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OAuth Working Group                                             M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                              J. Bradley
Expires: June 30, 2013                                     Ping Identity
                                                             N. Sakimura
                                                                     NRI
                                                       December 27, 2012


                          JSON Web Token (JWT)
                   draft-ietf-oauth-json-web-token-06

Abstract

   JSON Web Token (JWT) is a compact URL-safe means of representing
   claims to be transferred between two parties.  The claims in a JWT
   are encoded as a JavaScript Object Notation (JSON) object that is
   used as the payload of a JSON Web Signature (JWS) structure or as the
   plaintext of a JSON Web Encryption (JWE) structure, enabling the
   claims to be digitally signed or MACed and/or encrypted.

   The suggested pronunciation of JWT is the same as the English word
   "jot".

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 June 30, 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



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   (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
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  JSON Web Token (JWT) Overview  . . . . . . . . . . . . . . . .  6
     3.1.  Example JWT  . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  JWT Claims . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Reserved Claim Names . . . . . . . . . . . . . . . . . . .  7
       4.1.1.  "iss" (Issuer) Claim . . . . . . . . . . . . . . . . .  8
       4.1.2.  "sub" (Subject) Claim  . . . . . . . . . . . . . . . .  8
       4.1.3.  "aud" (Audience) Claim . . . . . . . . . . . . . . . .  8
       4.1.4.  "exp" (Expiration Time) Claim  . . . . . . . . . . . .  8
       4.1.5.  "nbf" (Not Before) Claim . . . . . . . . . . . . . . .  8
       4.1.6.  "iat" (Issued At) Claim  . . . . . . . . . . . . . . .  9
       4.1.7.  "jti" (JWT ID) Claim . . . . . . . . . . . . . . . . .  9
       4.1.8.  "typ" (Type) Claim . . . . . . . . . . . . . . . . . .  9
     4.2.  Public Claim Names . . . . . . . . . . . . . . . . . . . .  9
     4.3.  Private Claim Names  . . . . . . . . . . . . . . . . . . .  9
   5.  JWT Header . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     5.1.  "typ" (Type) Header Parameter  . . . . . . . . . . . . . . 10
     5.2.  "cty" (Content Type) Header Parameter  . . . . . . . . . . 10
   6.  Plaintext JWTs . . . . . . . . . . . . . . . . . . . . . . . . 10
     6.1.  Example Plaintext JWT  . . . . . . . . . . . . . . . . . . 11
   7.  Rules for Creating and Validating a JWT  . . . . . . . . . . . 11
     7.1.  String Comparison Rules  . . . . . . . . . . . . . . . . . 13
   8.  Cryptographic Algorithms . . . . . . . . . . . . . . . . . . . 14
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
     9.1.  JSON Web Token Claims Registry . . . . . . . . . . . . . . 14
       9.1.1.  Registration Template  . . . . . . . . . . . . . . . . 15
       9.1.2.  Initial Registry Contents  . . . . . . . . . . . . . . 15
     9.2.  Sub-Namespace Registration of
           urn:ietf:params:oauth:token-type:jwt . . . . . . . . . . . 16
       9.2.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 16
     9.3.  JSON Web Signature and Encryption Type Values
           Registration . . . . . . . . . . . . . . . . . . . . . . . 16
       9.3.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 16
     9.4.  Media Type Registration  . . . . . . . . . . . . . . . . . 16
       9.4.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 16



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   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 18
     11.2. Informative References . . . . . . . . . . . . . . . . . . 19
   Appendix A.  Example Encrypted JWT . . . . . . . . . . . . . . . . 19
   Appendix B.  Relationship of JWTs to SAML Assertions . . . . . . . 20
   Appendix C.  Relationship of JWTs to Simple Web Tokens (SWTs)  . . 21
   Appendix D.  Acknowledgements  . . . . . . . . . . . . . . . . . . 21
   Appendix E.  Open Issues . . . . . . . . . . . . . . . . . . . . . 22
   Appendix F.  Document History  . . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24








































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1.  Introduction

   JSON Web Token (JWT) is a compact claims representation format
   intended for space constrained environments such as HTTP
   Authorization headers and URI query parameters.  JWTs encode claims
   to be transmitted as a JavaScript Object Notation (JSON) [RFC4627]
   object that is used as the payload of a JSON Web Signature (JWS)
   [JWS] structure or as the plaintext of a JSON Web Encryption (JWE)
   [JWE] structure, enabling the claims to be digitally signed or MACed
   and/or encrypted.

   The suggested pronunciation of JWT is the same as the English word
   "jot".

