Re: APPSDIR review of draft-farrell-decade-ni-07

Stephen Farrell <stephen.farrell@cs.tcd.ie> Tue, 05 June 2012 11:11 UTC

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Date: Tue, 05 Jun 2012 12:11:42 +0100
From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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To: "\"Martin J. Dürst\"" <duerst@it.aoyama.ac.jp>
Subject: Re: APPSDIR review of draft-farrell-decade-ni-07
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Hi Martin,

First, thanks for the speedy and thorough review. Some
good points made, some with which I strongly disagree,
but thrashing stuff like that out is part of the point
of the reviews.

On 06/05/2012 10:42 AM, "Martin J. Dürst" wrote:
> Hello everybody,
> 
> [For replies, please trim the cc list, thanks!]

Not sure what trimming you mean. I've reduced it
to ietf-discuss and apps-discuss and authors.

> 
> 
> I have been selected as the Applications Area Directorate reviewer for
> this draft (for background on appsdir, please see
> http://trac.tools.ietf.org/area/app/trac/wiki/ApplicationsAreaDirectorate ).
> 
> 
> 
> Please resolve these comments along with any other Last Call comments
> you may receive. Please wait for direction from your document shepherd
> or AD before posting a new version of the draft.
> 
> 
> Document: draft-farrell-decade-ni-07
> Title: Naming Things with Hashes
> Reviewer: Martin Dürst
> Review Date: 2012-06-03, 2012 (written up 2012-06-04/05)
> IETF Last Call Date: started 2012-06-04, ends 2012-07-02
> 
> 
> Summary: This draft addresses a real generic need, but the current form
> of the draft is the result of adding more and more special cases without
> a clear overall view and a firm hand to separate the wheat from the
> chaff. This shows both in the technical issues as well as in many of the
> editorial issues below. This draft is not ready for publication without
> some serious additional work, but that work is mostly straightforward
> and should be easy to complete quickly.

Wheat? Chaff? Firm hand? Hmm. Are those useful phrases here?
I disagree about 'em in any case, and you're wrong as to how
we got here and IMO quite wrong in your main technical comment.
See below for that.

> 
> Major design issue:
> 
> The draft defines two schemes, which differ only slightly, and mostly
> just gratuitously (see also editorial issues).
> These are the ni: and the nih: scheme. As far as I understand, they
> differ as follows:
>                                     ni:                nih:
> authority:                          optional           disallowed
> ascii-compatible encoding:          base64url          base16
> check digit:                        disallowed         optional
> query part:                         optional           disallowed
> decimal presentation of algorithm:  disallowed         possible
> 
> The usability of URIs is strongly influenced by the number of different
> schemes, with the smaller a number, the better. As a somewhat made-up
> example, if the original URIs had been separated into httph: for HTML
> pages and httpi: for images, or any other arbitrary subdivision that one
> can envision, that would have hurt the growth and extensibility of the
> Web. Creating new URI schemes is occasionally necessary, and the ideas
> that lead to this draft definitely seem to warrant a new scheme (*), but
> there's no reason for two schemes.
> [(*) I know people who would claim the the .well-formed http/https thing
> is completely sufficient, no new scheme needed at all.]
> 
> More specifically, if the original URIs had been separated into httpm:
> (for machines) and httph: (for humans), the Web for sure wouldn't have
> grown at the speed it did (and does) grow. In practice, there are huge
> differences in human 'speakability' for URIs (and IRIs, for that
> matter); compare e.g. http://google.com with
> http://www.google.co.jp/#sclient=psy-ab&hl=en&site=&source=hp&q=hash&oq=hash&aq=f&aqi=g4&aql=
> 
> (which I have significantly shortened to hopefully eliminate potential
> privacy issues), or compare the average mailto: URI with the average
> data: URI. However, what's important is that there never has been a
> strong dividing line between machine-only and human-only URIs or
> schemes, the division has always been very gradual. Short and mainly
> human-oriented URIs have of course been handled by machines, and on the
> other hand, very long URIs have been spoken when really necessary.
> "Speakability" has been maintained to some extent by scheme designers,
> and to some extent by "survival of the fittest" (URIs that weren't very
> speakable (or spellable/memorizable/guessable/...), and their Web sites,
> might just die out slowly).
> 
> It should also be noted that the resistance against multiple URI schemes
> may have been low because there are so many different ways to express
> hashes in the draft anyway, and one more (the nih: section is the last
> one before the examples section) didn't seem like much of a deal
> anymore. But when it comes to URIs, one less is a lot better than one more.
> 
> In the above ni:/nih: distinction, nih: seems to have been added as an
> afterthought after realizing that reading an ni: URI aloud over the
> phone may be somewhat suboptimal because there is a need for repeated
> "upper case" - "lower case" (sure very quickly shortened to "upper" -
> "lower" and then to "up" - "low" or something similar). It is not a bad
> idea to try to make sure that IETF technology, and URIs in particular,
> are accessible to people with certain kinds of dislexya. (There are
> indeed people who have tremendous difficulties with distinguishing
> upper- and lower-case letters, and this may or may not be connected with
> other aspects of dislexya.) It is however totally unclear to this
> reviewer why this has to lead to two different URI schemes with other
> gratuitous differences.
> 
> Finding a solution is rather easy (of course, other solutions may also
> be possible): Merge the schemes, so that authority, check digit, and
> query part are all optional (an authority part and/or a query part may
> very well be very useful in human communication, and a check digit won't
> hurt when transmitted electronically) and the decimal presentation of
> the algorithm is always allowed, and use base32
> (http://tools.ietf.org/html/rfc4648) as the encoding. This leads to a
> 16.6% less efficient encoding of the value part of the ni: URI, but
> given that other URI-related encodings, e.g. the %-encoding resulting
> when converting an IRI to an URI, are much less efficient, and that URI
> infrastructure these days can handle URIs with more than 1000 bytes,
> this should not be a serious problem. Also, there's a separate binary
> format (section 6) that is more compact already.

