[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Nits] [IPR]

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: July 1, 2011                                             Google
                                                              J. Bradley
                                                             independent
                                                               Y. Goland
                                                               Microsoft
                                                               J. Panzer
                                                                  Google
                                                             N. Sakimura
                                               Nomura Research Institute
                                                       December 28, 2010


                          JSON Web Token (JWT)
                     draft-jones-json-web-token-00

Abstract

   JSON Web Token (JWT) defines a token format that can encode claims
   transferred between two parties.  The claims in a JWT are encoded as
   a JSON object that is digitally signed.

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
   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 July 1, 2011.

Copyright Notice



Jones, et al.             Expires July 1, 2011                  [Page 1]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Copyright (c) 2010 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.







































Jones, et al.             Expires July 1, 2011                  [Page 2]


Internet-Draft            JSON Web Token (JWT)             December 2010


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  JSON Web Token (JWT) Overview  . . . . . . . . . . . . . . . .  6
     3.1.  Example JWT  . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  JWT Claims . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Reserved Claim Names . . . . . . . . . . . . . . . . . . .  7
     4.2.  Public Claim Names . . . . . . . . . . . . . . . . . . . .  9
     4.3.  Private Claim Names  . . . . . . . . . . . . . . . . . . .  9
   5.  JWT Envelope . . . . . . . . . . . . . . . . . . . . . . . . . 10
     5.1.  Reserved Envelope Parameter Names  . . . . . . . . . . . . 10
     5.2.  Public Envelope Parameter Names  . . . . . . . . . . . . . 12
     5.3.  Private Envelope Parameter Names . . . . . . . . . . . . . 12
   6.  General Rules for Creating and Validating a JWT  . . . . . . . 12
   7.  Base64url encoding as used by JWTs . . . . . . . . . . . . . . 14
   8.  Signing JWTs with Cryptographic Algorithms . . . . . . . . . . 15
     8.1.  Signing a JWT with HMAC SHA-256  . . . . . . . . . . . . . 15
     8.2.  Signing a JWT with RSA SHA-256 . . . . . . . . . . . . . . 16
     8.3.  Signing a JWT with ECDSA P-256 SHA-256 . . . . . . . . . . 17
     8.4.  Additional Algorithms  . . . . . . . . . . . . . . . . . . 19
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 20
     10.1. Unicode Comparison Security Issues . . . . . . . . . . . . 20
   11. Open Issues  . . . . . . . . . . . . . . . . . . . . . . . . . 21
   12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
   13. Appendix - Non-Normative - JWT Examples  . . . . . . . . . . . 21
     13.1. JWT using HMAC SHA-256 . . . . . . . . . . . . . . . . . . 21
       13.1.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . 21
       13.1.2.  Decoding  . . . . . . . . . . . . . . . . . . . . . . 23
       13.1.3.  Validating  . . . . . . . . . . . . . . . . . . . . . 23
     13.2. JWT using RSA SHA-256  . . . . . . . . . . . . . . . . . . 23
       13.2.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . 23
       13.2.2.  Decoding  . . . . . . . . . . . . . . . . . . . . . . 26
       13.2.3.  Validating  . . . . . . . . . . . . . . . . . . . . . 27
     13.3. JWT using ECDSA P-256 SHA-256  . . . . . . . . . . . . . . 27
       13.3.1.  Encoding  . . . . . . . . . . . . . . . . . . . . . . 27
       13.3.2.  Decoding  . . . . . . . . . . . . . . . . . . . . . . 29
       13.3.3.  Validating  . . . . . . . . . . . . . . . . . . . . . 29
   14. Appendix - Non-Normative - Notes on implementing base64url
       encoding without padding . . . . . . . . . . . . . . . . . . . 29
   15. Appendix - Non-Normative - Relationship of JWTs to SAML
       Tokens . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
   16. Appendix - Non-Normative - Relationship of JWTs to Simple
       Web Tokens (SWTs)  . . . . . . . . . . . . . . . . . . . . . . 31
   17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
     17.1. Normative References . . . . . . . . . . . . . . . . . . . 31
     17.2. Informative References . . . . . . . . . . . . . . . . . . 32



Jones, et al.             Expires July 1, 2011                  [Page 3]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 33


















































Jones, et al.             Expires July 1, 2011                  [Page 4]


Internet-Draft            JSON Web Token (JWT)             December 2010


1.  Introduction

   JSON Web Token (JWT) is a simple token format intended for space
   constrained environments such as HTTP Authorization headers and URI
   query parameters.  JWTs encode the claims to be transmitted as a JSON
   object (as defined in RFC 4627 [RFC4627]) that is base64url encoded
   and digitally signed.

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


2.  Terminology

   JSON Web Token (JWT)  A string consisting of three JWT Token
      Segments: the JWT Envelope Segment, the JWT Claim Segment, and the
      JWT Crypto Segment, in that order, with the segments being
      separated by period ('.') characters.

   JWT Token Segment  One of the three parts that make up a JSON Web
      Token (JWT).  JWT Token Segments are always base64url encoded
      values.

   JWT Envelope Segment  A JWT Token Segment containing a base64url
      encoded JSON object that describes the signature applied to the
      JWT Claim Segment.

   JWT Claim Segment  A JWT Token Segment containing a base64url encoded
      JSON object that encodes the claims represented by the JWT.

   JWT Crypto Segment  A JWT Token Segment containing base64url encoded
      cryptographic signature material that secures the JWT Crypto
      Segment's contents.

   Decoded JWT Envelope Segment  A JWT Envelope Segment that has been
      base64url decoded back into a JSON object.

   Decoded JWT Claim Segment  A JWT Claim Segment that has been
      base64url decoded back into a JSON object.

   Decoded JWT Crypto Segment  A JWT Crypto Segment that has been
      base64url decoded back into cryptographic material.

   Base64url Encoding  For the purposes of this specification, this term
      always refers to the he URL- and filename-safe Base64 encoding
      described in RFC 4648 [RFC4648], Section 5, with the '=' padding
      characters omitted, as permitted by Section 3.2; see Section 7 for
      more details.



Jones, et al.             Expires July 1, 2011                  [Page 5]


Internet-Draft            JSON Web Token (JWT)             December 2010


3.  JSON Web Token (JWT) Overview

   JWTs represent a set of claims as a JSON object that is base64url
   encoded and digitally signed.  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 JSON object is base64url encoded to produce the JWT Claim
   Segment.  An accompanying base64url encoded JSON envelope object
   describes the signature method used.

   The names within the object MUST be unique.  The names within the
   JSON object are referred to as Claim Names.  The corresponding values
   are referred to as Claim Values.

   JWTs contain a signature that ensures the integrity of the content of
   the JSON Claim Segment.  This signature value is carried in the JWT
   Crypto Segment.  The JSON Envelope object MUST contain an "alg"
   parameter, the value of which is a string that unambiguously
   identifies the algorithm used to sign the JWT Claim Segment to
   produce the JWT Crypto Segment.

