Proof of creditworthiness short use case per issue #137

[ghost]

This is a proof of creditworthiness short use case per issue #137 by @kjetilk.

---

Preview | Diff

[jandrieu]

Let's shift this to using a digital fiduciary that inspects the credit data and generates a VC attesting to their judgment. In fact, it would be nice to include some personal information in that credit data. For example, getting credit based on self-employment often requires as much as five years of bank statements. With a trusted party in the middle, we can get a trustable attestation about income that can now be used without divulging the underlying finances of the business.

[jandrieu]

Let's rewrite to focus on custom predicates as a mechanism for distilling credit worthiness from selectively disclosable VCs.

[jandrieu]

The phrase underlying data reads to me as if the VP is doing a selective disclosure over the data in the VCs, but I don't believe we have a mechanism for that.

Suggested change

	<p>To prove her creditworthiness when applying for a mortgage, Alice acquires verifiable credentials issued by each bank containing type and balance for each account. She creates a verifiable presentation aggregating all accounts (type and balance) without revealing any issuers of the underlying data.</p>
	<p>To prove her creditworthiness when applying for a mortgage, Alice acquires verifiable credentials issued by each bank containing type and balance for each account. She creates a verifiable presentation aggregating all accounts (type and balance) without revealing any issuers of the underlying data.</p>

What we could do is pass the balance and bank info on, while avoiding the legacy approach of providing bank statements with all the account transactions.

Or maybe something with zksnarks to add a custom predicate to the VP, but I haven't seen anyone work through those details.

[jandrieu]

Per our conversation today, let's look at a set of selectively disclosable verifiable credentials which comprise a 3 year history of bank activity (one statement per months). Using predicate proofs, our hero is able to demonstrate that in each and every month they maintained a balance of at least $50,000 USD, without revealing the actual balance values nor the actual transactions.

[jandrieu]

Ok. Let's move this forward. I'm going to take on the assignment and base this on 9 annual statements, each a VC with BBS securing algorithm, and zkSnarks for predicate analysis. We'll derive 9 proofs (one from each year), which include the year, the account owner identifier (as DID), and the average balance for that year. These 9 proofs will show that in each year, the funds available to the subject, on average, exceeded $50,000.

[kjetilk]

Just wanted to add it looks good to me!