Equivalence-based Security for Querying Encrypted Databases: Theory and Application to Privacy Policy Audits

Motivated by the problem of simultaneously preserving confidentiality and usability of data outsourced to third-party clouds, we present two different database encryption schemes that largely hide data but reveal enough information to support a wide-range of relational queries. We provide a security definition for database encryption that captures confidentiality based on a notion of equivalence of databases from the adversary's perspective. As a specific application, we adapt an existing algorithm for finding violations of privacy policies to run on logs encrypted under our schemes and observe low to moderate overheads.Comment: CCS 2015 paper technical report, in progres

Designing information-preserving mapping schemes for XML

Journal ArticleAn XML-to-relational mapping scheme consists of a procedure for shredding XML documents into relational databases, a procedure for publishing databases back as documents, and a set of constraints the databases must satisfy. In previous work, we discussed two notions of information preservation for mapping schemes: losslessness, which guarantees the complete reconstruction of a document from a database; and validation, which guarantees that every update to a database corresponding to a valid document results in a database corresponding to another valid document. Also, we described one information preserving mapping scheme, called Edge++, and showed that, under reasonable assumptions, lossless and validation are both undecidable. This leads to the question we study in this paper: how to design information-preserving mapping schemes. We propose to do it by starting with a scheme known to be information preserving (such as Edge++) and applying to it equivalence-preserving transformations written in weakly recursive ILOG. We study a particular incarnation of this framework, the LILO algorithm, and show that it provides signfii cant performance improvements over Edge++ and that the constraints it introduces are efficiently enforced in practice

Relational Approach to Logical Query Optimization of XPath

To be able to handle the ever growing volumes of XML documents, effective and efficient data management solutions are needed. Managing XML data in a relational DBMS has great potential. Recently, effective relational storage schemes and index structures have been proposed as well as special-purpose join operators to speed up querying of XML data using XPath/XQuery. In this paper, we address the topic of query plan construction and logical query optimization. The claim of this paper is that standard relational algebra extended with special-purpose join operators suffices for logical query optimization. We focus on the XPath accelerator storage scheme and associated staircase join operators, but the approach can be generalized easily

Analysis of equivalence mapping for terminology services

This paper assesses the range of equivalence or mapping types required to facilitate interoperability in the context of a distributed terminology server. A detailed set of mapping types were examined, with a view to determining their validity for characterizing relationships between mappings from selected terminologies (AAT, LCSH, MeSH, and UNESCO) to the Dewey Decimal Classification (DDC) scheme. It was hypothesized that the detailed set of 19 match types proposed by Chaplan in 1995 is unnecessary in this context and that they could be reduced to a less detailed conceptually-based set. Results from an extensive mapping exercise support the main hypothesis and a generic suite of match types are proposed, although doubt remains over the current adequacy of the developing Simple Knowledge Organization System (SKOS) Core Mapping Vocabulary Specification (MVS) for inter-terminology mapping