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Versions: 00 01 02 03 04 05 06 07 08 09 10 draft-ietf-oauth-json-web-token

Network Working Group                                           M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                              D. Balfanz
Expires: November 9, 2012                                         Google
                                                              J. Bradley
                                                             independent
                                                               Y. Goland
                                                               Microsoft
                                                               J. Panzer
                                                                  Google
                                                             N. Sakimura
                                               Nomura Research Institute
                                                               P. Tarjan
                                                                Facebook
                                                             May 8, 2012


                          JSON Web Token (JWT)
                     draft-jones-json-web-token-09

Abstract

   JSON Web Token (JWT) is a means of representing claims to be
   transferred between two parties.  The claims in a JWT are encoded as
   a JSON object that is digitally signed or HMACed using JSON Web
   Signature (JWS) and/or encrypted using JSON Web Encryption (JWE).

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

Requirements Language

   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 RFC 2119 [RFC2119].

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



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   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 November 9, 2012.

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
   described in the Simplified BSD License.
































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  JSON Web Token (JWT) Overview  . . . . . . . . . . . . . . . .  5
     3.1.  Example JWT  . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  JWT Claims . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Reserved Claim Names . . . . . . . . . . . . . . . . . . .  7
     4.2.  Public Claim Names . . . . . . . . . . . . . . . . . . . .  9
     4.3.  Private Claim Names  . . . . . . . . . . . . . . . . . . .  9
   5.  JWT Header . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   6.  Plaintext JWTs . . . . . . . . . . . . . . . . . . . . . . . . 11
     6.1.  Example Plaintext JWT  . . . . . . . . . . . . . . . . . . 11
   7.  Rules for Creating and Validating a JWT  . . . . . . . . . . . 12
   8.  Cryptographic Algorithms . . . . . . . . . . . . . . . . . . . 14
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
     9.1.  JSON Web Token Claims Registry . . . . . . . . . . . . . . 15
     9.2.  Sub-Namespace Registration of
           urn:ietf:params:oauth:token-type:jwt . . . . . . . . . . . 15
     9.3.  Registration of application/jwt MIME Media Type  . . . . . 15
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 17
     10.1. Unicode Comparison Security Issues . . . . . . . . . . . . 17
   11. Open Issues and Things To Be Done (TBD)  . . . . . . . . . . . 18
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 18
     12.2. Informative References . . . . . . . . . . . . . . . . . . 19
   Appendix A.  Relationship of JWTs to SAML Tokens . . . . . . . . . 20
   Appendix B.  Relationship of JWTs to Simple Web Tokens (SWTs)  . . 20
   Appendix C.  Acknowledgements  . . . . . . . . . . . . . . . . . . 21
   Appendix D.  Document History  . . . . . . . . . . . . . . . . . . 21
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23




















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1.  Introduction

   JSON Web Token (JWT) is a compact token format intended for space
   constrained environments such as HTTP Authorization headers and URI
   query parameters.  JWTs encode claims to be transmitted as a JSON
   object (as defined in RFC 4627 [RFC4627]) that is base64url encoded
   and digitally signed or HMACed and/or encrypted.  Signing and HMACing
   is performed using JSON Web Signature (JWS) [JWS].  Encryption is
   performed using JSON Web Encryption (JWE) [JWE].

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


2.  Terminology

   JSON Web Token (JWT)  A string consisting of multiple parts, the
      first being the Encoded JWT Header, plus additional parts
      depending upon the contents of the header, with the parts being
      separated by period ('.') characters, and each part containing
      base64url encoded content.

   JWT Header  A string representing a JSON object that describes the
      cryptographic operations applied to the JWT.  When the JWT is
      digitally signed or HMACed, the JWT Header is a JWS Header.  When
      the JWT is encrypted, the JWT Header is a JWE Header.

   Header Parameter Names  The names of the members within the JWT
      Header.

   Header Parameter Values  The values of the members within the JWT
      Header.

