Re: Local Collections in Fabric 2.0 #fabric

Alessandro Sorniotti


A transaction that uses collections leaks information about the involved parties in 3 ways: 1) the creator; 2) the collection name and 3) endorsements. Point 1 can be addressed by using idemix. Local collections address point 2, and we have a (VERY ROUGH!) prototype here

We're working on point 3, so take a look at our playground for updates.


On Wed, 12 Feb 2020, at 10:50 AM, westerkamp@... wrote:
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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