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We consider the following problem: users in a dynamic group store their encrypted documents on an untrusted server, and wish to retrieve documents containing some keywords without any loss of data confidentiality. In this paper, we investigate common secure indices which can make multi-users in a dynamic group to obtain securely the encrypted documents shared among the group members without re-encrypting them. We give a formal definition of common secure index for conjunctive keyword-based retrieval over encrypted data (CSI-CKR), define the security requirement for CSI-CKR, and construct a CSI-CKR based on dynamic accumulators, Paillier's cryptosystem and blind signatures. The security of proposed scheme is proved under strong RSA and co-DDH assumptions. [ABSTRACT FROM AUTHOR]

As industries aggressively deploy Radio Frequency IDentification application systems, the user privacy invasion and system security threats are increasingly concernd by individuals and organizations. Recently several hash-based mutual authentication schemes have been proposed to resolve security-related problems. However, previous schemes either suffer from security loopholes or have system efficiency problem for identity match process. In this paper, the security flaws of two recently proposed hash-based authentication schemes are analyzed at first. Based on this analysis, we identify the security and privacy criterions for the authentication process of RFID systems, and propose a new mutual authentication scheme to eliminate possible security flaws and enhance privacy protection to the owner of an object with RFID tag attached on it. In addition, we develop an efficient identity match and retrieval mechanism to relieve the heavy computation load of traditional match scheme between received tag identity and records in backend database of RFID systems. [ABSTRACT FROM AUTHOR]

Database privacy is an ambiguous concept, whose meaning is usually context-dependent. We give a conceptual framework for technologies in that field in terms of three dimensions, depending on whose privacy is considered: i) respondent privacy (to avoid re-identification of patients or other individuals to whom the database records refer); ii) owner privacy (to ensure that the owner must not give away his dataset); and iii) user privacy (to preserve the privacy of queries submitted by a data user). Examples are given to clarify why these are three independent dimensions. Some of the pitfalls related to combining the privacy interests of respondents, owners and users are discussed. An assessment of database privacy technologies against the three dimensions is also included. [ABSTRACT FROM AUTHOR]

In this paper we present a hybrid system to protect private data from phishing attacks. Our solution uses intrusion detection methods to identify potential phishing emails then relies on web crawlers to validate or reject this suspicion. We also use external information coming through RDF Site Summaries (RSS) alerts about potential phishing sites. Our two-layered phishing detection system reside on the server of the organization, thus it is not vulnerable to blocking attacks targeting web browsers. [ABSTRACT FROM AUTHOR]

Recent compliance regulations are intended to foster and restore human trust in digital information records and, more broadly, in our businesses, hospitals, and educational enterprises. In the health sector, storage and management of electronic health records have become a vital issue. Specifically, with the passing of the Health Insurance Portability and Accountability Act (HIPAA), the security of medical records has come into focus. HIPAA and other regulations in the health sector require strict compliance with specific privacy and security requirements. Unfortunately, existing storage solutions do not live up to the task of ensuring compliance with mandated legislation. In this position paper, we discuss the main characteristics of the health sector record management regulations, and present a set of requirements for secure, trustworthy storage that complies with these regulations. We also briefly analyze existing storage models, and show that they are not suitable for meeting the requirements of health-care record storage. [ABSTRACT FROM AUTHOR]

It is now mandatory for healthcare organizations to specify and publish their privacy policies. This has made privacy management initiatives in the healthcare sector increasingly important. However, several recent reports in the public media and the research community about healthcare privacy [1,2] indicate that the use of privacy policies is not necessarily a strong indication of adequate privacy protection for the patient. These observations highlight the fact that the current state of privacy management in healthcare organizations needs improvement. In this paper, we present PRIMA, a PRIvacy Management Architecture, as a first step in addressing this concern. The fundamental idea behind PRIMA is to exploit policy refinement techniques to gradually and seamlessly embed privacy controls into the clinical workflow based on the actual practices of the organization in order to improve the coverage of the privacy policy. PRIMA effectively enables the transition from the current state of perceived to be privacy-preserving systems to actually privacy-preserving systems. [ABSTRACT FROM AUTHOR]

Privacy-invasive software, loosely labelled spyware, is an increasingly common problem for today's computer users, one to which there is no absolute cure. Most privacy-invasive software is positioned in a legal grey zone, as the user accepts the malicious behaviour when agreeing to the End User License Agreement. This paper proposes the use of a specialized reputation system to gather and share information regarding software behaviour between community users. A client application helps guide the user at the point of executing software on the local computer, displaying other users' feedback about the expected behaviour of the software. We discuss important aspects to consider when constructing such a system, and propose possible solutions. Based on the observations made, we implemented a client/server based proof-of-concept tool, which allowed us to demonstrate how such a system would work. We also compare this solution to other, more conventional, protection methods such as anti-virus and anti-spyware software. [ABSTRACT FROM AUTHOR]

