Jie Wu | Temple University (original) (raw)

Papers by Jie Wu

International Journal of Foundations of Computer Science, 2003

We propose a general framework for broadcasting in ad hoc networks through self-pruning. The appr... more We propose a general framework for broadcasting in ad hoc networks through self-pruning. The approach is based on selecting a small subset of hosts (also called nodes) to form a forward node set on carry out a broadcast process. Each node, upon receiving a broadcast packet, determines whether to forward the packet or not based on two neighborhood coverage conditions proposed in this paper. These coverage conditions depend on neighbor connectivity and history of visited nodes, and in general, resort to global network information. Using local information such as k-hop neighborhood information, the forward node set is selected through a distributed and local pruning process. The forward node set can be constructed and maintained through either a proactive process (i.e., "up-to-date") or a reactive process (i.e., "on-the-fly"). Several existing broadcast algorithms can be viewed as special cases of the coverage conditions with k-hop neighborhood information. Simulati...

2018 IEEE International Conference on Communications (ICC), 2018

2019 IEEE 16th International Conference on Mobile Ad Hoc and Sensor Systems Workshops (MASSW), 2019

A variety of architectures have been designed or repurposed for the task of facial forgery detect... more A variety of architectures have been designed or repurposed for the task of facial forgery detection. While many of these designs have seen great success, they largely fail to address challenges these models may face in practice. A major challenge is posed by generality, wherein models must be prepared to perform in a variety of domains. In this paper, we investigate the ability of state-of-the-art facial forgery detection architectures to generalize. We first propose two criteria for generality: reliably detecting multiple spoofing techniques and reliably detecting unseen spoofing techniques. We then devise experiments which measure how a given architecture performs against these criteria. Our analysis focuses on two state-of-the-art facial forgery detection architectures, MesoNet and XceptionNet, both being convolutional neural networks (CNNs). Our experiments use samples from six state-of-the-art facial forgery techniques: Deepfakes, Face2Face, FaceSwap, GANnotation, ICface, and X2Face. We find MesoNet and XceptionNet show potential to generalize to multiple spoofing techniques but with a slight trade-off in accuracy, and largely fail against unseen techniques. We loosely extrapolate these results to similar CNN architectures and emphasize the need for better architectures to meet the challenges of generality.

J. Inf. Sci. Eng., 2007

While restricted rule-k has been succeeded in generating a connected dominating set (CDS) of smal... more While restricted rule-k has been succeeded in generating a connected dominating set (CDS) of small size, not much theoretical analysis on the size has been done. In this paper, an analysis on the expected size of a CDS generated by such algorithm and its relation to different node density is presented. Assume N nodes are deployed uniformly and randomly in a square of size L(subscript N)×L(subscript N) (where N and L(subscript N)→∞∞); three results are obtained. (1) It is proved that the node degree distribution of such a network follows a Poisson distribution. (2) The expected size of a CDS that is derived by the restricted pruning rule-k is a decreasing function with respect to the node density (The Symbol is abbreviated). For (The Symbol is abbreviated)≥30. it is found that the expected size is close to N/(The Symbol is abbreviated). (3) It is proved that the lower bound on the expected size of a CDS for a Poissonian network of node density (The Symbol is abbreviated) is given b...

Cyber-Physical Systems, 2021

Gaining a better understanding of the relationship between attackers and defenders in cybersecuri... more Gaining a better understanding of the relationship between attackers and defenders in cybersecurity domains in order to protect computer systems is of great importance. From the defender's side, it is critical to choose the best reaction to maintain the system in a safe state, based on a given estimate of the attacker. One of the main challenges is that the defender may not be able to correctly detect a current attack due to incomplete and noisy information presented to them. Another important factor in the attack-defense interaction is the limited budget of both attackers and defenders. Therefore, both sides want to perform the best actions to maximize their gains. This paper focuses on an approach based on interactions between the attacker and defender by considering the problem of uncertainty and limitation of resources for the defender, given that the attacker's actions are given in all states of a Markov chain. The best actions by the defender can be characterized by a Markov Decision Process in a case of partially observability and importance of time in the expected reward, which is a Partially Observable Semi-Markov Decision model. Our simulation on a trace-based data set demonstrates that the proposed approach handles analyzing interactions of the attacker and defender with the limited budgets for both sides along with imperfect information for the defender.

