Re: draft-ietf-httpbis-unprompted-auth-03

On Thu, Jun 29, 2023 at 10:51:20AM -0700, David Schinazi wrote:
> Thanks for your review Ilari! Responses inline.
> David
> 
> On Thu, Jun 29, 2023 at 2:11 AM Ilari Liusvaara <ilariliusvaara@welho.com>
> wrote:
>
> > - There was a review comment about relative appeal of the options of
> >   doing validation in the TLS terminator versus pushing it downstream.
> >
> >   Two reasons one might want to push the validation downstream are:
> >
> >   1) Avoiding configuration logistics challenges with keys.
> >
> >   2) The backends being better equipped to deal with load compared to
> >      the TLS terminator (especially if using HTTP/3).
> >
> 
> Our "intermediary considerations" section presents two options for folks
> who want to push the validation to a backend, but I don't think we need
> to motivate that - every deployment has different requirements and I
> don't think these reasons apply to all.

That was bit unclear, that was intended to be list of examples that could
apply, instead of exhaustive list or something definitivenly applicable.

There likely are deployments that could do validation on TLS terminator,
or have some third reason (i.e., not configuration logistics nor load
issues) to push validation to backend.


> >  There was also comment about TLS terminator to be better equipped for
> >   caching. It seems to me that backend could cache N most recent
> >   successful nonces, and skip validation if nonce is found in the
> >   cache.
> >
> 
> I'm not sure I follow. This optimization seems risky and I don't think we
> need to specify it.

Yeah, it is broken if multiple security contexts (e.g., origins) are
multiplexed on the same connection and clients may send authorization
across contexts.

Caching hash of (nonce, signature) would block the attack.




-Ilari

Received on Thursday, 29 June 2023 18:25:29 UTC