I strongly disagree with merging ni & nih. Though that clearly
could be done, it would be an error.

There was no such comment on the uri-review list and the designated
expert was happy. That review was IMO the time for such comments
and second-guessing the designated expert at this stage seems
contrary to the registration requirements. So process-wise I
think your main comment is late.

But in any case, I also think you're wrong technically in this
case.

nih *is* intended for a corner case, where humans need to speak these
URIs and was added as a direct result of requirements from the core
WG and not as an afterthought. ni URIs are not intended for that
and so there really are IMO different requirements, (esp. e.g.
checkdigit) that are best met with different schemes.

Merging ni/nih would also add more complexity for no benefit,
which would be a bad idea.

Your analogy about httpm/h may appear reasonable, but it is always
unreasonable to draw conclusions from analogies. It is also unwise
to reason from counterfactuals, which we'd also be doing if we
accepted your argument. So I find that speculation utterly useless
to be honest.

In this case, we are dealing with different requirements so this
should stay as-is.

Finally, we have (some, early,) running code that matches the
current draft and that ought also count for something when compared
to a change that would be a gratuitous dis-improvement based it
seems upon dubious argument that is also offered at the wrong
point in the process. (I'd say that gets over the level of my
disagreement here with a firm hand:-)

> (relatively) Minor technical issues:
> 
> Section 2, "When the input to the hash algorithm is a public key value":
> Is it absolutely clear that this will work for any and all public key
> values, existing and future, and not only for what's currently around?
> After all, as far as I understand, the concept of a public key is a
> fairly general one.

Yes. SPKI is good for this and is what's used elsewhere, e.g. in
dane and websec. Its the right choice and will be so long as folks
still need to map public key formats to X.509 which I expect will
be the case for many years to come. (Not that we get new public
key formats very often in any case.)

> "Other than in the above special case where public keys are used, we do
> not specify the hash function input here.  Other specifications are
> expected to define this.": Do you really expect that to happen? 

I do, yes, assuming that ni URIs get adopted. If they don't, then
its not a problem:-)

> Wouldn't
> it be better limit variability here as much as possible, and to use
> media types to identify different kinds of data? 

To be honest, I think that's another day's work. I don't know that
there's a generic solution that'd work for enough protocols. If there
were, then that could, and I think, should, be done in another RFC.

