Dynamic Hidden Committee

Different from existing cross-chain solutions, Taker Bridge applies an external verification model to securely process cross-chain messages in a decentralized and distributed manner. Dynamic Hidden Committee (DHC) is proposed to guarantee the security of omnichain applications built on top of it. Each DHC manages a private key in Taker Bridge and the private key is distributed into key shares and stored in the DHC members, i.e. a group of MPC nodes. DHC follows a decentralized signature scheme that uses its underlying private key to sign cross-chain messages and yield signatures as on-chain verifiable "claims" to indicate the validity of cross-chain messages. More specifically, each user in Taker Bridge can deploy his application-specific DHCs to serve his own application's cross-chain bridge. Taker Bridge has provided a comprehensive interface for its users, i.e. bridge builders, to construct their personal and customizable bridge safeguards (DHC) and on-chain message endpoints (Anchor). To ultimately protect the identities of DHC members, i.e. MPC nodes, a ZKP-based algorithm, Ring Verifiable Random Function (Ring VRF) protocol, is proposed where the real public identification of each MPC node is hidden among a ring to considerably increase the costs of external attacks and simultaneously remove the possibility of internal collusion. Furthermore, all the key management procedures are executed in the TEE hardware, such as Intel SGX, of MPC nodes, to ensure the privacy and integrity of private key management.

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