In this paper we significantly extend the function privacy framework. First, we introduce the new notion of subspace-membership encryption, a generalization of inner-product encryption, and formalize a meaningful and realistic notion for capturing its function privacy. Then, we present a generic construction of a function-private subspace-membership encryption scheme based on any inner-product encryption scheme. Finally, we show that function-private subspace-membership encryption can be used to construct function-private identity-based encryption. These are the first generic constructions of function-private encryption schemes based on non-function-private ones, resolving one of the main open problems posed by Boneh, Raghunathan, and Segev.
Category / Keywords: public-key cryptography / Function privacy, functional encryption. Original Publication (with minor differences): IACR-ASIACRYPT-2013 Date: received 19 Jun 2013, last revised 28 Jul 2014 Contact author: segev at cs huji ac il Available format(s): PDF | BibTeX Citation Version: 20140729:055430 (All versions of this report) Short URL: ia.cr/2013/403