3.1.  Example JWT

   The following is an example of a JSON object that can be encoded to
   produce a JWT:
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}

   Base64url encoding the UTF-8 representation of the JSON object yields
   this JWT Claim Segment value:
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ

   The following example JSON envelope object declares that the encoded
   object is a JSON Web Token (JWT) and the JWT Claim Segment is signed
   using the HMAC SHA-256 algorithm:
   {"typ":"JWT",
    "alg":"HS256"}

   Base64url encoding the UTF-8 representation of the JSON envelope
   object yields this JWT Envelope Segment value:
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9

   Signing the JWT Claim Segment with the HMAC SHA-256 algorithm and
   base64url encoding the result, as per Section 8.1, yields this JWT
   Crypto Segment value:
   35usWj9X8HwGS-CDcx1JP2NmqcrLwZ4EKp8sNThf3cY



Jones, et al.             Expires July 1, 2011                  [Page 6]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Combining these segments in the order Envelope.Claims.Signature with
   period characters between the segments yields this complete JWT (with
   line breaks for display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
35usWj9X8HwGS-CDcx1JP2NmqcrLwZ4EKp8sNThf3cY

   This computation is illustrated in more detail in Section 13.1.


4.  JWT Claims

   The members of the JSON object represented by the Decoded JWT Claim
   Segment contain the claims.  Note however, that the set of claims a
   JWT must contain to be considered valid is context-dependent and is
   outside the scope of this specification.

   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
   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
   themselves to be short.






















Jones, et al.             Expires July 1, 2011                  [Page 7]


Internet-Draft            JSON Web Token (JWT)             December 2010


   +-------+---------+--------------+----------------------------------+
   | Claim | JSON    | Claim Syntax | Claim Semantics                  |
   | Name  | Value   |              |                                  |
   |       | Type    |              |                                  |
   +-------+---------+--------------+----------------------------------+
   | exp   | integer | 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.               |
   | iss   | string  | StringAndURI | The "iss" (issuer) claim         |
   |       |         |              | identifies the principal that    |
   |       |         |              | issued the JWT.  The processing  |
   |       |         |              | of this claim is generally       |
   |       |         |              | application specific.  This      |
   |       |         |              | claim is OPTIONAL.               |
   | aud   | string  | StringAndURI | The "aud" (audience) claim       |
   |       |         |              | identifies the audience that the |
   |       |         |              | JWT is intended for.  The        |
   |       |         |              | processing of this claim         |
   |       |         |              | requires that if a JWT consumer  |
   |       |         |              | receives a JWT with an "aud"     |
   |       |         |              | value that does not identify     |
   |       |         |              | itself as the JWT audience, then |
   |       |         |              | the JWT MUST be rejected.  The   |
   |       |         |              | interpretation of the audience   |
   |       |         |              | value is generally application   |
   |       |         |              | specific.  This claim is         |
   |       |         |              | OPTIONAL.                        |
   | typ   | string  | StringAndURI | The "typ" (type) claim is used   |
   |       |         |              | to declare a type for the        |
   |       |         |              | contents this JWT.  The value    |
   |       |         |              | MAY be a MIME [RFC2045] type.    |
   |       |         |              | This claim is OPTIONAL.          |
   +-------+---------+--------------+----------------------------------+

                    Table 1: Reserved Claim Definitions

   Additional reserved claim names MAY be defined via the IANA JSON Web



Jones, et al.             Expires July 1, 2011                  [Page 8]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Token Claims registry, as per Section 9.  The syntaxes referred to
   above are:

   +--------------+----------------------------------------------------+
   | Syntax Name  | Syntax Definition                                  |
   +--------------+----------------------------------------------------+
   | StringAndURI | Any string value MAY be used but a value           |
   |              | containing a ":" character MUST be a URI as        |
   |              | defined in RFC 3986 [RFC3986].                     |
   | URI          | A URI as defined in RFC 3986 [RFC3986].            |
   | 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.       |
   +--------------+----------------------------------------------------+

                                  Table 2

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 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 MUST 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.







Jones, et al.             Expires July 1, 2011                  [Page 9]


Internet-Draft            JSON Web Token (JWT)             December 2010


5.  JWT Envelope

   The members of the JSON object represented by the Decoded JWT
   Envelope Segment describe the signature applied to the JWT Claim
   Segment and optionally additional properties of the JWT.
   Implementations MUST understand the entire contents of the envelope;
   otherwise, the JWT MUST be rejected for processing.

5.1.  Reserved Envelope Parameter Names

   The following envelope parameter names are reserved.  All the names
   are short because a core goal of JWTs is for the tokens themselves to
   be short.

   +-----------+--------+--------------+-------------------------------+
   | Envelope  | JSON   | Envelope     | Envelope Parameter Semantics  |
   | Parameter | Value  | Parameter    |                               |
   | Name      | Type   | Syntax       |                               |
   +-----------+--------+--------------+-------------------------------+
   | alg       | string | StringAndURI | The "alg" (algorithm)         |
   |           |        |              | envelope parameter identifies |
   |           |        |              | the cryptographic algorithm   |
   |           |        |              | used to secure the JWT.  A    |
   |           |        |              | list of reserved alg values   |
   |           |        |              | is in Table 4.  The           |
   |           |        |              | processing of the "alg"       |
   |           |        |              | (algorithm) envelope          |
   |           |        |              | parameter, if present,        |
   |           |        |              | requires that the value of    |
   |           |        |              | the "alg" envelope parameter  |
   |           |        |              | MUST be one that is both      |
   |           |        |              | supported and for which there |
   |           |        |              | exists a key for use with     |
   |           |        |              | that algorithm associated     |
   |           |        |              | with the issuer of the JWT.   |
   |           |        |              | Note however, that if the     |
   |           |        |              | "iss" (issuer) claim is not   |
   |           |        |              | included in the JWT Claim     |
   |           |        |              | Segment, then the manner in   |
   |           |        |              | which the issuer is           |
   |           |        |              | determined is application     |
   |           |        |              | specific.  This envelope      |
   |           |        |              | parameter is REQUIRED.        |








Jones, et al.             Expires July 1, 2011                 [Page 10]


Internet-Draft            JSON Web Token (JWT)             December 2010


   | typ       | string | StringAndURI | The "typ" (type) envelope     |
   |           |        |              | parameter is used to declare  |
   |           |        |              | that this data structure is a |
   |           |        |              | JWT.  If a "typ" parameter is |
   |           |        |              | present, its value MUST be    |
   |           |        |              | "JWT".  This envelope         |
   |           |        |              | parameter is OPTIONAL.        |
   |           |        |              | (Non-normative note: Other    |
   |           |        |              | values could be used by other |
   |           |        |              | specifications to declare     |
   |           |        |              | data structures other than    |
   |           |        |              | JWTs, for instance, encrypted |
   |           |        |              | JSON tokens.)                 |
   | keyid     | string | String       | The "keyid" (key ID) envelope |
   |           |        |              | parameter is a hint           |
   |           |        |              | indicating which specific key |
   |           |        |              | owned by the signer should be |
   |           |        |              | used to validate the          |
   |           |        |              | signature.  This allows       |
   |           |        |              | signers to explicitly signal  |
   |           |        |              | a change of key to            |
   |           |        |              | recipients.  Omitting this    |
   |           |        |              | parameter is equivalent to    |
   |           |        |              | setting it to an empty        |
   |           |        |              | string.  The format of this   |
   |           |        |              | parameter is unspecified.     |
   |           |        |              | This envelope parameter is    |
   |           |        |              | OPTIONAL.                     |
   | curi      | string | URI          | The "curi" (certificates URI) |
   |           |        |              | envelope parameter is a URI   |
   |           |        |              | that points to X.509 public   |
   |           |        |              | key certificates that can be  |
   |           |        |              | used to validate the          |
   |           |        |              | signature.  This envelope     |
   |           |        |              | parameter is OPTIONAL.        |
   | ctp       | string | String       | The "ctp" (certificate        |
   |           |        |              | thumbprint) envelope          |
   |           |        |              | parameter provides a          |
   |           |        |              | base64url encoded SHA-1       |
   |           |        |              | thumbprint of the DER         |
   |           |        |              | encoding of a certificate     |
   |           |        |              | that can be used to validate  |
   |           |        |              | the signature.  This envelope |
   |           |        |              | parameter is OPTIONAL.        |
   +-----------+--------+--------------+-------------------------------+