IEEE Transactions on Network and Service Management, 2019

Changes in network state are a common source of instability in networks. An update event typicall... more Changes in network state are a common source of instability in networks. An update event typically involves multiple flows that compete for network resources at the cost of rescheduling and migrating some existing flows. Previous network updating schemes tackle such flows independently, rather than as the entity of an update event. They only optimize the flow-level metrics for the flows involved in an update event. In this paper, we present an event-level abstraction of network update that groups flows of an update event and schedules them together to minimize the event completion time (ECT). We then study the scheduling problem of multiple update events for achieving high scheduling efficiency and preserving fairness. The designed least migration traffic first (LMTF) method schedules all update events in the FIFO order, but it avoids head-of-line blocking by randomly finetuning the queue order of some events. It can considerably reduce the update cost, the average, and tail ECTs of update events. In addition, we design a general parallel-LMTF (P-LMTF) method to guarantee fairness and further improve scheduling efficiency among update events. This improves the LMTF method by opportunistically updating multiple events simultaneously. The comprehensive evaluation results indicate that the average ECT of our approach is up to 10× faster than the flow-level scheduling method for network update events, and its tail ECT is up to 6× faster. Our P-LMTF method incurs a 75% reduction in the average ECT compared with FIFO when the network utilization exceeds 70%, and it achieves a 42% reduction in tail ECT.

Journal of Parallel and Distributed Computing, 2018

h i g h l i g h t s • Consider the practical mutually exclusive data dissemination in opportunist... more h i g h l i g h t s • Consider the practical mutually exclusive data dissemination in opportunistic mobile networks. • An optimal expectation algorithm with topology information is proposed. • A probability-based algorithm based on k-hop forwarding paths is proposed. • A distributed algorithm with one hop information is proposed. • Experiments are based on two real human datasets.

IEEE Transactions on Mobile Computing, 2017

Delay tolerant network (DTN) routing provides a communication primitive in intermittently disconn... more Delay tolerant network (DTN) routing provides a communication primitive in intermittently disconnected networks, such as battlefield communications and human-contact networks. In these applications, the anonymity preserving mechanism, which hides the identities of communicating parties, plays an important role as a defense against cyber and physical attacks. While anonymous routing protocols for DTNs have been proposed in the past, to the best of our knowledge, there is no work that emphasizes the theoretical aspects. In this paper, we first design an abstract of anonymous routing protocols for DTNs and augment the existing solution with multi-copy message forwarding. Then, we construct simplified mathematical models, which can be used to understand the fundamental performance and security guarantees of onion-based anonymous routing in DTNs. The numerical and simulation results using randomly generated contact graphs and the real traces demonstrate that our models provide very close approximations to the performance of the anonymous DTN routing protocol.

2016 IEEE 36th International Conference on Distributed Computing Systems (ICDCS), 2016

2015 IEEE 12th International Conference on Mobile Ad Hoc and Sensor Systems, 2015

Recent advances in energy transfer technology is boosting the development of renewable sensor net... more Recent advances in energy transfer technology is boosting the development of renewable sensor networks. To sustain such a network, a mobile robot travels from node to node to recharge each sensor before its battery runs out. Consider each node's recharge as a real-time task; the robot needs to serve these tasks by their deadlines. This represents a class of challenging mobility scheduling problems, where the nodes' deadlines and spatial distribution are often at odds with each other. In this paper, we focus on the scenario where nodes have heterogeneous energy consumption rates, and our goal is to maximize the percentage of nodes alive. We formulate this scheduling problem and prove its NP-completeness. To solve this problem, we propose a spatial dependent task scheduling algorithm, which quantifies the impact of scheduling proximate tasks on the other tasks. With extensive simulations, we reveal the trade-offs of existing solutions under a wide range of network scenarios. Our evaluation results show that our algorithms out-perform classical TSP scheduler by up to 10% and 85% in terms of coverage ratio and average tardiness, respectively.

