Data Minimization
Full Title or Meme
For the purposes of Privacy it is generally a good idea to minimize the amount of data that is transmitted to that which is absolutely essential.
Context
- The original issue was limiting the amount of data that an IdP would transmit to an RDP.
- The issue that became important in 2021 was allowing an issuer to create a credential that had the capability to present a verified subset of the data that it carried.
Solutions
Using Zero Knowledge Proofs
If you want to know more about the arguments against a ZK approach, perhaps talk to Dave Longley, who has articulated some principled concerns. If you want to know more about those who are doing things like this, perhaps talk to the Hyperledger Indy community. Both parties will be able to give you much more detailed info.
In some of our more recent security & privacy architecture work, we also looked at some of the ZK approaches (such as BBS+ proofs) but have elected to instead focus on elision & redaction by a hash-tree-based graph, and enveloped encryption approaches. In particular, we felt that it was important that holders could also withhold details, not just issuers.
Though our MVA (minimum viable architecture) does not conform with the current W3C efforts for DID 1.0 or VC 1.1 / 2.0 (though someday we might submit for VC 3.0), they are quite parallel, and you might find them useful ground for defining your own requirements.
- Text "RWOT11 Topic Paper: Elision, Redaction, and Noncorrelation in Smart Documents": https://github.com/WebOfTrustInfo/rwot11-the-hague/blob/master/advance-readings/elision-redaction-correlation-smart-documents.md
- Video "Envelope Privacy Requirements for Non-Correlation & Support Elision Redaction Reference (2022-08-17)": https://youtu.be/ubqKJAizayU