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 Token (JWT)  A string representing a set of claims as a JSON
      object that is encoded in a JWS or JWE, enabling the claims to be
      digitally signed or MACed and/or encrypted.

   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.)

   JSON Text Object  A UTF-8 encoded text string representing a JSON
      object; the syntax of JSON objects is defined in Section 2.2 of
      [RFC4627].

   JWT Header  A JSON Text Object that describes the cryptographic
      operations applied to the JWT.  When the JWT is digitally signed
      or MACed, the JWT Header is a JWS Header.  When the JWT is
      encrypted, the JWT Header is a JWE Header.

   Header Parameter Name  The name of a member of the JWT Header.







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   Header Parameter Value  The value of a member of the JWT Header.

   JWT Claims Set  A JSON Text Object that contains the Claims conveyed
      by the JWT, where each claim is represented as a name/value pair
      of a Claim Name and a Claim Value.

   Claim  A piece of information asserted about a subject.  Here, Claims
      are represented name/value pairs, consisting of a Claim Name and a
      Claim Value.

   Claim Name  The name portion of a Claim representation.  A Claim Name
      is always a string.

   Claim Value  The value portion of a Claim representation.  A Claim
      Value can be any JSON value.

   Encoded JWT Header  Base64url encoding of the JWT Header.

   Nested JWT  A JWT in which nested signing or encryption are employed.
      In nested JWTs, a JWT is used as the payload or plaintext value of
      an enclosing JWS or JWE structure, respectively.

   Plaintext JWT  A JWT whose Claims are not integrity protected or
      encrypted.

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

   StringOrURI  A JSON string value, with the additional requirement
      that while arbitrary string values MAY be used, any value
      containing a ":" character MUST be a URI [RFC3986].  StringOrURI
      values are compared as case-sensitive strings with no
      transformations or canonicalizations applied.

   IntDate  A JSON numeric value representing the number of seconds from
      1970-01-01T0:0:0Z UTC until the specified UTC date/time.  See RFC
      3339 [RFC3339] for details regarding date/times in general and UTC
      in particular.



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3.  JSON Web Token (JWT) Overview

   JWTs represent a set of claims as a JSON object that is encoded in a
   JWS and/or JWE structure.  This JSON object is the JWT Claims Set. As
   per RFC 4627 [RFC4627] Section 2.2, the JSON object consists of zero
   or more name/value pairs (or members), where the names are strings
   and the values are arbitrary JSON values.  These members are the
   claims represented by the JWT.

   The member names within the JWT Claims Set are referred to as Claim
   Names.  The corresponding values are referred to as Claim Values.

   The contents of the JWT Header describe the cryptographic operations
   applied to the JWT Claims Set. If the JWT Header is a JWS Header, the
   JWT is represented as a JWS, and the claims are digitally signed or
   MACed, with the JWT Claims Set being the JWS Payload.  If the JWT
   Header is a JWE Header, the JWT is represented as a JWE, and the
   claims are encrypted, with the JWT Claims Set being the input
   Plaintext.  A JWT may be enclosed in another JWE or JWS structure to
   create a Nested JWT, enabling nested signing and encryption to be
   performed.

   A JWT is represented as a sequence of URL-safe parts separated by
   period ('.') characters.  Each part contains a base64url encoded
   value.  The number of parts in the JWT is dependent upon the
   representation of the resulting JWS or JWE.

3.1.  Example JWT

   The following example JWT Header declares that the encoded object is
   a JSON Web Token (JWT) and the JWT is MACed using the HMAC SHA-256
   algorithm:

     {"typ":"JWT",
      "alg":"HS256"}

   Base64url encoding the bytes of the UTF-8 representation of the JWT
   Header yields this Encoded JWS Header value, which is used as the
   Encoded JWT Header:

     eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9

   The following is an example of a JWT Claims Set:

     {"iss":"joe",
      "exp":1300819380,
      "http://example.com/is_root":true}




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   Base64url encoding the bytes of the UTF-8 representation of the JSON
   Claims Set yields this Encoded JWS Payload (with line breaks for
   display purposes only):

     eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly
     9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ

   Signing the Encoded JWS Header and Encoded JWS Payload with the HMAC
   SHA-256 algorithm and base64url encoding the signature in the manner
   specified in [JWS], yields this Encoded JWS Signature:

     dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk

   Concatenating these parts in this order with period ('.') characters
   between the parts yields this complete JWT (with line breaks for
   display purposes only):

     eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
     .
     eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
     cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
     .
     dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk

   This computation is illustrated in more detail in Appendix A.1 of
   [JWS].  See Appendix A for an example of an encrypted JWT.


