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Union

Union is a blockchain platform designed to facilitate secure and efficient cross-chain communication and bridging. It enables interoperability between different blockchain networks, including Layer 1 (L1) and Layer 2 (L2) solutions.

Overview​

Union addresses the challenges in existing cross-chain solutions, particularly:

  • Security concerns in bridging
  • High computational costs for consensus verification
  • Slow bridging and transfer times
  • Centralization risks in many existing bridge solutions

Union achieves its goals through several key innovations:

  1. CometBLS: An improved consensus mechanism based on Tendermint, optimized for zero-knowledge proofs and efficient bridging.
  2. Galois: A zero-knowledge consensus proving system that enables fast and low-cost proof generation.
  3. Voyager: An in-house relayer for supporting new networks and efficient message passing.
  4. Conditional Light Clients: Specialized light clients that can handle complex settlement conditions when bridging to L2 networks.

Architecture​

Detailed Process Flow Steps:​

  • Chain A emits an IBC send-packet event to initiate the cross-chain communication.
  • The Union Chain requests a zero-knowledge proof of its current state from Galois.
  • Galois generates a ZK consensus proof of the Union Chain's state.
  • Galois sends the generated proof to Voyager, the relayer.
  • Voyager processes the proof in its virtual machine.
  • Voyager updates the state of the Conditional Light Client with the new proof.
  • The Conditional Light Client verifies the settlement conditions for the transaction.
  • If conditions are met, the Conditional Light Client submits a state update to Chain B.
  • Chain B verifies and processes the incoming data, updating its own state.

Architectural Advantages​

  1. Improved Scalability: CometBLS allows the network to scale to hundreds of validators without impacting performance or bridging latency.
  2. Efficient Proof Generation: Galois can generate consensus proofs for 128 validators within seven seconds, using only 5GB of RAM.
  3. Decentralization: The system is designed to allow anyone to participate in proof generation and relaying, reducing centralization risks.
  4. Cost-Effective: Union's approach significantly reduces the cost of generating and verifying proofs compared to traditional methods.
  5. Flexibility: The use of conditional light clients allows for efficient bridging to various L2 solutions.
  6. Fast Bridging: The combination of efficient proof generation and BLS signatures enables faster cross-chain transactions.

Architectural Disadvantages​

  1. Complexity: The system involves multiple specialized components, which may increase the overall complexity of the network.
  2. Reliance on New Technologies: Some of the technologies used, such as BLS signatures and MiMC hashing, are relatively new in the blockchain space and may require further validation.
  3. Potential Learning Curve: The unique architecture may require developers and users to familiarize themselves with new concepts and tools.

Settlement Category​

Based on the provided information, Union falls under the Hybrid settlement category. This conclusion is drawn from the following observations:

  1. Native Elements:
    • Union has its own blockchain with a native consensus mechanism (CometBLS).
    • It uses its own validator set for consensus and proof generation.
  2. External Elements:
    • Union interacts with external chains (L1s, L2s, and sovereign rollups) through light clients and zero-knowledge proofs.
    • It uses conditional light clients to track and verify the state of external chains.
  3. Hybrid Approach:
    • The combination of internal consensus (CometBLS) with external bridging capabilities (Conditional Light Clients) creates a hybrid system.
    • Union acts as an intermediary layer between different blockchain networks, facilitating cross-chain communication while maintaining its own consensus.