datatracker.ietf.org
Sign in
Version 5.3.0, 2014-04-12
Report a bug

The OAuth 2.0 Authorization Framework: Holder-of-the-Key Token Usage
draft-tschofenig-oauth-hotk-03

Document type: Active Internet-Draft (individual)
Document stream: No stream defined
Last updated: 2014-01-13
Intended RFC status: Unknown
Other versions: plain text, xml, pdf, html

Stream State:No stream defined
Document shepherd: No shepherd assigned

IESG State: I-D Exists
Responsible AD: (None)
Send notices to: No addresses provided

Network Working Group                                         J. Bradley
Internet-Draft                                             Ping Identity
Intended status: Standards Track                                 P. Hunt
Expires: July 18, 2014                                Oracle Corporation
                                                              T. Nadalin
                                                               Microsoft
                                                           H. Tschofenig

                                                        January 14, 2014

  The OAuth 2.0 Authorization Framework: Holder-of-the-Key Token Usage
                   draft-tschofenig-oauth-hotk-03.txt

Abstract

   OAuth 2.0 deployments currently rely on bearer tokens for securing
   access to protected resources.  Bearer tokens require Transport Layer
   Security to be used between an OAuth client and the resource server
   when presenting the access token.  The security model is based on
   proof-of-possession: access token storage and transfer has to be done
   with care to prevent leakage.

   There are, however, use cases that require a more active involvement
   of the OAuth client for an increased level of security, particularly
   to secure against token leakage.  This document specifies an OAuth
   security framework using the holder-of-the-key concept, which
   requires the OAuth client when presenting an OAuth access token to
   also demonstrate knowledge of keying material that is bound to the
   token.

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 18, 2014.

Bradley, et al.           Expires July 18, 2014                 [Page 1]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

Copyright Notice

   Copyright (c) 2014 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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Protocol Specification  . . . . . . . . . . . . . . . . . . .   3
     3.1.  Binding a Key to an Access Token  . . . . . . . . . . . .   4
       3.1.1.  Symmetric Keys  . . . . . . . . . . . . . . . . . . .   4
       3.1.2.  Asymmetric Keys . . . . . . . . . . . . . . . . . . .   7
     3.2.  Accessing a Protected Resource  . . . . . . . . . . . . .   9
       3.2.1.  Symmetric Keys  . . . . . . . . . . . . . . . . . . .   9
       3.2.2.  Asymmetric Keys . . . . . . . . . . . . . . . . . . .  11
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
     4.1.  Security Threats  . . . . . . . . . . . . . . . . . . . .  12
     4.2.  Threat Mitigation . . . . . . . . . . . . . . . . . . . .  12
     4.3.  Summary of Recommendations  . . . . . . . . . . . . . . .  13
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     5.1.  OAuth Parameters Registration . . . . . . . . . . . . . .  14
     5.2.  The 'hotk' JSON Web Token Claims  . . . . . . . . . . . .  15
     5.3.  The 'hotk' OAuth Access Token Type  . . . . . . . . . . .  15
     5.4.  Profile Registry  . . . . . . . . . . . . . . . . . . . .  15
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   At the time of writing the OAuth 2.0 [3] and accompanying protocols
   offer one main security mechanism to access protected resources,
   namely the bearer token.  In [12] a bearer token is defined as

Bradley, et al.           Expires July 18, 2014                 [Page 2]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

      A security token with the property that any party in possession of
      the token (a "bearer") can use the token in any way that any other
      party in possession of it can.  Using a bearer token does not
      require a bearer to prove possession of cryptographic key
      material.

   The bearer token meets the security needs of number of use cases
   OAuth had been designed for.  There are, however, scenarios that
   require stronger security properties and ask for active participation
   of the OAuth client software in form of cryptographic computations
   when presenting an access token to a resource server.

   This specification defines a new security mechanism for usage with
   OAuth that combines various existing specifications to offer enhanced
   security properties for OAuth.  The incredients for this security
   solution are:

   1.  A mechanism for dynamic key distribution.

   2.  Data elements to bind emphemeral keying material to an access
       token.  For the access token we assume a JSON Web Token (JWT) [6]
       in this specification to specify a complete solution.  Future
       specifications may make this functionality available to other
       access token formats as well.

   3.  A mechanism to allow the OAuth client to demonstrate a proof of
       possession.

   The rest of the document describes how these different components
   work together.

2.  Terminology

   The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
   'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this
   specification are to be interpreted as described in [1].