   JWT Claims Set  A string representing a JSON object that contains the
      claims conveyed by the JWT.  When the JWT is digitally signed or
      HMACed, the bytes of the UTF-8 representation of the JWT Claims
      Set are base64url encoded to create the Encoded JWS Payload.  When
      the JWT is encrypted, the bytes of the UTF-8 representation of the
      JWT Claims Set are used as the JWE Plaintext.

   Claim Names  The names of the members of the JSON object represented
      by the JWT Claims Set.

   Claim Values  The values of the members of the JSON object
      represented by the JWT Claims Set.






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   Encoded JWT Header  Base64url encoding of the bytes of the UTF-8 RFC
      3629 [RFC3629] representation of the JWT Header.

   Base64url Encoding  For the purposes of this specification, this term
      always refers to 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.)


3.  JSON Web Token (JWT) Overview

   JWTs represent a set of claims as a JSON object that is base64url
   encoded and digitally signed or HMACed and/or encrypted.  The JWT
   Claims Set represents this JSON object.  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 bytes of the UTF-8 representation of the JWT Claims Set are
   digitally signed or HMACed in the manner described in JSON Web
   Signature (JWS) [JWS] and/or encrypted in the manner described in
   JSON Web Encryption (JWE) [JWE].

   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
   claims are digitally signed or HMACed.  If the JWT Header is a JWE
   Header, the claims are encrypted.

   A JWT is represented as a JWS or JWE.  The number of parts 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 HMACed 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:



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   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9

   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):
   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 [JWS], Appendix
   A.1.


4.  JWT Claims

   The JWT Claims Set represents a JSON object whose members are the
   claims conveyed by the JWT.  The Claim Names within this object MUST
   be unique.  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.







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4.1.  Reserved Claim Names

   The following claim names are reserved.  None of the claims defined
   in the table below are intended to be mandatory, 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 tokens to be
   compact.

   +-------+--------+-------------+------------------------------------+
   | Claim | JSON   | Claim       | Claim Semantics                    |
   | Name  | Value  | Syntax      |                                    |
   |       | Type   |             |                                    |
   +-------+--------+-------------+------------------------------------+
   | exp   | number | IntDate     | The "exp" (expiration time) claim  |
   |       |        |             | identifies the expiration time on  |
   |       |        |             | or after which the token 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.  This claim is OPTIONAL.     |
   | nbf   | number | IntDate     | The "nbf" (not before) claim       |
   |       |        |             | identifies the time before which   |
   |       |        |             | the token 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 provide for some  |
   |       |        |             | small leeway, usually no more than |
   |       |        |             | a few minutes, to account for      |
   |       |        |             | clock skew.  This claim is         |
   |       |        |             | OPTIONAL.                          |
   | iat   | number | IntDate     | 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   |
   |       |        |             | token.  This claim is OPTIONAL.    |







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   | iss   | string | StringOrURI | The "iss" (issuer) claim           |
   |       |        |             | identifies the principal that      |
   |       |        |             | issued the JWT.  The processing of |
   |       |        |             | this claim is generally            |
   |       |        |             | application specific.  The "iss"   |
   |       |        |             | value is case sensitive.  This     |
   |       |        |             | claim is OPTIONAL.                 |
   | aud   | string | StringOrURI | The "aud" (audience) claim         |
   |       |        |             | identifies the audience that the   |
   |       |        |             | JWT is intended for.  The          |
   |       |        |             | principal intended to process the  |
   |       |        |             | JWT MUST be identified with the    |
   |       |        |             | value of the audience claim.  If   |
   |       |        |             | the principal processing the claim |
   |       |        |             | does not identify itself with the  |
   |       |        |             | identifier in the "aud" claim      |
   |       |        |             | value then the JWT MUST be         |
   |       |        |             | rejected.  The interpretation of   |
   |       |        |             | the audience value is generally    |
   |       |        |             | application specific.  The "aud"   |
   |       |        |             | value is case sensitive.  This     |
   |       |        |             | claim is OPTIONAL.                 |
   | prn   | string | StringOrURI | The "prn" (principal) claim        |
   |       |        |             | identifies the subject of the JWT. |
   |       |        |             | The processing of this claim is    |
   |       |        |             | generally application specific.    |
   |       |        |             | The "prn" value is case sensitive. |
   |       |        |             | This claim is OPTIONAL.            |
   | jti   | string | String      | 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 case sensitive.     |
   |       |        |             | This claim is OPTIONAL.            |
   | typ   | string | String      | The "typ" (type) claim is used to  |
   |       |        |             | declare a type for the contents of |
   |       |        |             | this JWT Claims Set. The "typ"     |
   |       |        |             | value is case sensitive.  This     |
   |       |        |             | claim is OPTIONAL.                 |
   +-------+--------+-------------+------------------------------------+