> This would also work
> for public keys: If there's a MIME media type for a
> SubjectPublicKeyInfo, then the fact that this media type is the
> preferred way to transfer a public key becomes an application convention
> rather than a special case in the spec. If a better way (or just another
> way) to encode/transfer public keys became popular at a later date,
> there would be no need to change the spec.

See above.

> 
> Related, in Section 3:
>    The "val" field MUST contain the output of base64url encoding the
>    result of applying the hash function ("alg") to its defined input,
>    which defaults to the object bytes that are expected to be returned
>    when the URI is dereferenced.
> How do I know whether the default applies or not? The URI doesn't tell
> you. Deducing from context is a bad idea.

I agree that deducing the input from context alone could be
difficult, though you would know when you got the right answer.
I think the way to handle this is for other specifications that
use ni URIs to specify the inputs.

> 
> Section 3: "Thus to ensure interoperability, implementations SHOULD NOT
> generate URIs that employ URI character escaping": This is wrong and
> needs to be fixed. Characters such as "&", "=", "#", and "%", as well as
> ASCII characters not allowed in URIs and non-ASCII characters MUST be
> %-encoded if they appear in query parameter values in URIs (or in query
> parameter tags, which is however less likely). It would be better if the
> spec here deferred to the URI spec rather than trying to come up with
> its own rules.

Can you suggest text to include? I'm always uncertain about this
kind of thing and would be very happy to take your suggestion.

> 
> Section 3: "The Named Information URI adapts the URI definition from the
> URI Generic Syntax [RFC3986].": This sounds as if this were a voluntary
> decision (and the text should be changed to avoid such an impression),

Huh? I don't get what change you'd like.

> but if you don't conform to RFC 3986 syntax, you're not an URI. This is
> the first time I have seen an URI scheme definition starting explicitly
> with the top ABNF rule from RFC 3986
> (http://tools.ietf.org/html/rfc3986#appendix-A) This is completely
> unnecessary. Just make sure your production conforms to the generic URI
> syntax, and mention all the ABNF rules from RFC3986 that you use.
> 
> Also, using the "URI" production from RFC 3986, and then silently
> dropping the #fragment part, is technically wrong. Scheme definitions
> have nothing to do with the fragment (including the question of whether
> there's a fragment or not; the semantics of fragments are defined by the
> MIME media type that you get when you resolve). This may not be
> completely clear in RFC 4395, but the IRI WG is working on an update of
> RFC 4395 where this will be made clearer (see also
> http://trac.tools.ietf.org/wg/iri/trac/ticket/126; thanks for giving me
> a chance to remember that I had to create a new issue in the tracker for
> this :-).

Again, I'm not clear what change is suggested.

> 
> Section 3, ABNF:
>             ni-hier-part   = "//" authority path-algval
>                              / path-algval
> This gives you ni://example.com/sha-256;f4OxZX_x_FO5... (//authority/)
> and ni:/sha-256;f4OxZX_x_FO5... (one slash only), but the examples show
> ni:///sha-256;f4OxZX_x_FO5... (three slashes). It looks like the ABNF
> you want is:
>             ni-hier-part   = "//" authority path-algval
>                            / "//" path-algval
> (aligning "=" and "/" helps!)
> or more simply:
>             ni-hier-part   = "//" [authority] path-algval
> or even more simply:
>             ni-hier-part   = "//" authority path-algval
> because authority can be empty; let's show this:
>    authority     = [ userinfo "@" ] host [ ":" port ]
> If we can show that host can be empty, we're done:
>    host          = IP-literal / IPv4address / reg-name
> If we can show that any one of these can be empty, we're done, let's
> pick reg-name:
>    reg-name      = *( unreserved / pct-encoded / sub-delims )
> * means "zero or more", thus reg-name can be empty. QED.

Good catch. Will craft a fix that disallows "ni:/sha-s56;..."
and forces "ni:///sha-256;..." when the authority is empty.

