Please note: This seminar will take place in DC 1302.
Ioannis Demertzis, Assistant Professor
Computer Science and Engineering Department, University of California, Santa Cruz
Any privacy-preserving computation on encrypted data that relies solely on encryption can leak significant information about the plaintext input through leakage-abuse attacks. Industrial approaches that support confidential computing through hardware enclaves are susceptible to side-channel attacks; however, hardware enclaves provide an affordable and low-cost solution for any privacy-preserving computation. Oblivious primitives are a powerful cryptographic tool that, when combined with hardware enclaves, can mitigate leakage-abuse and software side-channel attacks.
Oblivious primitives find applications in various areas, including Signal’s contact discovery, Anonymous Key Transparency, end-to-end encrypted email search, differential privacy in the shuffle model, large-scale software monitoring (e.g., Google’s Prochlo), private federated learning/computation (Apple’s Private Cloud Compute), AWS Bedrock, AWS Data Clean Rooms, LLM privacy/private RAG (e.g., Amazon Kendra), Google’s Privacy Sandbox, Google’s FLEDGE, Titan Security Key, Asylo, and broader confidential computing efforts.
In this talk, we discuss our recent hardware-enclave-based oblivious primitives that scale private computations to terabyte-sized inputs—far exceeding the previous state-of-the-art 100MB–4GB range. Our scalable oblivious primitives include high-throughput oblivious key-value store (used in Signal’s contact discovery, SOSP’21; USENIX’26), a low-latency approach (PVLDB’24), scalable oblivious sort and shuffle (SP’24) primitives, and scalable oblivious filter, group-by, join approaches (USENIX’25).
Bio: Ioannis Demertzis is an Assistant Professor in the Computer Science and Engineering Dept. at the University of California, Santa Cruz. His research focuses on applied cryptography, security & privacy, and secure databases/systems. His work has been published at top security, system and database conferences including USENIX, CRYPTO, NDSS, S&P, SIGMOD, SOSP, PVLDB and TODS. He is the recipient of the ACM SIGSAC Doctoral Dissertation Award Runner-up, Distinguished Dissertation Award of ECE (University of Maryland), and the Symantec Research Labs Graduate Fellowship.
Before joining UCSC, he was a Postdoctoral Researcher at the EECS Dept. of UC Berkeley hosted by Prof. Raluca Ada Popa. He received his Ph.D. from the ECE Dept. of the University of Maryland, College Park advised by Prof. Charalampos Papamanthou. He obtained his ECE Diploma and M.Sc at the Technical University of Crete, under the supervision of Minos Garofalakis.