Verification

Dispatch uses two complementary mechanisms to catch bad providers: attestation (cryptographic proof of what was served) and quorum (cross-provider consensus on deterministic results).

Attestation

Every dispatch-service response carries a signed attestation header:

X-Drpc-Attestation: {"signer":"0x…","signature":"0x…"}

The provider signs the following message with its operator key:

keccak256(
    chain_id_be8        // chain ID as 8 bytes big-endian
    || method_utf8      // method name as UTF-8 bytes
    || keccak256(params_json)   // keccak of the serialised params field
    || keccak256(result_json)   // keccak of the serialised result (or error) field
)

The signature is a 65-byte secp256k1 ECDSA signature (r || s || v, Ethereum-style v = 27/28).

Gateway verification happens automatically on every response before it is forwarded to the consumer. The gateway recovers the signer from the signature and checks it matches the signer address stated in the header. A mismatch logs a warning and penalises the provider's QoS score.

Without slashing, attestations serve as:

• A tamper-evident audit trail — consumers can verify a provider claimed a specific response
• A QoS signal — providers that forge or omit attestations are deprioritised over time
• Future-proof groundwork — if slash infrastructure is added later, the format is already in place

Quorum

For deterministic methods, the gateway queries quorum_k providers (default: 3) concurrently and takes the majority result. If providers disagree, the minority is outvoted and the disagreement is logged as a warning.

Methods subject to quorum:

All other methods (including eth_blockNumber, eth_estimateGas, eth_sendRawTransaction) use concurrent dispatch — first valid response wins.

What is not implemented

• Slashing — slash() reverts with "not supported". RPC responses have no canonical on-chain truth to verify against, so there is no safe basis for slashing.
• EIP-1186 Merkle proof verification — on-demand proof attachment and MPT verification; deferred with slashing.
• Block header trust oracle — required for Merkle proof verification; not built.