Proof-based interoperability / Sepolia
A bidirectional SOS and Ethereum bridge built around proofs
The bridge is designed to replace a custody committee with verifiable state transitions. SOS to Ethereum proves a stake-weighted SOS quorum certificate and transaction inclusion. Ethereum to SOS proves finalized Ethereum state and the relevant burn storage.
Live on the public testnet against Ethereum Sepolia; not a mainnet deployment.
SOS to Ethereum
Finality plus inclusion proof
Ethereum to SOS
Finalized storage proof
Custody
No bridge multisig
Current network
SOS testnet and Sepolia
SOS to Ethereum
SOS finality contains many ML-DSA-65 validator signatures, which are too large to verify directly as ordinary EVM calldata. A recursive STARK verifies the real stake-weighted quorum certificate inside the proof, composes it with transaction inclusion, and commits a byte-exact journal that the bridge contract reconstructs.
The contract pins the accepted verifier and program identity. It also binds the bridge domain and validator-set commitment so a receipt from another deployment or validator set cannot be replayed as if it belonged to this one.
Ethereum to SOS
The reverse direction starts from Ethereum consensus finality. A light-client proof verifies the sync-committee path and extracts the burn from proven execution storage. The SOS node validates that proof before minting the corresponding testnet asset.
Relayers transport evidence and pay submission costs, but they do not receive authority to invent a deposit, rewrite finality, or sign on behalf of users.
Operational boundaries
Bridge safety also depends on release discipline: immutable program identifiers, validator-set transition policy, bridge-domain migration, TVL limits, monitoring, failover, and a drain procedure. The testnet exists to exercise those controls before any mainnet value is accepted.
Ethereum's present cryptography remains a non-post-quantum external boundary. SOS does not describe the counterparty chain or EVM verifier as quantum resistant.
Questions
Common questions
Is the SOS bridge a multisig bridge?
No. The intended authorization is proof based. Relayers transport proofs, while the receiving chain verifies the required finality and inclusion statements.
Which Ethereum network is currently supported?
The public SOS testnet bridge is paired with Ethereum Sepolia. It must not be treated as a mainnet asset bridge.
Does the bridge make Ethereum post-quantum?
No. Ethereum compatibility follows Ethereum's current consensus and EVM verification rules at an explicit external boundary.
Primary sources
Last reviewed: 2026-07-21