             Table 3: Reserved Envelope Parameter Definitions




Jones, et al.             Expires July 1, 2011                 [Page 11]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Additional reserved envelope parameter names MAY be defined via the
   IANA JSON Web Token Envelope Parameters registry, as per Section 9.
   The envelope value syntaxes referred to above are defined in Table 2.

5.2.  Public Envelope Parameter Names

   Additional envelope parameter names can be defined by those using
   JWTs.  However, in order to prevent collisions, any new envelope
   parameter name or algorithm value SHOULD either be defined in the
   IANA JSON Web Token Envelope Parameters registry or be defined as a
   URI that contains a collision resistant namespace.  In each case, the
   definer of the name or value MUST take reasonable precautions to make
   sure they are in control of the part of the namespace they use to
   define the envelope parameter name.

   New envelope parameters should be introduced sparingly, as they can
   result in non-interoperable JWTs.  Nonetheless, some extensions
   needed for some use cases may require them, such as an extension to
   enable the inclusion of multiple signatures.

5.3.  Private Envelope Parameter Names

   A producer and consumer of a JWT may agree to any envelope parameter
   name that is not a Reserved Name Section 5.1 or a Public Name
   Section 5.2.  Unlike Public Names, these private names are subject to
   collision and should be used with caution.

   New envelope parameters should be introduced sparingly, as they can
   result in non-interoperable JWTs.


6.  General Rules for Creating and Validating a JWT

   To create a JWT one MUST follow these steps:

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

   2.  Translate this JSON object's Unicode code points into UTF-8, as
       defined in RFC 3629 [RFC3629].

   3.  Base64url encode the UTF-8 representation of this JSON object as
       defined in this specification (without padding).  This encoding
       becomes the JWT Claim Segment.

   4.  Create a different JSON object containing the desired envelope
       parameters.  Note that white space is explicitly allowed in the



Jones, et al.             Expires July 1, 2011                 [Page 12]


Internet-Draft            JSON Web Token (JWT)             December 2010


       representation and no canonicalization is performed before
       encoding.

   5.  Translate this JSON object's Unicode code points into UTF-8, as
       defined in RFC 3629 [RFC3629].

   6.  Base64url encode the UTF-8 representation of this JSON object as
       defined in this specification (without padding).  This encoding
       becomes the JWT Envelope Segment.

   7.  Construct the JWT Crypto Segment as defined for the particular
       algorithm being used.  The "alg" envelope parameter MUST be
       present in the JSON Envelope Segment, with the algorithm value
       accurately representing the algorithm used to construct the JWT
       Crypto Segment.

   8.  Combine the JWT Envelope Segment, the JWT Claim Segment and then
       the JWT Crypto Segment in that order, separating each by period
       characters, to create the JWT.

   When validating a JWT the following steps MUST be taken.  If any of
   the listed steps fails then the token MUST be rejected for
   processing.

   1.   The JWT MUST contain two period characters.

   2.   The JWT MUST be split on the two period characters resulting in
        three non-empty segments.  The first segment is the JWT Envelope
        Segment; the second is the JWT Claim Segment; the third is the
        JWT Crypto Segment.

   3.   The JWT Envelope Segment MUST be successfully base64url decoded
        following the restriction given in this spec that no padding
        characters may have been used.

   4.   The Decoded JWT Envelope Segment MUST be completely valid JSON
        syntax.

   5.   The JWT Claim Segment MUST be successfully base64url decoded
        following the restriction given in this spec that no padding
        characters may have been used.

   6.   The Decoded JWT Claim Segment MUST be completely valid JSON
        syntax.

   7.   The JWT Crypto Segment MUST be successfully base64url decoded
        following the restriction given in this spec that no padding
        characters may have been used.



Jones, et al.             Expires July 1, 2011                 [Page 13]


Internet-Draft            JSON Web Token (JWT)             December 2010


   8.   The JWT Envelope Segment MUST be validated to only include
        parameters and values whose syntax and semantics are both
        understood and supported.

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

   10.  The JWT Crypto Segment MUST be successfully validated against
        the JWT Claim Segment in the manner defined for the algorithm
        being used, which MUST be accurately represented by the value of
        the "alg" envelope parameter, which MUST be present.

   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 Decoded JWT Envelope Segment to see if there is a
   matching envelope parameter name.  A similar process occurs when
   determining if the value of the "alg" envelope parameter represents a
   supported algorithm.  Comparing Unicode strings, however, has
   significant security implications, as per Section 10.

   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.


7.  Base64url encoding as used by JWTs

   JWTs make use of the base64url encoding as defined in RFC 4648
   [RFC4648].  As allowed by Section 3.2 of the RFC, this specification
   mandates that base64url encoding when used with JWTs MUST NOT use
   padding.  The reason for this restriction is that the padding
   character ('=') is not URL safe.

   For notes on implementing base64url encoding without padding, see
   Section 14.





Jones, et al.             Expires July 1, 2011                 [Page 14]


Internet-Draft            JSON Web Token (JWT)             December 2010


8.  Signing JWTs with Cryptographic Algorithms

   JWTs use specific cryptographic algorithms to sign the contents of
   the JWT Claim Segment.  The use of the following algorithms for
   producing JWTs is defined in this section.  The table below is the
   list of "alg" envelope parameter values reserved by this
   specification, each of which is explained in more detail in the
   following sections:

   +-----------------+-------------------------------------------------+
   | Alg Claim Value | Algorithm                                       |
   +-----------------+-------------------------------------------------+
   | HS256           | HMAC using SHA-256 hash algorithm               |
   | HS384           | HMAC using SHA-384 hash algorithm               |
   | HS512           | HMAC using SHA-512 hash algorithm               |
   | RS256           | RSA using SHA-256 hash algorithm                |
   | RS384           | RSA using SHA-384 hash algorithm                |
   | RS512           | RSA using SHA-512 hash algorithm                |
   | ES256           | ECDSA using P-256 curve and SHA-256 hash        |
   |                 | algorithm                                       |
   | ES384           | ECDSA using P-384 curve and SHA-384 hash        |
   |                 | algorithm                                       |
   | ES512           | ECDSA using P-521 curve and SHA-512 hash        |
   |                 | algorithm                                       |
   +-----------------+-------------------------------------------------+

             Table 4: JSON Web Token Reserved Algorithm Values

   Of these algorithms, only HMAC SHA-256 and RSA SHA-256 MUST be
   implemented.  It is RECOMMENDED that implementations also implement
   at least the ECDSA P-256 SHA-256 algorithm.