                    Table 1: Reserved Claim Definitions



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   Additional reserved claim names MAY be defined via the IANA JSON Web
   Token Claims Registry Section 9.1.  The syntax values used above are
   defined as follows:

   +-------------+-----------------------------------------------------+
   | Syntax Name | Syntax Definition                                   |
   +-------------+-----------------------------------------------------+
   | IntDate     | The number of seconds from 1970-01-01T0:0:0Z as     |
   |             | measured in UTC until the desired date/time.  See   |
   |             | RFC 3339 [RFC3339] for details regarding date/times |
   |             | in general and UTC in particular.                   |
   | String      | Any string value MAY be used.                       |
   | StringOrURI | Any string value MAY be used but a value containing |
   |             | a ":" character MUST be a URI as defined in RFC     |
   |             | 3986 [RFC3986].                                     |
   +-------------+-----------------------------------------------------+

                     Table 2: Claim Syntax Definitions

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
   defined in the IANA JSON Web Token Claims Registry Section 9.1 or be
   defined as a URI that contains a collision resistant namespace.
   Examples of collision resistant namespaces include:

   o  Domain Names,

   o  Object Identifiers (OIDs) as defined in the ITU-T X.660 and X.670
      Recommendation series, or

   o  Universally Unique IDentifier (UUID) as defined in RFC 4122
      [RFC4122].

   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 any claim name that is
   not a Reserved Name Section 4.1 or a Public Name Section 4.2.  Unlike
   Public Names, these 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.  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.

   There are two ways of distinguishing whether the JWT is a JWS or JWE.
   The first is by examining the "alg" (algorithm) header value.  If the
   value represents a signature algorithm, the JWT is a JWS; if it
   represents an encryption algorithm, the JWT is a JWE.  A second
   method is determining whether an "enc" (encryption method) member
   exists.  If the "enc" member exists, the JWT is a JWE; otherwise, the
   JWT is a JWS.  Both methods will yield the same result.

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



























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   +----------+-------+----------+-------------------------------------+
   | Header   | JSON  | Header   | Header Parameter Semantics          |
   | Paramete | Value | Paramete |                                     |
   | rName    | Type  | rSyntax  |                                     |
   +----------+-------+----------+-------------------------------------+
   | typ      | strin | String   | The "typ" (type) header parameter   |
   |          | g     |          | is used to declare structural       |
   |          |       |          | information about the JWT.  In the  |
   |          |       |          | normal case where nested signing or |
   |          |       |          | encryption operations are not       |
   |          |       |          | employed, the use of this header    |
   |          |       |          | parameter is OPTIONAL, and if       |
   |          |       |          | present, it is RECOMMENDED that its |
   |          |       |          | value be either "JWT" or            |
   |          |       |          | "urn:ietf:params:oauth:token-type:j |
   |          |       |          | wt".  In the case that nested       |
   |          |       |          |  signing or encryption steps are    |
   |          |       |          |  employed, the use of this header   |
   |          |       |          |  parameter is REQUIRED; in this     |
   |          |       |          |  case, the value MUST either be     |
   |          |       |          |  "JWS", to indicate that a nested   |
   |          |       |          |  digitally signed or HMACed JWT is  |
   |          |       |          |  carried in this JWT or "JWE", to   |
   |          |       |          |  indicate that a nested encrypted   |
   |          |       |          |  JWT is carried in this JWT.        |
   +----------+-------+----------+-------------------------------------+

