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Initial insights on DID spec based on this week’s DID:BTCR Hackathon

From: Christopher Allen <ChristopherA@blockstream.com>
Date: Fri, 14 Jul 2017 13:02:15 -0700
Message-ID: <CA+HTxFcoc1WRPAgqazdtvuJfJQ8tXVVgptB4+AEZTRr-M5aJEA@mail.gmail.com>
To: W3C Credentials CG Public List <public-credentials@w3.org>
At last falls #RebootingWebOfTrust after working on it for about a year, we
came up with an initial first implementors spec for DIDs. It was published
last winter at
https://github.com/WebOfTrustInfo/rebooting-the-web-of-trust-fall2016/blob/master/final-documents/did-implementer-draft-10.pdf

Two weeks ago, Manu team refactored that document for us to consider in the
W3C Credentials WG as a work item: https://opencreds.github.io/did-spec/

This week we attempted to implement the DID spec for use in the bitcoin
based BTCR method as part of the BTCR Hackathon:
https://github.com/WebOfTrustInfo/btcr-hackathon

The good news is that we’ll have in the next few days a number of
functioning verifiable and confirmable self-sovereign DID identifiers, a
number of real examples of verifiable DDOs, as well some sample Verified
Claims properly signed by bitcoin keys that can be proven to be issued by
the DDO which can prove that it has exclusive update rights to the DID
identifer. All good news.

However, we ran into a number of issues with the first implementors draft
of the DID spec.

I’ve written up some initial insights and thoughts
<https://github.com/opencreds/did-spec/issues/4#issuecomment-315449659> of
what we learned about the DID spec. The hackathon team will create
individual issues for these over the next week in the DID repo issues
<https://github.com/opencreds/did-spec/issues>, but to share an early
version of them now:

Personally I think owner and control need to be completely refactored and
renamed. Both terms are repeatedly not working and are being confused. (In
addition, a number of parts of the spec maybe should be moved the the
Sovrin Method instead of being in the DID spec.)

Insights:


   - We should rarely talk about keys, but instead proofs, of which a
   signature using a key is only one kind of proof (but very common). See:
   WebOfTrustInfo/btcr-hackathon#39
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/39>
   - The DDO object may in fact be composed of multiple parts, with
   different parts having different proofs. See:
   WebOfTrustInfo/btcr-hackathon#37
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/37>
   - The first part of the DDO may be deterministic based on the root of
   trust transaction (and in BTCR is in effect "signed" or "proven" by the
   "SatoshiBlockchainSignature" or "SatoshiBlockchainProof" . See
example at WebOfTrustInfo/btcr-hackathon#37
   (comment)
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/37#issuecomment-315289776>
   - We may even want to go back to all the JSON-LD signature schemas and
   replace the semantics consistent as proofs rather than signatures.
   - If there is a link from the deterministic DDO to the extended DDO (in
   BTCR the op_return pointer), we maybe should allow that to continue to be
   extended (especially useful the IPFS case). We need a better name for these
   links. See WebOfTrustInfo/btcr-hackathon#40
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/40>
   - Additional parts must be proven by the owner proof (typically a key)
   and likely in effect are self-signed verifiable claims that extend the
   deterministic DDO: see WebOfTrustInfo/btcr-hackathon#8
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/8> — This is
   particular important in some cases like IPFS and some future multisig
   possibilities where you can't put the DID identifier or proof into the DDO
   as you have to confirm the transaction in order to get that value — a catch
   22. Instead, the IPFS record extends the deterministic DDO with additional
   values, and doesn't have to have the DID identifier or DID proof as they
   come from the deterministically created root part of the DDO.
   - The owner list is overloaded. It should only be for associating any
   additional DDO parts or updates with the the DID root of trust transaction.
   See: WebOfTrustInfo/btcr-hackathon#38
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/38>
   - We need a separate list of proofs (which are typically keys) that are
   allowed to issue claims under this DID, which may include (or not) an owner
   proof. In the BTCR case, the owner proof is always a key, and it always is
   also an issuer key. See: WebOfTrustInfo/btcr-hackathon#38
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/38>
   - We have some better understanding of the roles of
   WebOfTrustInfo/btcr-hackathon#33
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/33> and in
   particular the short summary at WebOfTrustInfo/btcr-hackathon#33
   (comment)
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/33#issuecomment-314608959>
   - Rather than using control proofs for revocation, this may need to be a
   separate list of proofs also. This is our same problem with overloading
   owner. See more thoughts on revocation starting at
WebOfTrustInfo/btcr-hackathon#33
   (comment)
   <https://github.com/WebOfTrustInfo/btcr-hackathon/issues/33#issuecomment-314618077>

— Christopher Allen
Received on Friday, 14 July 2017 20:03:50 UTC

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