8.1.  Signing a JWT with HMAC SHA-256

   Hash based Message Authentication Codes (HMACs) enable one to use a
   secret plus a cryptographic hash function to generate a Message
   Authentication Code (MAC).  This can be used to demonstrate that the
   MAC matches the hashed content, in this case the JWT Claim Segment,
   which therefore demonstrates that whoever generated the MAC was in
   possession of the secret.

   The algorithm for implementing and validating HMACs is provided in
   RFC 2104 [RFC2104].  Although any HMAC can be used with JWTs, this
   section defines the use of the SHA-256 cryptographic hash function as
   defined in FIPS 180-3 [FIPS.180-3].  The reserved "alg" envelope
   parameter value "HS256" is used in the JWT Envelope Segment to
   indicate that the JWT Crypto Segment contains a base64url encoded
   HMAC SHA-256 HMAC value.



Jones, et al.             Expires July 1, 2011                 [Page 15]


Internet-Draft            JSON Web Token (JWT)             December 2010


   The HMAC SHA-256 MAC is generated as follows:

   1.  Take the bytes of the UTF-8 representation of the JWT Claim
       Segment and execute the HMAC SHA-256 algorithm on them using the
       shared key to produce an HMAC.

   2.  Base64url encode the HMAC as defined in this document.

   The output is placed in the JWT Crypto Segment for that JWT.

   The HMAC SHA-256 MAC on a JWT is validated as follows:

   1.  Take the bytes of the UTF-8 representation of the JWT Claim
       Segment and calculate an HMAC SHA-256 MAC on them using the
       shared key.

   2.  Base64url encode the previously generated HMAC as defined in this
       document.

   3.  If the JWT Crypto Segment and the previously calculated value
       exactly match in a character by character, case sensitive
       comparison, then one has confirmation that the key was used to
       generate the HMAC on the JWT and that the contents of the JWT
       Claim Segment have not be tampered with.

   4.  If the validation fails, the token MUST be rejected.

   Signing with the HMAC SHA-384 and HMAC SHA-512 algorithms is
   performed identically to the procedure for HMAC SHA-256 - just with
   correspondingly longer key and result values.

   JWT implementations MUST support the HMAC SHA-256 algorithm.  Support
   for the HMAC SHA-384 and HMAC SHA-512 algorithms is OPTIONAL.

8.2.  Signing a JWT with RSA SHA-256

   This section defines the use of the RSASSA-PKCS1-v1_5 signature
   algorithm as defined in RFC 3447 [RFC3447], Section 8.2 (commonly
   known as PKCS#1), using SHA-256 as the hash function.  Note that the
   use of the RSASSA-PKCS1-v1_5 algorithm is permitted in FIPS 186-3
   [FIPS.186-3], Section 5.5, as is the SHA-256 cryptographic hash
   function, which is defined in FIPS 180-3 [FIPS.180-3].  The reserved
   "alg" envelope parameter value "RS256" is used in the JWT Envelope
   Segment to indicate that the JWT Crypto Segment contains an RSA SHA-
   256 signature.

   A 2048-bit or longer key length MUST be used with this algorithm.




Jones, et al.             Expires July 1, 2011                 [Page 16]


Internet-Draft            JSON Web Token (JWT)             December 2010


   The RSA SHA-256 signature is generated as follows:

   1.  Let K be the signer's RSA private key and let M be the bytes of
       the UTF-8 representation of the JWT Claim Segment.

   2.  Compute the octet string S = RSASSA-PKCS1-V1_5-SIGN (K, M).

   3.  Base64url encode the octet string S, as defined in this document.

   The output is placed in the JWT Crypto Segment for that JWT.

   The RSA SHA-256 signature on a JWT is validated as follows:

   1.  Take the JWT Crypto Segment and base64url decode it into an octet
       string S. If decoding fails, then the token MUST be rejected.

   2.  Let M be the bytes of the UTF-8 representation of the JWT Claim
       Segment and let (n, e) be the public key corresponding to the
       private key used by the signer.

   3.  Validate the signature with RSASSA-PKCS1-V1_5-VERIFY ((n, e), M,
       S).

   4.  If the validation fails, the token MUST be rejected.

   Signing with the RSA SHA-384 and RSA SHA-512 algorithms is performed
   identically to the procedure for RSA SHA-256 - just with
   correspondingly longer key and result values.

   JWT implementations MUST support the RSA SHA-256 algorithm.  Support
   for the RSA SHA-384 and RSA SHA-512 algorithms is OPTIONAL.

8.3.  Signing a JWT with ECDSA P-256 SHA-256

   The Elliptic Curve Digital Signature Algorithm (ECDSA) is defined by
   FIPS 186-3 [FIPS.186-3].  ECDSA provides for the use of Elliptic
   Curve cryptography, which is able to provide equivalent security to
   RSA cryptography but using shorter key lengths and with greater
   processing speed.  This means that ECDSA signatures will be
   substantially smaller in terms of length than equivalently strong RSA
   Digital Signatures.

   This specification defines the use of ECDSA with the P-256 curve and
   the SHA-256 cryptographic hash function.  The P-256 curve is also
   defined in FIPS 186-3.  The reserved "alg" envelope parameter value
   "ES256" is used in the JWT Envelope Segment to indicate that the JWT
   Crypto Segment contains a ECDSA P-256 SHA-256 signature.




Jones, et al.             Expires July 1, 2011                 [Page 17]


Internet-Draft            JSON Web Token (JWT)             December 2010


   A JWT is signed with an ECDSA P-256 SHA-256 signature as follows:

   1.  Take the bytes of the UTF-8 representation of the JWT Claim
       Segment and generate a digital signature of them using ECDSA
       P-256 SHA-256 with the desired private key.  The output will be
       the EC point (R, S), where R and S are unsigned integers.

   2.  Turn R and S into byte arrays in big endian order.  Each array
       will be 32 bytes long.

   3.  Concatenate the two byte arrays in the order R and then S.

   4.  Base64url encode the 64 byte array as defined in this
       specification.

   The output becomes the JWT Crypto Segment for the JWT.

   The following procedure is used to validate the ECDSA signature of a
   JWT:

   1.  Take the JWT Crypto Segment and base64url decode it into a byte
       array.  If decoding fails, the token MUST be rejected.

   2.  The output of the base64url decoding MUST be a 64 byte array.

   3.  Split the 64 byte array into two 32 byte arrays.  The first array
       will be R and the second S. Remember that the byte arrays are in
       big endian byte order; please check the ECDSA validator in use to
       see what byte order it requires.

   4.  Submit the bytes of the UTF-8 representation of the JWT Claim
       Segment, R, S and the public key (x, y) to the ECDSA P-256 SHA-
       256 validator.

   5.  If the validation fails, the token MUST be rejected.

   The ECDSA validator will then determine if the digital signature is
   valid, given the inputs.  Note that ECDSA digital signature contains
   a value referred to as K, which is a random number generated for each
   digital signature instance.  This means that two ECDSA digital
   signatures using exactly the same input parameters will output
   different signatures because their K values will be different.  The
   consequence of this is that one must validate an ECDSA signature by
   submitting the previously specified inputs to an ECDSA validator.

