Organizer: Prof. Thomas Schneider
Secure Multi-Party Computation (MPC) with small number of parties is an interesting area of research, primarily due to its ability to model most real-life MPC applications and the simplicity and efficiency of the resulting protocols. We study constant-round 3-party (3PC) and 4-party (4PC) protocols in the honest-majority setting.
On the theoretical front, we settle the exact round complexity of 3PC, for a range of security notions such as selective abort, unanimous abort, fairness and guaranteed output delivery. Selective abort security, the weakest in the lot, allows the corrupt parties to selectively deprive some of the honest parties of the output. In the mildly stronger version of unanimous abort, either all or none of the honest parties receive the output. Fairness implies that the corrupted parties receive their output only if all honest parties receive output and lastly, the strongest notion of guaranteed output delivery implies that the corrupted parties cannot prevent honest parties from receiving their output.
On the practical front, we present efficient, constant-round 3PC and 4PC protocols that achieve strong security notions of fairness and guaranteed output delivery, with a nominal overhead compared to the known constructions achieving weaker notion of security. Being constant-round, our constructions are suitable for Internet-like high-latency networks and are built from garbled circuits (GC).
Arpita Patra is an Assistant Professor at Indian Institute of Science. Her area of interest is Cryptography, focusing on theoretical and practical aspects of secure multiparty computation protocols. She received her PhD from Indian Institute of Technology (IIT), Madras and held post-doctoral positions at University of Bristol, UK, ETH Zurich, Switzerland and Aarhus University, Denmark.