[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-jones-json-web-key) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                        November 6, 2012
Expires: May 10, 2013


                           JSON Web Key (JWK)
                    draft-ietf-jose-json-web-key-07

Abstract

   A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) data
   structure that represents a public key.  This specification also
   defines a JSON Web Key Set (JWK Set) JSON data structure for
   representing a set of JWKs.  Cryptographic algorithms and identifiers
   for use with this specification are described in the separate JSON
   Web Algorithms (JWA) specification.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 10, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



Jones                     Expires May 10, 2013                  [Page 1]

Internet-Draft                     JWK                     November 2012


   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Example JSON Web Key Set . . . . . . . . . . . . . . . . . . .  4
   4.  JSON Web Key (JWK) Format  . . . . . . . . . . . . . . . . . .  4
     4.1.  "alg" (Algorithm Family) Parameter . . . . . . . . . . . .  5
     4.2.  "use" (Key Use) Parameter  . . . . . . . . . . . . . . . .  5
     4.3.  "kid" (Key ID) Parameter . . . . . . . . . . . . . . . . .  5
   5.  JSON Web Key Set (JWK Set) Format  . . . . . . . . . . . . . .  6
     5.1.  "keys" (JSON Web Key Set) Parameter  . . . . . . . . . . .  6
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
     6.1.  JSON Web Key Parameters Registry . . . . . . . . . . . . .  7
       6.1.1.  Registration Template  . . . . . . . . . . . . . . . .  7
       6.1.2.  Initial Registry Contents  . . . . . . . . . . . . . .  8
     6.2.  JSON Web Key Set Parameters Registry . . . . . . . . . . .  8
       6.2.1.  Registration Template  . . . . . . . . . . . . . . . .  8
       6.2.2.  Initial Registry Contents  . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     8.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 10
   Appendix B.  Open Issues . . . . . . . . . . . . . . . . . . . . . 10
   Appendix C.  Document History  . . . . . . . . . . . . . . . . . . 10
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12





















Jones                     Expires May 10, 2013                  [Page 2]

Internet-Draft                     JWK                     November 2012


1.  Introduction

   A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) [RFC4627]
   data structure that represents a public key.  This specification also
   defines a JSON Web Key Set (JWK Set) JSON data structure for
   representing a set of JWKs.  Cryptographic algorithms and identifiers
   for use with this specification are described in the separate JSON
   Web Algorithms (JWA) [JWA] specification.

   Goals for this specification do not include representing private
   keys, representing symmetric keys, representing certificate chains,
   representing certified keys, and replacing X.509 certificates.

   JWKs and JWK Sets are used in the JSON Web Signature (JWS) [JWS] and
   JSON Web Encryption (JWE) [JWE] specifications.

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in Key words for use in
   RFCs to Indicate Requirement Levels [RFC2119].


2.  Terminology

   JSON Web Key (JWK)  A JSON data structure that represents a public
      key.

   JSON Web Key Set (JWK Set)  A JSON object that contains an array of
      JWKs as a member.

   Base64url Encoding  The URL- and filename-safe Base64 encoding
      described in RFC 4648 [RFC4648], Section 5, with the (non URL-
      safe) '=' padding characters omitted, as permitted by Section 3.2.
      (See Appendix C of [JWS] for notes on implementing base64url
      encoding without padding.)

   Collision Resistant Namespace  A namespace that allows names to be
      allocated in a manner such that they are highly unlikely to
      collide with other names.  For instance, collision resistance can
      be achieved through administrative delegation of portions of the
      namespace or through use of collision-resistant name allocation
      functions.  Examples of Collision Resistant Namespaces include:
      Domain Names, Object Identifiers (OIDs) as defined in the ITU-T
      X.660 and X.670 Recommendation series, and Universally Unique
      IDentifiers (UUIDs) [RFC4122].  When using an administratively
      delegated namespace, the definer of a name needs to take



Jones                     Expires May 10, 2013                  [Page 3]

Internet-Draft                     JWK                     November 2012


      reasonable precautions to ensure they are in control of the
      portion of the namespace they use to define the name.


3.  Example JSON Web Key Set

   The following example JWK Set contains two public keys represented as
   JWKs: one using an Elliptic Curve algorithm and a second one using an
   RSA algorithm.  The first specifies that the key is to be used for
   encryption.  Both provide a Key ID for key matching purposes.  In
   both cases, integers are represented using the base64url encoding of
   their big endian representations.  (Long lines are broken are for
   display purposes only.)

