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Architectural choices

Sidecar Network Approach​

Relay Sidecar

The Symbiotic Relay operates as a peer-to-peer sidecar network that runs alongside main blockchain nodes.

Stateless approach​

The relay network maintains a stateless design that eliminates dependencies on main node configurations. Instead, it relies entirely on on-chain state managed through:

  • ValSetDriver: manages validator set configuration and epoch transitions
  • Settlement Contract: handles validator set header commitments and signature verification

This approach requires minimal changes to existing main network node implementations for relay integration.

Flexible Verification​

The Settlement contract provides cryptographic verification of validator consensus.

It supports two verification strategies:

Simple BLS Verification​

Optimized for validator sets up to ~125 validators, requiring explicit validator data in proofs.

Zero-Knowledge Verification​

Uses ZK proofs for larger validator sets with near-constant verification gas costs.

Multichain​

Validator sets and their attestations can be verified across any EVM-compatible chain through the Settlement contract's cross-chain addressing system.

The system uses CrossChainAddress structures to identify contracts across different blockchain networks.

HTTP API​

Voting Power and Epoch Tracking​

The HTTP API serves as the primary interface for:

  • Querying current validator set
  • Tracking epoch transitions and validator set changes
  • Submit a signature requests
  • Tracking signature aggregation process

Quorum Signature Management​

The API provides endpoints for:

  • Requesting signature aggregation from the validator set
  • Tracking quorum signature generation progress
  • Verifying completed quorum signatures against on-chain state

Non-EVM Settlement​

Extending support to non-EVM chains requires only porting the core Settlement.sol contract logic to the target blockchain's smart contract platform.

The settlement verification logic is self-contained and doesn't depend on EVM-specific features beyond basic cryptographic operations and BLS