3.  Protocol Specification

   To describe the architecture of the proposed security mechanism it is
   best to start by looking at the main OAuth 2.0 protocol exchange
   sequence.  Figure 1 shows the abstract OAuth 2.0 protocol exchanges
   graphically.  The exchange in this document will focus on two
   interactions, namely

   1.  to allow the client to obtain the ephemeral asymmetric
       credentails in step (D)

Bradley, et al.           Expires July 18, 2014                 [Page 3]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   2.  to use the obtained asymmetric credentials for the interaction
       with the resource server in step (E)

        +--------+                               +---------------+
        |        |--(A)- Authorization Request ->|   Resource    |
        |        |                               |     Owner     |
        |        |<-(B)-- Authorization Grant ---|               |
        |        |                               +---------------+
        |        |
        |        |                               +---------------+
        |        |--(C)-- Authorization Grant -->| Authorization |
        | Client |                               |     Server    |
        |        |<-(D)----- Access Token -------|               |
        |        |                               +---------------+
        |        |
        |        |                               +---------------+
        |        |--(E)----- Access Token ------>|    Resource   |
        |        |                               |     Server    |
        |        |<-(F)--- Protected Resource ---|               |
        +--------+                               +---------------+

                Figure 1: Abstract OAuth 2.0 Protocol Flow

3.1.  Binding a Key to an Access Token

   OAuth 2.0 offers different ways to obtain an access token, namely
   using authorization grants and using a refresh token.  The core OAuth
   specification defines four authorization grants, see Section 1.3 of
   [3], and [11] adds an assertion-based authorization grant to that
   list.

   This document extends the communication with the token endpoint.  The
   token endpoint, which is described in Section 3.2 of [3], is used
   with every authorization grant except for the implicit grant type.
   In the implicit grant type the access token is issued directly.

   Two types of keying material can be bound to an access token, namely
   symmetric keys and asymmetric keys, and we explain them in separate
   sub-sections.

3.1.1.  Symmetric Keys

   In case a symmetric key shall be bound to an access token then the
   following procedure is applicable.  In the request message from the
   OAuth client to the authorization server the following parameters
   MUST be included:

Bradley, et al.           Expires July 18, 2014                 [Page 4]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   token_type:  REQUIRED.  For the symmetric holder-of-the-key variant
         the value MUST be set to "hotk-sk".

   profile:  REQUIRED.  The profile parameter provides information about
         what mechanisms the client supports to provide proof of
         possession of the key towards a resource server.  The value
         MUST be taken from the algorithm registry created in
         Section 5.4.  Algorithm names are case-sensitive.  If the
         client supports more than one profile then each individual
         value MUST be separated by a comma.

   For example, the client makes the following HTTP request using TLS
   (extra line breaks are for display purposes only):

        POST /token HTTP/1.1
        Host: server.example.com
        Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
        Content-Type: application/x-www-form-urlencoded;charset=UTF-8

        grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
        &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
        &token_type=hotk-sk
        &profile=jws,mac

                Example Request to the Authorization Server

   If the access token request is valid and authorized, the
   authorization server issues an access token and optionally a refresh
   token.  If the request client authentication failed or is invalid,
   the authorization server returns an error response as described in
   Section 5.2 of [3].

   The authorization server MUST include the following parameters in a
   successful response, if it supports any of the profiles listed by the
   client.

   id:   REQUIRED.  An ephemeral and unique key identifier.  The
         authorization server MUST NOT select the same key identifier
         twice within the lifetime of the access token, which is
         indicated by the 'expires_in' parameter.

   key:  REQUIRED.  A fresh and unique shared symmetric secret with
         sufficient entrophy.

   profile:  REQUIRED.  The profile parameter provides further
         information about how the client has to provide proof of

Bradley, et al.           Expires July 18, 2014                 [Page 5]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

         possession of the key with the resource server.  The
         authorization server chooses a value from the list of supported
         mechanisms supported by the client.

   For example:

     HTTP/1.1 200 OK
     Content-Type: application/json
     Cache-Control: no-store

     {
       "access_token":"SlAV.....32hkKG",
       "token_type":"hotk-sk",
       "expires_in":3600,
       "refresh_token":"8xLOxBtZp8",
       "id":"client12345@example.com",
       "key":"adijq39jdlaska9asud",
       "profile":"jws"
     }

     The content of the 'access_token' MUST contain
     the key identifier value in the 'hotk' element,
     as shown in the example below.

       {"typ":"JWT",
        "alg":"HS256"
       }
       .
       {"iss":"authorization-server-id",
        "exp":1300819380,
        "hotk":"client12345@example.com"
       }
       .
       bbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZC

   DISCUSSION: Should we put the encrypted key into the access token?
   This would make the mechanism more similar to a Kerberos-based
   scheme.

   The key identifier, the key, and the profile name MUST NOT include
   characters other than:

     %x20-21 / %x23-5B / %x5D-7E
     ; Any printable ASCII character except for <"> and <\>

Bradley, et al.           Expires July 18, 2014                 [Page 6]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

3.1.2.  Asymmetric Keys

   In case an asymmetric key shall be bound to an access token then the
   following procedure is applicable.  In the request message from the
   OAuth client to the authorization server the following parameters
   MUST be included:

   token_type:  REQUIRED.  For the asymmetric holder-of-the-key variant
         the value MUST be set to "hotk-pk".

   pk_info:  REQUIRED.  This field contains information about the public
         key the client would like to bind to the access token in the
         JSON Web Key format.  The public key is "application/x-www-
         form-urlencoded" encoded.

