Re: [Web Crypto WG] about defining profiles

On Thu, Mar 5, 2015 at 9:28 AM, Charles Engelke <w3c@engelke.com> wrote:

> On Thu, Mar 5, 2015 at 5:44 AM, GALINDO Virginie
> <Virginie.Galindo@gemalto.com> wrote:
> > Dear all,
> >
> > a question to the WG members (and specially to implementers) related to
> > defining profile(s) and tracked into the bug 25985 [1].
>
> As a developer, not UA implementer, I would find profiles very useful,
> especially a minimal one that all UAs support. That should include at
> least one each of PK signing, PK encryption, symmetric encryption,
> HMAC, hash, and key derivation. With those universally available I
> could build applications that could communicate with each other
> regardless of the browser they run on.
>
> > - what is the current overlapping coverage of algorithms across the
> > implementations ?
>
> It appears that browser makers pretty much support a common set of
> those kinds of algorithms (almost). I've got some sample applications
> at https://github.com/infotechinc, and have found that every browser
> I've tried that supports web crypto at all runs all of them
> successfully except key derivation. Specifically, I've found universal
> support for RSASSA-PKCS1-v1_5, RSA-OAEP, AES-CBC, and SHA-256. Only
> Chrome Canary and Opera Developer support PBKDF2 at this time.
>

Actually I believe Firefox supports PBKDF2 too.
(Seen in the code here:
http://lxr.mozilla.org/mozilla-central/source/dom/crypto/WebCryptoTask.cpp#3102
)


> I've tried these apps on Chrome, Opera, and Firefox on Ubuntu Linux
> and Windows 7, and Chrome on Android 5.0. (I'm still tickled that the
> ones that don't use files work on my Android Wear watch, too.) I'm
> putting together a table of browser support based on those apps plus
> the results from the Web Cryptography API Live Table from
> https://diafygi.github.io/webcrypto-examples/ . I'll share that when
> it's done, probably within a day or two.
>

In case it is helpful, there is a list of the algorithms supported by
Chromium here:
https://sites.google.com/a/chromium.org/dev/blink/webcrypto?pli=1#TOC-Supported-algorithms-as-of-Chrome-41-

PBKDF2 and HKDF are not available in the current stable version of Chrome,
but will be in the next version.
Also HKDF-CTR got implemented as HKDF.

I've also found Safari on OS/X, which has a prefixed subtle crypto
> implementation, seems to support many of the apps but still has issues
> that keep most of them from working. I haven't tried Internet
> Explorer's prefixed implementation because it is based on a much
> earlier version of the API that isn't compatible with the current one.
>

Other notable differences between implementations from memory (apologies if
this information has become out of date):
  * WebWorker support is not universal. I think Chromium is the only one to
support WebCrypto in workers
  * JWK is the only universally supported key format (Safari doesn't
implement PKCS8/SPKI)
  * 192-bit AES keys are not universally supported (as Chromium does not
support them, but other browser do)
  * Key import in general is likely to be an area with a number of subtle
implementation differences, especially around malformed JWK/PKCS8/SPKI
data. (For instance using non-base64url characters, incorrectly padded EC
parameters, invalid points, etc.)

> - what is your feeling about having a profile captured into a document ?
> > - which level of normalization would you like ot see associated with that
> > document ? (being a note, a recommendation...).
>
> I would very much like that. I'm not set on any particular level of
> normalization, probably because I don't have a good understanding of
> the differences.
>
> Thanks,
>
> Charlie
> --
> Charles Engelke, Chief Technology Officer
> Info Tech, Inc.
> Phone: +1 (352) 381-4400
>
>