Revisiting the Efficiency of Asynchronous MPC with Optimal Resilience Against General Adversaries

Ashish Choudhury
Tuesday | July 16, 2024 |11 AM
CSE Conference Room, KReSIT Building (1st Floor)

In this paper, we design unconditionally secure multi-party computation (MPC) protocols in the asynchronous communication setting with optimal resilience. Our protocols are secure against a computationally unbounded malicious adversary characterized by an adversary structure Z, which enumerates all possible subsets of potentially corrupt parties. We present protocols with both perfect-security, as well as with statistical-security. While the protocols in the former class achieve all the security properties in an error-free fashion, the protocols belonging to the latter category achieve all the security properties except with a negligible error. Our perfectly secure protocol incurs an amortized communication of |Z|^2 bits per multiplication. This improves upon the protocol of Choudhury and Pappu (INDOCRYPT 2020) with the least known amortized communication complexity of |Z|^3 bits per multiplication. On the other hand, our statistically secure protocol incurs an amortized communication of |Z| bits per multiplication. This is the first statistically secure asynchronous MPC protocol against general adversaries. Previously, perfectly secure and statistically secure MPC with an amortized communication cost of |Z|^2 and |Z| bits, respectively, per multiplication was known only in the relatively simpler synchronous communication setting (Hirt and Tschudi in ASIACRYPT, Springer, 2013).

Publication Information: published in Journal of Cryptology. Joint work with Ananya Appan and Anirudh Chandramouli.

Speaker Biography

Dr. Ashish Choudhury is an Associate Professor at the IIIT Bangalore. He received his Ph.D. in Computer Science from IIT Madras, India. Before joining IIIT Bangalore, Dr. Choudhury was an Assistant Professor at Jadavpur University. He held postdoctoral positions at University of Bristol and Indian Statistical Institute. Dr. Choudhury received Infosys Foundation Career Development Chair Professor award and Visvesvaraya Young Faculty Research Fellow award. His research interest is in the theoretical aspect of cryptography with a special focus on designing and analyzing multi-party computation protocols. Dr. Choudhury has co-authored a book titled “Secure Multi-Party Computation Against Passive Adversaries”.