4.  JWT Claims

   The JWT Claims Set represents a JSON object whose members are the
   claims conveyed by the JWT.  The Claim Names within a JWT Claims Set
   MUST be unique; JWTs with duplicate Claim Names MUST be rejected.
   Note however, that the set of claims that a JWT must contain to be
   considered valid is context-dependent and is outside the scope of
   this specification.  When used in a security-related context,
   implementations MUST understand and support all of the claims
   present; otherwise, the JWT MUST be rejected for processing.

   There are three classes of JWT Claim Names: Reserved Claim Names,
   Public Claim Names, and Private Claim Names.

4.1.  Reserved Claim Names

   The following Claim Names are reserved.  None of the claims defined
   below are intended to be mandatory to use, but rather, provide a
   starting point for a set of useful, interoperable claims.  All the
   names are short because a core goal of JWTs is for the representation



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   to be compact.  Additional reserved Claim Names MAY be defined via
   the IANA JSON Web Token Claims registry Section 9.1.

4.1.1.  "iss" (Issuer) Claim

   The "iss" (issuer) claim identifies the principal that issued the
   JWT.  The processing of this claim is generally application specific.
   The "iss" value is a case sensitive string containing a StringOrURI
   value.  Use of this claim is OPTIONAL.

4.1.2.  "sub" (Subject) Claim

   The "sub" (subject) claim identifies the principal that is the
   subject of the JWT.  The Claims in a JWT are normally statements
   about the subject.  The processing of this claim is generally
   application specific.  The "sub" value is a case sensitive string
   containing a StringOrURI value.  Use of this claim is OPTIONAL.

4.1.3.  "aud" (Audience) Claim

   The "aud" (audience) claim identifies the audiences that the JWT is
   intended for.  Each principal intended to process the JWT MUST
   identify itself with a value in audience claim.  If the principal
   processing the claim does not identify itself with a value in the
   "aud" claim, then the JWT MUST be rejected.  In the general case, the
   "aud" value is an array of case sensitive strings, each containing a
   StringOrURI value.  In the special case when the JWT has one
   audience, the "aud" value MAY be a single case sensitive string
   containing a StringOrURI value.  The interpretation of audience
   values is generally application specific.  Use of this claim is
   OPTIONAL.

4.1.4.  "exp" (Expiration Time) Claim

   The "exp" (expiration time) claim identifies the expiration time on
   or after which the JWT MUST NOT be accepted for processing.  The
   processing of the "exp" claim requires that the current date/time
   MUST be before the expiration date/time listed in the "exp" claim.
   Implementers MAY provide for some small leeway, usually no more than
   a few minutes, to account for clock skew.  Its value MUST be a number
   containing an IntDate value.  Use of this claim is OPTIONAL.

4.1.5.  "nbf" (Not Before) Claim

   The "nbf" (not before) claim identifies the time before which the JWT
   MUST NOT be accepted for processing.  The processing of the "nbf"
   claim requires that the current date/time MUST be after or equal to
   the not-before date/time listed in the "nbf" claim.  Implementers MAY



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   provide for some small leeway, usually no more than a few minutes, to
   account for clock skew.  Its value MUST be a number containing an
   IntDate value.  Use of this claim is OPTIONAL.

4.1.6.  "iat" (Issued At) Claim

   The "iat" (issued at) claim identifies the time at which the JWT was
   issued.  This claim can be used to determine the age of the JWT.  Its
   value MUST be a number containing an IntDate value.  Use of this
   claim is OPTIONAL.

4.1.7.  "jti" (JWT ID) Claim

   The "jti" (JWT ID) claim provides a unique identifier for the JWT.
   The identifier value MUST be assigned in a manner that ensures that
   there is a negligible probability that the same value will be
   accidentally assigned to a different data object.  The "jti" claim
   can be used to prevent the JWT from being replayed.  The "jti" value
   is a case sensitive string.  Use of this claim is OPTIONAL.

4.1.8.  "typ" (Type) Claim

   The "typ" (type) claim is used to declare a type for the contents of
   this JWT Claims Set. The "typ" value is a case sensitive string.  Use
   of this claim is OPTIONAL.

   The values used for the "typ" claim come from the same value space as
   the "typ" header parameter, with the same rules applying.

