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Re: [W3C WebCrypto API WG] Key discovery

From: Mark Watson <watsonm@netflix.com>
Date: Thu, 4 Apr 2013 17:25:03 -0700
Message-ID: <CAEnTvdDnOgTx4qk1biNBn9NdK=yfQ+EAAf0RtC+qUc9A5_8Qrg@mail.gmail.com>
To: Ryan Sleevi <sleevi@google.com>
Cc: Lu HongQian Karen <karen.lu@gemalto.com>, "public-webcrypto@w3.org" <public-webcrypto@w3.org>, Hutchinson Michael <Michael.Hutchinson@gemalto.com>
Scope issues aside, on the technical side it's difficult to see how this
could be interoperable without further specification.

Considering the use-case given, there would need to be a specification
(somewhere) of the format of the Government-issued certificate which
included details of how the various properties of that certificate were
handled by the ( attribute name, value ) filter matching (i.e. what are the
attribute names and how are their values derived from the certificate and
how is the matching done), how the Issuer and isPrivate should be set and
what kind of authentication was required.

UA's could then know how to support that kind of certificate and
applications would know what to look for.

Typically in these kind of situations we have a chicken-and-egg problem.
There is reluctance to specify a lookup capability in WebCrypto when we
have no idea what kinds of things we're trying to look up. On the other
hand, noone is going to write a "how to expose XYZ key in WebCrypto"
specification if there is obviously no method in WebCrypto to do that.

One way to resolve that problem is to signal intent with a simple API and
define a registry for specifications that define how it is used. For
example, if the getKeys() call included a "type" parameter, with a registry
for type values, then implementors would know that to implement getKeys()
they just have to look through the registry, get the specifications
registered there and implement zero or more of those. There's no
requirement to implement any of them.

Typically, W3C has preferred people to come to W3C itself and write those
specifications here. That has the advantage that the specifications fall
under the W3C patent policy. The W3C has deviated from this only when it
has been practically impossible. MIME types for media codecs would be an
example of a type field with a registry operating in very much the way I
described.

However, the scope quoted by Ryan does seem to rule out that approach in
the short term ...

...Mark



On Thu, Apr 4, 2013 at 4:37 PM, Ryan Sleevi <sleevi@google.com> wrote:

> Issuer is underspecified, and as such, not possible to implement.
>
> Further, this seems to directly conflict with the charter, which states:
>
> "Out of scope: features including special handling directly for
> non-opaque key identification schemes, access-control mechanisms
> beyond the enforcement of the same-origin policy, and functions in the
> API that require smartcard or other device-specific behavior"
>
> This requires both handling for non-opaque key identification scheme
> ("issuer") as well as an access control mechanism ("isPrivate")
>
> As such, we do not support the WG taking on this item.
>
> On Thu, Apr 4, 2013 at 4:21 PM, Lu HongQian Karen <karen.lu@gemalto.com>
> wrote:
> > Hi Mark,
> >
> > We would like to suggest expanding the key discovery specification by
> adding an API for discovering pre-provisioned cryptographic keys via any of
> their attributes. This gives web applications a mean to find
> pre-provisioned keys whose names are unknown to them.
> >
> > The contribution is attached for review.
> >
> > Regards,
> > Karen and Michael
> >
> >
>
Received on Friday, 5 April 2013 00:25:31 UTC

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