Re: [OAUTH-WG] Stephen Farrell's Discuss on draft-ietf-oauth-amr-values-05: (with DISCUSS)

[Mike Jones <[e-mail]>]

Thanks for the reply, Stephen.  I'll try to find better interop-producing references where possible.



In some cases, however, the values are intentionally intended to provide an identifier for a family of closely-related methods, such as "otp", which covers both time-based and HMAC-based OTPs.  Many relying parties will be content to know that an OTP has been used in addition to a password.  The distinction between which kind of OTP was used is not useful to them.  Thus, there's a single identifier that can be satisfied in two or more nearly equivalent ways.  I consider this to be a feature - not a bug.



Similarly, there's a whole range of nuances between different fingerprint matching algorithms.  They differ in false positive and false negative rates over different population samples and also differ based on the kind and model of fingerprint sensor used.  Like the OTP case, many RPs will be content to know that a fingerprint match mas made, without delving into and differentiating based on every aspect of the implementation of fingerprint capture and match.  Those that want more precision than this can always define new "amr" values.  But "fpt" is fine as is for what I believe will be the 90+% case.



Ultimately, the RP is depending upon the Identity Provider to do reasonable things.  If it didn't trust the IdP to do so, it has no business using it.  The "amr" value lets the IdP signal to the RP additional information about what it did, for the cases in which that information is useful to the RP.



Reducing this to the point of absurdity, the RP would almost never care about the make, model, and serial number of the fingerprint reader or OTP.  Values could be defined to provide that granularity.  But making those fine-grained distinctions are not useful in practice.



Please consider the existing definitions in light of that reductio ad absurdum.  The existing values only make distinctions that are known to be useful to RPs.  Slicing things more finely than would be used in practice actually hurts interop, rather than helping it, because it would force all RPs to recognize that several or many different values actually mean the same thing to them.



                                                                -- Mike



-----Original Message-----
From: Stephen Farrell [mailto:[e-mail]]
Sent: Monday, March 6, 2017 2:10 PM
To: Mike Jones <[e-mail]>; Anthony Nadalin <[e-mail]>; joel jaeggli <[e-mail]>; The IESG <[e-mail]>
Cc: [e-mail]; [e-mail]; [e-mail]
Subject: Re: [OAUTH-WG] Stephen Farrell's Discuss on draft-ietf-oauth-amr-values-05: (with DISCUSS)





Hi Mike,



Apologies - I updated the discuss ballot text [1] on Feb 28 but must've not sent it as an email or something. Anyway...



   [1] https://datatracker.ietf.org/doc/draft-ietf-oauth-amr-values/ballot/



On 06/03/17 20:38, Mike Jones wrote:

> Hi Stephen.  The changes in draft -06 were intended to address your

> DISCUSS points.  Are you satisfied with these changes or are there

> additional changes you want?  I'm asking partly because it's a week

> now until the submission cutoff and if additional changes are needed,

> I'd like to make them this week.



So I do think there's still work to be done, may as well copy the new ballot text here:



"

I think we still have the problem that the values "defined" here (e.g. "fpt") are under specified to a significant degree. RFC4949 does not tell anyone how to achieve interop with "fpt" (nor any of the other cases where you refer to 4949 I think). There is therefore no utility in "defining" "fpt" as it will not achieve interop and in fact is more likely to cause confusion than interop. If the solution of actually defining the meaning of things like "fpt" is not achievable then perhaps it will be better to only define those for which we can get interop ("pwd" and one or two others) and leave the definition of the rest for later. (In saying that I do recall that one of the authors said that there are implementations that use some of these type-names, but the point of RFCs is not to "bless"

such things, but to achieve interop.)

"



Cheers,

S.



>

> Thanks, -- Mike

>

> -----Original Message----- From: Mike Jones

> [mailto:[e-mail]] Sent: Tuesday, February 28, 2017

> 6:17 PM To: Stephen Farrell <[e-mail]<mailto:[e-mail]>>; Anthony

> Nadalin <[e-mail]<mailto:[e-mail]>>; joel jaeggli <[e-mail]<mailto:[e-mail]>>; The

> IESG <[e-mail]<mailto:[e-mail]>> Cc: [e-mail]<mailto:[e-mail]>;

> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]> Subject: RE:

> [OAUTH-WG] Stephen Farrell's Discuss on

> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>

> Hi Stephen,

>

> Draft -06 https://tools.ietf.org/html/draft-ietf-oauth-amr-values-06

> adds references for all of the defined "amr" values.  Thanks for

> taking the time to have a thoughtful discussion.

