Reversing the Panopticon: Decentralized Auditing of Trusted Platforms

Lunch will be served at 12:45PM.

Bio

Dr. Fan Zhang is an Assistant Professor in the Department of Computer Science at Yale University. His research spans computer security and applied cryptography, with a focus on novel systems with decentralized trust and governance. Several of his works, notably zkTLS, confidential smart contracts, trustless bridges, and anonymous communication, have been adopted by the industry. His research has been supported by awards and grants from the NSF, the Ethereum Foundation, Flashbots, Mysten Labs, the Yale Roberts Innovation Award, and IBM. He received his Ph.D. in Computer Science from Cornell University, advised by Prof. Ari Juels, and his Bachelor of Science from Tsinghua University, China.

Abstract

Cryptography has long pursued the goal of building systems that can enforce commitments without relying on trusted intermediaries. Blockchain-based smart contracts represent one realization of this vision: their transparency and integrity make it difficult for participants to violate agreed-upon rules. Yet much of today’s digital infrastructure—from advertising networks and social media platforms to online marketplaces—remains centralized and opaque. These systems operate as black boxes, leaving users and researchers with limited ability to verify how they behave in practice.

In this talk, I explore how cryptographic techniques can enable decentralized auditing of trusted platforms. I first discuss how tools such as zkTLS and trusted execution environments (TEEs) allow users to produce privacy-preserving and authentic evidence about what web services deliver to them, strengthening community-driven auditing efforts such as ad transparency studies. I then present Verifiable Aggregate Receipts (VAR), a protocol that enables users to collectively prove aggregate properties of platform behavior—such as the number of times content was served—without trusting the platform. Together, these techniques illustrate a broader vision of reversing the digital panopticon, where users can cryptographically audit powerful online systems.

Zoom Link: https://duke.zoom.us/j/97371787328?jst=3