP+ also supports (weak) local source authentication without precluding in-network processing. Our performance analysis shows that LEAP+ is very efficient in terms of computational, communication, and storage costs. We analyze the security of LEAP+ under various attack models and show that LEAP+ is very effective in defending against many sophisticated attacks, such as HELLO flood attacks, node cloning attacks, and wormhole attacks. A prototype implementation of LEAP+ on a sensor network testbed is also described.

An interleaved hop-by-hop authentication scheme for filtering of injected false data in sensor networks

Sensor networks are often deployed in unattended environments, thus leaving these networks vulnerable to false data injection attacks in which an adversary injects false data into the network with the goal of deceiving the base station or depleting the resources of the relaying nodes. Standard authentication mechanisms cannot prevent this attack if the adversary has compromised one or a small number of sensor nodes. In this paper, we present an interleaved hop-by-hop authentication scheme that guarantees that the base station will detect any injected false data packets when no more than a certain number t nodes are compromised. Further, our scheme provides an upper bound B for the number of hops that a false data packet could be forwarded before it is detected and dropped, given that there are up to t colluding compromised nodes. We show that in the worst case B is O(t/sup 2/). Through performance analysis, we show that our scheme is efficient with respect to the security it provides, and it also allows a tradeoff between security and performance.

Establishing pairwise keys for secure communication in ad hoc networks: a probabilistic approach

A prerequisite for a secure communication between two nodes in an ad hoc network is that the nodes share a key to bootstrap their trust relationship. In this paper, we present a scalable and distributed protocol that enables two nodes to establish a pairwise shared key on the fly, without requiring the use of any on-line key distribution center. The design of our protocol is based on a novel combination of two techniques - probabilistic key sharing and threshold secret sharing. Our protocol is scalable since every node only needs to possess a small number of keys, independent of the network size, and it is computationally efficient because it only relies on symmetric key cryptography based operations. We show that a pairwise key established between two nodes using our protocol is secure against a collusion attack by up to a certain number of compromised nodes. We also show through a set of simulations that our protocol can be parameterized to meet the desired levels of performance, security and storage for the application under consideration.

Kronos: a scalable group re-keying approach for secure multicast

The authors describe a novel approach to scalable group re-keying for secure multicast. Our approach, which we call Kronos, is based upon the idea of periodic group re-keying. We first motivate our approach by showing that if a group is re-keyed on each membership change, as the size of the group increases and/or the rate at which members leave and join the group increases, the frequency of rekeying becomes the primary bottle neck for scalable group re-keying. In contrast, Kronos can scale to handle large and dynamic groups because the frequency of re-keying is independent of the size and membership dynamics of the group. Next, we describe how Kronos can be used in conjunction with distributed key management frameworks such as IGKMP (T. Hardjono et al., 1998) that use a single group-wide session key for encrypting communications between members of the group. Using a detailed simulation, we compare the performance tradeoffs between Kronos and other key management protocols.

Availability and utility of idle memory in workstation clusters

In this paper, we examine the availability and utility of idle memory in workstation clusters. We attempt to answer the following questions. First, how much of the total memory in a workstation cluster can be expected to be idle? This provides an estimate of the opportunity for hosting guest data. Second, how much memory can be expected to be idle on individual workstations? This helps determine the recruitment policy – how much memory should be recruited on individual hosts? Third, what is the distribution of memory idle-times? This indicates how long guest data can be expected to survive; applications that access their data-sets frequently within the expected life-time of guest data are more likely to benefit from exploiting idle memory. Fourth, how much performance improvement can be achieved for off-the-shelf clusters without customizing the operating system and/or the processor firmware? Finally, how long and how frequently might a user have to wait to reclaim her machine if she volunteers to host guest pages on her machine? This helps answer the question of social acceptability. To answer the questions relating to the availability of idle memory, we have analyzed two-week long traces from two workstation pools with different sizes, locations, and patterns of use. To evaluate the expected benefits and costs, we have simulated five data-intensive applications (0.5 GB-5 GB) on these workstation pools.