                 Table 3: Reserved Header Parameter Usage


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 token
   (such as a signature on a data structure containing the token), JWTs
   MAY also be created without a signature or encryption.  A plaintext
   JWT is a JWS using the "none" JWS "alg" header parameter value
   defined in JSON Web Algorithms (JWA) [JWA]; it is a JWS with an empty
   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:



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   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.

   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.





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   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
       "typ" value of either "JWS" or "JWE" respectively 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 token 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.

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

   5.   The 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:





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        *  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 "typ" value of either "JWS" or
        "JWE", then the Message contains a JWT that was the subject of
        nested signing or encryption operations, respectively.  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.

   Processing a JWT inevitably requires comparing known strings to
   values in the token.  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.  A similar process occurs when determining if the
   value of the "alg" header parameter represents a supported algorithm.

   Comparisons between JSON strings and other Unicode strings MUST be
   performed as specified below:

   1.  Remove any JSON applied escaping to produce an array of Unicode
       code points.

   2.  Unicode Normalization [USA15] MUST NOT be applied at any point to
       either the JSON string or to the string it is to be compared
       against.

   3.  Comparisons between the two strings MUST be performed as a
       Unicode code point to code point equality comparison.


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.




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   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-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

   The IANA registry entitled "JSON Web Token Claims" for reserved JWT
   claim names is defined in Section 4.1.  Inclusion in the registry is
   RFC Required in the RFC 5226 [RFC5226] sense for reserved JWT claim
   names that are intended to be interoperable between implementations.
   The registry will just record the reserved claim name and a pointer
   to the RFC that defines it.  This specification defines inclusion of
   the claim names defined in Section 4.1.

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

   This is a request to IANA to register the value "token-type:jwt" in
   the registry urn:ietf:params:oauth established in An IETF URN Sub-
   Namespace for OAuth [I-D.ietf-oauth-urn-sub-ns].

   o  URN: urn:ietf:params:oauth:token-type:jwt

   o  Common Name: JSON Web Token (JWT) Token Type

   o  Change controller: IETF

   o  Description: [[this document]]

9.3.  Registration of application/jwt MIME Media Type

   This specification registers the "application/jwt" MIME Media Type.

   Type name:
      application





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   Subtype name:
      jwt

   Required parameters:
      n/a

   Optional parameters:
      n/a

   Encoding considerations:
      n/a

   Security considerations:
      See the Security Considerations section of this document

   Interoperability considerations:
      n/a

   Published specification:
      [[ this document ]]

   Applications that use this media type:
      OpenID Connect, Mozilla Browser ID, Salesforce, Google, numerous
      others

   Additional information:
      Magic number(s): n/a
      File extension(s): n/a
      Macintosh file type code(s): n/a

   Person & email address to contact for further information:
      Michael B. Jones
      mbj@microsoft.com

   Intended usage:
      COMMON

   Restrictions on usage:
      none

   Author:
      Michael B. Jones
      mbj@microsoft.com

   Change controller:
      Michael B. Jones
      mbj@microsoft.com




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10.  Security Considerations

   TBD: Lots of work to do here.  We need to remember to look into any
   issues relating to security and JSON parsing.  One wonders just how
   secure most JSON parsing libraries are.  Were they ever hardened for
   security scenarios?  If not, what kind of holes does that open up?
   Also, we need to walk through the JSON standard and see what kind of
   issues we have especially around comparison of names.  For instance,
   comparisons of claim names and other parameters must occur after they
   are unescaped.  Need to also put in text about: Importance of keeping
   secrets secret.  Rotating keys.  Strengths and weaknesses of the
   different algorithms.

