Re: Local Collections in Fabric 2.0 #fabric

David Enyeart

The pattern mentioned in 'Keeping transactors private' would meet the requirement of keeping the collaborators of a business transaction private in Fabric v2.0. In this pattern, each party writes common pre-image data, or a reference to each other's pre-image data, in their own private data collection that their own peer endorses. The pre-image data can later be shared as needed with other organizations, who can verify the hashes on the chain. If required in your scenario, you could also provide a third party such as a regulator access to the data so that they could verify both sets of hashes in chaincode and then 'settle' the business level transaction with a final Fabric transaction.

Concerning your specific question, I am aware of ongoing research to make either local collections proper, or private peer-to-peer transaction flows, available in a future version of Fabric. However, there is no specific plan or RFC available at this time.

Dave Enyeart

westerkamp---02/12/2020 04:50:16 AM---Hi everyone, Some time ago there has been a discussion concerning local collections with the goal to

From: westerkamp@...
To: fabric@...
Date: 02/12/2020 04:50 AM
Subject: [EXTERNAL] [Hyperledger Fabric] Local Collections in Fabric 2.0 #fabric
Sent by: fabric@...

Hi everyone,

Some time ago there has been a discussion concerning local collections with the goal to obscure members of a collection to other participants of a channel in FAB-7593.

I was wondering about the impact of novel Fabric 2.0 features on the proposal or if Fabric 2.0 delivers functionality that enables such collections already? In that context, I have checked out the private data sharing patterns descibed here. Especially the "Keeping transactors private" pattern seems very related.

I would like to introduce a short example to clearify the requirements: Four organizations A, B, C and D participate in a shared channel. A and B collaborate using chaincode containing a private data collection. C and D should not be able to observe that A and B are collaborating. Therefore, when A is submitting a transaction, C and D should not be able to tell who is affected by that transaction. Currently, the data collection definition reveals all members of the collections, so that C and D can derive that A and B are collaborating (from my understanding).

So my questions are:
- Can Fabric 2.0 already implement such a use can, e.g. by applying the "Keeping transactors private" pattern? If so, what would it look like in detail?
- If it cannot be implemented by Fabric 2.0 yet, what do we need to do so? Is FAB-7593 still relevant in context of Fabric 2.0?

Thanks and best regards,

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