Existing privacy regulations together with large amounts of available data have created a huge interest in data privacy research. A main research direction is built around the k-anonymity property. Several shortcomings of the k-anonymity model have been fixed by new privacy models such as p-sensitive k-anonymity, l-diversity, α, k-anonymity, and t-closeness. In this paper we introduce the EnhancedPKClustering algorithm for generating p-sensitive k-anonymous microdata based on frequency distribution of sensitive attribute values. The p-sensitive k-anonymity model and its enhancement, extended p-sensitive k-anonymity, are described, their properties are presented, and two diversity measures are introduced. Our experiments have shown that the proposed algorithm improves several cost measures over existing algorithms. [ABSTRACT FROM AUTHOR]

A database intrusion detection system (IDS) is a new database security mechanism to guard data, the most valuable assets of an organization. To provide the intrusion detection module with relevant audit data for further analysis, an effective data collection method is essential. Currently, very little work has been done on the data acquisition mechanisms tailored to the needs of database IDSs. Most researchers use the native database auditing functionality, which excludes privileged users such as database administrators (DBAs) from being monitored. In this paper, we present a new approach to data collection for database IDSs by situating data collecting sensors on the database server and having the data transmitted to the audit server on a physically different site for further processing. This approach can guarantee that behavior of both average users and privileged users are monitored for signs of intrusion. [ABSTRACT FROM AUTHOR]

Considered in this paper are numeric databases, whose instances are vectors in ${\cal R}^n$, queries involve their linear transformations, and imprecise query answers are intervals. Introduced for the first time is a security requirement function ρ for a query, to specify the maximum probability ρ(l) that the precise query answer is within any interval of size l. Developed are random disclosure algorithms that satisfy security requirement functions, and guarantee, under certain conditions, maximum data availability. [ABSTRACT FROM AUTHOR]

We investigate the experimental effectiveness of query rewriting over XML security views. Our model consists of access control policies specified over DTDs with XPath expression for data-dependent access control policies. We provide the notion of security views for characterizing information accessible to authorized users. This is a transformed (sanitized) DTD schema that is used by users for query formulation. To avoid the overhead of view materialization in query answering, these queries later undergo rewriting so that they are valid over the original DTD schema, and thus the query answer is computed from the original XML data. We provide an algorithm for query rewriting and show its performance compared with the naive approach, i.e. the approach that requires view materialization. [ABSTRACT FROM AUTHOR]

In data publishing model, data owners engage third-party data publishers to manage their data and process queries on their behalf. As the publishers may be untrusted or susceptible to attacks, it could produce incorrect query results. In this paper, we extend the signature-based mechanism for users to verify that their answers for k nearest neighbors queries on a multidimensional dataset are complete (i.e. no qualifying data points are omitted), authentic (i.e. no answer points are tampered) and minimal (i.e. no non-answer points are returned in the plain). Essentially, our scheme returns k answer points in the plain, and a set of ($\tilde{p}, q$)-pairs, where $\tilde{p}$ is the digest of a non-answer point p in the dataset used to facilitate the signature chaining mechanism to verify the authenticity of the answer points, and q is a reference point (not in the dataset) used to verify that p is indeed further away from the query point than the kth nearest point. We study two instantiations of the approach - one based on the native data space using space partitioning method (a.k.a. R-tree) and the other based on the metric space using iDistance. We conducted an experimental study, and report our findings here. [ABSTRACT FROM AUTHOR]

Flexibility of management is an important requisite for access control systems as it allows users to adapt the access control system in accordance with practical requirements. This paper builds on earlier work where we defined administrative policies for a general class of RBAC models. We present a formal definition of administrative refinement and we show that there is an ordering for administrative privileges which yields administrative refinements of policies. We argue (by giving an example) that this privilege ordering can be very useful in practice, and we prove that the privilege ordering is tractable. [ABSTRACT FROM AUTHOR]

In the context of regulatory compliance, the question is often whether an enterprise can guarantee that only certain people can access certain data or perform certain business functions on them. Examples are controls over financial data in Sarbanes-Oxley and access to personal information in privacy laws such as HIPAA and the California Senate Bill 1386. Such guarantees also have to be strictly audited. For individual access control systems, such questions are standard at least in theory. However, to the best of our knowledge such questions have never been addressed for entire system stacks containing multiple layers of data representation with potentially different access mechanisms. For instance, financial data may be accessed by using an access right to the official financial application, but also by using an administrator right to an underlying database or by logically or physically accessing an unencrypted backup tape with the data. We propose an overall model and algorithms to deal with this situation. We study both advance queries for validating a proposed system and a posteriori queries in audit, problem determination, or litigation. [ABSTRACT FROM AUTHOR]

Whilesome authorization models support either positive or negative authorizations, hybrid frameworks take advantage of both authorizations. Resolving authorization conflicts is quite a challenge due to the existence of sophisticated inheritance hierarchies and the diversity of ways to combine resolution policies. Some researchers have addressed conflict resolution for tree-structured hierarchies, and others have applied a simple conflict resolution policy. The challenge is to combine several policies and to support sophisticated structures in one single framework. This paper proposes a unified framework together with a single parametric algorithm that supports all the legitimate combinations simultaneously, based on four conflict resolution policies. We validate our approach by testing the algorithm against both real data and synthetic examples to provide extensive experimental results. [ABSTRACT FROM AUTHOR]