# Kage Protocol: Kurō Cross-Chain Bridge Proposal **URL:** \ **Category:** Aztec\ **Tags:** rfgp, bridge\ **Created:** [March 25, 2025, 2:05pm UTC](https://forum.aztec.network/t/kage-protocol-kuro-cross-chain-bridge-proposal/7626 "2025-03-25T14:05:29Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![LucidSamuel](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.aztec.network/lucidsamuel/32/2302_2.png) [@LucidSamuel](https://forum.aztec.network/u/LucidSamuel)\ **Post date:** [March 25, 2025, 2:05pm UTC](https://forum.aztec.network/t/kage-protocol-kuro-cross-chain-bridge-proposal/7626/1 "2025-03-25T14:05:29Z")
**Title: Kage Protocol: Kurō Cross-Chain Bridge Proposal** Contact Details Email: [sam@undefy.io](mailto:sam@undefy.io) Telegram: lucidsamuel **Summary** We propose to develop Kage Kurō, a privacy-first, cross-chain messaging and bridging infrastructure that enables secure asset transfers between Aztec and Ethereum-compatible Layer 2 networks (initially targeting Optimism). Our system is engineered to deliver trust-minimized, efficient interoperability while keeping transaction details confidential. By integrating EigenDA for decentralized data availability, we ensure that our protocol remains scalable, resilient, and verifiable even as cross-chain interactions grow. **About Kage Protocol:** Kage Protocol is a portal to private DeFi comprising of a suite of products that enable users to interact with decentralized finance while preserving confidentiality at every layer. Our team comprises blockchain engineers and cryptographers with deep expertise in: Zero-knowledge proofs (ZKPs) and privacy-preserving computations. - Cross-chain interoperability and bridging protocols. - EVM-compatible smart contract development and emerging ERC standards (e.g., ERC-4337). Kage Protocol will redefine the DeFi landscape by ensuring that every transaction from payments to lending and staking is executed with uncompromised privacy. **Technical Implementation & Architecture:** **1. Confidential Intent Creation on the Source Chain** - **Intent Submission:** Users initiate a cross-chain transfer by interacting with a specially designed ShadowContract on Ethereum. When a user submits an intent, the contract accepts parameters including: - **Commitment Generation:** The contract computes a commitment hash (e.g., note\_hash = H(asset, amount, sender, salt)) that represents the confidential transfer without revealing any sensitive details. **2. Off-Chain Aggregation & Messaging** - **Aggregated Intent Packaging:** Off-chain relayer nodes monitor the emitted events and collect updated Merkle roots. Instead of transmitting individual intents, these nodes aggregate multiple intents into a single proof package, drastically reducing on-chain data load. - We will employ a threshold signature scheme where a quorum of nodes collaboratively signs the new Merkle root. - This aggregated package (including the new root, a timestamp, batch ID, and the aggregate signature) is then prepared for transmission. Initially, a relayer will forward the aggregated package via an existing cross-chain messaging protocol (e.g., LayerZero). - The relayer’s role is to ensure secure, timely transmission of the package from the source chain to the target chain. - EigenDA Integration: In parallel, we will integrate EigenDA as our decentralized data availability layer to publish the aggregated Merkle roots and associated metadata. This addition ensures that our off-chain aggregation results are stored in a trust-minimized, verifiable manner, enhancing scalability and resilience. 1. **Intent Verification & Execution on the Target Chain** - **Merkle Root Update:** On the destination chain (starting with Optimism), a Target ShadowContract receives the aggregated package. The contract verifies the aggregate signature against a preconfigured public key set and updates its record of the foreign Merkle root accordingly. - This step ensures that the target chain holds a verifiable, up-to-date snapshot of all pending intents from the source chain. **4. Selective Disclosure & Privacy Enhancements** - **Private vs. Public Intents:** Our design supports both private and public intents: - **Selective Disclosure Mechanism:** To meet compliance needs, we incorporate a mechanism whereby authorized auditors or regulators can request a view key. This key allows them to decrypt