Leonardo Oliveira - Academia.edu (original) (raw)

Papers by Leonardo Oliveira

Fifth Annual IEEE International Conference on Pervasive Computing and Communications Workshops (PerComW'07), 2007

Signal Processing, 2007

Clustered sensor networks have recently been shown to increase system throughput, decrease system... more Clustered sensor networks have recently been shown to increase system throughput, decrease system delay, and save energy while performing data aggregation. Whereas those with rotating cluster heads, such as LEACH (low-energy adaptive clustering hierarchy), have also advantages in terms of security, the dynamic nature of their communication makes most existing security solutions inadequate for them. In this paper, we investigate the problem of adding security to hierarchical (cluster-based) sensor networks where clusters are formed dynamically and periodically, such as LEACH. For this purpose, we show how random key predistribution, widely studied in the context of flat networks, and μTESLAμTESLA, a building block from SPINS, can be both used to secure communications in this type of network. We present our solution, and provide a detailed analysis of how different values for the various parameters in such a system impact a hierarchical network in terms of security and energy efficiency. To the best of our knowledge, ours is the first that investigates security in hierarchical WSNs with dynamic cluster formation.

International Journal of Security and Networks, 2007

Journal of Parallel and Distributed Computing, 2005

Mobile ad hoc networks (MANETs) and peer-to-peer (P2P) applications are emerging technologies bas... more Mobile ad hoc networks (MANETs) and peer-to-peer (P2P) applications are emerging technologies based on the same paradigm: the P2P paradigm. Motivated, respectively, by the necessity of executing applications in environments with no previous infra-structure and the demand for applications that share files or distribute processing through the Internet, MANETs and P2P applications have received some interest from research community. As a characteristic of the distributed model, which they follow, such technologies face a difficult task of routing requests in a decentralized environment. In this paper, we conducted a detailed study of a Gnutella-like application running over a MANET where three different protocols were considered. The results show that each protocol that were analyzed performed well in under some conditions and for some metrics, while had drawbacks in others.

Integrated Network Management, 2005

Wireless sensor networks (WSNs) are ad hoc networks comprised mainly of small sensor nodes with l... more Wireless sensor networks (WSNs) are ad hoc networks comprised mainly of small sensor nodes with limited resources, and can be used to monitor areas of interest. In this paper, we propose a solution for securing heterogeneous hierarchical WSNs with an arbitrary number of levels. Our solution relies exclusively on symmetric key schemes, is highly distributed, and takes into account node interaction patterns that are specific to clustered WSNs.

Network Computing and Applications, 2006

Clustered sensor networks have been shown to increase system throughput, decrease system delay, a... more Clustered sensor networks have been shown to increase system throughput, decrease system delay, and save energy. While those with rotating cluster heads, such as LEACH, have also advantages in terms of security, the dynamic nature of their communication makes most existing security solutions inadequate for them. In this paper, we show how random key predistribution, widely studied in the context of flat networks, can be used to secure communication in hierarchical (cluster-based) protocols such as LEACH. To our knowledge, it is the first work that investigates random key predistribution as applied to hierarchical WSNs

Workshop on Wireless Mobile Multimedia, 2005

Both mobile ad hoc networks (MANETs) and peer-to-peer (P2P) networks are decentralized and self-o... more Both mobile ad hoc networks (MANETs) and peer-to-peer (P2P) networks are decentralized and self-organizing networks with dynamic topology and are responsible for routing queries in a distributed environment. Because MANETs are composed of resource-constrained devices susceptible to faults, whereas P2P networks are fault-tolerant, P2P networks are the ideal data sharing system for MANETs. We have conducted an evaluation of two approaches for P2P content discovery running over a MANET. The first, based on unstructured P2P networks, relies on controlled flooding, while the second, based on structured P2P networks, uses distributed indexing to optimize searches. We use simulations to evaluate the effect of network size, mobility, channel error rates, network workload, and application dynamics in the performance of P2P protocols over MANETs. Results show that unstructured protocols are the most resilient, although at higher energy and delay costs. Structured protocols, conversely, consume less energy and are more appropriate for MANETs where topology is mostly static.

