Idemix MSP Folder Structure incompatible with what Fabric expects

[adecaro]

Currently, Fabric-CA generates an Idemix MSP folder structure and file content that Fabric is not able to load.
Namely:

• The content of SignerConfig is encoded in json, Fabric expected proto
• Fabric expects the revocation public key to be stored in a file named RevocationPublicKey and IdemixRevocationPublicKey.

This git issue is to fix the above issues.

[arner]

Why was this change reverted?

[bestbeforetoday]

Why was this change reverted?

It broke the Java client SDK.

[adecaro]

Is anyone using the Idemix provided by Java client SDK's ? If no, I would suggest to drop it. No one is going to keep supporting that implementation.

[bestbeforetoday]

Yes, people are using it. We already encourage people to use the Fabric Gateway client API instead of the legacy Java SDK, and plan to deprecate the legacy Java SDK once Fabric v2.5 LTS is released. Certainly for Fabric v3 we can break compatibility with the v2.x Idemix implementation.

Producing a new release (v2) of the CA without support for the old style Idemix to go along with Fabric v3 sounds perfectly reasonable. Breaking compatibility with existing client applications or removing capability in a patch release (or even a minor version release) does not seem reasonable.

[adecaro]

But Gateway does not support Idemix yet, how are people using idemix moving there?

[bestbeforetoday]

The identity credentials and signing implementation are pluggable in the Fabric Gateway client API. Anyone could use the Idemix implementation from the legacy Java SDK with the new client API. I suspect nobody has done that - certainly not that I've seen - and there is currently no Idemix signing implementation provided out-of-the-box with the Fabric Gateway client API so I don't think anyone is using Idemix with that client API.

I really don't understand how that impacts whether it's OK to make breaking changes to the CA in patch releases.

[adecaro]

I pointed to that because there is no reason to consider this a breaking change if what gets broken should not be there anyway :)