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. In that design, SOS to Ethereum proves a stake-weighted SOS quorum certificate and transaction inclusion, and Ethereum to SOS proves finalized Ethereum state and the relevant burn storage.
Being prepared for the public test network and Ethereum Sepolia; not open yet, and not a mainnet deployment.
SOS to Ethereum
Finality plus inclusion proof
Ethereum to SOS
Finalized storage proof
Custody
No bridge multisig
Target networks
SOS testnet and Sepolia, being prepared
SOS to Ethereum
SOS finality contains many ML-DSA-65 validator signatures, which are too large to verify directly as ordinary EVM calldata. In the bridge design, 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 is designed to pin the accepted verifier and program identity, and to bind the bridge domain and validator-set commitment so that a receipt from another deployment or validator set cannot be replayed as if it belonged to this one.
Ethereum to SOS
The reverse direction is designed to start from Ethereum consensus finality: a light-client proof verifies the sync-committee path and extracts the burn from proven execution storage, and the SOS node validates that proof before minting the corresponding testnet asset.
Relayers are designed to transport evidence and pay submission costs without receiving 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: in the design, relayers transport proofs while the receiving chain verifies the required finality and inclusion statements.
Which Ethereum network will the bridge use first?
The bridge is being prepared for the public SOS testnet and Ethereum Sepolia, with test assets only. It is not open yet, and 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: 2026-09-25