In this paper we bridge the gap between SFE and PF-SFE with SFE of what we call {\em semi-private functions} (SPF-SFE), i.e., one function out of a given class of functions is evaluated without revealing which one.
We present a general framework for SPF-SFE allowing a fine-grained trade-off and tuning between SFE and PF-SFE covering both extremes. In our framework, semi-private functions can be composed from several privately programmable blocks (PPB) which can be programmed with one function out of a class of functions. The framework allows efficient and secure embedding of constants into the resulting circuit to improve performance. To demonstrate practicability of the framework we have implemented a compiler for SPF-SFE based on the Fairplay SFE framework.
SPF-SFE is sufficient for many practically relevant privacy-preserving applications, such as privacy-preserving credit checking which can be implemented using our framework and compiler as described in the paper.
Category / Keywords: cryptographic protocols / SFE of semi-private functions, Yao's protocol, topology, optimization, compiler, privacy Publication Info: ACNS 2009 Date: received 15 Mar 2009, last revised 23 Mar 2009 Contact author: thomas schneider at trust rub de Available format(s): PDF | BibTeX Citation Note: FairplaySPF is available online at http://www.trust.rub.de/FairplaySPF now. Version: 20090323:153245 (All versions of this report) Short URL: ia.cr/2009/124 Discussion forum: Show discussion | Start new discussion