4.2.  Public Claim Names

   Claim Names can be defined at will by those using JWTs.  However, in
   order to prevent collisions, any new Claim Name SHOULD either be
   registered in the IANA JSON Web Token Claims registry Section 9.1 or
   be a Public Name: a value that contains a Collision Resistant
   Namespace.  In each case, the definer of the name or value needs to
   take reasonable precautions to make sure they are in control of the
   part of the namespace they use to define the Claim Name.

4.3.  Private Claim Names

   A producer and consumer of a JWT may agree to use Claim Names that
   are Private Names: names that are not Reserved Names Section 4.1 or
   Public Names Section 4.2.  Unlike Public Names, Private Names are
   subject to collision and should be used with caution.






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5.  JWT Header

   The members of the JSON object represented by the JWT Header describe
   the cryptographic operations applied to the JWT and optionally,
   additional properties of the JWT.  The member names within the JWT
   Header are referred to as Header Parameter Names.  These names MUST
   be unique; JWTs with duplicate Header Parameter Names MUST be
   rejected.  The corresponding values are referred to as Header
   Parameter Values.

   Implementations MUST understand the entire contents of the header;
   otherwise, the JWT MUST be rejected for processing.

   JWS Header Parameters are defined by [JWS].  JWE Header Parameters
   are defined by [JWE].  This specification further specifies the use
   of the following header parameter in both the cases where the JWT is
   a JWS and where it is a JWE.

5.1.  "typ" (Type) Header Parameter

   The "typ" (type) header parameter is used to declare the type of this
   object.  If present, it is RECOMMENDED that its value be either "JWT"
   or "urn:ietf:params:oauth:token-type:jwt" to indicate that this
   object is a JWT.  The "typ" value is a case sensitive string.  Use of
   this header parameter is OPTIONAL.

5.2.  "cty" (Content Type) Header Parameter

   The "cty" (content type) header parameter is used to declare
   structural information about the JWT.  Its value MUST be a string.

   In the normal case where nested signing or encryption operations are
   not employed, the use of this header parameter is NOT RECOMMENDED.
   In the case that nested signing or encryption is employed, the use of
   this header parameter is REQUIRED; in this case, the value MUST be
   "JWT", to indicate that a Nested JWT is carried in this JWT.

   The values used for the "cty" header parameter come from the same
   value space as the "typ" header parameter, with the same rules
   applying.


6.  Plaintext JWTs

   To support use cases where the JWT content is secured by a means
   other than a signature and/or encryption contained within the JWT
   (such as a signature on a data structure containing the JWT), JWTs
   MAY also be created without a signature or encryption.  A plaintext



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   JWT is a JWS using the "none" JWS "alg" header parameter value
   defined in JSON Web Algorithms (JWA) [JWA]; it is a JWS with the
   empty string for its JWS Signature value.

6.1.  Example Plaintext JWT

   The following example JWT Header declares that the encoded object is
   a Plaintext JWT:

     {"alg":"none"}

   Base64url encoding the bytes of the UTF-8 representation of the JWT
   Header yields this Encoded JWT Header:

     eyJhbGciOiJub25lIn0

   The following is an example of a JWT Claims Set:

     {"iss":"joe",
      "exp":1300819380,
      "http://example.com/is_root":true}

   Base64url encoding the bytes of the UTF-8 representation of the JSON
   Claims Set yields this Encoded JWS Payload (with line breaks for
   display purposes only):

     eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
     cGxlLmNvbS9pc19yb290Ijp0cnVlfQ

   The Encoded JWS Signature is the empty string.

   Concatenating these parts in this order with period ('.') characters
   between the parts yields this complete JWT (with line breaks for
   display purposes only):

     eyJhbGciOiJub25lIn0
     .
     eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
     cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
     .


7.  Rules for Creating and Validating a JWT

   To create a JWT, one MUST perform these steps.  The order of the
   steps is not significant in cases where there are no dependencies
   between the inputs and outputs of the steps.




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   1.  Create a JWT Claims Set containing the desired claims.  Note that
       white space is explicitly allowed in the representation and no
       canonicalization is performed before encoding.

   2.  Let the Message be the bytes of the UTF-8 representation of the
       JWT Claims Set.

   3.  Create a JWT Header containing the desired set of header
       parameters.  The JWT MUST conform to either the [JWS] or [JWE]
       specifications.  Note that white space is explicitly allowed in
       the representation and no canonicalization is performed before
       encoding.

   4.  Base64url encode the bytes of the UTF-8 representation of the JWT
       Header.  Let this be the Encoded JWT Header.

   5.  Depending upon whether the JWT is a JWS or JWE, there are two
       cases:

       *  If the JWT is a JWS, create a JWS using the JWT Header as the
          JWS Header and the Message as the JWS Payload; all steps
          specified in [JWS] for creating a JWS MUST be followed.

