Re: TLS requirements (Last Call: draft-ietf-atompub-protocol to Proposed Standard)

[Julian Reschke <julian.reschke at gmx.de>]

Tim Bray wrote:
> On 5/18/07, Robert Sayre <sayrer at gmail.com> wrote:
> > I think the substituted text is inadequate, because it is not clear
> > which TLS version implementors MUST support. As I understand it, the
> > fact that it is "tricky", implying there may be trade-offs, is not
> > sufficient to avoid specifying a single, mandatory-to-implement TLS
> > version.
>
> Well Rob, I think the community at large and the IESG in particular
> would welcome suggestions on what to do with this one.  In fact, we
> know what's going to happen: implementors will use the default TLS
> library for whatever platform they're on, and this will do the job,
> most times.  However, I think that we have better-than-rough consensus
> that the specification landscape is a mess, making normative
> references  a bitch, and that this will probably bite nearly
> everything in the Apps area from here on in.
>
> I hope someone with the necessary expertise will take this bull by the
> horns.  -Tim

...and I would add that as the IESG got us into this situation, it's 
their job to clarify.

Let me add one data point... Another spec recently *approved* by the 
IESG says 
(<http://greenbytes.de/tech/webdav/draft-ietf-webdav-rfc2518bis-18.html#rfc.section.20.1>):

"20.1 Authentication of Clients

Due to their emphasis on authoring, WebDAV servers need to use 
authentication technology to protect not just access to a network 
resource, but the integrity of the resource as well. Furthermore, the 
introduction of locking functionality requires support for authentication.

A password sent in the clear over an insecure channel is an inadequate 
means for protecting the accessibility and integrity of a resource as 
the password may be intercepted. Since Basic authentication for HTTP/1.1 
performs essentially clear text transmission of a password, Basic 
authentication MUST NOT be used to authenticate a WebDAV client to a 
server unless the connection is secure. Furthermore, a WebDAV server 
MUST NOT send a Basic authentication challenge in a WWW-Authenticate 
header unless the connection is secure. An example of a secure 
connection would be a Transport Layer Security (TLS) connection 
employing a strong cipher suite and server authentication.

WebDAV applications MUST support the Digest authentication scheme 
[RFC2617]. Since Digest authentication verifies that both parties to a 
communication know a shared secret, a password, without having to send 
that secret in the clear, Digest authentication avoids the security 
problems inherent in Basic authentication while providing a level of 
authentication which is useful in a wide range of scenarios."

So apparently the whole mess involving RFC2818, RFC2246 and RFC4346 is 
not really required.

Best regards, Julian


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