   TBD: Need to put in text about why strict JSON validation is
   necessary.  Basically, that if malformed JSON is received then the
   intent of the sender is impossible to reliably discern.  One example
   of malformed JSON that MUST be rejected is an object in which the
   same member name occurs multiple times.  While in non-security
   contexts it's o.k. to be generous in what one accepts, in security
   contexts this can lead to serious security holes.  For example,
   malformed JSON might indicate that someone has managed to find a
   security hole in the issuer's code and is leveraging it to get the
   issuer to issue "bad" tokens whose content the attacker can control.

   TBD: Write about the need to secure the token content if a signature
   is not contained in the JWT itself.

10.1.  Unicode Comparison Security Issues

   Claim names in JWTs are Unicode strings.  For security reasons, the
   representations of these names must be compared verbatim after
   performing any escape processing (as per RFC 4627 [RFC4627], Section
   2.5).

   This means, for instance, that these JSON strings must compare as
   being equal ("JWT", "\u004aWT"), whereas these must all compare as
   being not equal to the first set or to each other ("jwt", "Jwt",
   "JW\u0074").

   JSON strings MAY contain characters outside the Unicode Basic
   Multilingual Plane.  For instance, the G clef character (U+1D11E) may
   be represented in a JSON string as "\uD834\uDD1E".  Ideally, JWT
   implementations SHOULD ensure that characters outside the Basic
   Multilingual Plane are preserved and compared correctly;
   alternatively, if this is not possible due to these characters
   exercising limitations present in the underlying JSON implementation,
   then input containing them MUST be rejected.




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11.  Open Issues and Things To Be Done (TBD)

   The following items remain to be done in this draft:

   o  EDITORIAL: Give each claim name and header parameter definition
      its own section.  This will let them appear in the index, will
      give space for examples when needed, and will get rid of the way-
      too-cramped tables.

   o  Add normative text that requires rejecting headers and Claim Sets
      in which member names occur multiple times, as apparently this is
      legal JSON.

   o  Provide an example of an encrypted JWT.

   o  Clarify the intended use of the "typ" Header Parameter across the
      JWS, JWE, and JWT specifications.  Decide whether a registry of
      "typ" values is appropriate.

   o  EDITORIAL: Think about how to best describe the concept currently
      described as "the bytes of the UTF-8 representation of".  Possible
      terms to use instead of "bytes of" include "byte sequence", "octet
      series", and "octet sequence".  Also consider whether we want to
      add an overall clarifying statement somewhere in each spec
      something like "every place we say 'the UTF-8 representation of
      X', we mean 'the bytes of the UTF-8 representation of X'".  That
      would potentially allow us to omit the "the bytes of" part
      everywhere else.

   o  Finish the Security Considerations section.

   o  Possibly write a companion specification that uses the JWS and JWE
      JSON Serializations.


12.  References

12.1.  Normative References

   [I-D.ietf-oauth-urn-sub-ns]
              Tschofenig, H., "An IETF URN Sub-Namespace for OAuth",
              draft-ietf-oauth-urn-sub-ns-02 (work in progress),
              January 2012.

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

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



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

   [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.

   [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.

   [USA15]    Davis, M., Whistler, K., and M. Duerst, "Unicode
              Normalization Forms", Unicode Standard Annex 15, 09 2009.

12.2.  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



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              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.


Appendix A.  Relationship of JWTs to SAML Tokens

   SAML 2.0 [OASIS.saml-core-2.0-os] provides a standard for creating
   tokens with much greater expressivity and more security options than
   supported by JWTs.  However, the cost of this flexibility and
   expressiveness is both size and complexity.  In addition, SAML's use
   of XML [W3C.CR-xml11-20021015] and XML DSIG [RFC3275] only
   contributes to the size of SAML tokens.

   JWTs are intended to provide a simple 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 Hash-based Message Authentication Codes (HMACs) and
   digital signatures using a smaller (and less flexible) format than
   XML DSIG.

