Yingjiu Li

Discovering calendar-based temporal association rules

We study the problem of mining association rules and related time intervals, where an association rule holds either in all or some of the intervals. To restrict to meaningful time intervals, we use calendar schemas and their calendar-based patterns. A calendar schema example is (year, month, day) and a calendar-based pattern within the schema is (*, 3, 15), which represents the set of time intervals each corresponding to the 15th day of a March. Our focus is finding efficient algorithms for this mining problem by extending the well-known Apriori algorithm with effective pruning techniques. We evaluate our techniques via experiments.

Fingerprinting relational databases: schemes and specialties

In this paper, we present a technique for fingerprinting relational data by extending Agrawal et al.s watermarking scheme. The primary new capability provided by our scheme is that, under reasonable assumptions, it can embed and detect arbitrary bit-string marks in relations. This capability, which is not provided by prior techniques, permits our scheme to be used as a fingerprinting scheme. We then present quantitative models of the robustness properties of our scheme. These models demonstrate that fingerprints embedded by our scheme are detectable and robust against a wide variety of attacks including collusion attacks.

Protecting RFID communications in supply chains

Recent years have seen much growing attention on RFID security. However, little work has been performed to address the security issues in the context of supply chain management, which is exactly the major field for RFID applications. Existing RFID solutions cannot be applied directly in this field because of a set of special RFID security requirements to be addressed for supply chain management. The major contribution of this paper is to identify the unique set of security requirements in supply chains and to propose a practical design of RFID communication protocols that satisfy the security requirements.

Tamper detection and localization for categorical data using fragile watermarks

Today, database relations are widely used and distributed over the Internet. Since these data can be easily tampered with, it is critical to ensure the integrity of these data. In this paper, we propose to make use of fragile watermarks to detect and localize malicious alterations made to a database relation with categorical attributes. Unlike other watermarking schemes which inevitably introduce distortions to the cover data, the proposed scheme is distortion free. In our algorithm, all tuples in a database relation are first securely divided into groups according to some secure parameters. Watermarks are embedded and verified in each group independently. Thus, any modifications can be localized to some specific groups. Theoretical analysis shows that the probability of missing detection is very low.

A fragile watermarking scheme for detecting malicious modifications of database relations

Nowadays, with more and more data publicly available on the Internet, it is increasingly important to ensure the integrity of these data. The traditional solution is to use a digital signature scheme. However, a digital signature can only detect whether the entire data set has been modified; it cannot localize and characterize the modifications. In this paper, a novel fragile watermarking scheme is proposed to detect malicious modifications of database relations. In the proposed scheme, all tuples in a database relation are first securely divided into groups; watermarks are embedded and verified group by group independently. The embedded watermarks cannot only detect but also localize, and even characterize, the modifications made to the database. In the worst case, the modifications can be narrowed down to tuples in a group. Rigorous analysis shows that the modifications can be detected and localized with high probability, which is also demonstrated by our experimental results.

A new framework for RFID privacy

Formal RFID security and privacy frameworks are fundamental to the design and analysis of robust RFID systems. In this paper, we develop a new definitional framework for RFID privacy in a rigorous and precise manner. Our framework is based on a zero-knowledge (ZK) formulation [8,6] and incorporates the notions of adaptive completeness and mutual authentication.We provide meticulous justification of the new framework and contrast it with existing ones in the literature. In particular, we prove that our framework is strictly stronger than the ind-privacy model of [18], which answers an open question posed in [18] for developing stronger RFID privacy models.We also clarify certain confusions and rectify several defects in the existing frameworks. Finally, based on the protocol of [20], we propose an efficient RFID mutual authentication protocol and analyze its security and privacy. The methodology used in our analysis can also be applied to analyze other RFID protocols within the new framework.

