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Abstract : |
Abstract. We consider a generalized adversary model for unconditionally secure multi-party computation. The adversary can actively corrupt (i.e. take full control over) a subset D ` P of the players, and, additionally, can passively corrupt (i.e. read the entire information of) another subset E ` P of the players. The adversary is characterized by a generalized adversary structure, i.e. a set of pairs (D; E), where he may select one arbitrary pair from the structure and corrupt the players accordingly. This generalizes the classical threshold results of Ben-Or, Goldwasser and Wigderson, Chaum, Cr'epeau, and Damgard, and Rabin and Ben-Or, and the non-threshold results of Hirt and Maurer. The generalizations and improvements on the results of Hirt and Maurer are three-fold: First, we generalize their model by considering mixed (active and passive) non-threshold adversaries and characterize completely the adversary structures for which unconditionally secure multi-party computation is possible, for four different models: Perfect security with, |