   Therefore, while JWTs can do some of the things SAML tokens do, JWTs
   are not intended as a full replacement for SAML tokens, but rather as
   a compromise token format to be used when space is at a premium.


Appendix B.  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 HMAC SHA-256,
   RSA SHA-256, and ECDSA P-256 SHA-256.





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Appendix C.  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.


Appendix D.  Document History

   -09

   o  Changed "http://openid.net/specs/jwt/1.0" to
      "urn:ietf:params:oauth:token-type:jwt" in preparation for OAuth WG
      draft.

   -08

   o  Removed language that required that a JWT must have three parts.
      Now the number of parts is explicitly dependent upon the
      representation of the underlying JWS or JWE.

   o  Moved the "alg":"none" definition to the JWS spec.

   o  Registered the "application/jwt" MIME Media Type.

   o  Clarified that the order of the creation and validation steps is
      not significant in cases where there are no dependencies between
      the inputs and outputs of the steps.

   o  Corrected the Magic Signatures and Simple Web Token (SWT)
      references.

   -07

   o  Defined the "prn" (principal) claim to identify the subject of the
      JWT.

   o  Defined the "jti" (JWT ID) claim to enable replay protection.

   o  Use the term "JWT Claims Set" rather than "JWT Claims Object"
      since this is actually a string representing a JSON object and not
      the JSON object itself.




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   o  Moved "MUST" requirements from the Overview to later in the spec.

   o  Respect line length restrictions in examples.

   o  Applied other editorial improvements.

   -06

   o  Reference and use content from [JWS] and [JWE], rather than
      repeating it here.

   o  Simplified terminology to better match JWE, where the terms "JWT
      Header" and "Encoded JWT Header" are now used, for instance,
      rather than the previous terms "Decoded JWT Header Segment" and
      "JWT Header Segment".  Also changed to "Plaintext JWT" from
      "Unsigned JWT".

   o  Describe how to perform nested encryption and signing operations.

   o  Changed "integer" to "number", since that is the correct JSON
      type.

   o  Changed StringAndURI to StringOrURI.

   -05

   o  Added the "nbf" (not before) claim and clarified the meaning of
      the "iat" (issued at) claim.

   -04

   o  Correct typo found by John Bradley: "the JWT Claim Segment is the
      empty string" -> "the JWT Crypto Segment is the empty string".

   -03

   o  Added "http://openid.net/specs/jwt/1.0" as a token type identifier
      URI for JWTs.

   o  Added "iat" (issued at) claim.

   o  Changed RSA SHA-256 from MUST be supported to RECOMMENDED that it
      be supported.  Rationale: Several people have objected to the
      requirement for implementing RSA SHA-256, some because they will
      only be using HMACs and symmetric keys, and others because they
      only want to use ECDSA when using asymmetric keys, either for
      security or key length reasons, or both.




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   o  Defined "alg" value "none" to represent unsigned JWTs.

   -02

   o  Split signature specification out into separate
      draft-jones-json-web-signature-00.  This split introduced no
      semantic changes.

   o  The JWT Compact Serialization is now the only token serialization
      format specified in this draft.  The JWT JSON Serialization can
      continue to be defined in a companion specification.

   -01

   o  Draft incorporating consensus decisions reached at IIW.

   -00

   o  Public draft published before November 2010 IIW based upon the
      JSON token convergence proposal incorporating input from several
      implementers of related specifications.


Authors' Addresses

   Michael B. Jones
   Microsoft

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


   Dirk Balfanz
   Google

   Email: balfanz@google.com


   John Bradley
   independent

   Email: ve7jtb@ve7jtb.com









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   Yaron Y. Goland
   Microsoft

   Email: yarong@microsoft.com


   John Panzer
   Google

   Email: jpanzer@google.com


   Nat Sakimura
   Nomura Research Institute

   Email: n-sakimura@nri.co.jp


   Paul Tarjan
   Facebook

   Email: pt@fb.com





























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