CHAINING WATERMARKS FOR DETECTING MALICIOUS MODIFICATIONS TO STREAMING DATA

Abstract Authenticating streaming data is a very important research area due to its wide range of applications. Previous technologies mainly focused on authenticating data packets at the IP layer and ensuring the robustness of the verification. These schemes usually incur large communications overhead, which is not desirable in applications with limited bandwidth. In this paper, we propose a novel fragile watermarking algorithm which verifies the integrity of streaming data at the application layer. The data are divided into groups based on synchronization points, so each group can be synchronized and any modifications made to one group only affect up to two groups. A unique watermark is embedded directly into each group to save communications bandwidth. The embedded watermark can detect as well as locate any modifications made to a data stream. To ensure the completeness of the data stream, watermarks are chained across groups so that no matter how many data are deleted, these deletions can be correctly detected. Security analysis and experimental results show that the proposed scheme can efficiently detect and locate modifications and ensure the completeness of data streams.

Permission based Android security: Issues and countermeasures

Abstract Android security has been a hot spot recently in both academic research and public concerns due to numerous instances of security attacks and privacy leakage on Android platform. Android security has been built upon a permission based mechanism which restricts accesses of third-party Android applications to critical resources on an Android device. Such permission based mechanism is widely criticized for its coarse-grained control of application permissions and difficult management of permissions by developers, marketers, and end-users. In this paper, we investigate the arising issues in Android security, including coarse granularity of permissions, incompetent permission administration, insufficient permission documentation, over-claim of permissions, permission escalation attack, and TOCTOU (Time of Check to Time of Use) attack. We illustrate the relationships among these issues, and investigate the existing countermeasures to address these issues. In particular, we provide a systematic review on the development of these countermeasures, and compare them according to their technical features. Finally, we propose several methods to further mitigate the risk in Android security.

RFID privacy: relation between two notions, minimal condition, and efficient construction

Privacy of RFID systems is receiving increasing attention in the RFID community. Basically, there are two kinds of RFID privacy notions: one based on the indistinguishability of two tags, denoted as ind-privacy, and the other based on the unpredictability of the output of a protocol, denoted as unp-privacy. In this paper, the definition of unp-privacy is refined and the relation between the two notions is clarified: it is proven that ind-privacy is weaker than unp-privacy. Moreover, the minimal (necessary and sufficient)condition on RFID tags to achieve unp-privacy is determined. It is shown that if an RFID system has strong (or weak) unp-privacy then the computational power of an RFID tag can be used to construct a pseudorandom function family provided that the RFID system is complete and sound. On the other hand, if each tag is able to compute a pseudorandom function, then the tags can be used to construct an RFID system with strong (or weak) unp-privacy. In this sense, a pseudorandom function family is the minimal requirement on an RFID tags computational power for enforcing strong RFID system privacy. Finally, a new RFID protocol is proposed to satisfy the minimal requirement, which also outperforms the state-of-the-art RFID protocols in terms of computational cost and communication overhead.

Two robust remote user authentication protocols using smart cards

With the rapid growth of electronic commerce and enormous demand from variants of Internet based applications, strong privacy protection and robust system security have become essential requirements for an authentication scheme or universal access control mechanism. In order to reduce implementation complexity and achieve computation efficiency, design issues for efficient and secure password based remote user authentication scheme have been extensively investigated by research community in these two decades. Recently, two well-designed password based authentication schemes using smart cards are introduced by Hsiang and Shih (2009) and Wang et al. (2009), respectively. Hsiang et al. proposed a static ID based authentication protocol and Wang et al. presented a dynamic ID based authentication scheme. The authors of both schemes claimed that their protocol delivers important security features and system functionalities, such as mutual authentication, data security, no verification table implementation, freedom on password selection, resistance against ID-theft attack, replay attack and insider attack, as well as computation efficiency. However, these two schemes still have much space for security enhancement. In this paper, we first demonstrate a series of vulnerabilities on these two schemes. Then, two enhanced protocols with corresponding remedies are proposed to eliminate all identified security flaws in both schemes.