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Versions: 00 draft-ietf-stir-enhance-rfc8226

Network Working Group                                         R. Housley
Internet-Draft                                            Vigil Security
Updates: 8226 (if approved)                              21 January 2021
Intended status: Standards Track
Expires: 25 July 2021


          Enhanced JWT Claim Constraints for STIR Certificates
                 draft-housley-stir-enhance-rfc8226-00

Abstract

   RFC 8226 provides a certificate extension to constrain the JWT claims
   that can be included in the PASSporT as defined in RFC 8225.  If the
   signer includes a JWT claim outside the constraint boundaries, then
   the recipient will reject the entire PASSporT.  This document defines
   additional ways that the JWT claims can be constrained.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 25 July 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   provided without warranty as described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Enhanced JWT Claim Constraints Syntax . . . . . . . . . . . .   2
   4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  ASN.1 Module . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The use of certificates [RFC5280] in establishing authority over
   telephone numbers is described in [RFC8226].

   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.

   This document defines an enhanced JWTClaimConstraints certificate
   extension, which provides all of the capabilities available in the
   original certificate extension as well as some additional ways to
   constrain the allowable JWT claims.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Enhanced JWT Claim Constraints Syntax

   Certificate subjects are limited to specific values for PASSporT
   claims with the Enhanced JWT Claim Constraints certificate extension;
   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].



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   The Enhanced JWT Claim Constraints certificate extension is optional,
   but when present, it constrains the JWT claims that authentication
   services may include in the PASSporT objects they sign.  Constraints
   are applied by certificate issuers and enforced by recipients when
   validating PASSporT claims as follows:

   1.  mustInclude indicates JWT claims that MUST appear in the PASSporT
       in addition to the iat, orig, and dest claims.  The baseline
       PASSporT claims ("iat", "orig", and "dest") are considered to be
       permitted by default, and these claims SHOULD NOT be part of the
       mustInclude list.  If mustInclude is absent, the iat, orig, and
       dest claims MUST appear in the PASSporT.

   2.  permittedValues indicates that if the claim name is present, the
       claim MUST contain one of the listed values.

   3.  mustExclude indicates JWT claims that MUST NOT appear in the
       PASSporT. in addition to the iat, orig, and dest claims.  The
       baseline PASSporT claims ("iat", "orig", and "dest") are
       considered to be permitted by default, and these claims MUST NOT
       be part of the mustExclude list.

   4.  excludedValues indicates that if the claim name is present, the
       claim MUST NOT contain any of the listed values.

   The Enhanced JWT Claim Constraints certificate extension is
   identified by the following object identifier (OID):

      id-pe-eJWTClaimConstraints OBJECT IDENTIFIER ::= { id-pe TBD1 }

   The Enhanced JWT Claim Constraints certificate extension has the
   following syntax:

       EnhancedJWTClaimConstraints ::= SEQUENCE {
         mustInclude [0] JWTClaimNames OPTIONAL,
           -- The listed claim names MUST appear in the PASSporT
           -- in addition to iat, orig, and dest.  If absent, iat, orig,
           -- and dest MUST appear in the PASSporT.
         permittedValues [1] JWTClaimValuesList OPTIONAL,
           -- If the claim name is present, the claim MUST contain one
           -- of the listed values.
         mustExclude [2] JWTClaimNames OPTIONAL,
           -- The listed claim names MUST NOT appear in the PASSporT.
         excludedValues [3] JWTClaimValuesList OPTIONAL }
           -- If the claim name is present, the claim MUST NOT contain
           -- any of the listed values.





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       ( WITH COMPONENTS { ..., mustInclude PRESENT } |
         WITH COMPONENTS { ..., permittedValues PRESENT } |
         WITH COMPONENTS { ..., mustExclude PRESENT } |
         WITH COMPONENTS { ..., excludedValues PRESENT } )

       JWTClaimValuesList ::= SEQUENCE SIZE (1..MAX) OF JWTClaimValues

       JWTClaimValues ::= SEQUENCE {
         claim JWTClaimName,
         values SEQUENCE SIZE (1..MAX) OF UTF8String }

       JWTClaimNames ::= SEQUENCE SIZE (1..MAX) OF JWTClaimName

       JWTClaimName ::= IA5String

4.  Examples

   Consider two examples with a PASSporT claim called "confidence" with
   values "low", "medium", and "high":

   *  If a CA issues to an authentication service certificate that
      includes an Enhanced JWT Claim Constraints certificate extension
      that contains the mustInclude JWTClaimName "confidence", then an
      authentication service is required to include the "confidence"
      claim in all PASSporTs it generates and signs; a verification
      service will treat as invalid any PASSporT it receives with a
      PASSporT claim that does not include the "confidence" claim.

   *  If a CA issues to an authentication service certificate that
      includes an Enhanced JWT Claim Constraints certificate extension
      that contains the permittedValues JWTClaimName "confidence" and a
      permitted "high" value, then a recipient authentication service
      will treat as invalid any PASSporT it receives with a PASSporT
      "confidence" claim with a value other than "high".  However, a
      recipient authentication service will not treat as invalid a
      PASSporT it receives without a PASSporT "confidence" claim at all.

   *  If a CA issues to an authentication service certificate that
      includes an Enhanced JWT Claim Constraints certificate extension
      that contains the mustExclude JWTClaimName "confidence", then a
      recipient authentication service will treat as invalid any
      PASSporT it receives with a PASSporT "confidence" claim regardless
      of the claim value.

