First CPIR Protocol with Data-Dependent Computation

We design a new (n, 1)-CPIR protocol BddCpir for -bit strings as a combination of a noncryptographic (BDD-based) data structure and a more basic cryptographic primitive (communication-efficient (2, 1)-CPIR). BddCpir is the first CPIR protocol where server's online computation depends substantially on the concrete database. We then show that (a) for reasonably small values of , BddCpir is guaranteed to have simultaneously log-squared communication and sublinear online computation, and (b) BddCpir can handle huge but sparse matrices, common in data-mining applications, significantly more efficiently compared to all previous protocols. The security of BddCpir can be based on the well-known Decisional Composite Residuosity assumption. Keywords. Binary decision diagram, computationally-private information retrieval, privacy-preserving data mining, sublinear communication.

• Type: Journal
• Year: 2009
• Where: ICISC
• Authors: Helger Lipmaa
• Keywords: Computationally-private Information Retrieval, Cryptology, Decisional Composite Residuosity Assumption, ICISC 2009, Online Computation