> 
> Section 4:
>    The HTTP(S) mapping MAY be used in any context where clients without
>    support for ni URIs are needed without loss of interoperability or
>    functionality.
> What is meant by "support for ni"? There's nowhere in the spec where
> this is explained clearly. If I were a browser maker, or writing an URI
> library,..., what would I do to support the ni scheme? The only thing I
> have come up with is to covert ni to the .well-known format, then use
> HTTP(S). In that case, the above text seems wrong, as it says that
> .well-known is used when there's no support for ni, not in order to
> support ni.

We can re-word, but personally I think its clear now. A suggestion
would be welcome.

> 
> Section 5: This defines an "URL segment format". It seems to be limited
> to path componest in HTTP URIs. What if I want to use this in a query
> part, or maybe even as a fragment identifier? What if I want to use this
> as a path component in an FTP URI? Or in some other schem? It would be
> better to define the alg-val (see next point) part as such (before the
> other things), with an explanation along the following lines: "This is
> defined here both for use in other sections of this document as well as
> for use in other places where it may be helpful, such as HTTP URI path
> segments,..."

Can do that. Good suggestion.

> 
> Section 5 (and Section 3): "To do this one simply uses the "alg;val"
> production": There is no "alg;val" production. Please change to "To do
> this one simply uses the <alg-val> production" and fix the ABNF in
> section 3 to
>             path-algval = "/" alg-val
>             alg-val     = alg ";" val
> It's probably even better to fold this in with the changes to
> ni-hier-part, resulting e.g. in:
>             ni-hier-part   = "//" authority "/" alg-val
>             alg-val     = alg ";" val

Ok.

> 
> Section 9.4: Status can be 'empty' or 'deprecated'. I suggest to replace
> 'empty' with something positive, such as 'valid' or 'active'. This will
> help people who go to the IANA page and start to ask "well, it doesn't
> have a status, what does that mean". 

Can do.

> Also, I strongly suggest to add an
> additional status 'reserved', and remove the current "Reserved" hash
> name string from the entries with IDs 0 and 32.

Huh? Wouldn't that confuse things more? IANA handles Reserved
values all the time.

> Section 9.4: "The Suite ID value 32 is reserved for compatibility with
> ORCHIDs [RFC4843].": How will compatibility be kept for future
> changes/additions in ORCHID?

Dunno actually:-) Ari might. But we can change it to just say "reserved
for compatibility with 4843"

> 
> Major editorial issues:
> 
> Title and abstract (and the spec itself) use the wording "Naming
> Things". While in a security context, it may be that there is an
> implicitly assumption that there are only digital things, in a wider
> context, this is of course not true. Research on the Internet of Things
> and efforts such as the Semantic Web/Linked Data try to deal with things
> in the real world. People in these areas it will be confused by title,
> abstract, and text, unless you can show (me and) them an ni: hash for a
> person, an apple, a building, or an elephant. Therefore, while it may be
> possible to keep the catchy title, the abstract has to be fixed to avoid
> such misunderstandings, e.g. by changing "to identify a thing" to "to
> identify a digital object" or some such in the abstract, and likewise in
> the main text of the spec.

First, I disagree that people will really be confused. I think this
is both a nit and a gratuitous one. However, I've no problem with
making that (tiny, inconsequential and by no means major:-) change to
the abstract.

> 
> "Human-speakable" (e.g. ), "human-readable" (e.g. section title of
> section 7), and "for humans" (e.g. section title of section 9.2): These
> terms are used throughout the spec, but are imprecise and confusing.

Imprecise: sure. Confusing: really? Were you really confused?

> First, there's the problem of interpreting "for humans" in the sense of
> the previous paragraph, which of course has to be fixed. But the main
> problem is that none of the "ni:" URIs are "non-human-readable" or
> "non-human-speakable". Reading them aloud is only somewhat more tedious,
> but not at all impossible. And because the value part of the nih: form
> is 50% longer, and people quickly develop conventions for shortening
> things such as "upper case" and "lower case", it's not even clear that
> reading aloud the nih: form will necessarily take that much time.
> Therefore, I strongly recommend to change all occurrences of
> "Human-speakable", "human-readable", "for humans", and the like, to the
> more precise "more easily read out aloud by humans" or something
> equivalent.

Happy to take a look. But I suspect we'll still disagree on
whether or not there's real confusion here.