   Signing with the ECDSA P-384 SHA-384 and ECDSA P-521 SHA-512
   algorithms is performed identically to the procedure for ECDSA P-256
   SHA-256 - just with correspondingly longer key and result values.



Jones, et al.             Expires July 1, 2011                 [Page 18]


Internet-Draft            JSON Web Token (JWT)             December 2010


   It is RECOMMENDED that JWT implementations support the ECDSA P-256
   SHA-256 algorithm.  Support for the ECDSA P-384 SHA-384 and ECDSA
   P-521 SHA-512 algorithms is OPTIONAL.

8.4.  Additional Algorithms

   Additional algorithms MAY be used to protect JWTs with corresponding
   "alg" envelope parameter values being defined to refer to them.  Like
   claim names, new "alg" envelope parameter values SHOULD either be
   defined in the IANA JSON Web Token Algorithms registry or be a URI
   that contains a collision resistant namespace.  In particular, the
   use of algorithm identifiers defined in XML DSIG [RFC3275] and
   related specifications is permitted.


9.  IANA Considerations

   This specification calls for:

   o  A new IANA registry entitled "JSON Web Token Claims" for reserved
      claim names Section 4.1 used in a Decoded JWT Claim Segment.
      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 Table 1.

   o  A new IANA registry entitled "JSON Web Token Envelope Parameters"
      for reserved envelope parameter names Section 5.1 used in a
      Decoded JWT Envelope Parameter Segment.  Inclusion in the registry
      is RFC Required in the RFC 5226 [RFC5226] sense for reserved JWT
      envelope parameter names that are intended to be interoperable
      between implementations.  The registry will just record the
      reserved envelope parameter name and a pointer to the RFC that
      defines it.  This specification defines inclusion of the envelope
      parameter names defined in Table 3.

   o  A new IANA registry entitled "JSON Web Token Algorithms" for
      reserved values used with the "alg" envelope parameter values used
      in a decoded JWT Envelope Segment.  Inclusion in the registry is
      RFC Required in the RFC 5226 [RFC5226] sense.  The registry will
      just record the "alg" value and a pointer to the RFC that defines
      it.  This specification defines inclusion of the algorithm values
      defined in Table 4.






Jones, et al.             Expires July 1, 2011                 [Page 19]


Internet-Draft            JSON Web Token (JWT)             December 2010


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.  Case sensitivity and more generally Unicode
   comparison issues that can cause security holes, especially in claim
   names and explain why Unicode Normalization is such a problem.

   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.  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.

10.1.  Unicode Comparison Security Issues

   Claim names in JWTs are Unicode strings.  For security reasons, the
   representations these names must be compared verbatim after
   performing any escape processing (as per RFC 4627 [RFC4627], Section
   2.5).  In particular, Unicode Normalization [USA15] or case folding
   MUST NOT be applied at any point to either the JSON string or to the
   string it is to be compared against.

   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.




Jones, et al.             Expires July 1, 2011                 [Page 20]


Internet-Draft            JSON Web Token (JWT)             December 2010


11.  Open Issues

   The following open issues have been identified during review of
   previous drafts.  Additional input on them is solicited.

   o  The draft currently defines no mechanism(s) for retrieving public
      keys that are not encoded as X.509 certificates.  A mechanism or
      mechanisms similar to the Magic Signatures key discovery process
      for Magic Keys could be added to future drafts.  Some have
      suggested that they keys themselves also be encoded as JWTs.

   o  Related to the above, it's not clear whether the "iss" claim
      should be expected to contain a location for retrieving non-X.509
      public keys, or whether a separate issuer key location parameter
      should be defined.  Also, does this belong in the envelope or the
      claims?


12.  Acknowledgements

   The authors acknowledge that the design of JWTs was intentionally
   influenced by the design and simplicity of Simple Web Tokens [SWT].
   Solutions for signing JSON tokens were also previously explored by
   Magic Signatures [MagicSignatures], JSON Simple Sign [JSS], and
   Canvas Applications [CanvasApp], all of which influenced this draft.


13.  Appendix - Non-Normative - JWT Examples

13.1.  JWT using HMAC SHA-256

13.1.1.  Encoding

   The Decoded JWT Claim Segment used in this example is:
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}

   Note that white space is explicitly allowed in Decoded JWT Claim
   Segments and no canonicalization is performed before encoding.  The
   following byte array contains the UTF-8 characters for the Decoded
   JWT Claim Segment:

   [123, 34, 105, 115, 115, 34, 58, 34, 106, 111, 101, 34, 44, 13, 10,
   32, 34, 101, 120, 112, 34, 58, 49, 51, 48, 48, 56, 49, 57, 51, 56,
   48, 44, 13, 10, 32, 34, 104, 116, 116, 112, 58, 47, 47, 101, 120, 97,
   109, 112, 108, 101, 46, 99, 111, 109, 47, 105, 115, 95, 114, 111,
   111, 116, 34, 58, 116, 114, 117, 101, 125]



Jones, et al.             Expires July 1, 2011                 [Page 21]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Base64url encoding the above yields the JWT Claim Segment value:
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ

   The following example JSON envelope object declares that the encoded
   object is a JSON Web Token (JWT) and the JWT Claim Segment is signed
   using the HMAC SHA-256 algorithm:
   {"typ":"JWT",
    "alg":"HS256"}

   The following byte array contains the UTF-8 characters for the
   Decoded JWT Envelope Segment:

   [123, 34, 116, 121, 112, 34, 58, 34, 74, 87, 84, 34, 44, 13, 10, 32,
   34, 97, 108, 103, 34, 58, 34, 72, 83, 50, 53, 54, 34, 125]

   Base64url encoding this UTF-8 representation yields this JWT Envelope
   Segment value:
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9

   HMACs are generated using keys.  This example used the key
   represented by the following byte array:

   [83, 159, 117, 12, 235, 169, 168, 200, 131, 152, 227, 246, 214, 212,
   188, 74, 71, 83, 244, 166, 90, 24, 239, 251, 32, 124, 6, 201, 194,
   104, 241, 62, 174, 246, 65, 111, 49, 52, 210, 118, 212, 124, 34, 88,
   167, 112, 84, 88, 83, 65, 155, 18, 234, 250, 224, 101, 147, 221, 23,
   104, 219, 170, 146, 215]

   Running the HMAC SHA-256 algorithm on the JWT Claim Segment with this
   key yields the following byte array:

   [223, 155, 172, 90, 63, 87, 240, 124, 6, 75, 224, 131, 115, 29, 73,
   63, 99, 102, 169, 202, 203, 193, 158, 4, 42, 159, 44, 53, 56, 95,
   221, 198]

   Base64url encoding the above HMAC output yields the JWT Crypto
   Segment value:
   35usWj9X8HwGS-CDcx1JP2NmqcrLwZ4EKp8sNThf3cY

   Combining these segments in the order Envelope.Claims.Signature with
   period characters between the segments yields this complete JWT (with
   line breaks for display purposes only):
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
35usWj9X8HwGS-CDcx1JP2NmqcrLwZ4EKp8sNThf3cY




Jones, et al.             Expires July 1, 2011                 [Page 22]


Internet-Draft            JSON Web Token (JWT)             December 2010


13.1.2.  Decoding

   Decoding the JWT first requires removing the base64url encoding from
   the JWT Envelope Segment and the JWT Claim Segment.  We base64url
   decode the segments per Section 7 and turn them into the
   corresponding UTF-8 byte arrays, which we then translate into the
   Decoded JWT Envelope Segment and Decoded JWT Claim Segment strings.

