Paper 2005/297

DSAC: An Approach to Ensure Integrity of Outsourced Databases using Signature Aggregation and Chaining

Maithili Narasimha and Gene Tsudik

Abstract

Database outsourcing is an important emerging trend which involves data owners delegating their data management needs to an external service provider. In this model, a service provider hosts clients' databases and offers mechanisms to create, store, update and access (query) outsourced databases. Since a service provider is almost never fully trusted, security and privacy of outsourced data are important concerns. A core security requirement is the integrity and authenticity of outsourced databases. Whenever someone queries a hosted database, the results must be demonstrably authentic (with respect to the actual data owner) to ensure that the data has not been tampered with. Furthermore, the results must carry a proof of completeness which will allow the querier to verify that the server has not omitted any valid tuples that match the query predicate. Notable prior research (\cite{DpGmMcSs00, McNgDpGmKwSs02, PanTan04}) focused on so-called \textit{Authenticated Data Structures}. Another prior approach involved the use of special digital signature schemes. In this paper, we extend the state-of-the-art to provide both authenticity and completeness guarantees of query replies. Our work also analyzes the new approach for various base query types and compares the new approach with Authenticated Data Structures.\footnote{We also point out some possible security flaws in the approach suggested in the recent work of \cite{PanTan04}.}