> 
> Abstract and further on: "specifying URI, URL": By all URx theories (see
> e.g. http://www.w3.org/TR/uri-clarification/) URLs are a subset of
> URIs, and therefore saying that the spec specifies an URI and an URL is
> somewhat confusing. I'd propose using wording along the following lines:
> "specifying an URI scheme and a way to map these URIs to http".

Sure. Happy to make this *minor* change:-)

> 
> Section 2, "When the input to the hash algorithm is a public key value",
> and example section: It took me a while to understand that the "public
> key" stuff was not yet another way to present a hash, and also not a way
> to mix in a public key to the hash in order to obtain some specific
> security property (I wasn't able to figure out how that would work, but
> draft-hallambaker-decade-ni-params contains something similar involving
> digital signatures and a public key). The document would be much easier
> to understand if there was a section e.g. entitled "Forms of input to
> hash", with subsections e.g. "general data", "public keys", "other stuff
> (not defined in this document)". As it is written, the relevant
> paragraphs in section 2 look like an afterthought, and it's not clear to
> what.

I really don't get what's not clear there and I suspect I don't like
the suggested re-structuring but I'll take a look. Be good if you can
make a suggestion for text to add to the current structure that would
have avoided your confusion.

> Also, the example section should be fixed as follows: 1) say upfront
> that there will be two examples, one for a short string and another for
> a public key. 2) Make sure both examples exercise all forms (the public
> key example seems to be pretty complete, but the "Hello World!" example
> seems to be incomplete). 3) Use the same form of presentation (either a
> table in both cases or short paragaphs in both cases.
> The caption on Figure 7 is also way too unspecific.

I'll take a look. I entirely disagree that these are *major*
editorial changes.

> 
> Section 9.4: "Hash Name Algorithm Registry", and later "a new registry
> for hash algorithms as used in the name formats specified here": IANA
> will be helped tremendously if your draft comes with an
> easy-to-understand and unambiguous name for the new registry. "Hash Name
> Algorithm Registry" may be okay, but is probably not specific enough.
> The circumscription at the start of the section is definitely not good
> enough because you're not registering hash algorithms, but names of hash
> algorithms and their truncations.

I'll take a look.

> Minor editorial issues:
> 
> Introduction: It would be good to have a general reference to hashing
> (for security purposes) for people not utterly familiar with the subject.

Disagree. If I added that I could reasonably be asked to introduce
URIs for the security folks. Serious and pointless ratholes would ensue.

> Intro: After reading the whole document, the structure of the Intro
> seems to make some sense, but it didn't on first reading (where it's
> actually more important). The main problem I was able to identify was
> that after a general outlook in paragraph 1, the Intro drops into a list
> of examples without saying what they are good for. I suggest to, after
> the sentence "This document specifies standard ways to do that to aid
> interoperability.", add a sentence along the lines: "The next few
> paragraphs give usage examples for the various ways to include a hash in
> a name or identifier as they are defined later in this document.". It
> may also make sense to further streamline the following paragraphs, so
> that it is clearer which pieces of text refer each to one of the
> "standard ways".
> 
> There are two instances of the term "binary presentation". Looking
> around, it seems that they are supposed to mean the same as "binary
> format". Please replace all instances of "binary presentation" with
> "binary format" to avoid misunderstandings and useless seach time.
> 
> Section 3: "A Named Information (ni) URI consists of the following
> components:": It would be good to know exactly where the list ended. One
> way to do this would be to say "consists of the following nine components".

Those look reasonable. Will see if the changes work out.

> Section 3: "Note that while the ni names with and without an authority
> differ syntactically, both names refer to the same object if the digest
> algorithm and value are the same.": What about cases with different
> authority? The text seems to apply by transitivity, but this may be easy
> to miss for an implementer. I suggest changing to: "Note that while ni
> names with and without an authority, and ni names with different
> authorities, differ syntactically, they all refer to the same object if
> the digest algorithm and value are the same.".

Sure.

> Section 3: "Consequently no special escaping mechanism is required for
> the query parameter portion of ni URIs.": Does this mean "no escaping
> mechanism at all"? Or "nothing besides %-encoding"? Or something else?
> Please clarify.

