The practicality of the keyword search using PIR

Nowadays, there are more and more use of storage-provider through the Internet, such as Google and Hotmail e-mail accounts, which are convenient to store and transfer electronic files and medias. Though the storage-provider offers users the capability to collect, retrieve and search on the emails, however, there is no protection of the users´ privacy. For example, it is unknown how to prevent some honest-but-curious storage-provider from learning the private information of the user, such as, searching criterion and access pattern, etc. In CRYPTO´07, Boneh et al. put forward a privacy-preserving solution to solve this open problem, under the public key infrastructure. They made use of PIR (private information retrieval) and several other techniques, which are theoretically interesting and likely to be the best approach in the underlying setting. In this paper, we investigate the practicality of the proposed scheme by Boneh et al. Surprisingly, our evaluation result shows that their proposal seems unlikely to be implementable with the latest technology, due to a large amount of computational cost involved. Note that it is the first time to analyze and examine the practicality of this public key encryption based keyword search protocol using PIR.