     {"keys":
       [
         {"alg":"EC",
          "crv":"P-256",
          "x":"MKBCTNIcKUSDii11ySs3526iDZ8AiTo7Tu6KPAqv7D4",
          "y":"4Etl6SRW2YiLUrN5vfvVHuhp7x8PxltmWWlbbM4IFyM",
          "use":"enc",
          "kid":"1"},

         {"alg":"RSA",
          "n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx
     4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMs
     tn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2
     QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbI
     SD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqb
     w0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
          "e":"AQAB",
          "kid":"2011-04-29"}
       ]
     }


4.  JSON Web Key (JWK) Format

   A JSON Web Key (JWK) is a JSON object containing specific members, as
   specified below.  Those members that are common to all key types are
   defined below.

   In addition to the common parameters, each JWK will have members that
   are specific to the key being represented.  These members represent
   the parameters of the key.  Section 5 of the JSON Web Algorithms
   (JWA) [JWA] specification defines multiple kinds of public keys and
   their associated members.




Jones                     Expires May 10, 2013                  [Page 4]

Internet-Draft                     JWK                     November 2012


   The member names within a JWK MUST be unique; objects with duplicate
   member names MUST be rejected.

   Additional members MAY be present in the JWK.  If present, they MUST
   be understood by implementations using them.  Member names used for
   representing key parameters for different kinds of keys need not be
   distinct.  Member names SHOULD either be registered in the IANA JSON
   Web Key Parameters registry Section 6.1 or be URIs that contain a
   Collision Resistant Namespace.

4.1.  "alg" (Algorithm Family) Parameter

   The "alg" (algorithm family) member identifies the cryptographic
   algorithm family used with the key. "alg" values SHOULD either be
   registered in the IANA JSON Web Key Algorithm Families registry [JWA]
   or be a URI that contains a Collision Resistant Namespace.  The "alg"
   value is a case sensitive string.  This member is REQUIRED.

   A list of defined "alg" values can be found in the IANA JSON Web Key
   Algorithm Families registry [JWA]; the initial contents of this
   registry are the values defined in Section 5.1 of the JSON Web
   Algorithms (JWA) [JWA] specification.

   Additional members used with these "alg" values can be found in the
   IANA JSON Web Key Parameters registry Section 6.1; the initial
   contents of this registry are the values defined in Sections 5.2 and
   5.3 of the JSON Web Algorithms (JWA) [JWA] specification.

4.2.  "use" (Key Use) Parameter

   The "use" (key use) member identifies the intended use of the key.
   Values defined by this specification are:

   o  "sig" (signature)

   o  "enc" (encryption)

   Other values MAY be used.  The "use" value is a case sensitive
   string.  This member is OPTIONAL.

4.3.  "kid" (Key ID) Parameter

   The "kid" (key ID) member can be used to match a specific key.  This
   can be used, for instance, to choose among a set of keys within a JWK
   Set during key rollover.  The interpretation of the "kid" value is
   unspecified.  Key ID values within a JWK Set need not be unique.  The
   "kid" value is a case sensitive string.  This member is OPTIONAL.




Jones                     Expires May 10, 2013                  [Page 5]

Internet-Draft                     JWK                     November 2012


   When used with JWS or JWE, the "kid" value MAY be used to match a JWS
   or JWE "kid" header parameter value.

   In some contexts, different keys using the same Key ID value might be
   present, with the keys being disambiguated using other information,
   such as the "alg" or "use" values.  For example, imagine "kid" values
   like "Current", "Upcoming", and "Deprecated", used for key rollover
   guidance.  One could apply a label to all keys where the
   classification fits.  If there are multiple "Current" keys, then in
   this example, they might be differentiated either by having different
   "alg" or "use" values, or some combination of both.  As one example,
   there might only be one current RSA signing key and one current
   Elliptic Curve signing key, but both would be "Current".


5.  JSON Web Key Set (JWK Set) Format

   A JSON Web Key Set (JWK Set) is a JSON object that contains an array
   of JSON Web Key values as the value of its "keys" member.

   The member names within a JWK Set MUST be unique; objects with
   duplicate member names MUST be rejected.

   Additional members MAY be present in the JWK Set. If present, they
   MUST be understood by implementations using them.  Parameters for
   representing additional properties of JWK Sets SHOULD either be
   registered in the IANA JSON Web Key Set Parameters registry
   Section 6.2 or be a URI that contains a Collision Resistant
   Namespace.