I wish I knew:-) What do you think is right here? (Honestly,
input on this would be appreciated.)

> 
> Figure 3: the "=" characters of the various rules should be aligned as
> much as possible to make it easier to scan the productions (see
> http://tools.ietf.org/html/rfc3986#appendix-A for an example).

Ack.

> 
> Section 3:
>             unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
>                 ;  directly from RFC 3986, section 2.3
>                 ; "authority" and "pct-encoded" are also from RFC 3986
> Please don't copy productions. Please don't copy half (or one-third,
> actually) of the productions you use, and reference the rest. Please
> don't say what productions you copy from where in a comment, and even
> less in a comment for an unrelated production. Please before the ABNF,
> say which productions are used from another spec.

We got contrary advice from elsewhere (can't recall where right now;-).
I'll let Barry (as sponsoring AD) just tell us his preference and go
with that if that's ok.

> Section 4:
>    The HTTP(S) mapping MAY be used in any context where clients without
>    support for ni URIs are needed without loss of interoperability or
>    functionality.
> This is difficult to understand. If some new functionality is proposed,
> it's usually a client *with* the new functionality that's needed, not
> one without. Also, the "without loss of interoperability or
> functionality" is unclear: Sure if ni isn't supported, there's a loss in
> interoperability. So I suggest to rewrite this as:
>    The HTTP(S) mapping MAY be used in any context where clients with
>    support for ni URIs are not available.

Sure.

> (but see also the comment in minor technical issues)
> 
> Section 6: "binary format name": Why 'name'? Why not just "binary
> format"? The later is completely clear in the context of the document or
> together with an indication of the document; for something that can be
> used independently, even "binary format name" isn't enough.

I don't get the problem with that.

> Section 6: "suite ID": The word "suite" seems out of place here. In the
> general use of the term, it refers to "a group of things forming a unit
> or constituting a collection" (see
> http://www.merriam-webster.com/dictionary/suite) A good definition that
> works for the uses I'm familiar with in digital security would be "An
> algorithm suite is a coherent collection of cryptographic algorithms for
> performing operations such as signing, encryption, generating message
> digests, and so on."
> (http://fusesource.com/docs/framework/2.4/security/MsgProtect-SOAP-SpecifyAlgorithmSuite.html;
> disclaimer: I'm in no way a SOAP fan). The use here is not for a
> collection, but for a single truncated-length variant of a single hash
> algorithm. I seriously hope you can find a better name.

That's a don't-care for me. I think suite is fine, but could
take other terms (so long as its not "algorithm"). Suite could
be justified since we have alg+truncation here, but like I
said I'd be fine to change, if a good suggestion is made.

> 
> Section 6: "Note that a hash value that is truncated to 120 bits will
> result in the overall name being a 128-bit value which may be useful
> with certain use-cases.": This left me really wondering: Is there
> something magic to 128 bits in computer/internet security? What are the
> "certain use cases"? Or is this just an example to make sure the reader
> got the relationships, and it could have been as well "Note that a hash
> value that is truncated to 64 bits will result in the overall name being
> a 72-bit value which may be useful with certain use-cases." (or whatever
> other value that's registered in section 9)?

Bit of both. I believe the core WG are keen to end up with a 128 bit
binary value as their preferred option.

> 
> Section 7: Just for the highly unfortunate case that this doesn't
> disappear, it would be very helpful if the presentation of this section
> paralleled section 3.

Disagree. Different requirements, different URIs, different
presentation. I don't think there's a real problem here.

> 
> Section 7: "contain the ID value as a UTF-8 encoded decimal number": I'm
> an internationalization expert with a strong affection for UTF-8, but
> even for me, this should be "contain the ID value as an ASCII encoded
> decimal number".

Fine.

> 
> Section 9: The registration templates refer to sections. This is fine
> for readers of the draft, but not if the template is standalone. I
> suggest using a format such as that at
> http://tools.ietf.org/html/rfc6068#section-8.1, which in draft stage may
> look e.g. like
> http://tools.ietf.org/html/draft-duerst-eai-mailto-03#section-8.1.