Secure Data Aggregation in Wireless Sensor Networks

In a large sensor network, in-network data aggregation significantly reduces the amount of communication and energy consumption. Recently, the research community has proposed a robust aggregation framework called synopsis diffusion which combines multipath routing schemes with duplicate-insensitive algorithms to accurately compute aggregates (e.g., predicate Count, Sum) in spite of message losses resulting from node and transmission failures. However, this aggregation framework does not address the problem of false subaggregate values contributed by compromised nodes resulting in large errors in the aggregate computed at the base station, which is the root node in the aggregation hierarchy. This is an important problem since sensor networks are highly vulnerable to node compromises due to the unattended nature of sensor nodes and the lack of tamper-resistant hardware. In this paper, we make the synopsis diffusion approach secure against attacks in which compromised nodes contribute false subaggregate values. In particular, we present a novel lightweight verification algorithm by which the base station can determine if the computed aggregate (predicate Count or Sum) includes any false contribution. Thorough theoretical analysis and extensive simulation study show that our algorithm outperforms other existing approaches. Irrespective of the network size, the per-node communication overhead in our algorithm is O(1).

Efficient Distributed Detection of Node Replication Attacks in Sensor Networks

Wireless sensor nodes lack hardware support for tamper- resistance and are often deployed in unattended environments, thus leaving them vulnerable to capture and compromise by an adversary. In a node replication attack, an adversary uses the credentials of a compromised node to surreptitiously introduce replicas of that node into the network. These replicas are then used to launch a variety of attacks that subvert the goal of the sensor application, and the operation of the underlying protocols. We present a novel distributed approach called Localized Multicast for detecting node replication attacks. We evaluate the performance and security of our approach both theoretically and via simulation. Our results show that Localized Multicast is more efficient than previous distributed approaches in terms of communication and memory costs. Further, in our approach, the probability of detecting node replicas is much higher than that achieved in previous distributed protocols.

LHAP: a lightweight hop-by-hop authentication protocol for ad-hoc networks

Most ad hoc networks do not implement any network access control, leaving these networks vulnerable to resource consumption attacks where a malicious node injects packets into the network with the goal of depleting the resources Of the nodes relaying the packets. To thwart or prevent such attacks, it is necessary to employ authentication mechanisms that ensure that only authorized nodes can inject traffic into the network. In this paper we present LHAP a scalable and light-weight authentication protocol for ad hoc networks. LHAP is based on two techniques: (i) hop-by-hop authentication for verifying the authenticity of all the packets transmitted in the network and (ii) one-way key chain and TESLA for packet authentication and for reducing the overhead for establishing trust among nodes. We analyze the security of LHAP and show LHAP is a lightweight security protocol through detailed performance analysis.

GKMPAN: an efficient group rekeying scheme for secure multicast in ad-hoc networks

We present GKMPAN, an efficient and scalable group rekeying protocol for secure multicast in ad hoc networks. Our protocol exploits the property of ad hoc networks that each member of a group is both a host and a router, and distributes the group key to member nodes via a secure hop-by-hop propagation scheme. A probabilistic scheme based on predeployed symmetric keys is used for implementing secure channels between members for group key distribution. GKMPAN also includes a novel distributed scheme for efficiently updating the predeployed keys. GKMPAN has three attractive properties. First, it is significantly more efficient than group rekeying schemes that were adapted from those proposed for wired networks. Second, GKMPAN has the property of partial statelessness; that is, a node can decode the current group key even if it has missed a certain number of previous group rekeying operations. This makes it very attractive for ad hoc networks where nodes may lose packets due to transmission link errors or temporary network partitions. Third, in GKMPAN the key server does not need any information about the topology of the ad hoc network or the geographic location of the members of the group. We study the security and performance of GKMPAN through detailed analysis and simulation.

Localized Multicast: Efficient and Distributed Replica Detection in Large-Scale Sensor Networks

Due to the poor physical protection of sensor nodes, it is generally assumed that an adversary can capture and compromise a small number of sensors in the network. In a node replication attack, an adversary can take advantage of the credentials of a compromised node to surreptitiously introduce replicas of that node into the network. Without an effective and efficient detection mechanism, these replicas can be used to launch a variety of attacks that undermine many sensor applications and protocols. In this paper, we present a novel distributed approach called Localized Multicast for detecting node replication attacks. The efficiency and security of our approach are evaluated both theoretically and via simulation. Our results show that, compared to previous distributed approaches proposed by Parno et al., Localized Multicast is more efficient in terms of communication and memory costs in large-scale sensor networks, and at the same time achieves a higher probability of detecting node replicas.