5.1.  "keys" (JSON Web Key Set) Parameter

   The value of the "keys" (JSON Web Key Set) member is an array of JSON
   Web Key (JWK) values.  This member is REQUIRED.


6.  IANA Considerations

   The following registration procedure is used for all the registries
   established by this specification.

   Values are registered with a Specification Required [RFC5226] after a
   two-week review period on the [TBD]@ietf.org mailing list, on the
   advice of one or more Designated Experts.  However, to allow for the
   allocation of values prior to publication, the Designated Expert(s)
   may approve registration once they are satisfied that such a
   specification will be published.




Jones                     Expires May 10, 2013                  [Page 6]

Internet-Draft                     JWK                     November 2012


   Registration requests must be sent to the [TBD]@ietf.org mailing list
   for review and comment, with an appropriate subject (e.g., "Request
   for access token type: example"). [[ Note to RFC-EDITOR: The name of
   the mailing list should be determined in consultation with the IESG
   and IANA.  Suggested name: jose-reg-review. ]]

   Within the review period, the Designated Expert(s) will either
   approve or deny the registration request, communicating this decision
   to the review list and IANA.  Denials should include an explanation
   and, if applicable, suggestions as to how to make the request
   successful.

   IANA must only accept registry updates from the Designated Expert(s)
   and should direct all requests for registration to the review mailing
   list.

6.1.  JSON Web Key Parameters Registry

   This specification establishes the IANA JSON Web Key Parameters
   registry for reserved JWK parameter names.  The registry records the
   reserved parameter name and a reference to the specification that
   defines it.  This specification registers the parameter names defined
   in Section 4.  The same JWK parameter name may be registered multiple
   times, provided that duplicate parameter registrations are only for
   algorithm-specific JWK parameters; in this case, the meaning of the
   duplicate parameter name is disambiguated by the "alg" value of the
   JWK containing it.

6.1.1.  Registration Template

   Parameter Name:
      The name requested (e.g., "example").  This name is case
      sensitive.  Names that match other registered names in a case
      insensitive manner SHOULD NOT be accepted.

   Change Controller:
      For Standards Track RFCs, state "IETF".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   Specification Document(s):
      Reference to the document(s) that specify the parameter,
      preferably including URI(s) that can be used to retrieve copies of
      the document(s).  An indication of the relevant sections may also
      be included but is not required.






Jones                     Expires May 10, 2013                  [Page 7]

Internet-Draft                     JWK                     November 2012


6.1.2.  Initial Registry Contents

   o  Parameter Name: "alg"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1 of [[ this document ]]

   o  Parameter Name: "use"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.2 of [[ this document ]]

   o  Parameter Name: "kid"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.3 of [[ this document ]]

6.2.  JSON Web Key Set Parameters Registry

   This specification establishes the IANA JSON Web Key Set Parameters
   registry for reserved JWK Set parameter names.  The registry records
   the reserved parameter name and a reference to the specification that
   defines it.  This specification registers the parameter names defined
   in Section 5.

6.2.1.  Registration Template

   Parameter Name:
      The name requested (e.g., "example").  This name is case
      sensitive.  Names that match other registered names in a case
      insensitive manner SHOULD NOT be accepted.

   Change Controller:
      For Standards Track RFCs, state "IETF".  For others, give the name
      of the responsible party.  Other details (e.g., postal address,
      email address, home page URI) may also be included.

   Specification Document(s):
      Reference to the document(s) that specify the parameter,
      preferably including URI(s) that can be used to retrieve copies of
      the document(s).  An indication of the relevant sections may also
      be included but is not required.

6.2.2.  Initial Registry Contents

   o  Parameter Name: "keys"
   o  Change Controller: IETF
   o  Specification Document(s): Section 5.1 of [[ this document ]]






Jones                     Expires May 10, 2013                  [Page 8]

Internet-Draft                     JWK                     November 2012


7.  Security Considerations

   All of the security issues faced by any cryptographic application
   must be faced by a JWS/JWE/JWK agent.  Among these issues are
   protecting the user's private key, preventing various attacks, and
   helping the user avoid mistakes such as inadvertently encrypting a
   message for the wrong recipient.  The entire list of security
   considerations is beyond the scope of this document, but some
   significant concerns are listed here.

   A key is no more trustworthy than the method by which it was
   received.

   Per Section 4.3, applications should not assume that "kid" values are
   unique within a JWK Set.

   The security considerations in XML DSIG 2.0
   [W3C.CR-xmldsig-core2-20120124], about public key representations
   also apply to this specification, other than those that are XML
   specific.


