...for his work on "An Efficient Protocol for Secure Two-Party Computation in the Presence of Malicious Adversaries."

The IACR Test-of-Time Award is given to one paper from each of the IACR General Conferences (Eurocrypt, Crypto, and Asiacrypt). VMware's Benny Pinkas and Yehuda Lindell won the award for their Eurocrypt 2007 paper "for providing the first implementable protocol for actively secure variants of Yao's protocol, and thus paving the way to more practical constructions."

Authors: Benny Pinkas (VMware) and Yehuda Lindell (Bar-Ilan University)

Abstract: We show an efficient secure two-party protocol, based on Yao’s construction, which provides security against malicious adversaries. Yao’s original protocol is only secure in the presence of semi-honest adversaries. Security against malicious adversaries can be obtained by applying the compiler of Goldreich, Micali and Wigderson (the “GMW compiler”). However, this approach does not seem to be very practical as it requires using generic zero-knowledge proofs.

Our construction is based on applying cut-and-choose techniques to the original circuit and inputs. Security is proved according to the ideal/real simulation paradigm, and the proof is in the standard model (with no random oracle model or common reference string assumptions). The resulting protocol is computationally efficient: the only usage of asymmetric cryptography is for running O(1) oblivious transfers for each input bit (or for each bit of a statistical security parameter, whichever is larger). Our protocol combines techniques from folklore (like cut-and-choose) along with new techniques for efficiently proving consistency of inputs. We remark that a naive implementation of the cut-and-choose technique with Yao’s protocol does not yield a secure protocol. This is the first paper to show how to properly implement these techniques, and to provide a full proof of security.

Our protocol can also be interpreted as a constant-round black-box reduction of secure two-party computation to oblivious transfer and perfectly-hiding commitments, or a black-box reduction of secure two-party computation to oblivious transfer alone, with a number of rounds which is linear in a statistical security parameter. These two reductions are comparable to Kilian’s reduction, which uses OT alone but incurs a number of rounds which is linear in the depth of the circuit.

Learn more at the IACR Test-of-Time Awards page.