13.1.3.  Validating

   Next we validate the decoded results.  Since the "alg" parameter in
   the envelope is "HS256", we validate the HMAC SHA-256 signature
   contained in the JWT Crypto Segment.  If any of the validation steps
   fail, the token MUST be rejected.

   First, we validate that the decoded envelope and claim segment
   strings are both legal JSON.

   To validate the signature, we repeat the previous process of using
   the correct key and the JWT Claim Segment as input to a SHA-256 HMAC
   function and then taking the output, base64url encoding it, and
   determining if it matches the JWT Crypto Segment in the JWT.  If it
   matches exactly, the token has been validated.

13.2.  JWT using RSA SHA-256

13.2.1.  Encoding

   The Decoded JWT Claim Segment used in this example is the same as in
   the previous example:
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}

   Since the JWT Claim Segment will therefore be the same, its
   computation is not repeated here.  However, the Decoded JWT Envelope
   Segment is different in two ways: First, because a different
   algorithm is being used, the "alg" value is different.  Second, for
   illustration purposes only, the optional "typ" parameter is not used.
   (This difference is not related to the signature algorithm employed.)
   The Decoded JWT Envelope Segment used is:
   {"alg":"RS256"}

   The following byte array contains the UTF-8 characters for the
   Decoded JWT Envelope Segment:

   [123, 34, 97, 108, 103, 34, 58, 34, 82, 83, 50, 53, 54, 34, 125]




Jones, et al.             Expires July 1, 2011                 [Page 23]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Base64url encoding this UTF-8 representation yields this JWT Envelope
   Segment value:
   eyJhbGciOiJSUzI1NiJ9

   The RSA key consists of a public part (n, e), and a private exponent
   d.  The values of the RSA key used in this example, presented as the
   byte arrays representing big endian integers are:

   +-----------+-------------------------------------------------------+
   | Parameter | Value                                                 |
   | Name      |                                                       |
   +-----------+-------------------------------------------------------+
   | n         | [210, 252, 123, 106, 10, 30, 108, 103, 16, 74, 235,   |
   |           | 143, 136, 178, 87, 102, 155, 77, 246, 121, 221, 173,  |
   |           | 9, 155, 92, 74, 108, 217, 168, 128, 21, 181, 161, 51, |
   |           | 191, 11, 133, 108, 120, 113, 182, 223, 0, 11, 85, 79, |
   |           | 206, 179, 194, 237, 81, 43, 182, 143, 20, 92, 110,    |
   |           | 132, 52, 117, 47, 171, 82, 161, 207, 193, 36, 64,     |
   |           | 143, 121, 181, 138, 69, 120, 193, 100, 40, 133, 87,   |
   |           | 137, 247, 162, 73, 227, 132, 203, 45, 159, 174, 45,   |
   |           | 103, 253, 150, 251, 146, 108, 25, 142, 7, 115, 153,   |
   |           | 253, 200, 21, 192, 175, 9, 125, 222, 90, 173, 239,    |
   |           | 244, 77, 231, 14, 130, 127, 72, 120, 67, 36, 57, 191, |
   |           | 238, 185, 96, 104, 208, 71, 79, 197, 13, 109, 144,    |
   |           | 191, 58, 152, 223, 175, 16, 64, 200, 156, 2, 214,     |
   |           | 146, 171, 59, 60, 40, 150, 96, 157, 134, 253, 115,    |
   |           | 183, 116, 206, 7, 64, 100, 124, 238, 234, 163, 16,    |
   |           | 189, 18, 249, 133, 168, 235, 159, 89, 253, 212, 38,   |
   |           | 206, 165, 178, 18, 15, 79, 42, 52, 188, 171, 118, 75, |
   |           | 126, 108, 84, 214, 132, 2, 56, 188, 196, 5, 135, 165, |
   |           | 158, 102, 237, 31, 51, 137, 69, 119, 99, 92, 71, 10,  |
   |           | 247, 92, 249, 44, 32, 209, 218, 67, 225, 191, 196,    |
   |           | 25, 226, 34, 166, 240, 208, 187, 53, 140, 94, 56,     |
   |           | 249, 203, 5, 10, 234, 254, 144, 72, 20, 241, 172, 26, |
   |           | 164, 156, 202, 158, 160, 202, 131]                    |
   | e         | [1, 0, 1]                                             |















Jones, et al.             Expires July 1, 2011                 [Page 24]


Internet-Draft            JSON Web Token (JWT)             December 2010


   | d         | [95, 135, 19, 181, 226, 88, 254, 9, 248, 21, 131,     |
   |           | 236, 92, 31, 43, 117, 120, 177, 230, 252, 44, 131,    |
   |           | 81, 75, 55, 145, 55, 17, 161, 186, 68, 154, 21, 31,   |
   |           | 225, 203, 44, 160, 253, 51, 183, 113, 230, 138, 59,   |
   |           | 25, 68, 100, 157, 200, 103, 173, 28, 30, 82, 64, 187, |
   |           | 133, 62, 95, 36, 179, 52, 89, 177, 64, 40, 210, 214,  |
   |           | 99, 107, 239, 236, 30, 141, 169, 116, 179, 82, 252,   |
   |           | 83, 211, 246, 18, 126, 168, 163, 194, 157, 209, 79,   |
   |           | 57, 65, 104, 44, 86, 167, 135, 104, 22, 78, 77, 218,  |
   |           | 143, 6, 203, 249, 199, 52, 170, 232, 0, 50, 36, 39,   |
   |           | 142, 169, 69, 74, 33, 177, 124, 176, 109, 23, 128,    |
   |           | 117, 134, 140, 192, 91, 61, 182, 255, 29, 253, 195,   |
   |           | 213, 99, 120, 180, 237, 173, 237, 240, 195, 122, 76,  |
   |           | 220, 38, 209, 212, 154, 194, 111, 111, 227, 181, 34,  |
   |           | 10, 93, 210, 147, 150, 98, 27, 188, 104, 140, 242,    |
   |           | 238, 226, 198, 224, 213, 77, 163, 199, 130, 1, 76,    |
   |           | 208, 115, 157, 178, 82, 204, 81, 202, 235, 168, 211,  |
   |           | 241, 184, 36, 186, 171, 36, 208, 104, 236, 144, 50,   |
   |           | 100, 215, 214, 120, 171, 8, 240, 110, 201, 231, 226,  |
   |           | 61, 150, 6, 40, 183, 68, 191, 148, 179, 105, 70, 86,  |
   |           | 70, 60, 126, 65, 115, 153, 237, 115, 208, 118, 200,   |
   |           | 145, 252, 244, 99, 169, 170, 156, 230, 45, 169, 205,  |
   |           | 23, 226, 55, 220, 42, 128, 2, 241]                    |
   +-----------+-------------------------------------------------------+

