The document will get a new RFC number.

Russ


> On Jun 8, 2021, at 5:13 PM, Gorman, Pierce <[email protected]> wrote:
> 
> Russ and Theresa,
> 
> Please forgive my ignorance, but is the intent to issue an RFC 8226bis?  Or 
> is the intent that the I-D result in a new numbered RFC which updates 8226?
> 
>> From reading various things I've learned, I think, that new RFCs and updates 
>> to existing RFCs begin life as an Internet-Draft which may or may not be 
>> adopted by a working group as a work item.  If adopted by the group, the 
>> author/editor continues development of the I-D until such time as it expires 
>> or is promoted to last call, et cetera.  The end result in many cases are 
>> new numbered RFCs which may obsolete or update existing RFCs as appropriate. 
>>  The STIR RFC 4474 had a 4474bis version that remained unchanged for some 
>> years before being obsoleted by RFC 8224 for which it was a conceptual 
>> foundation and that is now a key component of the STIR/SHAKEN set of 
>> standards required to be used by US VoIP service providers by law and 
>> federal mandate.
> 
> The reason I ask was because of some of the conversation at the last (I 
> think) interim meeting and on the e-mail distribution where proposed changes 
> were suggested to be submitted as a new I-D.  This -02 version may be the 
> same sort of thing but confusion/ignorance on my part about naming and 
> procedures made me want to ask.
> 
> Respectfully,
> 
> Pierce Gorman
> 
> -----Original Message-----
> From: stir <[email protected]> On Behalf Of Russ Housley
> Sent: Saturday, June 5, 2021 3:18 PM
> To: Theresa Enghardt <[email protected]>
> Cc: [email protected]; IETF Gen-ART 
> <[email protected]>; [email protected]; IETF STIR Mail List <[email protected]>
> Subject: Re: [stir] [Last-Call] Genart last call review of 
> draft-ietf-stir-enhance-rfc8226-02
> 
> [External]
> 
> 
> Theresa:
> 
> Thanks for your thoughtful review.
> 
> See my responses in-line.  I'll post an updated I-D when IETF Last Call ends.
> 
>> Reviewer: Theresa Enghardt
>> Review result: Ready with Issues
>> 
>> I am the assigned Gen-ART reviewer for this draft. The General Area 
>> Review Team (Gen-ART) reviews all IETF documents being processed by 
>> the IESG for the IETF Chair.  Please treat these comments just like 
>> any other last call comments.
>> 
>> For more information, please see the FAQ at
>> 
>> <https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrac.ietf.org%2Ftrac%2Fgen%2Fwiki%2FGenArtfaq&amp;data=04%7C01%7Cpierce.gorman%40t-mobile.com%7C40491250c2394836923608d9285f1574%7Cbe0f980bdd994b19bd7bbc71a09b026c%7C0%7C0%7C637585211113043953%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=QbFtT%2FIZ0CUXQB%2B0LUm3zIzgWqQQ%2BTk%2BNUJtuJelda8%3D&amp;reserved=0>.
>> 
>> Document: draft-ietf-stir-enhance-rfc8226-02
>> Reviewer: Theresa Enghardt
>> Review Date: 2021-06-04
>> IETF LC End Date: 2021-06-10
>> IESG Telechat date: Not scheduled for a telechat
>> 
>> Summary: The draft is basically ready for publication as a Standards 
>> Track RFC, but it has some clarity issues that need to be addressed before 
>> publication.
>> 
>> Major issues: None.
>> 
>> Minor issues:
>> 
>> Abstract:
>> 
>> Please expand JWT on first use.
>> Assuming PASSporT is an acronym, please expand it on first use.
>> The phrase "STIR certificates" appears in the title, but is not used 
>> in the abstract, introduction, or the draft in general. Is this 
>> intentional? Is STIR the same as PASSporT, in which case it could be 
>> replaced?
> 
> How about the replacement Abstract:
> 
>   RFC 8226 specifies the use of certificates for Secure Telephone
>   Identity Credentials, and these certificates are often called "STIR
>   Certificates".  RFC 8226 provides a certificate extension to
>   constrain the JSON Web Token (JWT) claims that can be included in the
>   Personal Assertion Token (PASSporT) as defined in RFC 8225.  If the
>   PASSporT signer includes a JWT claim outside the constraint
>   boundaries, then the PASSporT recipient will reject the entire
>   PASSporT.  This document updates RFC 8226 to define an additional way
>   that the JWT claims can be constrained.
