Case Study: COMBO x Polyhedra Network — Seamless Cross-Chain Asset Transfers via zkBridge
I. Executive Summary
COMBO and Polyhedra Network are engaged in an ongoing strategic partnership to enhance the overall web3 gaming experience using zero-knowledge proof (ZKP) technology.
Following COMBO’s successful testnet launch on April 25, 2023, we rolled out a free NFT mint events to celebrate this milestone and reward early community members. The primary challenge was ensuring seamless interoperability between distinct blockchain networks, which we addressed with the integration of zkBridge into the COMBO network.
By working together, we leveraged Polyhedra’s zkBridge technology to introduce seamless cross-chain NFT transfers and messaging within the blockchain ecosystem. This approach resulted in a breakthrough of over 223,076 Cobee NFTs successfully transferred from the BNB chain to the COMBO network, which was a remarkable success with important implications for the broader web3 gaming space.
II. Challenges
Following the COMBO testnet launch, the principal challenge was the absence of interoperability between various blockchain networks. This acted as a barrier for users intending to transfer NFTs across chains or send messages seamlessly, and ensuring COMBO’s cross-chain interoperability was a top priority, with implications that go far beyond the Cobee free NFT mint event.
In short, this collaboration was aimed at crafting an interconnected web3 ecosystem capable of offering the desired flexibility and seamless experience to the users. Given COMBO’s recent entry into the game and a lack of viable options among competitors, it was crucial that we get this step right.
III. Methodology
While there were many technical complex aspects to the task at hand, our general approach was based on the following:
- Integration and Compilation: Integrate zkBridge on the COMBO network, compiling light client protocols such as BNB Chain into zk-SNARK circuits to ensure their correctness during execution.
- Execution Verification and Relay Network: Verify the execution of the light client protocol on the COMBO network’s receiver chain with minimal effort. Set up a block header relay network to fetch block headers from the sender chain (e.g., BNB Chain).
- Validity Proofs and Updater Contract: Generate proofs of the validity of the fetched block headers within the block header relay network. Send the block headers along with their validity proofs to the updater contract deployed on the receiver chain.
- Light-Client State Maintenance and Relaying: Maintain a light-client state within the updater contract, automatically incorporating verified block headers from the sender chain. Relay BNB block headers to the COMBO network using a dedicated relayer.
- Proof Verification and NFT Transfer: Verify the proof of relayed block headers within the updater contract on the COMBO network. Utilize the zkBridge design to facilitate the secure transfer of NFTs from the BNB Chain to the COMBO network.
For context: zkBridge, powered by Polyhedra network, is the world’s first trustless, efficient, secure, and universal cross-chain interoperability infrastructure using zkSNARKs. It leverages zkSNARKs to enable a prover to convincingly demonstrate to the receiver chain that a specific state transition occurred on the sender chain. Imagine a scenario where a user wants to move assets from BNB Chain or Ethereum to the COMBO network. With zkBridge, this transaction can be directly executed, ensuring both the security and authenticity of the transfer without relying on trust.
IV. Key Results
The successful integration of zkBridge on the COMBO network enabled trustless and highly-efficient interoperability for game asset transfer, message passing, and data sharing between COMBO and other L1 and L2 blockchain networks. This collaboration with Polyhedra resulted in over 223,076 Cobee NFTs being seamlessly transferred from the BNB chain to the COMBO network via the zkBridge, representing a significant achievement in terms of cross-chain NFT transfers.
This successful zkBridge deployment is a real-world example of how COMBO is enabling cross-chain, cross-game, and cross-platform interoperability while safeguarding asset authenticity and ownership in web3 gaming. The ability to effortlessly move over 223,076 Cobee NFTs from the BNB chain to the COMBO network is a game-changer for the broader web3 gaming industry and sets a promising precedent for future forms of interoperability.
V. Conclusion & Next Steps
To unleash the full potential of COMBO’s growing ecosystem, it’s important to have flexible and cost-effective asset interoperability across multiple popular blockchains. That’s where zkBridge came in. By integrating zkBridge, COMBO network now ensures smooth interoperability between its assets, data, and messages with other blockchain ecosystems. This boosts accessibility and functionality, opening up a world of possibilities for developers in the web3 gaming space.
Given the success of this partnership, COMBO and Polyhedra Network have plans to extend their collaboration and continue to innovate within the blockchain ecosystem. In addition to the integration of zkBridge, COMBO will work with Polyhedra Network to build a web3 gaming SDK based on ZKP (Zero-Knowledge Proofs). The ZKP gaming SDK ensures fair and secure allocation of in-game assets, while preserving players’ privacy by not revealing sensitive data such as identities or ownership of assets. With the ZKP gaming SDK, game developers can enjoy the benefits of zero-knowledge proof technology — improved security, user-friendliness, fairness, and cost efficiency — without the need for specialized infrastructure or expertise.
Going forward, this partnership will continue to unleash the full potential of web3 gaming infrastructure to improve interoperability, fairness, security, and privacy by using ZKP as a building block for web3 games. We invite our community to join us on this journey and stay tuned for more thrilling developments!
About Polyhedra Network
Polyhedra Network is building the next generation of infrastructure for Web3 interoperability, scalability, and privacy through advanced Zero-knowledge proof (ZKP) technology. Polyhedra Network provides trustless and highly-efficient interoperability solutions for asset transfers, message passing, and data sharing between various Web2 and Web3 systems. Learn more here.
About COMBO
COMBO is a leading provider of scaling solutions for Web3 game developers. By leveraging the world’s top game engine, COMBO is building an open-source, decentralized, game-oriented Layer2 that is accessible to everyone. It aims to maximize the potential of Web3 games by connecting game developers with the entire ecosystem in an efficient, affordable, and secure way. Learn more here.