   The RSA private key (n, d) is then passed to the RSA signing
   function, which also takes the hash type, SHA-256, and the JWT Claim
   Segment as inputs.  The result of the signature is a byte array S,
   which represents a big endian integer.  In this example, S is:






















Jones, et al.             Expires July 1, 2011                 [Page 25]


Internet-Draft            JSON Web Token (JWT)             December 2010


   +--------+----------------------------------------------------------+
   | Result | Value                                                    |
   | Name   |                                                          |
   +--------+----------------------------------------------------------+
   | S      | [208, 141, 219, 44, 66, 129, 179, 230, 69, 120, 123,     |
   |        | 108, 203, 96, 182, 145, 66, 179, 198, 104, 43, 187, 199, |
   |        | 159, 175, 5, 217, 101, 109, 236, 88, 136, 193, 133, 79,  |
   |        | 39, 162, 131, 58, 114, 133, 202, 171, 227, 135, 157,     |
   |        | 123, 188, 90, 111, 66, 241, 38, 238, 59, 18, 125, 146,   |
   |        | 129, 14, 54, 183, 10, 221, 33, 105, 37, 173, 119, 239,   |
   |        | 92, 27, 232, 175, 173, 49, 21, 28, 252, 237, 183, 107,   |
   |        | 98, 156, 113, 116, 162, 219, 53, 96, 44, 214, 175, 154,  |
   |        | 61, 100, 175, 90, 118, 247, 42, 196, 45, 74, 217, 145,   |
   |        | 92, 39, 123, 224, 247, 171, 206, 203, 91, 167, 103, 57,  |
   |        | 163, 87, 172, 67, 77, 255, 9, 218, 107, 62, 228, 71,     |
   |        | 239, 36, 246, 23, 96, 108, 28, 19, 179, 24, 167, 196,    |
   |        | 42, 97, 198, 80, 241, 79, 31, 0, 85, 17, 50, 6, 143,     |
   |        | 238, 214, 131, 246, 13, 49, 111, 30, 142, 182, 145, 200, |
   |        | 17, 127, 76, 236, 69, 66, 133, 198, 137, 103, 45, 3, 48, |
   |        | 123, 203, 17, 162, 1, 105, 133, 22, 105, 25, 63, 173,    |
   |        | 186, 231, 206, 246, 22, 243, 250, 53, 237, 209, 36, 111, |
   |        | 168, 11, 40, 237, 179, 83, 125, 180, 84, 231, 129, 37,   |
   |        | 236, 172, 22, 234, 58, 198, 187, 124, 65, 145, 148, 227, |
   |        | 122, 177, 16, 176, 84, 28, 1, 141, 179, 57, 96, 232,     |
   |        | 215, 51, 7, 49, 63, 195, 155, 94, 51, 22, 239, 90, 138,  |
   |        | 207, 41, 62]                                             |
   +--------+----------------------------------------------------------+

   Base64url encoding the signature produces this value for the JWT
   Crypto Segment:
0I3bLEKBs-ZFeHtsy2C2kUKzxmgru8efrwXZZW3sWIjBhU8nooM6coXKq-OHnXu8Wm9C8SbuOxJ9koEONrcK3SFpJa1371wb6K-tMRUc_O23a2KccXSi2zVgLNavmj1kr1p29yrELUrZkVwne-D3q87LW6dnOaNXrENN_wnaaz7kR-8k9hdgbBwTsxinxCphxlDxTx8AVREyBo_u1oP2DTFvHo62kcgRf0zsRUKFxolnLQMwe8sRogFphRZpGT-tuufO9hbz-jXt0SRvqAso7bNTfbRU54El7KwW6jrGu3xBkZTjerEQsFQcAY2zOWDo1zMHMT_Dm14zFu9ais8pPg

   Combining these segments in the order Envelope.Claims.Signature with
   period characters between the segments yields this complete JWT (with
   line breaks for display purposes only):
eyJhbGciOiJSUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
0I3bLEKBs-ZFeHtsy2C2kUKzxmgru8efrwXZZW3sWIjBhU8nooM6coXKq-OHnXu8Wm9C8SbuOxJ9koEONrcK3SFpJa1371wb6K-tMRUc_O23a2KccXSi2zVgLNavmj1kr1p29yrELUrZkVwne-D3q87LW6dnOaNXrENN_wnaaz7kR-8k9hdgbBwTsxinxCphxlDxTx8AVREyBo_u1oP2DTFvHo62kcgRf0zsRUKFxolnLQMwe8sRogFphRZpGT-tuufO9hbz-jXt0SRvqAso7bNTfbRU54El7KwW6jrGu3xBkZTjerEQsFQcAY2zOWDo1zMHMT_Dm14zFu9ais8pPg

13.2.2.  Decoding

   Decoding the JWT from this example requires processing the JWT
   Envelope Segment and Claim Segment exactly as done in the first
   example.





Jones, et al.             Expires July 1, 2011                 [Page 26]


Internet-Draft            JSON Web Token (JWT)             December 2010


13.2.3.  Validating

   Since the "alg" parameter in the envelope is "RS256", we validate the
   RSA SHA-256 signature contained in the JWT Crypto Segment.  If any of
   the validation steps fail, the token MUST be rejected.

   First, we validate that the decoded envelope and claim segment
   strings are both legal JSON.

   Validating the JWT Crypto Segment is a little different from the
   previous example.  First, we base64url decode the JWT Crypto Segment
   to produce a signature S to check.  We then pass (n, e), S and the
   JWT Claim Segment to an RSA signature verifier that has been
   configured to use the SHA-256 hash function.

13.3.  JWT using ECDSA P-256 SHA-256

13.3.1.  Encoding

   The Decoded JWT Claim Segment used in this example is the same as in
   the previous examples:
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}

   Since the JWT Claim Segment will therefore be the same, its
   computation is not repeated here.  However, the Decoded JWT Envelope
   Segment is differs from the previous example because a different
   algorithm is being used.  The Decoded JWT Envelope Segment used is:
   {"alg":"ES256"}

   The following byte array contains the UTF-8 characters for the
   Decoded JWT Envelope Segment:

   [123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 50, 53, 54, 34, 125]

   Base64url encoding this UTF-8 representation yields this JWT Envelope
   Segment value:
   eyJhbGciOiJFUzI1NiJ9

   The ECDSA key consists of a public part, the EC point (x, y), and a
   private part d.  The values of the ECDSA key used in this example,
   presented as the byte arrays representing big endian integers are:








Jones, et al.             Expires July 1, 2011                 [Page 27]


Internet-Draft            JSON Web Token (JWT)             December 2010


   +-----------+-------------------------------------------------------+
   | Parameter | Value                                                 |
   | Name      |                                                       |
   +-----------+-------------------------------------------------------+
   | x         | [48, 160, 66, 76, 210, 28, 41, 68, 131, 138, 45, 117, |
   |           | 201, 43, 55, 231, 110, 162, 13, 159, 0, 137, 58, 59,  |
   |           | 78, 238, 138, 60, 10, 175, 236, 62]                   |
   | y         | [224, 75, 101, 233, 36, 86, 217, 136, 139, 82, 179,   |
   |           | 121, 189, 251, 213, 30, 232, 105, 239, 31, 15, 198,   |
   |           | 91, 102, 89, 105, 91, 108, 206, 8, 23, 35]            |
   | d         | [243, 189, 12, 7, 168, 31, 185, 50, 120, 30, 213, 39, |
   |           | 82, 246, 12, 200, 154, 107, 229, 229, 25, 52, 254, 1, |
   |           | 147, 141, 219, 85, 216, 247, 120, 1]                  |
   +-----------+-------------------------------------------------------+

