# Systematizing Decentralization and Privacy: Lessons from 15 Years of Research and Deployments

## TL;DR

This paper reviews 15 years of research on decentralization and privacy, highlighting key systems, insights, and trade-offs for designing scalable, privacy-preserving decentralized systems.

## Contribution

It provides a comprehensive overview of decentralization and privacy research, offering insights and trade-offs for future system design based on interdisciplinary lessons.

## Key findings

- Decentralized systems can improve privacy, integrity, and availability.
- Designers must carefully balance system complexity and decentralization levels.
- Cryptography, distributed systems, and mechanism design are crucial for scalable privacy-preserving systems.

## Abstract

Decentralized systems are a subset of distributed systems where multiple authorities control different components and no authority is fully trusted by all. This implies that any component in a decentralized system is potentially adversarial. We revise fifteen years of research on decentralization and privacy, and provide an overview of key systems, as well as key insights for designers of future systems. We show that decentralized designs can enhance privacy, integrity, and availability but also require careful trade-offs in terms of system complexity, properties provided, and degree of decentralization. These trade-offs need to be understood and navigated by designers. We argue that a combination of insights from cryptography, distributed systems, and mechanism design, aligned with the development of adequate incentives, are necessary to build scalable and successful privacy-preserving decentralized systems.