Re: [secdir] SECDIR review of draft-ietf-httpbis-p7-auth-24

Julian Reschke <julian.reschke@gmx.de> Wed, 30 October 2013 14:45 UTC

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Date: Wed, 30 Oct 2013 15:45:16 +0100
From: Julian Reschke <julian.reschke@gmx.de>
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To: Stephen Kent <kent@bbn.com>, secdir <secdir@ietf.org>, fielding@gbiv.com, mnot@pobox.com, Barry Leiba <barryleiba@computer.org>, Pete Resnick <presnick@qti.qualcomm.com>, "Mankin, Allison" <amankin@verisign.com>, HTTP Working Group <ietf-http-wg@w3.org>
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Subject: Re: [secdir] SECDIR review of draft-ietf-httpbis-p7-auth-24
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Hi Stephen,

On 2013-10-30 15:32, Stephen Kent wrote:
> ...
>>> The SC section here addresses only two issues: purging credentials in
>>> clients and user agents, and protection spaces. The discussion of the
>>> former topic does not discuss how credential purging applies to proxies.
>>
>> As per httpbis-p1, a proxy is a client as well ('An HTTP "client" is a
>> program that establishes a connection to a server for the purpose of
>> sending one or more HTTP requests.' --
>> <http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p1-messaging-24.html#rfc.section.2.1>).
>> Does this address your comment?
> yes, but it might be clearer to note this, parenthetically, in this doc.
> For example, page 5 includes the following text:
>
>     The 407 (Proxy Authentication Required) response message is used by a
>
> proxy to challenge the authorization of a client and MUST include a
>
> Proxy-Authenticate header field containing at least one challenge
>
> applicable to the proxy for the requested resource.
>
>
> The use of the terms "proxy" and "client" here suggest that they are
> distinct notions,
> not that a proxy is also considered a client.

In the context of this paragraph, the proxy is indeed the server.

>>> Also, it is not clear that a user control for credential purging will
>>> have the desired effect given a potentially complex GUI environment. The
>>
>> Any proposal for enhancing the text?
>
> User agents that cache credentials are encouraged to provide a
>
> readily accessible mechanism for discarding cached credentials under
>
> user control. *We recognize that this may not be a trivial task.**
> **   Designing a UI that will encourage users to purge credentials when**
> **   appropriate, but not cause them to prematurely do so may be difficult.*

In my experience, the implementers of browsers are very aware of the 
problems with coming up with a good UI. I really don't think that adding 
more prose here will help at all. (But hey, I asked for a proposal and 
you sent one; thanks for that!).

> ...

Best regards, Julian