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Re: Proposed work item: WebKMS

From: Anders Rundgren <anders.rundgren.net@gmail.com>
Date: Sun, 24 Nov 2019 17:29:10 +0100
To: Manu Sporny <msporny@digitalbazaar.com>, public-credentials@w3.org
Message-ID: <0170609e-b652-f662-37a6-c9717c1a8ab4@gmail.com>
Hi Manu,
Thanx for the prompt answer.  From:
https://w3c-ccg.github.io/credential-handler-api/
I extracted the following line:

    "This specification does not address how software built with
     operating-system specific mechanisms (e.g., "native mobile apps")
     handle credential requests and credential storage"

Your buddies in the W3C Payment WG stubbornly continue with Web based Payment Handlers although all payment providers I know of put their muscles behind native apps.
The PR/Android and PR/iOS is all that was needed, and it is a deal done.

https://github.com/cyberphone/doc/blob/gh-pages/payments/paymenthandler.md#the-w3c-paymenthandler

WebAuth as a solution for payments also seem like a unlikely win.

Pardon, me for interfering, I will remain silent now :-)

Anders

On 2019-11-24 16:27, Manu Sporny wrote:
> On 11/24/19 1:23 AM, Anders Rundgren wrote:
>> Hi Manu, From the ZCAP-LD draft:
>>
>> "Web-based applications could provide choice in Key Management
>> Systems -- potentially allowing customers to bring their own Key
>> Management Systems with them just as they bring their own devices
>> today"
>>
>> Wouldn't it be logical to have KMSes in these devices as well?
> 
> Yes, either in the devices (where the WebKMS driver is WebAuthn) or
> using the device's keys to access a remote HSM (where the WebKMS driver
> is something like AWS Cloud HSM).
> 
> All the pieces are there today... mobile phones do have HSMs that are
> accessible via native applications and soon to be broadly accessible via
> WebAuthn.
> 
>> I may [surely] be biased but this is at least what my 10Y+(!)
>> SKS/KeyGen2 project builds on. The (ab)use of W3C's PaymentRequest
>> made it pretty cool as well :-)
>> https://cyberphone.github.io/doc/web/calling-apps-from-the-web.pdf
> 
> Yes, and this is why the Credential Handler API (CHAPI) is designed the
> way it is and supports not only sending Verifiable Credentials through
> CHAPI, but ZCAPs as well. CHAPI was built from years of hard won
> knowledge gained (and mistakes made) during the creation of Payment
> Request and Payment Handler in the Web Payments WG.
> 
>> The use-case you mention like car keys are very interesting but I
>> can't imagine that car keys would be stored anywhere but in client
>> devices. Now, how do you get such keys? In my world through
>> (non-standard) authentication to a service provider.  I.e. I (FWIW)
>> do not see that an end-user would ever talk directly to a cloud-HSM,
>> that's reserved for service providers.
> 
> Yes, keys can be on client devices, and they can also exist in the
> cloud, and it's up to the application to determine which keys will be
> used to do what.
> 
> WebKMS provides the added flexibility of being able to lose your phone
> and all of your phone HSM keys, but not have to rotate out your signing
> keys, which exist in the cloud HSM. WebKMS isn't really meant to be
> accessed directly from the Web, but will most likely sit behind an
> agent/digital wallet of some kind.
> 
> To summarize, these scenarios are possible via WebKMS:
> 
> * Local HSM only
> * Cloud HSM only
> * Local HSM that authzs to Cloud HSM
> * Local HSM that authzs to shared Cloud HSM (multisig)
> 
> ... and the benefit of WebKMS is that the same operations are possible
> via a unified API for the four scenarios above. Clearly, lots of
> discussion needs to happen, and this isn't as fundamental as VCs and
> DIDs... but if folks want to do key management in an interoperable way,
> WebKMS is one possible way forward.
> 
> -- manu
> 
Received on Sunday, 24 November 2019 16:29:16 UTC

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