- We study whether known impossibilities for achieving strong SIM based security imply actual real world attacks. For this, we present a new UC-style SIM based definition of security that captures both data and function hiding, both public key and symmetric key settings and represents the "dream" security of FE. While known impossibilities rule out its achievability in the standard model, we show, surprisingly, that it can be achieved in the generic group model for Inner Product FE (Katz et al., Eurocrypt 2008). This provides evidence that FE implementations may enjoy extremely strong security against a large class of real world attacks, namely generic attacks.
- We provide several improvements to known constructions of Inner Product FE. In the private key setting, the construction by Shen et al. (TCC 2009) was based on non-standard assumptions, used composite order groups, and only achieved selective security. We give the first construction of a symmetric key inner product FE which is built using prime order groups, and is fully secure under the standard DLIN assumption. Our scheme is more efficient in the size of key and ciphertext than Shen et al.'s, when the latter is converted to prime-order groups.
- We give the first construction of a property preserving encryption (PPE) scheme for inner-products. Our scheme is secure under the DLIN assumption and satisfies the strongest definition of security -- Left-or-Right security in the standard model. Note that the only previously known construction for PPE by Pandey et al. (Eurocrypt 2012), which was claimed to be secure in the generic group model, was recently attacked Chatterjee and Das, making our construction the first candidate for PPE.
Category / Keywords: - Original Publication (with major differences): IACR-PKC-2015 Date: received 13 Nov 2013, last revised 6 Sep 2015 Contact author: shweta a at gmail com, abishekk@gmail com, sagrawl2@illinois edu Available format(s): PDF | BibTeX Citation Note: Substantial revision. The relaxed simulation part of the paper has been removed due to technical issues. Also, the private-key functional encryption and property preserving encryption schemes given in the paper do not appear in the proceedings of PKC 2015. Version: 20150907:042729 (All versions of this report) Short URL: ia.cr/2013/744