Adaptive versus non-adaptive security of multi-party protocols (Q1882568)

The article is devoted to comparative security analysis of multi-party cryptographic protocols with two types of adversarial settings. In the non-adaptive setting the set of corrupted parties is chosen in advance. In the adaptive case a corrupted member is defined during the course of the communication. The equivalence relations between adaptive and non-adaptive security are studied. It is proved that under the basic definition adaptive security is equivalent to non-adaptive security when the number of parties is logarithmic. For Byzantine adversaries adaptive security is stronger that non-adaptive security.