   *  If a CA issues to an authentication service certificate that
      includes an Enhanced JWT Claim Constraints certificate extension
      that contains the excludedValues JWTClaimName "confidence" and a
      permitted "low" value, then a recipient authentication service



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      will treat as invalid any PASSporT it receives with a PASSporT
      "confidence" claim with a value of "low".  However, a recipient
      authentication service will not treat as invalid a PASSporT it
      receives without a PASSporT "confidence" claim at all.

5.  IANA Considerations

   This document makes use of object identifiers for the Enhanced JWT
   Claim Constraints certificate extension defined in Section 3 and the
   ASN.1 module identifier defined in Appendix A.  Therefore, IANA is
   asked to made the following assignments within the SMI Numbers
   Registry.

   For the Enhanced JWT Claim Constraints certificate extension in the
   "SMI Security for PKIX Certificate Extension" (1.3.6.1.5.5.7.1)
   registry:

         TBD1  id-pe-eJWTClaimConstraints

   For the ASN.1 module identifier in the "SMI Security for PKIX Module
   Identifier" (1.3.6.1.5.5.7.0) registry:

         TBD2  id-mod-eJWTClaimConstraints-2021

6.  Security Considerations

   For further information on certificate security and practices, see
   [RFC5280], especially the Security Considerations section.

   The Enhanced JWT Claim Constraints certificate extension can be used
   by certificate issuers to provide limits on the acceptable PASSporT
   that will be accepted by recipient verification services.
   Enforcement of these limits depends upon proper implementation by the
   recipient verification services.  The digital signature on the
   PASSportT data structure will be valid even if the limits are
   violated.

7.  Acknowledgements

   Many thanks to Chris Wendt for his insight into the need for the for
   the Enhanced JWT Claim Constraints certificate extension.

8.  References

8.1.  Normative References






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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8225]  Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
              Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
              <https://www.rfc-editor.org/info/rfc8225>.

   [RFC8226]  Peterson, J. and S. Turner, "Secure Telephone Identity
              Credentials: Certificates", RFC 8226,
              DOI 10.17487/RFC8226, February 2018,
              <https://www.rfc-editor.org/info/rfc8226>.

   [X.680]    International Telecommunication Union, "Information
              Technology - Abstract Syntax Notation One (ASN.1):
              Specification of basic notation", ISO/IEC 8824-1, August
              2021.

8.2.  Informative References

   [RFC5912]  Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
              Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
              DOI 10.17487/RFC5912, June 2010,
              <https://www.rfc-editor.org/info/rfc5912>.

Appendix A.  ASN.1 Module

   This appendix provides the ASN.1 [X.680] definitions for the Enhanced
   JWT Claim Constraints certificate extension.  The module defined in
   this appendix are compatible with the ASN.1 specifications published
   in 2015.

   This ASN.1 module imports ASN.1 from [RFC5912].







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   <CODE BEGINS>
   EnhancedJWTClaimConstraints-2021
     { iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) pkix(7) id-mod(0)
       id-mod-eJWTClaimConstraints-2021(TBD2) }

   DEFINITIONS EXPLICIT TAGS ::= BEGIN

   IMPORTS

   id-pe
   FROM PKIX1Explicit-2009  -- From RFC 5912
     { iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) pkix(7) id-mod(0)
       id-mod-pkix1-explicit-02(51) }

   EXTENSION
   FROM PKIX-CommonTypes-2009  -- From RFC 5912
     { iso(1) identified-organization(3) dod(6) internet(1)
       security(5) mechanisms(5) pkix(7) id-mod(0)
       id-mod-pkixCommon-02(57) } ;

   -- Enhanced JWT Claim Constraints Certificate Extension

   ext-eJWTClaimConstraints EXTENSION ::= {
     SYNTAX EnhancedJWTClaimConstraints
     IDENTIFIED BY id-pe-JWTClaimConstraints }

   id-pe-eJWTClaimConstraints OBJECT IDENTIFIER ::= { id-pe TBD1 }

   EnhancedJWTClaimConstraints ::= SEQUENCE {
     mustInclude [0] JWTClaimNames OPTIONAL,
       -- The listed claim names MUST appear in the PASSporT
       -- in addition to iat, orig, and dest.  If absent, iat, orig,
       -- and dest MUST appear in the PASSporT.
     permittedValues [1] JWTClaimValuesList OPTIONAL,
       -- If the claim name is present, the claim MUST contain one
       -- of the listed values.
     mustExclude [2] JWTClaimNames OPTIONAL,
       -- The listed claim names MUST NOT appear in the PASSporT.
     excludedValues [3] JWTClaimValuesList OPTIONAL }
       -- If the claim name is present, the claim MUST NOT contain
       -- any of the listed values.
   ( WITH COMPONENTS { ..., mustInclude PRESENT } |
     WITH COMPONENTS { ..., permittedValues PRESENT } |
     WITH COMPONENTS { ..., mustExclude PRESENT } |
     WITH COMPONENTS { ..., excludedValues PRESENT } )




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   JWTClaimValuesList ::= SEQUENCE SIZE (1..MAX) OF JWTClaimValues

   JWTClaimValues ::= SEQUENCE {
     claim JWTClaimName,
     values SEQUENCE SIZE (1..MAX) OF UTF8String }

   JWTClaimNames ::= SEQUENCE SIZE (1..MAX) OF JWTClaimName

   JWTClaimName ::= IA5String

   END
   <CODE ENDS>

Author's Address

   Russ Housley
   Vigil Security, LLC
   516 Dranesville Road
   Herndon, VA,  20170
   United States of America

   Email: housley@vigilsec.com





























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