   The ECDSA private part d is then passed to an ECDSA signing function,
   which also takes the curve type, P-256, the hash type, SHA-256, and
   the JWT Claim Segment as inputs.  The result of the signature is the
   EC point (R, S), where R and S are unsigned integers.  In this
   example, the R and S values, given as byte arrays representing big
   endian integers are:

   +--------+----------------------------------------------------------+
   | Result | Value                                                    |
   | Name   |                                                          |
   +--------+----------------------------------------------------------+
   | R      | [175, 11, 115, 42, 160, 182, 181, 28, 135, 222, 52, 154, |
   |        | 182, 237, 206, 137, 82, 20, 243, 7, 12, 164, 107, 72,    |
   |        | 236, 187, 241, 190, 26, 76, 32, 181]                     |
   | S      | [120, 23, 189, 205, 202, 13, 177, 187, 23, 47, 12, 227,  |
   |        | 237, 250, 230, 233, 245, 216, 9, 170, 24, 185, 198, 187, |
   |        | 193, 94, 158, 117, 167, 88, 153, 196]                    |
   +--------+----------------------------------------------------------+

   Concatenating the S array to the end of the R array and base64url
   encoding the result produces this value for the JWT Crypto Segment:
rwtzKqC2tRyH3jSatu3OiVIU8wcMpGtI7LvxvhpMILV4F73Nyg2xuxcvDOPt-ubp9dgJqhi5xrvBXp51p1iZxA

   Combining these segments in the order Envelope.Claims.Signature with
   period characters between the segments yields this complete JWT (with
   line breaks for display purposes only):
eyJhbGciOiJFUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ
.
rwtzKqC2tRyH3jSatu3OiVIU8wcMpGtI7LvxvhpMILV4F73Nyg2xuxcvDOPt-ubp9dgJqhi5xrvBXp51p1iZxA





Jones, et al.             Expires July 1, 2011                 [Page 28]


Internet-Draft            JSON Web Token (JWT)             December 2010


13.3.2.  Decoding

   Decoding the JWT from this example requires processing the JWT
   Envelope Segment and Claim Segment exactly as done in the first
   example.

13.3.3.  Validating

   Since the "alg" parameter in the envelope is "ES256", we validate the
   ECDSA P-256 SHA-256 signature contained in the JWT Crypto Segment.
   If any of the validation steps fail, the token MUST be rejected.

   First, we validate that the decoded envelope and claim segment
   strings are both legal JSON.

   Validating the JWT Crypto Segment is a little different from the
   first example.  First, we base64url decode the JWT Crypto Segment as
   in the previous examples but we then need to split the 64 member byte
   array that must result into two 32 byte arrays, the first R and the
   second S. We then pass (x, y), (R, S) and the JWT Claim Segment to an
   ECDSA signature verifier that has been configured to use the P-256
   curve with the SHA-256 hash function.

   As explained in Section 8.3, the use of the k value in ECDSA means
   that we cannot validate the correctness of the signature in the same
   way we validated the correctness of the HMAC.  Instead,
   implementations MUST use an ECDSA validator to validate the
   signature.


14.  Appendix - Non-Normative - Notes on implementing base64url encoding
     without padding

   This appendix describes how to implement base64url encoding and
   decoding functions without padding based upon standard base64
   encoding and decoding functions that do use padding.

   To be concrete, example C# code implementing these functions is shown
   below.  Similar code could be used in other languages.












Jones, et al.             Expires July 1, 2011                 [Page 29]


Internet-Draft            JSON Web Token (JWT)             December 2010


   static string base64urlencode(byte [] arg)
   {
     string s = Convert.ToBase64String(arg); // Standard base64 encoder
     s = s.Split('=')[0]; // Remove any trailing '='s
     s = s.Replace('+', '-'); // 62nd char of encoding
     s = s.Replace('/', '_'); // 63rd char of encoding
     return s;
   }

   static byte [] base64urldecode(string arg)
   {
     string s = arg;
     s = s.Replace('-', '+'); // 62nd char of encoding
     s = s.Replace('_', '/'); // 63rd char of encoding
     switch (s.Length % 4) // Pad with trailing '='s
     {
       case 0: break; // No pad chars in this case
       case 2: s += "=="; break; // Two pad chars
       case 3: s += "="; break; // One pad char
       default: throw new System.Exception(
         "Illegal base64url string!");
     }
     return Convert.FromBase64String(s); // Standard base64 decoder
   }

   As per the example code above, the number of '=' padding characters
   that needs to be added to the end of a base64url encoded string
   without padding to turn it into one with padding is a deterministic
   function of the length of the encoded string.  Specifically, if the
   length mod 4 is 0, no padding is added; if the length mod 4 is 2, two
   '=' padding characters are added; if the length mod 4 is 3, one '='
   padding character is added; if the length mod 4 is 1, the input is
   malformed.

   An example correspondence between unencoded and encoded values
   follows.  The byte sequence below encodes into the string below,
   which when decoded, reproduces the byte sequence.
   3 236 255 224 193
   A-z_4ME


15.  Appendix - Non-Normative - 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



Jones, et al.             Expires July 1, 2011                 [Page 30]


Internet-Draft            JSON Web Token (JWT)             December 2010


   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.


16.  Appendix - Non-Normative - 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.


17.  References

17.1.  Normative References

   [FIPS.180-3]
              National Institute of Standards and Technology, "Secure
              Hash Standard (SHS)", FIPS PUB 180-3, October 2008.

   [FIPS.186-3]
              National Institute of Standards and Technology, "Digital
              Signature Standard (DSS)", FIPS PUB 186-3, June 2009.

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, November 1996.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              February 1997.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate



Jones, et al.             Expires July 1, 2011                 [Page 31]


Internet-Draft            JSON Web Token (JWT)             December 2010


              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.

   [RFC3447]  Jonsson, J. and B. Kaliski, "Public-Key Cryptography
              Standards (PKCS) #1: RSA Cryptography Specifications
              Version 2.1", RFC 3447, February 2003.

   [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.

17.2.  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", August 2010.

   [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



Jones, et al.             Expires July 1, 2011                 [Page 32]


Internet-Draft            JSON Web Token (JWT)             December 2010


              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.


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


   Yaron Y. Goland
   Microsoft

   Email: yarong@microsoft.com


   John Panzer
   Google

   Email: jpanzer@google.com





Jones, et al.             Expires July 1, 2011                 [Page 33]


Internet-Draft            JSON Web Token (JWT)             December 2010


   Nat Sakimura
   Nomura Research Institute

   Email: n-sakimura@nri.co.jp















































Jones, et al.             Expires July 1, 2011                 [Page 34]


Html markup produced by rfcmarkup 1.123, available from https://tools.ietf.org/tools/rfcmarkup/