IEEE International Conference on Pervasive Computing and Communications, 2007

... idA, encPA (idM | idA | kM,A) N → B : idB, encPB (idN | idB | kN,B) ... Secure exchange of ..... more ... idA, encPA (idM | idA | kM,A) N → B : idB, encPB (idN | idB | kN,B) ... Secure exchange of ... usingkey k enck() : Encryption computed using key k m : Message information ⇒, →: Broadcast and unicast ... In the context of WSNs, recall from Section 3 that we envision that nodes will use ...

Computer Communications, 2008

Key distribution in wireless sensor networks (WSNs) is challenging. Symmetric cryptosystems can p... more Key distribution in wireless sensor networks (WSNs) is challenging. Symmetric cryptosystems can perform it efficiently, but they often do not provide a perfect trade-off between resilience and storage. Further, even though conventional public key and elliptic curve cryptosystem are computationally feasible on sensor nodes, protocols based on them are not. They require exchange and storage of large keys and certificates, which is expensive. Using pairing-based cryptography (PBC) protocols, conversely, parties can agree on keys without any interaction. In this work, we (i) show how security in WSNs can be bootstrapped using an authenticated identity based non-interactive protocol and (ii) present TinyPBC, to our knowledge, the most efficient implementation of PBC primitives for an 8-bit processor. TinyPBC is able to compute pairings in about 5.5s on an ATmega128L clocked at 7.3828-MHz (the MICA2 and MICAZ node microcontroller).

Computer Communications, 2009

Content dissemination over mobile ad hoc networks (MANETs) is usually performed using peer-to-pee... more Content dissemination over mobile ad hoc networks (MANETs) is usually performed using peer-to-peer (P2P) networks due to its increased resiliency and efficiency when compared to client–server approaches. P2P networks are usually divided into two types, structured and unstructured, based on their content discovery strategy. Unstructured networks use controlled flooding, while structured networks use distributed indexes. This article evaluates the performance of these two approaches over MANETs and proposes modifications to improve their performance. Results show that unstructured protocols are extremely resilient, however they are not scalable and present high energy consumption and delay. Structured protocols are more energy-efficient, however they have a poor performance in dynamic environments due to the frequent loss of query messages. Based on those observations, we employ selective forwarding to decrease the bandwidth consumption in unstructured networks, and introduce redundant query messages in structured P2P networks to increase their success ratio.

Network Computing and Applications, 2007

After a few years of intense research, wireless sensor networks (WSNs) still demand new secure an... more After a few years of intense research, wireless sensor networks (WSNs) still demand new secure and cryptographic schemes. On the other hand, the advent of cryptography from pairings has enabled a wide range of novel cryptosystems. In this work we present TinyTate, the first known implementation of pairings for sensor nodes based on the 8-bit/7.3828-MHz ATmega128L microcontroller (e.g., MICA2 and MICAz motes). We then conclude that cryptography from pairings is indeed viable in resource-constrained nodes.

International Workshop on Modeling Analysis and Simulation of Wireless and Mobile Systems, 2004

International Conference on Networking, 2005

Wireless sensor networks are ad hoc networks comprised mainly of small sensor nodes with limited ... more Wireless sensor networks are ad hoc networks comprised mainly of small sensor nodes with limited resources, and are rapidly emerging as a technology for large-scale, low-cost, automated sensing and monitoring of different environments of interest. Cluster-based communication has been proposed for these networks for various reasons such as scalability and energy efficiency. In this paper, we investigate the problem of adding security to cluster-based communication protocols for homogeneous wireless sensor networks consisting of sensor nodes with severely limited resources, and propose a security solution for LEACH, a protocol where clusters are formed dynamically and periodically. Our solution uses building blocks from SPINS, a suite of highly optimized security building blocks that rely solely on symmetric-key methods; is lightweight and preserves the core of the original LEACH.

Wireless sensor networks, 2008

Advances in Mathematics of Communications, 2010

Computer Communications, 2011