Practical Secure Evaluation of Semi-private Functions

Abstract. Two-party Secure Function Evaluation (SFE) is a very useful cryptographic tool which allows two parties to evaluate a function known to both parties on their private (secret) inputs. Some applications with sophisticated privacy needs require the function to be known only to one party and kept private (hidden) from the other one. However, existing solutions for SFE of private functions (PF-SFE) deploy Universal Circuits (UC) and are still very inecient in practice. In this paper we bridge the gap between SFE and PF-SFE with SFE of what we call 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 ne-grained trade-o and tuning between SFE and PF-SFE covering both extremes. In our framework, semiprivate functions can be composed from several privately programmable blocks (PPB) which can be programmed with one function out of a class of functions. Th...

• Type: Conference
• Year: 2009
• Where: ACNS
• Authors: Annika Paus, Ahmad-Reza Sadeghi, Thomas Schneider
• Keywords: ACNS 2009, Cryptography, Fairplay SFE Framework, Semi-private Functions, Two-party Secure Function