specific intent details for audit or tax reporting purposes without compromising the privacy of everyday transactions. **5. Future Enhancements & Scalability** - **Merkle Tree Batching:** Future iterations will introduce advanced Merkle tree batching to further reduce gas costs by transmitting only the aggregated root periodically. - **Extended Interoperability:** While Optimism serves as the initial testnet target, our architecture is modular and can be extended to Arbitrum, Base, and non-Ethereum-settled chains using state-sharing models akin to Hashi. Milestones & Roadmap - **Phase 1 – Design & Prototype (Weeks 1–4):** - **Phase 2 – Beta Testing & Multi-Chain Expansion (Weeks 5–8):** **Future Development** - **Phase 3 – Public Deployment & Decentralization (Month 3+):** - Full public deployment with comprehensive documentation, SDKs, and developer tools. - Expand interoperability to non-EVM chains. ![Milestones & Roadmap - visual selection (2)](https://europe1.discourse-cdn.com/flex013/uploads/aztec/original/2X/5/5c62df8935d2854c9e4c9610f4cb1328980aed81.png) Grant Amount Requested: We request $50,000 to build, deploy, and operate an MVP that enables secure, confidential intent execution between Aztec and L2s (Optimism Superchain) testnets key components of the Kage ecosystem. Our goal is to have a fully functional MVP, demonstrating cross-chain asset transfers with enhanced privacy, ready for public testing by June 2025. ---
**Author:** ![rahul-kothari](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.aztec.network/rahul-kothari/32/34_2.png) [@rahul-kothari](https://forum.aztec.network/u/rahul-kothari)\ **Post date:** [April 2, 2025, 9:25am UTC](https://forum.aztec.network/t/kage-protocol-kuro-cross-chain-bridge-proposal/7626/2 "2025-04-02T09:25:17Z")
Hi! Thanks for your proposal! I have some questions: > [@LucidSamuel](#): > > Initially, a relayer will forward the aggregated package via an existing cross-chain messaging protocol (e.g., LayerZero). LayerZero (and other well known messaging protocols) are not integrated into Aztec yet and won’t be in time for the deadline. This RFP is for folks to build the cross chain messaging protocol. Does this change things for you at all? > Our goal is to have a fully functional MVP, demonstrating cross-chain asset transfers Is there a way you could implement something more interesting? Such as depositing into some defi protocol OR some interesting identity based primtivies (like dao voting or multisig signing)? ---
**Author:** ![LucidSamuel](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.aztec.network/lucidsamuel/32/2302_2.png) [@LucidSamuel](https://forum.aztec.network/u/LucidSamuel)\ **Post date:** [April 9, 2025, 2:56pm UTC](https://forum.aztec.network/t/kage-protocol-kuro-cross-chain-bridge-proposal/7626/3 "2025-04-09T14:56:14Z")
Hi Rahul, thanks for your feedback and thoughtful questions. Let me address them point by point. * * * On LayerZero & Messaging Protocols You’re absolutely right, Our Initial goal was to either integrate it ourselves and add private intents or implement our own minimal intent-based relayer mechanism using: - A lightweight `PortalContract` on the source chain (Ethereum L1 or L2 like Optimism) - Merkle root commitment + proof batching - A basic off-chain relayer responsible for message propagation - A `PortalReceiver` contract on the destination chain (Aztec) to verify Merkle proofs and authorize execution without any dependencies. On Building Something More “Interesting” Absolutely, Kage Protocol’s broader mission is to build an end-to-end privacy portal to DeFi: from lending and staking to LP provisioning and cross-chain liquidity flows. While we initially scoped this MVP tightly around bridging and message passing, we’d be excited to extend it toward **private DeFi interactions** , which are core to our roadmap. A proposed upgrade to the MVP could look like: - Users on Ethereum or an L2 submit an intent to **lend or swap** via an Aztec-native private DeFi primitive - A relayer transmits this intent to Aztec, where it is privately executed (e.g., via a mock swap or lending pool) - The fulfillment proof unlocks a claimable token or message on the origin chain Essentially demonstrating a novel cross-chain, private DeFi orchestration flow proving Aztec’s capability for a secure coordination layer for multi-chain intent execution.