Re: [Ace] Barry Leiba's No Objection on draft-ietf-ace-coap-est-17: (with COMMENT)

[Barry Leiba <[e-mail]>]

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

Barry

On Tue, Dec 24, 2019 at 10:50 AM Panos Kampanakis (pkampana)
<[e-mail]> wrote:
>
> Hi Barry,
>
> This commit https://github.com/SanKumar2015/EST-coaps/commit/01f7014e2348d09c0a1ff768eea7d53f4c5471f2 tries to address your feedback. The full discussion is in https://github.com/SanKumar2015/EST-coaps/issues/153
>
> Let us know if it does not make sense.
>
> Rgs,
> Panos
>
> -----Original Message-----
> From: Ace <[e-mail]> On Behalf Of Panos Kampanakis (pkampana)
> Sent: Saturday, December 21, 2019 10:49 PM
> To: Barry Leiba <[e-mail]>; The IESG <[e-mail]>
> Cc: [e-mail]; [e-mail]; [e-mail]; [e-mail]
> Subject: Re: [Ace] Barry Leiba's No Objection on draft-ietf-ace-coap-est-17: (with COMMENT)
>
> Hi Barry,
>
> Thank you for the thorough review. We are tracking your feedback and our responses in a git issue https://github.com/SanKumar2015/EST-coaps/issues/153 We mostly confirm all your minor text changes and nit fixes. The TBD one we will not fix as we are waiting on IANA.
>
> Let us know if something does not make sense.
>
> Rgs,
> Panos
>
>
> -----Original Message-----
> From: Ace <[e-mail]> On Behalf Of Barry Leiba via Datatracker
> Sent: Monday, December 16, 2019 9:59 PM
> To: The IESG <[e-mail]>
> Cc: [e-mail]; [e-mail]; [e-mail]; [e-mail]
> Subject: [Ace] Barry Leiba's No Objection on draft-ietf-ace-coap-est-17: (with COMMENT)
>
> Barry Leiba has entered the following ballot position for
> draft-ietf-ace-coap-est-17: No Objection
>
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>
> The document, along with other ballot positions, can be found here:
> https://datatracker.ietf.org/doc/draft-ietf-ace-coap-est/
>
>
>
> ----------------------------------------------------------------------
> 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.
>
> -- 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"?
>
>    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
>
>    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
>
> 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
>
> -- 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".
>
> -- 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.
>
> -- 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
>
>    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." ?
>
>    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
>
> -- 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
>
>    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
>
>    server or proxy to generate the private key and the certificate which
>    are transferred back to the client
>
> Needs a comma before "which".
>
>    or the asymmetric keypair establishment method is out of scope of the
>    specification.
>
> "of this specification".
>
>    [I-D.ietf-core-multipart-ct] containing a CBOR array with four items
>
>    (Section 5.3)
>
>    .  The two representations
>
> More odd spacing.
>
>    Dependent on the request, the
>    private key can be in unprotected PKCS#8 [RFC5958] format
>
> "Depending upon the request"
>
>    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".
>
> -- 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
>
> 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.
>
> -- 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?
>
> — 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
>
>
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