SoK: Content Moderation Schemes in End-to-End Encrypted Systems

TL;DR

This survey reviews content moderation techniques in end-to-end encrypted systems, analyzing their effectiveness, limitations, and recent developments aimed at balancing privacy with moderation needs.

Contribution

It provides a comprehensive overview of existing methods, highlights their limitations, and discusses new security primitives designed to enable moderation without compromising privacy.

Findings

Current techniques often violate encryption goals

New security primitives are being developed for moderation

Analysis of effectiveness and limitations of existing methods

Abstract

This paper aims to survey various techniques utilized for content moderation in end-to-end encryption systems. We assess the challenging aspect of content moderation: maintaining a safe platform while assuring user privacy. We study the unique features of some content moderation techniques, such as message franking and perceptual hashing, and highlight their limitations. Currently implemented content moderation techniques violate the goals of end-to-end encrypted messaging to some extent. This has led researchers to develop remediations and design new security primitives to make content moderation compatible with end-to-end encryption systems. We detail these developments, analyze the proposed research efforts, assess their security guarantees, correlate them with other proposed solutions, and determine suitable improvements under specific scenarios.