       *  Else, if the JWT is a JWE, create a JWE using the JWT Header
          as the JWE Header and the Message as the JWE Plaintext; all
          steps specified in [JWE] for creating a JWE MUST be followed.

   6.  If a nested signing or encryption operation will be performed,
       let the Message be the JWS or JWE, and return to Step 3, using a
       "cty" (content type) value of "JWT" in the new JWT Header created
       in that step.

   7.  Otherwise, let the resulting JWT be the JWS or JWE.

   When validating a JWT the following steps MUST be taken.  The order
   of the steps is not significant in cases where there are no
   dependencies between the inputs and outputs of the steps.  If any of
   the listed steps fails then the JWT MUST be rejected for processing.

   1.   The JWT MUST contain at least one period ('.') character.

   2.   Let the Encoded JWT Header be the portion of the JWT before the
        first period ('.') character.

   3.   The Encoded JWT Header MUST be successfully base64url decoded
        following the restriction given in this specification that no
        padding characters have been used.




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   4.   The resulting JWT Header MUST be completely valid JSON syntax
        conforming to RFC 4627 [RFC4627].

   5.   The resulting JWT Header MUST be validated to only include
        parameters and values whose syntax and semantics are both
        understood and supported.

   6.   Determine whether the JWT is a JWS or a JWE by examining the
        "alg" (algorithm) header value and optionally, the "enc"
        (encryption method) header value, if present.

   7.   Depending upon whether the JWT is a JWS or JWE, there are two
        cases:

        *  If the JWT is a JWS, all steps specified in [JWS] for
           validating a JWS MUST be followed.  Let the Message be the
           result of base64url decoding the JWS Payload.

        *  Else, if the JWT is a JWE, all steps specified in [JWE] for
           validating a JWE MUST be followed.  Let the Message be the
           JWE Plaintext.

   8.   If the JWT Header contains a "cty" (content type) value of
        "JWT", then the Message contains a JWT that was the subject of
        nested signing or encryption operations.  In this case, return
        to Step 1, using the Message as the JWT.

   9.   Otherwise, let the JWT Claims Set be the Message.

   10.  The JWT Claims Set MUST be completely valid JSON syntax
        conforming to RFC 4627 [RFC4627].

   11.  When used in a security-related context, the JWT Claims Set MUST
        be validated to only include claims whose syntax and semantics
        are both understood and supported.

7.1.  String Comparison Rules

   Processing a JWT inevitably requires comparing known strings to
   values in JSON objects.  For example, in checking what the algorithm
   is, the Unicode string encoding "alg" will be checked against the
   member names in the JWT Header to see if there is a matching Header
   Parameter Name.

   Comparisons between JSON strings and other Unicode strings MUST be
   performed by comparing Unicode code points without normalization as
   specified in the String Comparison Rules in Section 5.3 of [JWS].




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8.  Cryptographic Algorithms

   JWTs use JSON Web Signature (JWS) [JWS] and JSON Web Encryption (JWE)
   [JWE] to sign and/or encrypt the contents of the JWT.

   Of the JWS signing algorithms, only HMAC SHA-256 and "none" MUST be
   implemented by conforming JWT implementations.  It is RECOMMENDED
   that implementations also support the RSA SHA-256 and ECDSA P-256
   SHA-256 algorithms.  Support for other algorithms and key sizes is
   OPTIONAL.

   If an implementation provides encryption capabilities, of the JWE
   encryption algorithms, only RSA-PKCS1-1.5 with 2048 bit keys, AES-
   128-KW, AES-256-KW, AES-128-CBC, and AES-256-CBC MUST be implemented
   by conforming implementations.  It is RECOMMENDED that
   implementations also support ECDH-ES with 256 bit keys, AES-128-GCM,
   and AES-256-GCM.  Support for other algorithms and key sizes is
   OPTIONAL.


9.  IANA Considerations

9.1.  JSON Web Token Claims Registry

   This specification establishes the IANA JSON Web Token Claims
   registry for reserved JWT Claim Names.  The registry records the
   reserved Claim Name and a reference to the specification that defines
   it.  This specification registers the Claim Names defined in
   Section 4.1.

   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.

   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: claims-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.



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

9.1.1.  Registration Template

   Claim 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.

