SignedProposal Has No Signature?

[jonmchan]

I noticed that none of the implementations utilize the signature field in the SignedProposals in the proposal_builder (for example - https://github.com/hyperledger/fabric-gateway/blob/main/pkg/client/proposalbuilder.go#L42). Could anyone explain the reasoning for this? Without that, can't any parameter be changed in the proposal and be accepted as valid? I don't see any other place where the content is being signed or hashed.

[jonmchan]

It dawned on me - it isn't automatically signed to support offline signing. I now see there is a setSignature method in the proposal. By not automatically signing it, we can send it to be offline signed in the event that the private key is not in the identity. Would this be accurate?

[bestbeforetoday]

The proposal is always signed just before it is sent using the signer specified when connecting the Gateway, unless it has already been signed using the off-line signing flow:

• Endorse:

  fabric-gateway/pkg/client/proposal.go

  Line 64 in 1e4a926

  if err := proposal.sign(); err != nil {

• Evaluate:

  fabric-gateway/pkg/client/proposal.go

  Line 104 in 1e4a926

  if err := proposal.sign(); err != nil {

The off-line signing flow sets the supplied signature, which makes the signing during the endorse and evaluate a no-op since the signature is already present:

• fabric-gateway/pkg/client/gateway.go

  Line 194 in 1e4a926

  result.setSignature(signature)

The reason a signature isn’t created when the proposal is created is that, if you are exclusively using off-line signing, you can connect the Gateway without a signer. In this case, creating the signature using the Gateway’s signer when the proposal is created would fail.

[jonmchan]

I'll study the offline scenario tests. I appreciate the testing on this project! Thanks!