Introduction

Scale and compose zero-knowledge proofs on Ethereum.

NEBRA is a research & development organization working to make the zero-knowledge future a reality. We research and build technologies, infrastructure, and products to facilitate the mass adoption of zero-knowledge proofs.

Our first step towards this goal is to scale the proof settlement capabilities of Ethereum in a trustless and censorship resistant manner. To achieve this, we are developing Universal Proof Aggregation technologies, to aggregate proofs generated from different circuits, different proof systems and different parties.

The Problem: expensive ZKP onchain settlement

One of the biggest problems preventing the zero-knowledge future from becoming reality is the high cost of onchain settlement (verification). The table below shows the cost of verifying different kinds of zero-knowledge proofs on Ethereum today:

Proof System	Gas Cost	FIAT cost (30 gwei gas/ Ether 3000 USD)
Groth16	250,000	22.5 US Dollar
Halo2-KZG	400,000	36 US Dollar
STARK-FRI	1,500,000	105 US Dollar

This expensive proof verification cost means that only a few kinds of applications can be built today (namely those that can justify the high verification cost), and only a subset of users (those that can afford it) have access to proof verification. We believe that a future where onboarding to vote privately on a DAO costs $20 will exclude a majority of the world, a majority who we believe blockchain technology should also serve.

NEBRA proposes using zero knowledge proofs themselves to scale zero knowledge proof verification. As a result, zero knowledge proof settlement on Ethereum can be more accessible to the general public. The core idea is to use highly efficient recursive SNARKs (IVCs/PCDs) to get a near unlimited amount of recursion (almost) for free. This means we can recursively prove multiple zero-knowledge proofs off-chain, and verify only a single aggregated proof onchain. This significantly improves on the status quo, and provides nearly unbounded efficiency.