2015 IEEE 16th International Symposium on A World of Wireless, Mobile and Multimedia Networks (WoWMoM), 2015

As the popularity of wireless devices (e.g. smartphones and tablets) increases, watching videos o... more As the popularity of wireless devices (e.g. smartphones and tablets) increases, watching videos over the Internet is becoming a main device application. Two important challenges in wireless communications are the unreliability of the wireless links and the interference among the wireless links. In order to exploit reliable video multicast, forward error correction and network coding can be used. In this paper, we propose a reliable video multicast method over wireless networks with multiple Access Points (AP). Using multiple APs, the multicast receivers can benefit from both spatial and time diversities, which results in more reliable transmissions. In order to utilize the shared wireless network efficiently, we propose a resource allocation algorithm. We show that a systematic concurrent transmission of the interfering AP nodes can enhance the total system performance and provide fairness to the client nodes. Therefore, in contrast with the previous resource sharing methods, which only permit the AP nodes that do not interfere with each other to transmit concurrently, we allow the interfering nodes to transmit concurrently, and we propose a two-phase resource allocation algorithm to further enhance the system utility. We show the effectiveness of our proposed method through extensive simulations.

Frontiers of Computer Science in China, 2011

Web-based social networking is increasingly gaining popularity due to the rapid development of co... more Web-based social networking is increasingly gaining popularity due to the rapid development of computer networking technologies. However, social networking applications still cannot obtain a wider acceptance by many users due to some unresolved issues, such as trust, security, and privacy. Trust, in social networks, mainly studies whether a remote user, called a trustee, behaves as expected by an interested user, called a trustor, through other users, called recommenders. A trusted graph consists of a trustor, a trustee, recommenders, and trust relationships among them. In this paper, we propose a novel FlowTrust approach to model a trusted graph with network flows, and evaluate the maximum amount of trust that can flow among a trusted graph using the network flow theory. FlowTrust supports multidimensional trust. We use trust value and confidence level as two trust factors. We deduce four trust metrics from these two trust factors, which are maximum flow of trust value, maximum flow of confidence level, minimum cost of uncertainty with maximum flow of trust value, and minimum cost of untrust with maximum flow of confidence level. We also propose three FlowTrust algorithms to normalize these four trust metrics. We compare our proposed FlowTrust approach with existing RelTrust and CircuitTrust approaches. We have shown that all three approaches are comparable to each other in terms of the inferred trust values. Therefore, FlowTrust is the best of the three since it also supports multidimensional trust.

2009 IEEE 6th International Conference on Mobile Adhoc and Sensor Systems, 2009

A key challenge of message forwarding in delay tolerant networks (DTNs) is to increase delivery r... more A key challenge of message forwarding in delay tolerant networks (DTNs) is to increase delivery rate and decrease delay and cost. When information for future connectivity is not available, opportunistic routing is preferred in DTNs in which messages are forwarded opportunistic/non-deterministically to nodes with higher delivery probabilities. Many real objects have non-deterministic but cyclic motions; however, few prior research work has investigated a multi-copy opportunistic message forwarding algorithm for DTNs with cyclic mobility patterns. Cyclic MobiSpace is a generalization of DTNs with cyclic mobility patterns. In this paper, we propose an optimal opportunistic multi-copy message forwarding algorithm in Cyclic MobiSpace. Specifically, we model a Cyclic MobiSpace as a state-space graph, and apply the optimal stopping rule to derive a delivery metric for each message state using the state-space graph. We perform simulation to compare our protocol, called Multicopy Forwarding in Cyclic MobiSpace (MFC), against existing forwarding protocols, using UMassDieselNet trace. Simulation results show that, MFC delivers up to 100% more messages than the compared forwarding protocols under the same delay and forwarding cost.

