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Sisu: Decentralized Trustless Bridge For Full Ethereum Node

Billy Pham, Huy Le

TL;DR

Sisu tackles the problem of building a trustless bridge by proving Ethereum full nodes with a two-phase recursive SNARK approach. It combines distributed GKR over a general arithmetic circuit with accumulation gates, a novel associative hash for validator distinctness, and zero worker-to-worker communication to reduce network traffic, while enabling GPU acceleration. The paper demonstrates a practical prototype showing phase-1 scalability and phase-2 constraint counts that scale with cluster size, suggesting viability in distributed prover markets. This work offers a path toward scalable, decentralized ZK bridges capable of handling Ethereum’s large validator set and complex beacon-state proofs, with potential applicability to other ZK-enabled cross-chain and on-chain verification tasks.

Abstract

In this paper, we present a detailed approach and implementation to prove Ethereum full node using recursive SNARK, distributed general GKR and Groth16. Our protocol's name is Sisu whose architecture is based on distributed Virgo in zkBridge with some major improvements. Besides proving signature aggregation, we provide solutions to 2 hard problems in proving Ethereum full node: 1) any public key is valid under previous beacon state and 2) all public keys are pairwise distinct. Our solution does not require worker-to-worker communication and therefore reduce total worker-to-worker network traffic from terabyte of data to zero compared to zkBridge. This makes our approach suitable for emerging distributed prover markets and more decentralized compared to zkBridge. Our design is highly parallelable and capable of running on GPU for most parts.

Sisu: Decentralized Trustless Bridge For Full Ethereum Node

TL;DR

Sisu tackles the problem of building a trustless bridge by proving Ethereum full nodes with a two-phase recursive SNARK approach. It combines distributed GKR over a general arithmetic circuit with accumulation gates, a novel associative hash for validator distinctness, and zero worker-to-worker communication to reduce network traffic, while enabling GPU acceleration. The paper demonstrates a practical prototype showing phase-1 scalability and phase-2 constraint counts that scale with cluster size, suggesting viability in distributed prover markets. This work offers a path toward scalable, decentralized ZK bridges capable of handling Ethereum’s large validator set and complex beacon-state proofs, with potential applicability to other ZK-enabled cross-chain and on-chain verification tasks.

Abstract

In this paper, we present a detailed approach and implementation to prove Ethereum full node using recursive SNARK, distributed general GKR and Groth16. Our protocol's name is Sisu whose architecture is based on distributed Virgo in zkBridge with some major improvements. Besides proving signature aggregation, we provide solutions to 2 hard problems in proving Ethereum full node: 1) any public key is valid under previous beacon state and 2) all public keys are pairwise distinct. Our solution does not require worker-to-worker communication and therefore reduce total worker-to-worker network traffic from terabyte of data to zero compared to zkBridge. This makes our approach suitable for emerging distributed prover markets and more decentralized compared to zkBridge. Our design is highly parallelable and capable of running on GPU for most parts.
Paper Structure (33 sections, 8 equations, 8 figures, 2 algorithms)

This paper contains 33 sections, 8 equations, 8 figures, 2 algorithms.

Table of Contents

  1. Introduction
  2. The problems
  3. Related Work
  4. Our Contribution
  5. Background
  6. Zero Knowledge Proof
  7. GKR Protocol
  8. Libra protocol
  9. Virgo protocol
  10. Recursive SNARK and Computation Compression
  11. zkBridge protocol
  12. General Arithmetic Circuit
  13. Distributed Prover Market
  14. Sisu Protocol
  15. Overview
  16. ...and 18 more sections

Figures (8)

  • Figure 1: A common flow of how assets or data are transferred from chain A to chain B.
  • Figure 2: Overlapping execution of phase 1 and phase 2 for different blocks
  • Figure 3: Each worker independently writes to its designated area in the mempool. The cluster leader later assembles all the pieces of data to create final proof.
  • Figure 4: An overview of public key aggregation. Besides verifying each subcircuit's proof, the verifier also checks if the output of one circuit is in the input of the next circuit.
  • Figure 5: Bit Change Probability of $\mathcal{F}(x+1)$ - $\mathcal{F}(x)$
  • ...and 3 more figures