XRD - Scalable Messaging System with Cryptographic Privacy

Explore a cutting-edge scalable messaging system with cryptographic privacy in this 22-minute conference talk from NSDI '20. Dive into XRD (Crossroads), a novel approach that addresses metadata leakages in end-to-end encrypted communication. Learn how XRD utilizes multiple mix networks in parallel and innovative techniques like aggregate hybrid shuffle to support millions of users while maintaining cryptographic privacy. Discover the system's architecture, deployment model, and threat analysis. Understand how XRD tackles active attacks using zero-knowledge proofs and implements chain selection for enhanced security. Examine the scalability properties of XRD, including its linear latency increase with user growth and improved performance through server expansion. Compare XRD's efficiency to other cryptographically private messaging systems like Atom and Pung. Gain insights into the implementation, setup, and overall benefits of this groundbreaking system that combines cryptographic metadata privacy with scalability.

Intro
Motivation: whistleblowing
Metadata private messaging system
Deployment and threat model
XRD: Overview
Problem: Active attack
Solution: Zero-knowledge proofs
Chain selection
Scalability properties
Implementation and setup
Latency increases linearly with the number of users
XRD scales with more servers
Summary of XRD • Cryptographic metadata privacy + scalability