9.1.2.  Initial Registry Contents

   o  Claim Name: "iss"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.1 of [[ this document ]]

   o  Claim Name: "sub"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.2 of [[ this document ]]

   o  Claim Name: "aud"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.3 of [[ this document ]]

   o  Claim Name: "exp"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.4 of [[ this document ]]

   o  Claim Name: "nbf"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.5 of [[ this document ]]

   o  Claim Name: "iat"
   o  Change Controller: IETF





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   o  Specification Document(s): Section 4.1.6 of [[ this document ]]

   o  Claim Name: "jti"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.7 of [[ this document ]]

   o  Claim Name: "typ"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.8 of [[ this document ]]

9.2.  Sub-Namespace Registration of urn:ietf:params:oauth:token-type:jwt

9.2.1.  Registry Contents

   This specification registers the value "token-type:jwt" in the IANA
   urn:ietf:params:oauth registry established in An IETF URN Sub-
   Namespace for OAuth [RFC6755].

   o  URN: urn:ietf:params:oauth:token-type:jwt
   o  Common Name: JSON Web Token (JWT) Token Type
   o  Change Controller: IETF
   o  Specification Document(s): [[this document]]

9.3.  JSON Web Signature and Encryption Type Values Registration

9.3.1.  Registry Contents

   This specification registers the "JWT" type value in the IANA JSON
   Web Signature and Encryption Type Values registry [JWS]:

   o  "typ" Header Parameter Value: "JWT"
   o  Abbreviation for MIME Type: application/jwt
   o  Change Controller: IETF
   o  Specification Document(s): Section 5.1 of [[ this document ]]

9.4.  Media Type Registration

9.4.1.  Registry Contents

   This specification registers the "application/jwt" Media Type
   [RFC2046] in the MIME Media Type registry [RFC4288] to indicate that
   the content is a JWT.

   o  Type Name: application
   o  Subtype Name: jwt
   o  Required Parameters: n/a





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   o  Optional Parameters: n/a
   o  Encoding considerations: JWT values are encoded as a series of
      base64url encoded values (some of which may be the empty string)
      separated by period ('.') characters
   o  Security Considerations: See the Security Considerations section
      of this document
   o  Interoperability Considerations: n/a
   o  Published Specification: [[ this document ]]
   o  Applications that use this media type: OpenID Connect, Mozilla
      Browser ID, Salesforce, Google, numerous others
   o  Additional Information: Magic number(s): n/a, File extension(s):
      n/a, Macintosh file type code(s): n/a
   o  Person & email address to contact for further information: Michael
      B. Jones, mbj@microsoft.com
   o  Intended Usage: COMMON
   o  Restrictions on Usage: none
   o  Author: Michael B. Jones, mbj@microsoft.com
   o  Change Controller: IETF


10.  Security Considerations

   All of the security issues faced by any cryptographic application
   must be faced by a JWT/JWS/JWE/JWK agent.  Among these issues are
   protecting the user's private and symmetric keys, 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.

   All the security considerations in the JWS specification also apply
   to JWT, as do the JWE security considerations when encryption is
   employed.  In particular, the JWS JSON Security Considerations and
   Unicode Comparison Security Considerations apply equally to the JWT
   Claims Set in the same manner that they do to the JWS Header.

   While syntactically, the signing and encryption operations for Nested
   JWTs may be applied in any order, normally senders should sign the
   message and then encrypt the result (thus encrypting the signature).
   This prevents attacks in which the signature is stripped, leaving
   just an encrypted message, as well as providing privacy for the
   signer.  Furthermore, signatures over encrypted text are not
   considered valid in many jurisdictions.


11.  References






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11.1.  Normative References

   [JWA]      Jones, M., "JSON Web Algorithms (JWA)",
              draft-ietf-jose-json-web-algorithms (work in progress),
              December 2012.

   [JWE]      Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
              Encryption (JWE)", draft-ietf-jose-json-web-encryption
              (work in progress), December 2012.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", draft-ietf-jose-json-web-signature (work
              in progress), December 2012.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

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

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and
              Registration Procedures", BCP 13, RFC 4288, December 2005.

   [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.

   [RFC6755]  Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace
              for OAuth", RFC 6755, October 2012.

   [USA15]    Davis, M., Whistler, K., and M. Duerst, "Unicode



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              Normalization Forms", Unicode Standard Annex 15, 09 2009.

11.2.  Informative References

   [CanvasApp]
              Facebook, "Canvas Applications", 2010.

   [JSS]      Bradley, J. and N. Sakimura (editor), "JSON Simple Sign",
              September 2010.

