Barry L.'s IESG COMMENTS

[petervanderstok]

---

COMMENT:

Thanks for this — a useful document. I have a bunch of comments, but they’re all editorial. Please consider them, but there’s not a need to give a detailed reply.

[pvds] Many thanks for the suggestions; they realy help to pinpoint the problem and simplifiy the author's liife

-- Section 4 --

In that case, the
server MAY want to authenticate a client certificate against its
trust store although the certificate is expired (Section 10).

Total nit: Why "want to"? Why not "server MAY authenticate"?

[pvds] Much better indeed

  As described in Section 2.1 of [RFC5272] proof-of-identity refers to
  a value that can be used to prove that the private key corresponding
  to the certified public key is in the possession of and can be used
  by an end-entity or client.

I find the passive voice to be quite awkward here, and suggest making it active:

NEW As described in Section 2.1 of [RFC5272], proof-of-identity refers to a value that can be used to prove that an end-entity or client is in possession of and can use the private key corresponding to the certified public key. END

[pvds] Thanks, prefer your suggestion

   the event of handshake message fragmentation, the Hash of the
   handshake messages used in the MAC calculation of the Finished
   message must be computed as if each handshake message had been sent
   as a single fragment (Section 4.2.6 of [RFC6347]).

I know this wording is directly from 6347, but I think it's unclear and would like to suggest an alternative. The "as a single fragment" part is odd, because I think what it's really saying is that it's computed as if it had not been fragmented. My suggestion is to change it thus (and similarly for the next paragraph after):

NEW the event of handshake message fragmentation, the Hash of the handshake messages used in the MAC calculation of the Finished message must be computed on each reassembled message, as if each handshake message had not been fragmented (Section 4.2.6 of [RFC6347]). END

[pvds] For me it is clearer

[Panos] Looks good.

If that's not correct, please take that as further evidence that it's unclear, and adjust accordingly.

   To alleviate this
   situation, an EST-coaps DTLS connection MAY remain open for
   sequential EST transactions which was not the case with [RFC7030].
   For example, an EST csrattrs request that is followed by a
   simpleenroll request can use the same authenticated DTLS connection.

Two total nits: a. Comma before "which", please. b. The "for example" needs some rewording to make it work:

NEW For example, if an EST csrattrs request is followed by a simpleenroll request, both can use the same authenticated DTLS connection. END

[pvds] in NEW: s/if/when/

-- Section 5.1 --

EST-coaps is targeted for low-resource networks with small packets.
Two types of installations are possible (1) rigid ones where the
address and the supported functions of the EST server(s) are known,
and (2) flexible one where the EST server and it supported functions
need to be discovered.

This needs a colon (:) after "possible", a comma after "rigid ones", "a" before "flexible one", another comma after "flexible one", and make it "its supported".

[pvds] aboslutely right

-- Section 5.5 --

   Similarly, 2.04

   is used in successfull response to EST-coaps POST requests (/sen,
   /sren, /skg, /skc).

There's odd spacing here; please fix it. And "successful" is misspelled.

[pvds] will do

-- Section 5.7 --

   If the server is very slow (i.e., minutes) in providing the response
   (i.e., when a manual intervention is needed),

I think you mean "e.g." for both of those, evidence for my general aversion to using Latin abbreviations that many people don't fully understand. It also feels odd to have the two examples separated in this way. I suggest this:

NEW If the server is very slow in providing the response (for example, manual intervention is required and it could take minutes for it to respond), END

[pvds] I think the first i.e. is correct, but I understand the suggestion to remove latin abbrevations. Differently worded again:

NEWNEW When the server is very slow (taking minutes) in providing the response (for example, because manual intervention is required ), END

[Panos] I like Barry's rephrase. Using "(taking minutes)" could mean that minutes is slow, but what is consider slow depends on the use-case.

   it SHOULD respond with
   an ACK containing response code 5.03 (Service unavailable) and a Max-
   Age Option to indicate the time the client SHOULD wait to request the
   content later.

Perhaps, "to indicate the time the client SHOULD wait before sending another request to obtain the content." ?

