Hi, I am Yulong Ming!

Research

• MHcast: Metadata-hiding Multicast with Resilience against Malicious Clients and Servers

  Updated:2026-07-11

  In this paper, we present MHcast, a high-throughput metadata-hiding multicast system. MHcast uses two distributed comparison functions with a public mapping to construct a multicast scheme. MHcast enforces a mailbox access control scheme to prevent malicious clients from disrupting multicast through malformed or junk messages. Additionally, MHcast provides an identification scheme that allows honest clients to assist an honest server in identifying the malicious server. We implement and evaluate MHcast in comparison to other metadata-hiding systems. Experiments show that MHcast’s throughput is 2–10× higher than repeatedly using the unicast protocol when the group size is only 16. MHcast supports groups of any size, from 0 to N, where N is the total number of clients.

• P²RAG: Efficient Privacy-Preserving RAG Service Supporting Arbitrary Top-k Retrieval

  Updated:2026-06-11

  Unlike existing systems, P²RAG avoids sorting candidate documents. Instead, it uses an interactive bisection method to determine the set of top-k documents. For security, P²RAG uses secret sharing on two semi-honest non-colluding servers to protect the data owner's database and the user's prompt. It enforces restrictions and verification to defend against malicious users and tightly bounds the information leakage of the database. The experiments show that P²RAG is 3--300× faster than the state-of-the-art PRAG for k = 16--1024.