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

   [OASIS.saml-core-2.0-os]
              Cantor, S., Kemp, J., Philpott, R., and E. Maler,
              "Assertions and Protocol for the OASIS Security Assertion
              Markup Language (SAML) V2.0", OASIS Standard saml-core-
              2.0-os, March 2005.

   [RFC3275]  Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup
              Language) XML-Signature Syntax and Processing", RFC 3275,
              March 2002.

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

   [SWT]      Hardt, D. and Y. Goland, "Simple Web Token (SWT)",
              Version 0.9.5.1, November 2009.

   [W3C.CR-xml11-20021015]
              Cowan, J., "Extensible Markup Language (XML) 1.1", W3C
              CR CR-xml11-20021015, October 2002.

   [W3C.REC-xml-c14n-20010315]
              Boyer, J., "Canonical XML Version 1.0", World Wide Web
              Consortium Recommendation REC-xml-c14n-20010315,
              March 2001,
              <http://www.w3.org/TR/2001/REC-xml-c14n-20010315>.


Appendix A.  Example Encrypted JWT

   This example encrypts the same claims as used in Section 3.1 to the
   recipient using RSAES-PKCS1-V1_5 and AES CBC.  AES CBC does not have
   an integrated integrity check, so a separate integrity check
   calculation is performed using HMAC SHA-256, with separate encryption



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   and integrity keys being derived from a master key using the Concat
   KDF with the SHA-256 digest function.

   The following example JWE Header (with line breaks for display
   purposes only) declares that:

   o  the Content Master Key is encrypted to the recipient using the
      RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and

   o  the Plaintext is encrypted using the AES CBC algorithm with a 128
      bit key to produce the Ciphertext, with the integrity of the
      Ciphertext and the parameters used to create it being secured
      using the HMAC SHA-256 algorithm.


         {"alg":"RSA1_5","enc":"A128CBC+HS256"}

   Other than using the bytes of the UTF-8 representation of the JSON
   Claims Set from Section 3.1 as the plaintext value, the computation
   of this JWT is identical to the computation of the JWE in Appendix
   A.2 of [JWE], including the keys used.

   The final result in this example (with line breaks for display
   purposes only) is:

        eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
        pwaFh7yJPivLjjPkzC-GeAyHuy7AinGcS51AZ7TXnwkC80Ow1aW47kcT_UV54ubo
        nONbeArwOVuR7shveXnwPmucwrk_3OCcHrCbE1HR-Jfme2mF_WR3zUMcwqmU0RlH
        kwx9txo_sKRasjlXc8RYP-evLCmT1XRXKjtY5l44Gnh0A84hGvVfMxMfCWXh38hi
        2h8JMjQHGQ3mivVui5lbf-zzb3qXXxNO1ZYoWgs5tP1-T54QYc9Bi9wodFPWNPKB
        kY-BgewG-Vmc59JqFeprk1O08qhKQeOGCWc0WPC_n_LIpGWH6spRm7KGuYdgDMkQ
        bd4uuB0uPPLx_euVCdrVrA.
        AxY8DCtDaGlsbGljb3RoZQ.
        7MI2lRCaoyYx1HclVXkr8DhmDoikTmOp3IdEmm4qgBThFkqFqOs3ivXLJTku4M0f
        laMAbGG_X6K8_B-0E-7ak-Olm_-_V03oBUUGTAc-F0A.
        OwWNxnC-BMEie-GkFHzVWiNiaV3zUHf6fCOGTwbRckU


Appendix B.  Relationship of JWTs to SAML Assertions

   SAML 2.0 [OASIS.saml-core-2.0-os] provides a standard for creating
   security tokens with greater expressivity and more security options
   than supported by JWTs.  However, the cost of this flexibility and
   expressiveness is both size and complexity.  SAML's use of XML
   [W3C.CR-xml11-20021015] and XML DSIG [RFC3275] contributes to the
   size of SAML assertions; its use of XML and especially XML
   Canonicalization [W3C.REC-xml-c14n-20010315] contributes to their
   complexity.



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   JWTs are intended to provide a simple security token format that is
   small enough to fit into HTTP headers and query arguments in URIs.
   It does this by supporting a much simpler token model than SAML and
   using the JSON [RFC4627] object encoding syntax.  It also supports
   securing tokens using Message Authentication Codes (MACs) and digital
   signatures using a smaller (and less flexible) format than XML DSIG.

   Therefore, while JWTs can do some of the things SAML assertions do,
   JWTs are not intended as a full replacement for SAML assertions, but
   rather as a token format to be used when ease of implementation or
   compactness are considerations.

