Presentation on theme: "Efficient Multiparty Protocols via Log-Depth Threshold Formulae Ron Rothblum Weizmann Institute Joint work with Gil Cohen, Ivan Damgard, Yuval Ishai, Jonas."— Presentation transcript:
Efficient Multiparty Protocols via Log-Depth Threshold Formulae Ron Rothblum Weizmann Institute Joint work with Gil Cohen, Ivan Damgard, Yuval Ishai, Jonas Kolker, Peter Bro Miltersen and Ran Raz
Secure Multiparty Computation (MPC) [Yao86,GMW87] An adversary that controls a (limited) subset of the parties learns nothing more than the inputs and outputs of the parties it controls.
Our Contribution Huge body of work on secure MPC but protocols are fairly complicated. We suggest a conceptually simple and flexible approach to designing efficient MPC protocols. Building blocks: 1.Player emulation - builds on Hirt-Maurer [HM00] but with a different motivation. 2.Simple constant-party MPC protocols. 3.Threshold formulae composed of threshold gates.
Applications 1.Conceptually simple protocols for perfectly secure MPC – obtaining passive/active security. 2.New results on feasibility of MPC in a variety of settings, e.g., secure MPC over algebraic structures such as non-Abelian groups. 3.Distributed computing – broadcast/Byzantine agreement.
3-Party Protocols Can use BGW restricted to 3 parties or better yet use the MPC made simple protocol of [Maurer02]. Maurers protocol is simple and elegant but exponential in the number of parties. For 3 parties– not an issue!
Conclusions and Open Questions MPC methodology: 1.Design simple constant-party protocols. 2.Prove player emulation theorem. Intriguing connections to open questions in complexity-theory: 1.Explicit exact majority-from-majorities formula. 2.Exact threshold-from-thresholds formula (even non-explicit).