| PhD Seminar

Name of the Speaker: Mr. Avik Mukhopadhyay (EE21D002)
Guide: Dr. Pradeep Sarvepalli
Venue: ESB-234 (Malaviya Hall)
Online meeting link: https://meet.google.com/bau-osgg-gqx
Date/Time: 16th December 2025 (Tuesday ), 9:00am
Title: Communication-Efficient Quantum Secret Sharing in the Presence of Malicious Adversaries

Abstract :

Secret sharing is a fundamental tool for protecting sensitive data. Quantum secret sharing (QSS) extends classical secret sharing to share quantum information with stronger security guarantees. QSS schemes distribute a secret state, either quantum or classical, among multiple parties so that authorized parties can recover it, while unauthorized participants learn nothing. An important challenge in QSS is the quantum communication cost during secret recovery. Prior work on communication-efficient QSS (CE-QSS) shows that recovery costs can be reduced when more than the threshold number of parties participate. However, these schemes do not consider malicious adversaries, leaving open the question of how to recover the secret with minimal communication cost in adversarial settings. In this work, we address this gap by introducing the first CE-QSS schemes that remain secure even when adversaries can corrupt multiple shares. By viewing corrupted shares as errors and unaccessed shares as erasures, the recovery task reduces to an erasure–error correction problem. This motivates the use of quantum error-correcting codes in our CE-QSS constructions. We develop fixed-d schemes, where a fixed number of parties participate in recovery, and universal schemes, which allow recovery with any number of parties above the threshold. Our universal CE-QSS framework stems from two approaches: one yields a smaller secret size, and the other lowers per-qudit communication cost, thereby highlighting a trade-off. This study offers new design choices for robust and resource-efficient QSS.