Will take a peek. Not sure I agree. (Nor disagree:-)

> Section 9.3: "Assignment of Well Known URI prefix ni" and later (and
> elsewhere in the draft) "URI suffix": Are we dealing with a prefix or a
> suffix here?

Will take a peek.

> Section 9.4: "This registry has five fields, the binary suite ID,...":
> Better to remove the word "binary", because the actual number is decimal.

Ack.

> 
> Section 9.4: "The expert SHOULD seek IETF review before approving a
> request to mark an entry as "deprecated."  Such requests may simply take
> the form of a mail to the designated expert (an RFC is not required).
> IETF review can be achieved if the designated expert sends a mail to the
> IETF discussion list.  At least two weeks for comments MUST be allowed
> thereafter before the request is approved and actioned.": I'm at a loss
> to see why asking the IETF at large is a SHOULD, but if it's done, then
> the two weeks period is a MUST.

I don't get your comment. The two weeks is a MUST already.

> 
> Section 9.4: The registry initialization in Fig. 8 refers to RFC4055
> many times. But RFC 4055 does in no way define SHA-256. It looks like
> the actual spec is http://tools.ietf.org/html/rfc4055#ref-SHA2 (National
> Institute of Standards and Technology (NIST), FIPS 180-2: Secure Hash
> Standard, 1 August 2002.) I think this should be cited, in particular
> because there is a "Specification Required" requirement, and this sure
> should mean that there is a Specification for the actual algorithm, and
> not just a specification that mentions some labels. So using RFC4055 as
> a reference could be taken as creating bad precedent.

I guess so. Good catch.

> Section 9.4: "The designated expert is responsible for ensuring that the
> document referenced for the hash algorithm is such that it would be
> acceptable were the "specification required" rule applied.": Why all
> this circumscription? Why not just say something like: "The designated
> expert is responsible for ensuring that the document referenced for the
> hash algorithm meets the "specification required" rule."

Honestly? I can't recall:-) Will change unless I do remember.

> Nits:
> 
> Author's list: Last time I heard about this, there was a general limit
> of 5 authors per RFC. I'm not sure whether this still exists, and what'd
> be needed to get around it, but I just wanted to point out that this may
> be a potential problem or additional work (hoops to get through).
> 
> Intro: "Since, there is no standard" -> "Since there is no standard"
> 
> Intro: "for these various purposes" -> "for these purposes" or "for
> various purposes" (the indefinite 'various' is incompatible with the
> definite 'these').
> 
> "2.  Hashes are what Count" -> "2.  Hashes are what Counts" (the former
> may look logically correct, but 'what' requires a singular verb form.
> 
> Section 2: "the left-most or most significant in network byte order N
> bits from the binary representation of the hash value" -> "the left-most
> (or most significant in network byte order) N bits from the binary
> representation of the hash value" or "the left-most N bits, or the N
> most significant bits in network byte order, from the binary
> representation of the hash value" (the current text is virtually
> unparsable).
> 
> Figure 1: The 0x notation is never explained. A short clause or pharse
> is all that would be needed, but it would be better if this were spelled
> out.
> 
> Section 3, Query Parameter separator: "The query parameter separator
> acts a separator between" -> "The query parameter separator acts *as* a
> separator between".
> 
> Section 3, Query Parameters: "A tag=value list of optional query
> parameters as are used with HTTP URLs" ->  "A tag=value list of optional
> query parameters as used with HTTP URLs" (or "A tag=value list of
> optional query parameters as they are used with HTTP URLs").
> 
> Section 4: "the object named by the ni URI will be available at the
> corresponding HTTP(S) URL" -> "the object named by the ni URI will be
> available via the corresponding HTTP(S) URL" (via stresses the point
> that this should be done via (sic) redirection)
> 
> Section 4: "so there may still be reasons to use" -> "so there can still
> be reasons to use" (better to use can because non-normative; the
> document otherwise does a good job on this)
> 
> Section 10: "Note that fact that" -> "Note the fact that", or much
> better: "Note that".

Those look ok or are nits in any case.

Thanks again for the thorough review even though we disagree as
to the main point.

Cheers,
Stephen.


> 
> 
> Regards,     Martin.
> 
> 
>