Shijie Zhou

Interconnected RFID Reader Collision Model and its Application in Reader Anti-collision

While several readers are placed together for improving read rate and correctness, reader collision problems happen frequently and inevitably. High probability of collision not only impairs the benefit of multi-reader deployment, but also results in misreading in moving tags RFID applications. In order to eliminate or reduce reader collision, a current centralized reader network can be modeled as a collaborative network for readers to directly exchange information with other readers. Peer-to-peer computing technology is an emergent technology and is also a preferred candidate for this purpose. Hence, in this paper we present a collaborative peer-to-peer network for reader collision model. This Interconnected RFID Reader Collision Model (IRCD) is constructed upon the RFID reader collision so that it is a fully distributed and self-organized overlay network. IRCD can be used in a dense reader environment to exchange collision related information directly among readers without any central control or intermediation. To illustrate how to use IRCD, a query-hit rate-based dynamic anti-collision scheme is also proposed in this paper.

A lightweight anti-desynchronization RFID authentication protocol

Radio frequency identification (RFID) technology has been widely used in ubiquitous infrastructures. However, resource constraint in the low-cost RFID systems has posed potential risks such as privacy and security problems, becoming adoption barrier for RFID-based applications. In this paper, current security issues in RFID are introduced firstly. Then, we propose a lightweight Anti-desynchronization privacy preserving RFID authentication protocol. It is particularly suitable for the low-cost RFID environment for only the capacity of one-way hash function and XOR operation is needed. In this lightweight Anti-desynchronization RFID authentication protocol, the back-end server keeps the history of the random key update to prevent the active attackers from de-synchronizing the shared secret between the tag and the back-end server. The security and the performance of the proposed protocol are analyzed as well.

A survey on metric of software complexity

With the evolution of the software development, the scale of the software is increasingly growing to the extent that we cannot hand it easily. Some metrics are proposed to measure the complexity of software in last a few years. This article aims at a comprehensive survey of the metric of software complexity. Some classic and efficient software complexity metrics, such as Lines of Codes (LOC), Halstead Complexity Metric (HCM) and Cyclomatic Complexity Metric (CCM), are discussed and analyzed first. Then, some other approaches driven from above classic metrics are also discussed. The comparison and the relationship of these metrics of software complexity are also presented.

Modeling and analysis of self-stopping BTWorms using dynamic hit list in P2P networks

Worm propagation analysis, including exploring mechanisms of worm propagation and formulating effects of network/worm parameters, has great importance for worm containment and host protection in P2P networks. Previous work only focuses on topological worm propagation where worms search a hosts neighbor-list to find new victims. In BitTorrent (BT) networks, the information from servers or trackers, however, could be fully exploited to design effective worms. In this paper, we propose a new approach for worm propagation in BT-like P2P networks. The worm, called Dynamic Hit-List (DHL) worm, locates new victims and propagates itself by requesting a tracker to build a dynamic hit list, which is a self-stopping BT worm to be stealthy. We construct an analytical model to study the propagation of such a worm: breadth-first propagation and depth-first propagation. The analytical results provide insights of the worm design into choosing parameters that enable the worm to stop itself after compromising a large fraction of vulnerable peers in a P2P network. We finally evaluate the performance of DHL worm through simulations. The simulation results verify the correctness of our model and show the effectiveness of the worm by comparing it with the topological worm.

Detecting Malware Variants by Byte Frequency

In order to make lots of new malwares fast and cheaply, attacker can simply modify the existing malwares based on their binary files to produce new ones, malware variants. Malware variants refer to all the new malwares manually or automatically produced from any existing malware. However, such simple approach to produce malwares can change signatures of the original malware so that the new malware variants can confuse and bypass most of popular signature-based anti-malware tools. In this paper we propose a novel byte frequency based detecting model (BFBDM) to deal with the malware variants identification issue. The byte frequency of software refers to the frequency of the different unsigned bytes in the corresponding binary file. In order to implement BFBDM, two metrics, the distance and the similarity between the suspicious software and base sample, a known malware, are defined and calculated. According to the experimental results, we found out that if the distance is low and the similarity is high, the suspicious software is a variant of the selected malware with very high probability. The primary experimental results show that our model is efficient and effective for the identification of malware variants, especially for the manual variant.

Malware variants identification based on byte frequency

Malware variants refer to all the new malwares manually or automatically produced from any existing malware. However, such simple approach to produce malwares can change signatures of the original malware to confuse and bypass most of popular signature-based anti-malware tools. In this paper we propose a novel byte frequency based detecting model (BFBDM) to deal with the malware variants identification issue. The primary experimental results show that our model is efficient and effective for the identification of malware variants, especially for the manual variant.

A Range-Free Localization of Passive RFID Tags Using Mobile Readers

Recently, there has been growing interest in indoor localization, because numerous applications depend on the rapid and accurate position estimation of tagged objects. While RFID-based indoor localization is attractive, the need for a large-scale and high-density deployment of readers and reference tags is costly. Being the range-free localization, our schemes depend solely on mobile readers without reference tags or other devices, and it avoids the need of distance estimation according to RSSI or phase difference. We propose two novel algorithms, continuous scanning and category-based scheduling, for locating single and multiple tagged objects, respectively. Our primary experimental results show that the system can achieve high time efficiency and localization accuracy.

A general approach for the intensive RFID reader deployment

We usually need to deploy a large number of readers to cover a certain area due to the limited read region of RFID readers. The challenge of the intensive reader deployment lies in that the collision among readers decreases the read rate and speed. In this paper, we propose a general approach to reduce the collision among readers and the number of readers. The basic idea of the approach is to maximise the coverage rate and minimise the overlapping rate. Such an approach contains two parts: grid-based model and PSO-based algorithm. We first build a grid-based model to describe both deployment area and read region. In particular, we divide them into small grids, and express grid graphs in a matrix form. Then, we propose a PSO-based algorithm to optimise the intensive reader deployment. Our simulation results show that the general approach can achieve high coverage rate and low overlapping rate.

Design and Analysis for RFID Authentication Protocol

Radio frequency identification (RFID) technology has been widely used in ubiquitous infrastructures. On the other hand, the low-cost RFID system has potential risks such as privacy and security problems, which would be a big barrier for the application. First of all, we analyze the current security protocols for the RFID system. To protect user privacy and remove security vulnerabilities, we propose a robust and privacy preserving mutual authentication protocol that is suitable for the low-cost RFID environment. Finally, the correctness of the proposed authentication protocol is proved by the BAN logic.

Understanding and Improving Piece-Related Algorithms in the BitTorrent Protocol

Piece-related algorithms, including piece revelation, selection, and queuing, play a crucial role in the BitTorrent (BT) protocol, because the BT system can be viewed as a market where peers trade their pieces with one another. During the piece exchanging, a peer selects some pieces revealed by neighbors, and queues them up for downloading. In this paper, we provide a deep understanding of these algorithms, and also propose some improvements to them. Previous study has shown that the piece revelation strategy is vulnerable to under-reporting. We provide a game-theoretic analysis for this selfish gaming, and propose a distributed credit method to prevent it. Existing piece selection strategies, though long believed to be good enough, may fail to balance piece supply and demand. We propose a unified strategy to shorten the download time of peers by applying utility theory. The design of the piece queuing algorithm has a conflict with that of piece selection strategy, because it is not possible to assume that the queued requests for a selected piece can always be available on multiple neighbors. We give a possible fix to address the conflict by allowing peers to dynamically manage their unfulfilled requests. To evaluate the performance of the proposed algorithms, we run several experiments in a live swarm. Our primary results show that they can achieve fast individual and system-wide download time.