>

> -- Mike

>

> -----Original Message----- From: Stephen Farrell

> [mailto:[e-mail]] Sent: Wednesday, February 1, 2017

> 4:45 PM To: Mike Jones <[e-mail]<mailto:[e-mail]>>; Anthony Nadalin

> <[e-mail]<mailto:[e-mail]>>; joel jaeggli <[e-mail]<mailto:[e-mail]>>; The IESG

> <[e-mail]<mailto:[e-mail]>> Cc: [e-mail]<mailto:[e-mail]>;

> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]> Subject: Re:

> [OAUTH-WG] Stephen Farrell's Discuss on

> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>

>

>

> On 02/02/17 00:35, Mike Jones wrote:

>> You can call me lazy if you want.

>

> I don't think you're lazy:-) Were I to guess I'd guess that interop

> for these wasn't a priority and that we're defining them a bit early

> and a little too generically.

>

>> Some of them are so well known, such as "password" or "PIN" it didn't

>> seem worthwhile to try to track down a reference.

>

> Sure, those are fine. The only issues would be if there's a string2key

> function somewhere but I don't expect there is in this context.

>

>> But I'm willing to work with others to find decent references for the

>> rest of them, if you believe that would improve the quality of the

>> specification.

>

> I do think it would, esp for cases where there are known different

> options (e.g. otp) or likely ill-defined or proprietary formats. My

> guess is that some biometrics fit that latter but I could be wrong.

> If they do, then one runs into the problem of having to depend on

> magic numbers in the encodings or similar to distinguish which is

> really error prone and likely to lead to what our learned transport

> chums are calling ossification;-)

>

> Cheers, S.

>

>

>>

>> Best wishes, -- Mike

>>

>> -----Original Message----- From: Stephen Farrell

>> [mailto:[e-mail]] Sent: Wednesday, February 1,

>> 2017 4:31 PM To: Mike Jones <[e-mail]<mailto:[e-mail]>>; Anthony

>> Nadalin <[e-mail]<mailto:[e-mail]>>; joel jaeggli <[e-mail]<mailto:[e-mail]>>; The

>> IESG <[e-mail]<mailto:[e-mail]>> Cc: [e-mail]<mailto:[e-mail]>;

>> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]> Subject: Re:

>> [OAUTH-WG] Stephen Farrell's Discuss on

>> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>>

>>

>>

>> On 02/02/17 00:28, Mike Jones wrote:

>>> The other case of known interop testing of "amr" values is for

>>> MODRNA (OpenID Connect Mobile Profile) implementations.  There's a

>>> reference to its use of "amr" values in the spec.

>>

>> Yeah, iirc, that one seemed ok (assuming the reference tells me what

>> code to write which I assume it does).

>>

>> I'm still not seeing why some do have sufficient references and

>> others do not.

>>

>> Is there some difficulty with finding references or something?

>>

>> S

>>

>>>

>>> -----Original Message----- From: Anthony Nadalin Sent: Wednesday,

>>> February 1, 2017 4:27 PM To: Stephen Farrell

>>> <[e-mail]<mailto:[e-mail]>>; Mike Jones

>>> <[e-mail]<mailto:[e-mail]>>; joel jaeggli <[e-mail]<mailto:[e-mail]>>; The

>>> IESG <[e-mail]<mailto:[e-mail]>> Cc: [e-mail]<mailto:[e-mail]>;

>>> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]> Subject: RE:

>>>  [OAUTH-WG] Stephen Farrell's Discuss on

>>> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>>>

>>> We have interoped between FIDO authenticators vendors and Windows

>>> Hello

>>>

>>> -----Original Message----- From: Stephen Farrell

>>> [mailto:[e-mail]] Sent: Wednesday, February 1,

>>> 2017 4:24 PM To: Mike Jones <[e-mail]<mailto:[e-mail]>>; Anthony

>>> Nadalin <[e-mail]<mailto:[e-mail]>>; joel jaeggli <[e-mail]<mailto:[e-mail]>>;

>>> The IESG <[e-mail]<mailto:[e-mail]>> Cc:

>>> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>;

>>> [e-mail]<mailto:[e-mail]> Subject: Re: [OAUTH-WG] Stephen Farrell's Discuss on

>>> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>>>

>>>

>>>

>>> On 02/02/17 00:21, Mike Jones wrote:

>>>> Thanks, Tony.  I can add that reference.

>>>>

>>>> Stephen, the sets of initial values were chosen from those used in

>>>> practice by Microsoft and Google in real deployments.

>>>

>>> Genuine questions: do you aim to have interop between those

>>> deployments? What if I wanted to write code that'd interop with msft

>>> or google?

>>>

>>> S.

