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Re: A Decentralized Hashtable for the Web

From: Dave Longley <dlongley@digitalbazaar.com>
Date: Wed, 4 Nov 2015 20:34:08 -0500
To: David Nicol <davidnicol@gmail.com>, Manu Sporny <msporny@digitalbazaar.com>
Cc: Web Payments CG <public-webpayments@w3.org>
Message-ID: <563AB210.7080702@digitalbazaar.com>
On 11/02/2015 05:25 PM, David Nicol wrote:
> I'm of the opinion that a hash of a public key makes a fine DHT
> handle for an identity that can be validated by demonstration of
> access to the matching private key.

In a separate thread in response to this we discussed how it's important
to loosely couple keys and identifiers. However, I wanted to say that we
may still use a public key hash as the basis for the identifier so as to
simplify the initial claiming process. But, post claim, there would be
no tie between any keys associated with the identifier and the value of
the identifier itself.

In short, to claim a decentralized identifier you could:

1. Generate a key pair.
2. Create a URL: `did:<hash-identifier>:<hash of public key>`.
3. Create a DID document containing an ACL with your public key in it.
4. Digitally-sign the DID document and send it to the WebDHT for publishing.

The WebDHT could then check the value of the identifier you wish to
claim against the public key in the associated document and check the
signature on the document. If all of these match, the DID would be
considered claimed and the document accepted and stored on the WebDHT.
However, from that point forward, different keys could be associated
with the document (and the original key could be removed entirely if so

This gives us the best of both worlds: A simple way to assert ownership
over an identifier and no strong link between keys and the identifier
after the identifier has been claimed. After it has been claimed, the
identifier can be treated as an opaque value.

There might be a reason to keep the original public key around for
provenance to help prevent certain attacks on the WebDHT, but that is TBD.

Dave Longley
Digital Bazaar, Inc.
Received on Thursday, 5 November 2015 01:34:37 UTC

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