On unconditionally secure multi-party sampling from scratch1

In the problem of secure multi-party sampling, n parties wish to securely sample an n-variate joint distribution, with each party receiving a sample of one of the correlated variables. The objective is to correctly produce the samples using a distributed message passing protocol, while maintaining privacy against a coalition of passively cheating parties. In the two-party case, we fully characterize the joint distributions that can be securely sampled under perfect correctness and privacy requirements as well as under weakened correctness and privacy requirements. Furthermore, we show that the distributions that can be securely sampled can be produced with a protocol that only uses one round of unidirectional communication. For the n-party case, any distribution can be securely sampled with privacy against a strict minority coalition, due to well-known results in secure multi-party computation. However, when privacy against a majority coalition is required, not all distributions can be securely sampled. We give necessary conditions and sufficient conditions for distributions that can be securely sampled. However, the exact characterization of the distributions that can be securely sampled remains open.