>>>

>>>>

>>>> About "otp", there are existing use cases for indicating that an

>>>> OTP was used.  I'm not aware of any of these use cases where the

>>>> distinction between TOTP and HOTP is important.  Thus, having "otp"

>>>> now makes sense, where having "hotp" and "totp"

>>>> now doesn't.

>>>>

>>>> Stephen, this may seem like splitting hairs, but the registry

>>>> instructions for "Specification Document(s)" are about having a

>>>> reference for the document where the Authentication Method

>>>> Reference Name (such as "otp") is defined.  In all cases for the

>>>> initial values, this is the RFC-to-be, so the registry instructions

>>>> are satisfied.  If someone were, for instance, to define the string

>>>> "hotp", it would be incumbent on the person requesting its

>>>> registration to provide a URL to the document where the string

>>>> "hotp" is defined.  Also having a reference to RFC 4226 in that

>>>> document would be a good thing, but that isn't what the registry

>>>> instructions are about.

>>>>

>>>> All that said, I can look at also finding appropriate references

>>>> for the remaining values that don't currently have them. (Anyone

>>>> got a good reference for password or PIN to suggest, for instance?)

>>>>

>>>> -- Mike

>>>>

>>>> -----Original Message----- From: Anthony Nadalin Sent:

>>>> Wednesday, February 1, 2017 4:10 PM To: Stephen Farrell

>>>> <[e-mail]<mailto:[e-mail]>>; Mike Jones

>>>> <[e-mail]<mailto:[e-mail]>>; joel jaeggli <[e-mail]<mailto:[e-mail]>>;

>>>> The IESG <[e-mail]<mailto:[e-mail]>> Cc: [e-mail]<mailto:[e-mail]>;

>>>> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]> Subject:

>>>> RE: [OAUTH-WG] Stephen Farrell's Discuss on

>>>> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>>>>

>>>> NIST asked for the addition of IRIS (as they are seeing more use of

>>>> IRIS over retina due to the accuracy of iris)  as they have been

>>>> doing significant testing on various iris devices and continue to

>>>> do so, here is a report that NIST released

>>>> http://2010-2014.commerce.gov/blog/2012/04/23/nist-iris-recognition

>>>> -report-evaluates-needle-haystack-search-capability.html

>>>>

>>>>

>>>>

>>>>

>>

>>>>

>

>>>>

-----Original Message----- From: Stephen Farrell

>>>> [mailto:[e-mail]] Sent: Wednesday, February 1,

>>>>  2017 2:26 PM To: Mike Jones <[e-mail]<mailto:[e-mail]>>; joel

>>>> jaeggli <[e-mail]<mailto:[e-mail]>>; The IESG <[e-mail]<mailto:[e-mail]>> Cc:

>>>> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>;

>>>> [e-mail]<mailto:[e-mail]> Subject: Re: [OAUTH-WG] Stephen Farrell's Discuss on

>>>> draft-ietf-oauth-amr-values-05: (with DISCUSS)

>>>>

>>>>

>>>> Hi Mike,

>>>>

>>>> On 01/02/17 17:00, Mike Jones wrote:

>>>>> Thanks for the discussion, Stephen.

>>>>>

>>>>> To your point about "otp", the working group discussed this very

>>>>> point.  They explicitly decided not to introduce "hotp"

>>>>> and "totp" identifiers because no one had a use case in which the

>>>>> distinction mattered.

>>>>

>>>> Then I'm not following why adding "otp" to the registry now is a

>>>> good plan.

>>>>

>>>> If there's a use-case now, then adding an entry with a good

>>>> reference to the relevant spec seems right.

>>>>

>>>> If there's no use-case now, then not adding it to the registry

>>>> seems right. (Mentioning it as a possible future entry would be

>>>> fine.)

>>>>

>>>> I think the same logic would apply for all the values that this

>>>> spec adds to the registry. Why is that wrong?

>>>>

>>>>> Others can certainly introduce those identifiers and register

>>>>> them if they do have such a use case, once the registry has been

>>>>> established.  But the working group wanted to be conservative

>>>>> about the identifiers introduced to prime the registry, and this

>>>>> is such a case.

>>>>>

>>>>> What identifiers to use and register will always be a balancing

>>>>> act. You want to be as specific as necessary to add practical and

>>>>> usable value, but not so specific as to make things unnecessarily

>>>>> brittle.

>>>>

>>>> Eh... don't we want interop? Isn't that the primary goal here?

>>>>

>>>>> While some might say there's a difference between serial number

>>>>> ranges of particular authentication devices, going there is

>>>>> clearly in the weeds.  On the other hand, while there used to be

>>>>> an "eye" identifier, Elaine Newton of NIST pointed out that there

>>>>> are significant differences between retina and iris matching, so

>>>>> "eye" was replaced with "retina"

>>>>> and "iris". Common sense informed by actual data is the key here.

