Séminaire de Cryptographie

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Martin Hirt

Introduction to Secure Multi-Party Computation

Consider a set of $n$ players, each holding a value $x_1,...,x_n$, and an $n$-ary function $f$, specified as an arithmetic circuit over a finite field. How can the players compute $y=f(x_1,...,x_n)$ in such a way that no (small enough) set of dishonest players obtains any joint information about the input values of the honest players (beyond of what they can infer from $y$)?

In this talk, we present a protocol that allows the players to compute an arbitrary function $f$, such that any subset of up to $t< n/2$ dishonest players do not obtain any information about the other players' inputs.

Finally, we briefly sketch an extension of the protocol, which guarantees the correctness of the outcome even when the dishonest players misbehave in arbitrary manner.