Polyhedra and NEBRA Strategic Partnership
September 13th, 2024

Polyhedra and NEBRA are partnering to make ZK bridging more efficient and cost-effective.

  • Nebra's Universal Proof Aggregation (UPA) can significantly reduce the onchain verification costs for Polyhedra's zkBridge on Layer 1. By aggregating multiple proofs into a single verification, UPA can lower gas costs by up to 90%, making cross-chain communication more efficient and cost-effective.

  • NEBRA is committed to support Polyhedra’s next generation proof system, Expander, to lower the onchain verification cost of Expander developers

How UPA reduces zkBridge costs on L1

Polyhedra's zkBridge uses zkSNARKs to enable efficient cross-chain communication. The system consists of two main components:

Block header relay network: Retrieves block headers from the sender chain and generates validity proofs.

Updater contract: Deployed on the receiver chain, it maintains a light-client state of the sender chain.

Currently, each proof verification on L1 requires significant gas, limiting the scalability and cost-effectiveness of the zkBridge. UPA addresses this issue through proof aggregation.

Key benefits of UPA for zkBridge:

Proof batching: UPA aggregates multiple zkSNARK proofs into a single, compact proof. This reduces the number of onchain verifications needed.

Universal compatibility: UPA works with proofs from any circuit, making it suitable for zkBridge's diverse proof types.

Amortized costs: By batching proofs from various sources, UPA creates an "economy of scale" effect, further reducing per-proof verification costs.

Gas savings: Early estimates suggest UPA could reduce gas costs for proof verification by up to 90%.

Impact on zkBridge operations

Integrating UPA with Polyhedra's zkBridge offers several advantages:

Lower transaction fees: Reduced gas costs translate to lower fees for bridge users.

Increased throughput: Lower per-proof verification costs allow the zkBridge to handle higher volumes of cross-chain communications within the same gas limits.

Enhanced scalability: Cost-effectiveness provided by UPA allows the zkBridge to scale more efficiently, potentially enabling support for higher-frequency updates.

Why use UPA with zkBridge?

Significant cost reduction: UPA can lower proof verification costs from hundreds of thousands of gas to tens of thousands, a 10x or greater improvement.

Universality: UPA's ability to aggregate proofs from any circuit makes it ideal for zkBridge's diverse proof requirements.

Permissionless design: As an onchain protocol, anyone can submit proofs to UPA, maintaining the open nature of zkBridge.

Censorship resistance: UPA's forced-inclusion design ensures that valid proofs cannot be censored, maintaining the security properties of zkBridge.

The integration of UPA with Polyhedra's zkBridge represents a significant improvement in cross-chain communication efficiency. By dramatically reducing the costs associated with onchain proof verification, UPA can help unlock the full potential of zkBridge, enabling more frequent updates, supporting more chains, and making cross-chain interactions more accessible.

Advancing Prover Technology

NEBRA is working together with Polyhedra on moving forward the state of art proof system research. Proof system is a cornerstone of zero-knowledge proof scaling solutions and applications. NEBRA and Polyhedra both have deep theoretical and academic backgrounds in proof system research. NEBRA proposed UniPlonk, the first plonk proof system with unified verifiers. Polyhedra has authored a series of impactful papers, including Virgo, zkBridge and many others, and is developing the state of art proof system, Expander. We would expect the collaboration on fundamental proof system research can benefit the entire industry for the decades to come.

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