8.  References

8.1.  Normative References

   [JWA]      Jones, M., "JSON Web Algorithms (JWA)", November 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, October 2006.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [W3C.CR-xmldsig-core2-20120124]
              Reagle, J., Solo, D., Datta, P., Hirsch, F., Eastlake, D.,
              Cantor, S., Roessler, T., and K. Yiu, "XML Signature
              Syntax and Processing Version 2.0", World Wide Web
              Consortium CR CR-xmldsig-core2-20120124, January 2012,
              <http://www.w3.org/TR/2012/CR-xmldsig-core2-20120124>.




Jones                     Expires May 10, 2013                  [Page 9]

Internet-Draft                     JWK                     November 2012


8.2.  Informative References

   [JWE]      Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
              Encryption (JWE)", November 2012.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", November 2012.

   [MagicSignatures]
              Panzer (editor), J., Laurie, B., and D. Balfanz, "Magic
              Signatures", January 2011.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              July 2005.


Appendix A.  Acknowledgements

   A JSON representation for RSA public keys was previously introduced
   by John Panzer, Ben Laurie, and Dirk Balfanz in Magic Signatures
   [MagicSignatures].

   Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
   Sean Turner and Stephen Farrell served as Security area directors
   during the creation of this specification.


Appendix B.  Open Issues

   [[ to be removed by the RFC editor before publication as an RFC ]]

   The following items remain to be considered or done in this draft:

   o  No known open issues.


Appendix C.  Document History

   [[ to be removed by the RFC editor before publication as an RFC ]]

   -07

   o  Changed the name of the JWK RSA modulus parameter from "mod" to
      "n" and the name of the JWK RSA exponent parameter from "xpo" to
      "e", so that the identifiers are the same as those used in RFC
      3447.




Jones                     Expires May 10, 2013                 [Page 10]

Internet-Draft                     JWK                     November 2012


   -06

   o  Changed the name of the JWK RSA exponent parameter from "exp" to
      "xpo" so as to allow the potential use of the name "exp" for a
      future extension that might define an expiration parameter for
      keys.  (The "exp" name is already used for this purpose in the JWT
      specification.)

   o  Clarify that the "alg" (algorithm family) member is REQUIRED.

   o  Correct an instance of "JWK" that should have been "JWK Set".

   o  Applied changes made by the RFC Editor to RFC 6749's registry
      language to this specification.

   -05

   o  Indented artwork elements to better distinguish them from the body
      text.

   -04

   o  Refer to the registries as the primary sources of defined values
      and then secondarily reference the sections defining the initial
      contents of the registries.

   o  Normatively reference XML DSIG 2.0 [W3C.CR-xmldsig-core2-20120124]
      for its security considerations.

   o  Added this language to Registration Templates: "This name is case
      sensitive.  Names that match other registered names in a case
      insensitive manner SHOULD NOT be accepted."

   o  Described additional open issues.

   o  Applied editorial suggestions.

   -03

   o  Clarified that "kid" values need not be unique within a JWK Set.

   o  Moved JSON Web Key Parameters registry to the JWK specification.

   o  Added "Collision Resistant Namespace" to the terminology section.

   o  Changed registration requirements from RFC Required to
      Specification Required with Expert Review.




Jones                     Expires May 10, 2013                 [Page 11]

Internet-Draft                     JWK                     November 2012


   o  Added Registration Template sections for defined registries.

   o  Added Registry Contents sections to populate registry values.

   o  Numerous editorial improvements.

   -02

   o  Simplified JWK terminology to get replace the "JWK Key Object" and
      "JWK Container Object" terms with simply "JSON Web Key (JWK)" and
      "JSON Web Key Set (JWK Set)" and to eliminate potential confusion
      between single keys and sets of keys.  As part of this change, the
      top-level member name for a set of keys was changed from "jwk" to
      "keys".

   o  Clarified that values with duplicate member names MUST be
      rejected.

   o  Established JSON Web Key Set Parameters registry.

   o  Explicitly listed non-goals in the introduction.

   o  Moved algorithm-specific definitions from JWK to JWA.

   o  Reformatted to give each member definition its own section
      heading.

   -01

   o  Corrected the Magic Signatures reference.

   -00

   o  Created the initial IETF draft based upon
      draft-jones-json-web-key-03 with no normative changes.


Author's Address

   Michael B. Jones
   Microsoft

   Email: mbj@microsoft.com
   URI:   http://self-issued.info/







Jones                     Expires May 10, 2013                 [Page 12]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/