IBC Vector Commitments functionality

[adizere]

Context

Vector commitments are the mechanism underlying verification methods. IBC clients use & implement these methods to verify proofs that the state of foreign chains at a certain height contains a certain key/value (or alternatively the absence of that key/value).

Further reading

IBC Vector Commitments English spec: ics-023-vector-commitments

Dependencies

For basic implementation:

• ICS24 host-requirements

For complete implementation & acceptance:

• ICS02: ics-02-client-semantics
• ICS03: ics-03-connection-semantics
  • proof verification is also specified in ICS04: ics-04-channel-and-packet-semantics
  • and ICS07: ics-007-tendermint-client and other clients
• ICS26: ics-026-routing-module
• ICS18: ics-018-relayer-algorithms
• model-based testing (MBT) harness

Building blocks:

• confio/ics23 for proof representation and verification
• A Merkle store for storing/verifying on-chain data

Acceptance criteria

Component	Functionality	Criteria	Status
Chain (SDK or Mock)	Merkle store	Impl & unit tests	[ ]
Module	Verification methods (wrappers over confio/ics23)	Impl & unit tests	[ ]
Module	Verification methods	MBT tests	[ ]
Module	Verification methods	Mock tests	[ ]
CLI	Proof queries against Mock chain	end-to-end tests	[ ]

Related issues

The following ongoing issues provide a more fine-grained perspective about the progress on vector commitments:

• Incomplete ICS 02 verification functions: https://github.com/informalsystems/ibc-rs/issues/726
• Unreachable MissingLocalConsensusState error in verify_consensus_proof Unreachable MissingLocalConsensusState error in verify_consensus_proof cosmos/ibc-rs#33
• MVP Client Relayer: Periodic Client Updates MVP Client Relayer: Periodic Client Updates #216
• Modular logic for ICS3 Connection handshake protocol Modular logic for ICS3 Connection handshake protocol #92