🔧Cross chain protocol
Cross - Chain Protocol: Notary Model + MPC Multi - Party Signature
Roles in Cross - Chain Swaps
Sender: Users who interact with the core cross - chain system and can initiate cross - chain swaps.
Verifier: Adopting the notary model, it uses MPC (Multi - Party Computation) multi - party signature to verify users' deposit transactions.
Repeater: Based on the successful verification results from the Verifier, it submits to the cross - chain system to complete users' swaps.
Settlement: The executor of transactions on the target chain.
Workflow
OmniBridge is a permissionless cross-chain bridge built on the notary model + MPC multi-party signature, developed by the Omni team, aiming to enable one-click cross-chain swaps.
On the source network, Senders can initiate cross-chain transactions via our frontend system or decentralized wallets integrated with our API. The Verifier then uses the notary model to validate the user's deposit transaction on the source chain, applying a 3/5 threshold gate. If validation fails, the order halts—though the probability of this is extremely low. We currently deploy 5 nodes across web3 industry communities, requiring at least 3 nodes to approve. Even if nodes act maliciously or fail, at least 3 concurrent failures are needed to disrupt the process.
Once source network transaction validation passes, the Repeater collects verification results from nodes and submits them to our core cross-chain system for swapping. The swap process is near-instantaneous. Upon completion, the final verification occurs: the Settlement sends tokens to the user on the target chain.
On the target chain, the Settlement also uses multi-node validation to verify the deposit and swap process. After approval, the Sender receives the desired tokens on the target chain.
Nodes
We currently utilize 5 web3 community nodes participating in validation: OmniBridge, Bridgers, MetaPath, MpcWallet, ETHF, etc., all operating smoothly. Nodes must be deployed in respective communities and added to our whitelist to join validation.
Rewards
Validation nodes receive regular incentive rewards for participating in transaction verification.
Slashing
Malicious validation or persistent non-participation triggers our slashing policy. Penalties are determined by the ratio of failed validations to successful ones. Triggering this policy results in node removal and slashing.
Security Mechanisms
Signature Classification
Single-Signature Notary: Centralized nodes validate independently (high efficiency but concentrated risk), common in exchange cross-chain swaps.
Multi-Signature Notary: A union of notaries requires majority signatures for consensus, reducing single-point failure risks.
Distributed MPC Signature: Key sharding with multi-party computation (MPC) for combined signatures, balancing security and decentralization.
Notary Model + MPC Multi-Party Signature
Third-party notaries act as intermediaries to verify cross-chain transaction authenticity and relay data. Notaries handle data collection, validation, and confirmation, enabling indirect trust between non-interoperable chains.
Why Notary Model + MPC Is Secure
Key Management: Eliminating Single-Point Risk
Distributed Private Key Storage
MPC splits private keys into shards via secret sharing (e.g., Shamir's protocol), with each notary node holding independent fragments. No single node can reconstruct the key or sign transactions, eliminating single-point compromise risks.
Dynamic Signing Process
During transaction signing, nodes use MPC to collaboratively generate valid signatures without reconstructing the full key, avoiding exposure risks in traditional multi-signature setups.
Transaction Validation: Dual Consensus Mechanisms
Off-Chain Consensus in Notary Clusters
Notary nodes achieve consensus on transaction legitimacy via BFT (Byzantine Fault Tolerance) algorithms, ensuring authenticity—e.g., distributed signature notaries require majority approval.
MPC Threshold Signature Constraints
Setting a signature threshold (e.g., 3/5) ensures valid signatures only when sufficient nodes participate. Attackers must compromise over the threshold to manipulate transactions, raising attack costs exponentially.
Anti-Attack and Fault Tolerance
Defense Against Internal Collusion
MPC cryptography prevents notaries from accessing others' key shards. Even colluding nodes can't forge transactions without meeting the signature threshold.
Node Failure Tolerance
If some nodes go offline or are compromised, active nodes can still sign (e.g., 3 out of 5 nodes operating). MPC's fault tolerance ensures continuous system operation.
Technical Synergy Enhancing Security
Single-Point Failure
Multi-node distributed responsibility
Key shards without complete form
Protocol Compatibility
Adapts to validation rules of different chains
MPC based on standard cryptography (e.g., ECDSA) for cross-chain universality
Transparency & Audit
On-chain transaction records are traceable
Signing processes have auditable, tamper-proof logs
Additional Security Layers
Notary Node Screening
Reputation mechanisms (e.g., renowned institutions as nodes) or staking economies raise malicious behavior costs. Random node rotation reduces long-term collusion risks.
MPC Security Implementation
Relies on academically validated cryptographic schemes (e.g., ECDSA) and third-party audits (e.g., NCC Group penetration testing) to avoid algorithmic vulnerabilities.
Conclusion: Security Through Layered Defense
Physical Layer: Distributed private key storage, no complete key form.
Consensus Layer: Multi-node notary validation + MPC threshold signatures.
Algorithmic Layer: Cryptographic protocols ensuring shard privacy and computational legitimacy.
This combination balances off-chain efficiency and on-chain trustworthiness, making it ideal for high-value cross-chain asset custody, DAO multi-signature vaults, and similar scenarios.
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