Re: [W3C Web Crypto WG] Deciding if we need a discovery mechanism

On Tue, May 15, 2012 at 10:59 AM, GALINDO Virginie <
Virginie.GALINDO@gemalto.com> wrote:

>  Dear all,
>
> Some people mentioned that a webapp may be able to discover the algorithms
> supported the environment it is running in, thus identifying algorithms
> available thanks to the Web Crypto API. There are several means to do that
> (1) either by an actual discovery mechanism sending back the entire list of
> algorithms, (2) or by creating ‘cipher suite’. In addition to that, we may
> be able to mandate a minimum set of algorithms that should be supported
> when implementing the API.
>
> I would like to get your feedback on that one, (or any alternative
> proposal).
>
> Regards,
> Virginie
> gemalto
>
>

I'd say a combination of 1 and 2 are satisfying.  If there's a way to use 1
and then create/discover a particular permutation of a 'cipher suite', as
well as a way to request it via a cipher suite identifying string for
example, then I think we get the best of both worlds in terms of robustness
and discoverability.

Once again, it is my opinion that mandating a minimum set of algorithms is
aggressive.  While it does have its benefits in the short term like
predictability for authors and establishing a deterministic test suite for
the WG, there are a number of reasons I am against it:

   - It could cause bad decisions in the API that take advantage of knowing
   a particular algorithm is meant to be implemented, or even worse, are
   decided solely for a particular algorithm.  The temptation could get the
   best of us ;)
   - It means that vendors will have to come to consensus (assuming they
   all care about being compliant to the spec) on that set of algorithms, and
   that can be a slippery slope and a time sink because there might be
   differences in requirements between some vendors and/or the locales they
   support.
   - Authors will undoubtedly write code that is not future proof, always
   assuming certain support with no feature detection. This will make it
   harder for vendors to deprecate & remove algorithm support in the future
   when e.g. the algorithm is no longer considered strong enough in the
   post-quantum cryptography world.  If we can nail down easy discoverability
   and feature detection, then library authors will code defensively (as they
   should) without a lot of effort.

Thanks,
Jarred