Scaling at a (Security) Cost: Unveiling the Security Assumptions Behind Today’s Blockchain Layer 2 Scaling Solutions

Abstract

Blockchains promise trust without intermediaries - but only if their security assumptions hold. To push throughput from tens to thousands of transactions per second, the industry and market now leans towards Layer 2 (L2) solutions such as Payment Channel Networks, Optimistic Rollups, Zero-Knowledge Rollups, Validium and Volition. Each provide with scalability, yet each quietly adds new security assumptions and/or trust assumptions.

This talk presents a concise tour of the first comprehensive taxonomy of those assumptions. In particular, we will:

1. Revisit the baseline security assumptions of permissionless Layer 1 Blockchains.
2. Review the inherited and additional security assumptions that Layer 2 Scaling Solutions put on top of the baseline ones.
3. Compare how different L2 designs trade censorship-resistance, data availability and decentralisation for scalability.
4. Offer a number of insights that practitioners can use to evaluate whether an L2’s threat model matches their risk tolerance.

Attendees will leave with a sharper understanding of the hidden costs of “scaling solutions”, the questions to ask before integrating or investing, and a roadmap for research directions that could reclaim security without sacrificing performance.