[Gen-art] Genart telechat review of draft-gutmann-scep-08

[Christer Holmberg <[e-mail]>]

Reviewer: Christer Holmberg
Review result: Ready with Nits

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Document: draft-gutmann-scep-08
Reviewer: Christer Holmberg
Review Date: 2018-01-25
IETF LC End Date: None
IESG Telechat date: 2018-03-08

Summary: The document is well written, and almost ready for publication.
However, there are some issues (mostly editorial) that I would like the authors
to address.

Major issues: None

Minor issues: None

Nits/editorial comments:

Section 1:
----------

Q1:

The text says:

   “While widely deployed, this protocol omits some certificate
   management features, e.g. certificate revocation transactions, which
   may enhance the security achieved in a PKI.”

I suggest to remove the “While widely deployed” part. I assume you refer to the
Cisco protocol that SCEP is based on. If so, I suggest that you move the
following sentence from the Abstract to the Introduction:

   “SCEP is the evolution of the enrolment protocol sponsored by Cisco Systems,
   which enjoys wide support in both client and server implementations, as well
   as being relied upon by numerous other industry standards that work with
   certificates.”

In the Abstract, I think it is enough to keep the following:

   "SCEP is the evolution of the enrolment protocol sponsored by Cisco Systems."

Then, you can also remove the following from the Introduction:

   "so that it enjoys widespread support and ready interoperability across a
   range of platforms"

…or combine it with the sentence above.

Q2:

Doesn’t the "While implementers are encouraged to…" sentence belong to the
Security Considerations?

Section 2.1.2:
--------------

Q3:

The text says:

   "A CA MAY enforce any arbitrary policies and apply them to certificate
   requests, and MAY reject any request."

The "MAY reject any request" parts sounds unfinished. I assume it’s refers to
cases where the client don’t support such arbitrary policies? If so, I suggest
to explicitly say so.

Currently it sounds like a generic CA-may-reject-any-request statement, which I
assume is not what you intend to say :)

Section 2.1.3:
--------------

Q4:

As the text talks about certificate distribution, is this really a subsection
to section 2.1?

Q5:

The 4th paragraph contains a couple of SHOULDs. Is there a reason they can’t be
MUST?

Section 4.1:
------------

Q6:

The 5th paragraph talks about how early versions of the draft used GET messages
for all communication.

The text also says:

“If the remote CA supports it, any of the CMS-encoded SCEP messages SHOULD be
sent via HTTP POST instead of HTTP GET.”

If the remove CA supports what? HTTP POST?

Why SHOULD, and not MUST?

…and later:

   "If a client or CA uses HTTP GET and encounters HTTP-related problems
   such as messages being truncated, seeing errors such as HTTP 414
   ("Request URI too long"), or simply having the message not sent/
   received at all, when standard requests to the server (for example
   via a web browser) work, then this is a symptom of the problematic
   use of HTTP GET.  The solution to this problem is typically to move
   to HTTP POST instead."

If the client understands to use POST if GET fails, why can’t it use POST to
begin with?

In general, what is the reason for having this text about early versions of the
draft? Backward compatibility with CAs that will only support GET?

Section 5:
----------

Q7:

The title of the section talks about state transitions, but then the text says
that the section contains examples.

Is there a reference to the state machine(s) that are represented in the
examples? OR, does the section define the state machine(s)?

If the main purpose of the section is to show example flows, I think the title
of the section should be "Examples".

Section 6:
----------

Q8:

The text says “previous editors” and “earlier editors”. Please pick one and use
it in both places :)