MockClient verifyMembership error

[yoshidan]

The proof commitment for MsgRecvPacket uses sha256 + sha256 .

yui-ibc-solidity/pkg/relay/ethereum/chain.go

Line 229 in 64b9547

commitment := chantypes.CommitPacket(c.Codec(), packet)

https://github.com/cosmos/ibc-go/blob/12c00ec85c1238a0b9075a14593485c60f0da729/modules/core/04-channel/types/packet.go#L19

On the other hand, IBCPacket uses sha256 + sha256 and MockClient verifyMembership further performs sha256, which always seems to cause an error. In fact, it failed in my environment.

yui-ibc-solidity/contracts/core/04-channel/IBCPacket.sol

Lines 113 to 120 in 64b9547

	sha256(
	abi.encodePacked(
	msg_.packet.timeout_timestamp,
	msg_.packet.timeout_height.revision_number,
	msg_.packet.timeout_height.revision_height,
	sha256(msg_.packet.data)
	)
	)

yui-ibc-solidity/contracts/clients/MockClient.sol

Line 149 in 64b9547

return sha256(value) == proof.toBytes32(0);

It looks like we should'n use sha256 for verifyMembership in MockClient, but it is still an error because sha256 is used in yui-relayer for connection and channel.
https://github.com/hyperledger-labs/yui-relayer/blob/d4cc52059626e9dd86433dbd78de0c40fba87f5b/provers/mock/prover.go#L159

As a tentative response, I was able to prevent the error by modifying MockClient's verifyMembership as follows.

//before 
return sha256(value) == proof.toBytes32(0);

//after
bytes32 v = value.toBytes32(0); // for packet
bytes32 s = sha256(value); // for connection and channel
bytes32 p = proof.toBytes32(0);
return s == p; || v == p;

[bluele]

I think the problem is that the mock-client does not support the generic verification function.
https://github.com/datachainlab/ibc-mock-client/blob/main/modules/light-clients/xx-mock/types/client_state.go#L225

The property of being able to verify commtiment in the same method, independent of the commitment path, would be important to support some applications (e.g. https://github.com/cosmos/ibc/tree/main/spec/app/ics-031-crosschain-queries)

[bluele]

I close this issue since already opened the issue in ibc-mock-client: datachainlab/ibc-mock-client#7