Re: [core] Comments on draft-ietf-core-echo-request-tag-02

[Jim Schaad <[e-mail]>]

> -----Original Message-----
> From: Christian M. Amsüss <[e-mail]>
> Sent: Wednesday, October 17, 2018 7:18 AM
> To: Jim Schaad <[e-mail]>
> Cc: [e-mail]; [e-mail]
> Subject: Re: Comments on draft-ietf-core-echo-request-tag-02
> 
> Hello Jim,
> 
> thanks for your review; we're working it into an updated document for
WGLC.
> 
> Responding to the comments related to Request-Tag:
> 
> On Thu, Oct 11, 2018 at 03:17:12PM -0700, Jim Schaad wrote:
> > * Section 3.1 - The note to the RFC editor has me confused.  Firstly,
> > I am not sure why it should be moved rather than just staying here.
> 
> Updated. I hope that the process of submission will be clear enough
beforehand
> that we can remove the paragraph or move the text ourselves
> -- if (as I expect) OSCORE enters AUTH48 before we submit ERT to the RFC
> editor, that text will be gone by then.
> 
> > * Section 3.1 - I think that the value of Request-Tag is potentially
> > going to be different depending on if it is in the inside rather than
the outside.
> > You may be doing two different block transfers and each needs its own
value.
> 
> Updated to explicitly state that those values are independent because they
> relate to an inner or outer blockwise transfer.
> 
> > * Section 3.2 - the first paragraph does not scan.  I am not sure what
> > it says as it seems to be contradictory.
> 
> That paragraph assumed a very particular implementation method for servers
> (that unknown options are processed in bulk before known options); does
this
> re-wording read better to you?:
> 
>   The Request-Tag option does not require any particular processing on
>   the server side outside of the processing already necessary for any
>   unknown elective proxy-safe cache-key option: The option varies the
>   properties that distinguish blockwise operations (which includes all
>   options except elective NoCacheKey and except Block1/2), and thus the
>   server can not treat messages with a different list of Request-Tag
>   options as belonging to the same operation.

Yes that reads better

> 
> > * Section 3.2 - para 2 - The example sentence looks odd.  Do you mean
> > it can have a cached response not a free response?
> 
> That was worded confusingly and is now changed.
> 
> > * Section 3.2 - para "especially" - I find the first sentence very
> > hard to understand.
> 
> That paragraph has become obsolete with the presence of core-stateless
> anyway and was replaced with a reference there later in the proxy
application.
> 
> > * Section 3.3 - last para - how do you recycle something that is
> > absent?  I think the last clause needs examining.
> 
> Added a sentence on absent Request-Tag options being a value of its own,
> explaining why that can be recycled just as well.
> 
> > * Section 3.4.1 - Item 2 - how is a client supposed to be able to know
> > this if the proxy in the middle just passes it through w/o changing
> > it?  Two different clients could end up with the same Request-Tag.
> > One would hope that they would have different tokens because of the
proxy
> however.
> 
> The whole 3.4.1 is, as per item 1, only applicable to blockwise operations
split
> into end-to-end protected individual exchanges.
> 
> (Ie. DTLS w/o proxies, or inner blockwise in OSCORE).
> 
> If that does not answer the question, I don't fully understand it, please
help me
> find where we diverge.

Ok - if you say proxies are not there then I have no issues

> 
> > * Section 3.4.1 - This seems backwards.  I thought that OSCORE was
> > tightly bound to the end point, but this paragraph says it is not.
> 
> That was my idea of OSCORE inner-blockwise being allowed to jump
transports
> (which it could easily do but is not specified that way); I've replaced
the
> paragraph with a weaker and more hypothetical one.
> 
> (By "bound to the end point" I meant that whereas a running DTLS session
will
> only stay alive while IP/port/interface quintuple stays the same, an
OSCORE
> context can be used even after those endpoint identifiers have
> changed.)

That makes sense - It might be better to talk about endpoint addresses then
rather than just using endpoint which corresponds to a server (or client).


> 
> > * Section 3.4.3 - You have a "Section TBA" here
> >
> > * Section 3.4.3 - Please keep the section for justification of
> > Request-Tag being repeatable.
> 
> Given that we now do groundwork for Stateless which is more directly
> applicable, that document is now referenced instead, and left in.

Look good

Jim

> 
> 
> Thanks again
> Christian
> 
> --
> To use raw power is to make yourself infinitely vulnerable to greater
powers.
>   -- Bene Gesserit axiom