   SAML Assertions are always statements made by an entity about a
   subject.  JWTs are often used in the same manner, with the entity
   making the statements being represented by the "iss" (issuer) claim,
   and the subject being represented by the "sub" (subject) claim.
   However, with these claims being optional, other uses of the JWT
   format are also permitted.


Appendix C.  Relationship of JWTs to Simple Web Tokens (SWTs)

   Both JWTs and Simple Web Tokens SWT [SWT], at their core, enable sets
   of claims to be communicated between applications.  For SWTs, both
   the claim names and claim values are strings.  For JWTs, while claim
   names are strings, claim values can be any JSON type.  Both token
   types offer cryptographic protection of their content: SWTs with HMAC
   SHA-256 and JWTs with a choice of algorithms, including signature,
   MAC, and encryption algorithms.


Appendix D.  Acknowledgements

   The authors acknowledge that the design of JWTs was intentionally
   influenced by the design and simplicity of Simple Web Tokens [SWT]
   and ideas for JSON tokens that Dick Hardt discussed within the OpenID
   community.

   Solutions for signing JSON content were previously explored by Magic
   Signatures [MagicSignatures], JSON Simple Sign [JSS], and Canvas
   Applications [CanvasApp], all of which influenced this draft.

   This specification is the work of the OAuth Working Group, which
   includes dozens of active and dedicated participants.  In particular,
   the following individuals contributed ideas, feedback, and wording
   that influenced this specification:

   Dirk Balfanz, Richard Barnes, Brian Campbell, Breno de Medeiros, Dick



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   Hardt, Joe Hildebrand, Jeff Hodges, Edmund Jay, Yaron Y. Goland, Ben
   Laurie, James Manger, Prateek Mishra, Tony Nadalin, Axel Nennker,
   John Panzer, Emmanuel Raviart, David Recordon, Eric Rescorla, Jim
   Schaad, Paul Tarjan, Hannes Tschofenig, and Sean Turner.

   Hannes Tschofenig and Derek Atkins chaired the OAuth working group
   and Sean Turner and Stephen Farrell served as Security area directors
   during the creation of this specification.


Appendix E.  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  Track changes to the underlying JOSE specifications.

   o  Should all claims continue to be required to be understood by
      implementations using them when used in a security-related context
      or should a means of declaring that specific claims may be safely
      ignored if not understood should be defined?  This is related to
      the similar JOSE issue about whether all header fields must
      continue to be understood.


Appendix F.  Document History

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

   -06

   o  Changed the name of the "prn" claim to "sub" (subject) both to
      more closely align with SAML name usage and to use a more
      intuitive name.

   o  Allow JWTs to have multiple audiences.

   o  Applied editorial improvements suggested by Jeff Hodges, Prateek
      Mishra, and Hannes Tschofenig.  Many of these simplified the
      terminology used.

   o  Explained why Nested JWTs should be signed and then encrypted.

   o  Clarified statements of the form "This claim is OPTIONAL" to "Use
      of this claim is OPTIONAL".





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   o  Referenced String Comparison Rules in JWS.

   o  Added seriesInfo information to Internet Draft references.

   -05

   o  Updated values for example AES CBC calculations.

   -04

   o  Promoted Initialization Vector from being a header parameter to
      being a top-level JWE element.  This saves approximately 16 bytes
      in the compact serialization, which is a significant savings for
      some use cases.  Promoting the Initialization Vector out of the
      header also avoids repeating this shared value in the JSON
      serialization.

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

   o  Reference RFC 6755 -- An IETF URN Sub-Namespace for OAuth.

   -03

   o  Added statement that "StringOrURI values are compared as case-
      sensitive strings with no transformations or canonicalizations
      applied".

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

   -02

   o  Added an example of an encrypted JWT.

   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  Applied editorial suggestions.

   -01

   o  Added the "cty" (content type) header parameter for declaring type
      information about the secured content, as opposed to the "typ"
      (type) header parameter, which declares type information about
      this object.  This significantly simplified nested JWTs.




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   o  Moved description of how to determine whether a header is for a
      JWS or a JWE from the JWT spec to the JWE spec.

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

   o  Added Registration Template sections for defined registries.

   o  Added Registry Contents sections to populate registry values.

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

   o  Numerous editorial improvements.

   -00

   o  Created the initial IETF draft based upon
      draft-jones-json-web-token-10 with no normative changes.


Authors' Addresses

   Michael B. Jones
   Microsoft

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


   John Bradley
   Ping Identity

   Email: ve7jtb@ve7jtb.com


   Nat Sakimura
   Nomura Research Institute

   Email: n-sakimura@nri.co.jp












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