2007 IEEE International Conference on Communications, 2007

Securing broadcast communication over sensor networks is an important research challenge. In gene... more Securing broadcast communication over sensor networks is an important research challenge. In general, broadcast communication has two important metrics: security and reliability. Though the reliability metric has drawn sufficient attention in the research community, the security metric has failed to do so. In this paper we address both these metrics with more emphasis on the former and address the Denial-of-Broadcast Message attacks (DoBM) in sensor networks. We propose a tree based model called the k-parent Flooding Tree Model (k-FTM) and present algorithms for the construction of k-FTM. The proposed k-FTM is robust against DoBM and enables the base station to detect DoBM very efficiently even in the presence of a prudent adversary who focuses on remaining undetected by causing damage below the detection threshold. k-FTM is, to our best knowledge, the first fault tolerant tree model, that is both secure and reliable. We confirm through simulations that our model achieves detection rates close to a static tree and a broadcast reliability close to blind flooding.

2012 IEEE Global Communications Conference (GLOBECOM), 2012

Battery-powered wireless sensor devices need to be charged to provide the desired functionality a... more Battery-powered wireless sensor devices need to be charged to provide the desired functionality after deployment. Task or even device failures can occur if the voltage of the battery is low. It is very important to schedule the recharge of batteries in time. Existing battery scheduling algorithms usually charge a battery when its voltage drops below a fixed level. Such algorithms work well when the workloads are predictable. However, workloads of wireless sensors can be highly bursty, i.e., extensive sensing and communication tasks usually occur in a very short time period. If such a bursty workload occurs when the battery voltage is low, the battery energy can be depleted very quickly, resulting in system task failures before the device can be recharged. To deal with unpredictable bursty workloads, we investigate battery characteristics with different workloads via experiments. Based on the empirical results, we build an adaptive linear model and propose a feedback control based battery charge scheduling algorithm. This algorithm dynamically adjusts the battery charge threshold for recharge scheduling, adapting to bursty workloads. We have tested our algorithms in extensive simulations with traces obtained from real experiments. Evaluation results show that our algorithms can adapt to bursty workloads. Compared to existing algorithms, our algorithm achieves a 68.26% lower task failure ratio with a 3.45% sacrifice on system lifetime under bursty workloads.

Journal of Parallel and Distributed Computing, 2012

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Journal of Network and Computer Applications, 2007

In mobile ad hoc networks, due to unreliable wireless media, host mobility and lack of infrastruc... more In mobile ad hoc networks, due to unreliable wireless media, host mobility and lack of infrastructure, providing secure communications is a big challenge in this unique network environment. Usually cryptography techniques are used for secure communications in wired and wireless networks. The asymmetric cryptography is widely used because of its versatileness (authentication, integrity, and confidentiality) and simplicity for key distribution. However, this approach relies on a centralized framework of public key infrastructure (PKI). The symmetric approach has computation efficiency, yet it suffers from potential attacks on key agreement or key distribution. In fact, any cryptographic means is ineffective if the key management is weak. Key management is a central aspect for security in mobile ad hoc networks. In mobile ad hoc networks, the computational load and complexity for key management is strongly subject to restriction of the node's available resources and the dynamic nature of network topology. In this paper, we propose a secure and efficient key management framework (SEKM) for mobile ad hoc networks. SEKM builds PKI by applying a secret sharing scheme and an underlying multicast server group. In SEKM, the server group creates a view of the certification authority (CA) and provides certificate update service for all nodes, including the servers themselves. A ticket scheme is introduced for efficient certificate service. In addition, an efficient server group updating scheme is proposed. The secret can be recovered by combining k pieces based on Lagrange interpolation. Secret splitting, reconstruction, and verification is quickly reviewed in Section 3. These cryptography tools are widely used in wired and wireless networks, obviously they could also be used in mobile ad hoc networks. Key management is a basic part of any secure communication. Most cryptosystems rely on some underlying secure, robust, and efficient key management system. Key management deals with key generation, storage, distribution, updating, revocation, and certificate service, in accordance with security policies. Key management primitives and a trust model are presented in Section 3. The outline of key management is described below. First, secrecy of key itself must be assured in the local host system. Second, secure network communications involve key distribution procedure between communication parties, in which the key may be transmitted through insecure channels. Key confidentiality, integrity, and ownership must be enforced in the whole procedure. Third, a framework of trust relationships needs to be built for authentication of key ownership. While some frameworks are based on a centralized Trusted Third Party (TTP), others could be fully distributed. For example, a Certificate Authority is the TTP in PKI, Key Distribution Center (KDC) is the TTP in the symmetric system, meanwhile in PGP, no such a trusted entity is assumed.