[pvds] probably clearer

   After a delay of Max-Age, the client SHOULD resend
   the identical CSR to the server.  As long as the server responds with
   response code 5.03 (Service Unavailable) with a Max-Age Option, the
   client SHOULD keep resending the enrollment request until the server
   responds with the certificate or the client abandons the request for
   other reasons.

That last sentence reads very strangely to me. It SHOULD keep resending the request until it decides to stop? What does that actually mean?

Maybe what you're really trying to say is something like this?:

NEW As long as the server continues responding with response code 5.03 (Service Unavailable) with a Max-Age Option, the client will continue to delay for Max-Age and then resend the enrollment request until the server responds with the certificate or the client abandons the request for policy or other reasons. END

[pvds] Fine, thanks.

-- Section 5.8 --

   In scenarios where it is desirable that the server generates the
   private key, server-side key generation is available.

This seems like a content-free sentence. Maybe this?:

NEW Private keys can be generated on the server. Scenarios where that makes sense include those where it is considered more secure... END

[pvds] NEWNEW Private keys can be generated on the server to support scenarios where serer-side key generation is needed.

   Of course, that does not eliminate the
   need for proper random numbers in various protocols like (D)TLS
   (Section 10.1).

May I suggest this?:

NEW As always, it is necessary to use proper random numbers in various protocols such as (D)TLS (Section 10.1). END

[pvds] thank for the suggestion

   server or proxy to generate the private key and the certificate which
   are transferred back to the client

Needs a comma before "which".

[pvds] yep

   or the asymmetric keypair establishment method is out of scope of the
   specification.

"of this specification".

[pvds] better

   [I-D.ietf-core-multipart-ct] containing a CBOR array with four items

   (Section 5.3)

   .  The two representations

More odd spacing.

[pvds] will repair

   Dependent on the request, the
   private key can be in unprotected PKCS#8 [RFC5958] format

"Depending upon the request"

[pvds] better English

   In
   the case where the asymmetric encryption key is suitable for
   transport key operations the generated private key is encrypted with
   a symmetric key which is encrypted by the client-defined (in the CSR)
   asymmetric public key and is carried in an encryptedKey attribute in
   a KeyTransRecipientInfo structure.

Long sentence that needs punctuation: comma after "operations", comma before "which", comma before "and". Also, I would move "(in the CSR)" a few words later, after "public key".

[pvds] thanks for the suggestion

-- Section 7 --

   It is recommended, based on experiments,

   to follow the default CoAP configuration parameters ([RFC7252]).

Odd spacing, again. But "it is recommended to follow" is also odd English. I suggest making this active, rather than passive, thus:

NEW Implementations should follow the default CoAP configuration parameters ([RFC7252]). END

[pvds] thanks

I don't think the "based on experiments" bit adds anything, but if you want to keep it you can prepend "Experiments have shown that" to my suggestion.

[pvds] will do

-- Section 9.1 -- Don't you want to remove the "TBD" on "TBD287" here? Wasn't the "TBD" just a flag to remind people that it hadn't been formally allocated yet?

[pvds] Really don't know what to do, IANA allocates and approves. Suggest to leave it like it is.

— Section 10.1 —

   It is important to note that sources contributing to the randomness
   pool used to generate random numbers on laptops or desktop PCs are
   not available on many constrained devices, such as mouse movement,
   timing of keystrokes, or air turbulence on the movement of hard drive
   heads, as pointed out in [PsQs].

The sentence order is wrong here. For example, mouse movement is not a constrained device. The correct order is more like this:

NEW It is important to note that, as pointed out in [PsQs], sources contributing to the randomness pool used to generate random numbers on laptops or desktop PCs, such as mouse movement, timing of keystrokes, or air turbulence on the movement of hard drive heads, are not available on many constrained devices. END

[pvds] much clearer

[csosto-pk]

Changes committed in https://github.com/SanKumar2015/EST-coaps/commit/01f7014e2348d09c0a1ff768eea7d53f4c5471f2

[csosto-pk]

Thanks, Panos; it all looks good, and thanks for considering my comments.

Barry

[csosto-pk]

Uploaded in v-18