W3C home > Mailing lists > Public > public-webcrypto@w3.org > October 2012

Re: Usefulness of WebCrypto API - proposal to move forward

From: David Dahl <ddahl@mozilla.com>
Date: Fri, 12 Oct 2012 18:16:40 -0500
Message-ID: <5078A4D8.4020506@mozilla.com>
To: Ryan Sleevi <sleevi@google.com>
CC: GALINDO Virginie <Virginie.GALINDO@gemalto.com>, Mountie Lee <mountie.lee@mw2.or.kr>, Seetharama Rao Durbha <S.Durbha@cablelabs.com>, Vijay Bharadwaj <Vijay.Bharadwaj@microsoft.com>, Harry Halpin <hhalpin@w3.org>, David Rogers <david.rogers@copperhorses.com>, Nadim Kobeissi <nadim@nadim.cc>, "public-webcrypto@w3.org" <public-webcrypto@w3.org>

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Ryan:

Indeed, the wording is too specific. I am hopeful that other browsers
beyond Mozilla products will take up Open Web Apps.

It sounds like the idea of recommending the API for 'restricted browser
environments only' is not working for you. Is there there any kind of
language along these lines you can imagine? Should we revisit *strict*
CSP + HTTPS as another avenue?

Cheers,

david

On 10/12/2012 05:48 PM, Ryan Sleevi wrote:
> As previously mentioned, I object to the wording "This API is not
> recommended for use in content DOM web pages".
>
> While I have great respect for the Mozilla team, and definitely appreciate
> your wording changes, I am apprehensive about the proposed wording that
> specifically suggests that the only safe place to do this is within a
> Firefox-exclusive model.
>
> I've repeatedly provided examples of where the supposed benefits of the
> Firefox model can be accomplished within W3C work (again, namely CSP, and
> preferably HTTPS). Again, as I've repeatedly said, I think the insistence
> or recommendation that requires signed apps, or requires or recommends
> Firefox OS provides no security benefit (above and beyond the
> aforementioned W3C standards).
>
> On Fri, Oct 12, 2012 at 2:45 PM, David Dahl <ddahl@mozilla.com> wrote:
>
>>
> On 10/12/2012 02:55 PM, GALINDO Virginie wrote:
> >>> Dear all,
> >>>
> >>> >From the different exchanges held on this mailing list, I think that
> we do have a structure for enriching our security considerations about
> the API. I think that we can write a WG position - as suggested by Vijay
> - with all the details and rationale, make sure we all agree and
> consider putting this (or a summary) in the specification itself.
> >>>
> >>> I would suggest the following outline :
> >>>
> >>>
> >>> 1- Considerations on 'local resources' (I mean UA and OS) security
> >>>
> >>> 2- Considerations on server-webapp communication security
> >>>
> >>> 3- Considerations on the benefit brought by the API (e.g. functional
> and interoperability)
> >>>
> >>> 4- Recommendation to developers to establish a trusted environment to
> complete their security model (like : audit the platform (UA+OS), use
> CSP, use TLS, signature, ...)
> >>>
> >>> We discussed during our last call that David D would write something
> about security and environment : David would you like to expand this
> outline ?
> >>> Anyone else to support this work ?
> >>>
>
> Indeed, and the week has gotten away from me, however, this is what I
> wanted to propose we begin the section "Security Considerations" in the
> API draft:
>
> ---
>
> With the understanding that the web browser DOM is a perilous place
> fraught with multiple attack surfaces, the point of creating this API is
> not to solve these "generally insecure JS/DOMWindow context" problems.
> The point is to design a crypto API that can theoretically be used to
> fulfill the use cases the Web Crypto API WG has drafted.
>
> While this API is not recommended for use in content DOM web pages,
> there are DOM environments that can more securely host this API.
> ('Privileged' and 'Certified') Open WebApps ( see:
> https://developer.mozilla.org/en-US/docs/Apps ), like those being
> created for Firefox and Firefox OS enable a restricted environment where
> the apps are cryptographically signed (and then verified upon install or
> update) remote resources are quite limited, explicitly-granted
> permissions are required, eval() and additional JS and browser features
> are disabled, making the DOM a much more 'trusted' environment to
> operate in. ( see:
> https://wiki.mozilla.org/Apps/Security#Installed_privileged_application )
>
> Web browser extensions are also a potential consumer of this API, as the
> extension APIs and SDKs of modern web browsers are arguably more secure
> contexts for code like this to run in.
>
> ---
>
> I have already discussed this concept somewhat with Ryan and others on
> the mailing list, with Ryan concluding that these environments are not
> any more secure than a web page with strict CSP and HTTPS enabled, I
> have re-read the Open WebApps security model (for 'privileged' and
> 'certified' apps) remembering that the eval attack surface is gone as
> well as a very strict CSP is in place. These restrictions along with a
> signed, installed zip-based application do seem to me to be a leap
> forward in securing and being able to trust the web app.
>
> Thoughts? Edits?
>
> Cheers,
>
> David
>
>
>>
>>
>

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Received on Friday, 12 October 2012 23:17:12 GMT

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