Journal of Network and Computer Applications, 2012

Cloud storage services enable users to remotely access data in a cloud anytime and anywhere, usin... more Cloud storage services enable users to remotely access data in a cloud anytime and anywhere, using any device, in a pay-as-you-go manner. Moving data into a cloud offers great convenience to users since they do not have to care about the large capital investment in both the deployment and management of the hardware infrastructures. However, allowing a cloud service provider (CSP), whose purpose is mainly for making a profit, to take the custody of sensitive data, raises underlying security and privacy issues. To keep user data confidential against an untrusted CSP, a natural way is to apply cryptographic approaches, by disclosing the data decryption key only to authorized users. However, when a user wants to retrieve files containing certain keywords using a thin client, the adopted encryption system should not only support keyword searching over encrypted data, but also provide high performance. In this paper, we investigate the characteristics of cloud storage services and propose a secure and privacy preserving keyword searching (SPKS) scheme, which allows the CSP to participate in the decipherment, and to return only files containing certain keywords specified by the users, so as to reduce both the computational and communication overhead in decryption for users, on the condition of preserving user data privacy and user querying privacy. Performance analysis shows that the SPKS scheme is applicable to a cloud environment.

Journal of Communications, 2011

Delay tolerant networks (DTNs) are a special type of wireless mobile networks which may lack cont... more Delay tolerant networks (DTNs) are a special type of wireless mobile networks which may lack continuous network connectivity. Multicast supports the distribution of data to a group of users, a service needed for many potential DTNs applications. While multicasting in the Internet and mobile ad hoc networks has been studied extensively, due to the unique characteristic of frequent partitioning in DTNs, multicasting in DTNs is a considerably different and challenging problem. It not only requires new destinations of multicast semantics, but also brings new issues to the design of routing algorithms. In this paper, we propose new forwarding models for DTNs multicast and develop several multicast forwarding algorithms. We use delegation forwarding (DF) in DTNs multicast and compare it with single and multiple copy multicast models, which are also proposed in this paper. From the analytical results, we have the following conclusions: (1) Although the single copy model has the smallest number of forwardings, its latency is much longer than the other two models. (2) Among these three models, the delegation forwarding model has the least delay. The effectiveness of our approach is verified through extensive simulation both in synthetic and real traces.

IEEE Transactions on Parallel and Distributed Systems, 2011

When applied in high-churn Internet environments, P2P systems face a dilemma: although most parti... more When applied in high-churn Internet environments, P2P systems face a dilemma: although most participants are too unstable, a P2P system requires sufficient stable peers to provide satisfactory core services. Thus, determining how to leverage unstable nodes seems to be the only choice. Our primary idea is to group unstable nodes together in order to form an adequate number of stable service groups. Focusing on this topic, our main findings are three folds: 1) A general analytical model to investigate the grouping process of P2P systems is established, in which the stability-scalability tradeoff problem is paid special attention to; 2) We formalize the target of grouping as the Maximum Stability Grouping (MSG) problem. It proves to be not only NP-hard, but also infeasible; therefore, we restrict it to a feasible Homogeneous MSG (H-MSG) problem and deduce its optimal solution under the stochastic model; 3) We propose a homogeneous grouping strategy to fulfil the optimal solution. Comprehensive simulations have been performed on generated data sets and real-world traces from a P2P storage system and a P2P streaming system. Results show that our grouping strategy effectively captures the stability-scalability tradeoff: besides excellent stability, it gains much higher stable service capacity, with acceptable loss in scalability.