State verification

The localhost client handles state verification through the LightClientModule interface methods VerifyMembership and VerifyNonMembership by performing read-only operations directly on the core IBC store.

When verifying channel state in handshakes or processing packets the 09-localhost client can simply compare bytes stored under the standardized key paths defined by ICS-24.

For existence proofs via VerifyMembership the 09-localhost client will retrieve the value stored under the provided key path and compare it against the value provided by the caller. In contrast, non-existence proofs via VerifyNonMembership assert the absence of a value at the provided key path.

Relayers are expected to provide a sentinel proof when sending IBC messages. Submission of nil or empty proofs is disallowed in core IBC messaging. The 09-localhost light client module defines a SentinelProof as a single byte. Localhost client state verification will fail if the sentinel proof value is not provided.

var SentinelProof = []byte{0x01}

The ClientState of 09-localhost is stateless, so it is not directly provable with VerifyMembership or VerifyNonMembership.