Publishing data about individuals without revealing sensitive information about them is an important problem. In recent years, a new definition of privacy called k-anonymity has gained popularity. In a k-anonymized dataset, each record is indistinguishable from at least k − 1 other records with respect to certain identifying attributes.In this article, we show using two simple attacks that a k-anonymized dataset has some subtle but severe privacy problems. First, an attacker can discover the values of sensitive attributes when there is little diversity in those sensitive attributes. This is a known problem. Second, attackers often have background knowledge, and we show that k-anonymity does not guarantee privacy against attackers using background knowledge. We give a detailed analysis of these two attacks, and we propose a novel and powerful privacy criterion called e-diversity that can defend against such attacks. In addition to building a formal foundation for e-diversity, we show in an experimental evaluation that e-diversity is practical and can be implemented efficiently.

/pdf/l-diversity-privacy-beyond-k-anonymity-54qdj1526d.pdf

L-diversity: Privacy beyond k-anonymity

Publishing data about individuals without revealing sensitive information about them is an important problem. In recent years, a new definition of privacy called \kappa-anonymity has gained popularity. In a \kappa-anonymized dataset, each record is indistinguishable from at least k—1 other records with respect to certain "identifying" attributes. In this paper we show with two simple attacks that a \kappa-anonymized dataset has some subtle, but severe privacy problems. First, we show that an attacker can discover the values of sensitive attributes when there is little diversity in those sensitive attributes. Second, attackers often have background knowledge, and we show that \kappa-anonymity does not guarantee privacy against attackers using background knowledge. We give a detailed analysis of these two attacks and we propose a novel and powerful privacy definition called \ell-diversity. In addition to building a formal foundation for \ell-diversity, we show in an experimental evaluation that \ell-diversity is practical and can be implemented efficiently.

/pdf/l-diversity-privacy-beyond-k-anonymity-43op5i6gzs.pdf

L-diversity: privacy beyond k-anonymity

http://emamispnu.persiangig.com/Projects/Cloud%20Computing/science_2.pdf

Review: A survey on security issues in service delivery models of cloud computing

XML is quickly becoming the de facto standard for data exchange over the Internet. This is creating a new set of data management requirements involving XML, such as the need to store and query XML documents. Researchers have proposed using relational database systems to satisfy these requirements by devising ways to "shred" XML documents into relations, and translate XML queries into SQL queries over these relations. However, a key issue with such an approach, which has largely been ignored in the research literature, is how (and whether) the ordered XML data model can be efficiently supported by the unordered relational data model. This paper shows that XML's ordered data model can indeed be efficiently supported by a relational database system. This is accomplished by encoding order as a data value. We propose three order encoding methods that can be used to represent XML order in the relational data model, and also propose algorithms for translating ordered XPath expressions into SQL using these encoding methods. Finally, we report the results of an experimental study that investigates the performance of the proposed order encoding methods on a workload of ordered XML queries and updates.

http://db.ucsd.edu/static/cse232b-archive/papers/tatarinov02.pdf

Storing and querying ordered XML using a relational database system

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

Encryption is a well established technology for protecting sensitive data. However, once encrypted, data can no longer be easily queried aside from exact matches. We present an order-preserving encryption scheme for numeric data that allows any comparison operation to be directly applied on encrypted data. Query results produced are sound (no false hits) and complete (no false drops). Our scheme handles updates gracefully and new values can be added without requiring changes in the encryption of other values. It allows standard databse indexes to be built over encrypted tables and can easily be integrated with existing database systems. The proposed scheme has been designed to be deployed in application environments in which the intruder can get access to the encrypted database, but does not have prior domain information such as the distribution of values and annot encrypt or decrypt arbitrary values of his choice. The encryption is robust against estimation of the true value in such environments.

/pdf/order-preserving-encryption-for-numeric-data-22ble2t4uw.pdf

Order preserving encryption for numeric data

Publisher Summary
The Hippocratic Oath has guided the conduct of physicians for centuries. Inspired by its tenet of preserving privacy, it has been argued that future database systems must include responsibility for the privacy of data that they manage as a founding tenet. The explosive progress in networking, storage, and processor technologies is resulting in an unprecedented amount of digitization of information. It is estimated that the amount of information in the world is doubling every 20 months, and the size and number of databases are increasing even faster. In concert with this dramatic and escalating increase in digital data, concerns about the privacy of personal information have emerged globally. Privacy issues have been further exacerbated, now that the Internet makes it easy for new data to be automatically collected and added to databases. Privacy is the fight of individuals to determine for themselves when, how, and to what extent information about them is communicated to others. Privacy concerns are being fueled by an ever-increasing list of privacy violations, ranging from privacy accidents to illegal actions. Lax security for sensitive data is of equal concern.

Chapter 14 – Hippocratic Databases

The Hippocratic Oath has guided the conduct of physicians for centuries. Inspired by its tenet of preserving privacy, we argue that future database systems must include responsibility for the privacy of data they manage as a founding tenet. We enunciate the key privacy principles for such Hippocratic database systems. We propose a strawman design for Hippocratic databases, identify the technical challenges and problems in designing such databases, and suggest some approaches that may lead to solutions. Our hope is that this paper will serve to catalyze a fruitful and exciting direction for future database research.

Hippocratic databases

We enunciate the need for watermarking database relations to deter their piracy, identify the unique characteristics of relational data which pose new challenges for watermarking, and provide desirable properties of a watermarking system for relational data. A watermark can be applied to any database relation having attributes which are such that changes in a few of their values do not affect the applications.

We then present an effective watermarking technique geared for relational data. This technique ensures that some bit positions of some of the attributes of some of the tuples contain specific values. The tuples, attributes within a tuple, bit positions in an attribute, and specific bit values are all algorithmically determined under the control of a private key known only to the owner of the data. This bit pattern constitutes the watermark. Only if one has access to the private key can the watermark be detected with high probability. Detecting the watermark neither requires access to the original data nor the watermark. The watermark can be detected even in a small subset of a watermarked relation as long as the sample contains some of the marks.

Our extensive analysis shows that the proposed technique is robust against various forms of malicious attacks and updates to the data. Using an implementation running on DB2, we also show that the performance of the algorithms allows for their use in real world applications.

/pdf/watermarking-relational-databases-2w9l4y70i3.pdf

Watermarking relational databases

XML has emerged as the standard data exchange format for Internet-based business applications. This has created the need to publish existing business data, stored in relational databases, as XML. A general way to publish relational data as XML is to provide XML views over relational data, and allow business partners to query these views using an XML query language. In this paper, we address the problem of evaluating XML queries over XML views of relational data. This paper makes two main contributions. The first is a general framework for processing arbitrarily complex queries specified using the XQuery query language. The second is a technique for efficiently evaluating XML queries by pushing most of the query computation down to the relational engine.

/pdf/querying-xml-views-of-relational-data-34empmxxkt.pdf

Jerry Kiernan

Papers

Order preserving encryption for numeric data

Chapter 14 – Hippocratic Databases

Hippocratic databases

Watermarking relational databases

Querying XML Views of Relational Data