> 
>> Section 1: Introduction
>> 
>> "Section 8 of [RFC8226] provides a certificate extension to constrain
>>  the JWT claims that can be included in the PASSporT [RFC8225].  If
>>  the signer includes a JWT claim outside the constraint boundaries,
>>  then the recipient will reject the entire PASSporT."
>> 
>> That's basically copied straight out of the Abstract (or the other way 
>> round).
>> Please provide some basic context for those who are not deeply 
>> involved with JWT/PassporT.
> 
> I do think that it makes sense to expand the Introduction to say more about 
> STIR certificates, but I do not think that the Introduction should repeat too 
> much of RFC 8226.
> 
>> For example:
>> - How does establishing authority over telephone numbers work, 
>> broadly? Does establishing authority mean that certifying that a 
>> telephone number belongs to, say, a specific organization? Or does 
>> anything happen "over" something telephony-related, as in some VoIP 
>> technology? (The "over telephone numbers" is ambiguous on first read.) 
>> - Is the PASSPorT a set of certificates or something else? Are these 
>> X.509 certificates or some other kind of certificates? Is the technology 
>> described in this doc independent of the format of the certificate?
>> - Does the actual process of "establishing authority" happen over, 
>> e.g., a Web API? Are there other ways? Is the technology described 
>> here specific to some way of "establishing authority"? - What is JWT 
>> and what are JWT claims? - Are JWT claim constraints provided in the 
>> certificate (PASSportT?) or are they communicated separately? Who 
>> provides them? The draft later talks about CA, authentication service, 
>> verification service - It would be good to briefly name these actors 
>> in the Introduction already and briefly describe to whom the change in this 
>> doc applies.
> 
> Is this enough?
> 
>   The use of certificates [RFC5280] in establishing authority over
>   telephone numbers is described in [RFC8226].  These certificates are
>   often called "STIR Certificates".  STIR certificates are an important
>   element of the overall system that prevents the impersonation of
>   telephone numbers on the Internet.
> 
>   Section 8 of [RFC8226] provides a certificate extension to constrain
>   the JSON Web Token (JWT) claims that can be included in the Personal
>   Assertion Token (PASSporT) [RFC8225].  If the PASSporT signer
>   includes a JWT claim outside the constraint boundaries, then the
>   PASSporT recipient will reject the entire PASSporT.
> 
>   This document defines an enhanced JWTClaimConstraints certificate
>   extension, which provides all of the capabilities available in the
>   original certificate extension as well as an additional way to
>   constrain the allowable JWT claims.  That is, the enhanced extension
>   can provide a list of claims that are not allowed to be included in
>   the PASSporT.
> 
>> Please consider adding a brief explanation why further constraints on 
>> PASSporT claims may be necessary.
> 
> I suggest two additional paragraphs at the end of the above Introduction:
> 
>   The Enhanced JWT Claim Constraints certificate extension is needed to
>   limit the authority when a parent STIR certificate delegates to a
>   subordinate STIR certificate.  For example,
>   [I-D.ietf-stir-cert-delegation] describes the situation where service
>   providers issue a STIR certificate to enterprises or other customers
>   to sign PASSporTs, and the Enhanced JWT Claim Constraints certificate
>   extension can be used to prevent specific claims from being included
>   in PASSporTs and accepted as valid by the PASSporT recipient.
> 
>   The JWT Claim Constraints certificate extension defined in [RFC8226]
>   provides a list of claims that must be included in a valid PASSporT
>   as well as a list if permitted values for selected claims.  The
>   Enhanced JWT Claim Constraints certificate extension defined in this
>   document includes those capabilities and adds a list of claims that
>   must not be included in a valid PASSporT.
> 
>> Section 3: Enhanced JWT Claim Constraints Syntax
>> 
>> "The Enhanced JWT Claim Constraints certificate extension limits the
>>  PASSporT claims and the claim values that can successfully validated
>>  by the certificate that contains the extension."
>> Are the claims and claim values validated BY the certificate? Aren't 
>> they validated by some recipient, e.g., a verification service? (A 
>> similar statement appears in Section 7: "[...] some combinations can 
>> prevent any PASSporT from being successfully validated by the 
>> certificate.")
