Extended Private Information Retrieval (EPIR) has been introduced at CANS'07 by Bringer  et al.  as a generalization of the notion of Private Information Retrieval (PIR). The principle is to enable a user to privately evaluate a fixed and public function with two inputs, a chosen block from a database and an additional string.#R##N##R##N#The main contribution of our work is to extend this notion in order to add more flexibility during the system life. As an example, we introduce a general protocol enabling polynomial evaluations. We also revisit the protocol for Hamming distance computation which was described at CANS'07 to obtain a simpler construction. As to practical concern, we explain how amortizing database computations when dealing with several requests.
['Julien Bringer', 'Hervé Chabanne']
Another Look at Extended Private Information Retrieval Protocols