>>>>

>>>> That's another good example. There's no reference for "iris."

>>>> If that is used in some protocol, then what format(s) are expected

>>>> to be supported? Where do I find that spec? If we can answer that,

>>>> then great, let's add the details. If not, then I'd suggest we omit

>>>> "iris" and leave it 'till later to add an entry for that. And

>>>> again, including text with "iris" as an example is just fine, all

>>>> I'm asking is that we only add the registry entry if we can meet

>>>> the same bar that we're asking the DE to impose on later additions.

>>>>

>>>> And the same for all the others...

>>>>

>>>> Cheers, S.

>>>>

>>>>

>>>>>

>>>>> The point of the registry requiring a specification reference is

>>>>> so people using the registry can tell where the identifier is

>>>>> defined. For all the initial values, that requirement is

>>>>> satisfied, since the reference will be to the new RFC.  I think

>>>>> that aligns with the point that Joel was making.

>>>>>

>>>>> Your thoughts?

>>>>>

>>>>> -- Mike

>>>>>

>>>>> -----Original Message----- From: OAuth

>>>>> [mailto:[e-mail]] On Behalf Of Stephen Farrell

>>>>>  Sent: Wednesday, February 1, 2017 7:03 AM To: joel jaeggli

>>>>> <[e-mail]<mailto:[e-mail]>>; The IESG <[e-mail]<mailto:[e-mail]>> Cc:

>>>>> [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>;

>>>>>  [e-mail]<mailto:[e-mail]> Subject: Re: [OAUTH-WG] Stephen Farrell's Discuss

>>>>> on draft-ietf-oauth-amr-values-05: (with DISCUSS)

>>>>>

>>>>>

>>>>>

>>>>> On 01/02/17 14:58, joel jaeggli wrote:

>>>>>> On 1/31/17 8:26 AM, Stephen Farrell wrote:

>>>>>>> Stephen Farrell has entered the following ballot position for

>>>>>>> draft-ietf-oauth-amr-values-05: Discuss

>>>>>>>

>>>>>>> When responding, please keep the subject line intact and  reply

>>>>>>> to all email addresses included in the To and CC lines. (Feel

>>>>>>> free to cut this introductory paragraph,

>>>>>>> however.)

>>>>>>>

>>>>>>>

>>>>>>> Please refer to

>>>>>>> https://www.ietf.org/iesg/statement/discuss-criteria.html

>>>>>>>

>>>>>>>

for more information about IESG DISCUSS and COMMENT

>>>>>>> positions.

>>>>>>>

>>>>>>>

>>>>>>> The document, along with other ballot positions, can be found

>>>>>>> here:

>>>>>>> https://datatracker.ietf.org/doc/draft-ietf-oauth-amr-values/

>>>>>>>

>>>>>>>

>>>>>>>

>>>>>>>

>>>>>>>

>>

>>>>>>>

>

>>>>>>>

---------------------------------------------------------------------

>>>>>>>

>>>>>>>

>>>>

>>>>>>>

>>> -

>>>>>>> DISCUSS:

>>>>>>> ----------------------------------------------------------------

>>>>>>> -----

>>>>>>>

>>>>>>>

>>>>

>>>>>>>

>>>

>>>>>>>

>>

>>>>>>>

>

>>>>>>>

-

>>>>>>>

>>>>>>> This specification seems to me to break it's own rules.

>>>>>>> You state that registrations should include a reference to a

>>>>>>> specification to improve interop. And yet, for the strings added

>>>>>>> here (e.g. otp) you don't do that (referring to section 2 will

>>>>>>> not improve interop) and there are different ways in which many

>>>>>>> of the methods in section 2 can be done. So I think you need to

>>>>>>> add a bunch more references.

>>>>>>

>>>>>> Not clear to me that the document creating the registry needs to

>>>>>> adhere to the rules for further allocations in order to

>>>>>> prepoulate the registry. that is perhaps an appeal to future

>>>>>> consistency.

>>>>>

>>>>> Sure - I'm all for a smattering of inconsistency:-)

>>>>>

>>>>> But I think the lack of specs in some of these cases could impact

>>>>> on interop, e.g. in the otp case, they quote two RFCs and yet only

>>>>> have one value. That seems a bit broken to me, so the discuss

>>>>> isn't really about the formalism.

>>>>>

>>>>> S.

>>>>>

>>>>>

>>>>>>>

>>>>>>>

>>>>>>>

>>>>>>

>>>>>>

>>>>>

>>>>

>>>

>>

>