> 
> Addressing comments below changed this part of Section 3.  More on Section 7 
> below.
> 
>> "Certificate issuers
>>  permit all claims by omitting the Enhanced JWT Claim Constraints
>>  certificate extension from the extension field of the certificate
>>  [RFC5280].  The certificate extension is non-critical, applicable
>>  only to end-entity certificates, and defined with ASN.1 [X.680].  The
>>  syntax of the JWT claims in a PASSporT is specified in [RFC8225]."
>> As this paragraph defines the scope of the extension, it seems 
>> misplaced under "Enhanced JWT Claim Constraints Syntax" as it's not 
>> describing the actual syntax. Maybe either some of this text should be 
>> moved to "Introduction", or a new section could be added, e.g., titled 
>> "Scope of Enhanced JWT Claim Constraints"?
> 
> As you can see above, I moved some of this to the end of the Introduction.  
> This part remains:
> 
>   The Enhanced JWT Claim Constraints certificate extension is non-
>   critical, applicable only to end-entity certificates, and defined
>   with ASN.1 [X.680].  The syntax of the JWT claims in a PASSporT is
>   specified in [RFC8225].
> 
>> The section then goes on to describe constraints. What is the 
>> difference between the described constrains and RFC 8226, i.e., what is 
>> added by this doc?
> 
> I think that is now answered by the last paragraph of the Introduction.
> 
>> Section 7: Security considerations
>> 
>> "Certificate issuers should not include an entry in mustExclude for
>>  the "rcdi" claim for a certificate that will be used with the
>>  PASSporT Extension for Rich Call Data defined in
>>  [I-D.ietf-stir-passport-rcd].  Excluding this claim would prevent the
>>  integrity protection mechanism from working properly."
>> Is this supposed to be a normative SHOULD? If it is, perhaps it should 
>> be moved up to, e.g., Section 3.
> 
> I do not think so.  I have been coordinating with the authors of 
> draft-ietf-stir-passport-rcd, and both documents will warn implementers about 
> the situation.
> 
>> Several paragraphs here describe scenarios that prevent successful 
>> validation of any PASSporT. What is the specific security risk here, 
>> e.g., Denial of Service? Any other consequences? Could there be a 
>> possibility for, e.g., a malicious actor introducing constraints that 
>> prevent successful validation? Are any (other) attacks possible on 
>> this technology (e.g., malicious deletion of constraints, replay attacks), 
>> and what countermeasures exist?
> 
> If the malicious actors can sign certificates, then these constraints will be 
> the least of the worries.  I think that is covered by the pointer to RFC 5280.
> 
>> Nits/editorial comments:
>> 
>> Section 3: Enhanced JWT Claim Constraints Syntax
>> 
>> OLD: "[...] the claim values that can successfully validated by the 
>> certificate [...]" NEW: "[...] the claim values that can be successfully 
>> validated by the certificate [...]" (And/or rephrase sentence, see 
>> comment above)
> 
> Addressing above comments changed this part of Section 3.
> 
>> Section 4: Usage Examples
>> 
>> OLD: "If a CA issues to an authentication service certificate that
>>         includes an Enhanced JWT Claim Constraints certificate extension 
>> [...]"
>> Is this either:
>> NEW: "If a CA issues to an authentication service a certificate that
>>         includes an Enhanced JWT Claim Constraints certificate extension 
>> [...]"
>> Or is it:
>> NEW: "If a CA issues an authentication service certificate that
>>         includes an Enhanced JWT Claim Constraints certificate extension 
>> [...]"
>> (This sentence is very long and not easy to parse in general, maybe it 
>> can be rephrased or split?)
> 
> It is "If a CA issues a certificate to an authentication service ,,,"
> 
> I got rid of the semicolon, and made two sentences.
> 
>> Section 7: Security Considerations
>> 
>> This paragraph appears twice, unless I'm missing a subtle difference:
>> "   Certificate issuers must take care when imposing constraints on the
>>  PASSporT claims and the claim values that can successfully validated;
>>  some combinations can prevent any PASSporT from being successfully
>>  validated by the certificate.  For example, an entry in mustInclude
>>  and an entry in mustExclude for the same claim will prevent
>>  successful validation on any PASSporT."
> 
> Good catch.  I deleted one of them.
> 
> Russ
> 
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