   For example, the client makes the following HTTP request using TLS
   (extra line breaks are for display purposes only):

        POST /token HTTP/1.1
        Host: server.example.com
        Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
        Content-Type: application/x-www-form-urlencoded;charset=UTF-8

        grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
        &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
        &token_type=hotk-pk
        &pk_info=eZQQYbYS6WxS...lxlOB

      whereby the content of the pk_info field represents the following
      structure:

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

                Example Request to the Authorization Server

Bradley, et al.           Expires July 18, 2014                 [Page 7]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   If the access token request is valid and authorized, the
   authorization server issues an access token and optionally a refresh
   token.  If the request client authentication failed or is invalid,
   the authorization server returns an error response as described in
   Section 5.2 of [3].

   The authorization server also places information about the public key
   used by the client into the access token to create the binding
   between the two.  The new token type, called 'hotk-pk', is placed
   into the 'token_type' parameter.

   An example of a successful response is shown below:

Bradley, et al.           Expires July 18, 2014                 [Page 8]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

        HTTP/1.1 200 OK
        Content-Type: application/json;charset=UTF-8
        Cache-Control: no-store
        Pragma: no-cache

        {
          "access_token":"2YotnFZFE....jr1zCsicMWpAA",
          "token_type":"hotk-pk",
          "expires_in":3600,
          "refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA"
        }

       whereby the content of the 'access_token' field, for example,
       contains an encoded JWT with the following raw structure:

       {"typ":"JWT",
        "alg":"HS256"}
       .
       {"iss":"authorization-server-id",
        "exp":1300819380,
        "hotk": {"keys":
        [
          {"alg":"RSA",
           "mod": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx
       4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMs
       tn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2
       QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbI
       SD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqb
       w0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
           "exp":"AQAB",
           "kid":"2011-04-29"}
        ]
       }
       }
       .
       bbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZC

              Example Response from the Authorization Server

3.2.  Accessing a Protected Resource

   Accessing a protected resource depends on the chosen credential type.

3.2.1.  Symmetric Keys

   When a symmetric key was used as a holder-of-the-key then the client
   has to demonstrate possession of the key that corresponds to the key
   identifier found in the access token.

Bradley, et al.           Expires July 18, 2014                 [Page 9]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   This specification defines three ways for providing this proof of
   possession, which are indicated as profiles in Section 3.1.1:

   jws:  When the 'jws' profile is chosen then the client MUST compute
      the following string by concatenating together, in order, the
      following HTTP request elements:

      1.  The HTTP request method in upper case.  For example: "HEAD",
          "GET", "POST", etc.

      2.  The HTTP request-URI as defined by Section 5.1.2 of [2].

      3.  The hostname included in the HTTP request using the "Host"
          request header field in lower case.

      4.  The port as included in the HTTP request using the "Host"
          request header field.  If the header field does not include a
          port, the default value for the scheme MUST be used (e.g., 80
          for HTTP and 443 for HTTPS).

      5.  The value of the "ext" "Authorization" request header field
          attribute if one was included in the request, otherwise, an
          empty string.

      Each element is followed by a new line character (%x0A) including
      the last element and even when an element value is an empty
      string.  The resulting value MUST be put into the "request"
      element of a JSON document that is then subject to JWS processing
      [7].  The resulting JWS structure is put into the body of the HTTP
      request.  A receiving authorization server MUST use the value in
      the 'kid' structure to identify the shared key and then use that
      key to verify the keyed message digest.  Additionally, the content
      of the 'request' field needs to be verified against the HTTP
      header information.  If any of these verification steps fail then
      the request to the protected resource MUST fail with a "401
      Unauthorized" error message back to the OAuth client.

      The following example shows and the corresponding encoding in a
      JWS structure:

Bradley, et al.           Expires July 18, 2014                [Page 10]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   1) HTTP Request

        POST /request?b5=%3D%253D&a3=a&c%40=&a2=r%20b&c2&a3=2+q HTTP/1.1
        Host: example.com

   2) JWS Document

      {"typ":"HOTK-SK",
       "alg":"HS256",
       "kid":"client12345@example.com",
       "timestamp":"2012-07-15T10:20:00.000-05:00" }
      .
      {"request":"POST/request?b5=%3D%253D&a3=a&c%40=&a2=r%20b&c2&a3=
       2+qexample.com80"}
      .
      dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk

                                JWS Example

   mac:  When the 'mac' profile is chosen then the client MUST follow
      the description in [10].

3.2.2.  Asymmetric Keys

   The client accesses protected resources by presenting the access
   token to the resource server.  It does so via a Transport Layer
   Security (TLS) secured channel.  Since the client had previously
   bound a public key to an access token it selects this key for usage
   with TLS as described in [5].

   The resource server validates the access token and ensure it has not
   expired and that its scope covers the requested resource.
   Additionally, the resource server verifies that the public key
   presented during the TLS handshake corresponds to the public key that
   is contained in the access token.

   Note that this step confirms that the client is in possession of the
   private key corresponding to the public key previously bound to the
   access token.  Information about the client authentication may be
   contained in the token in case the authorization server added this
   information when it authenticated the client.

4.  Security Considerations

Bradley, et al.           Expires July 18, 2014                [Page 11]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

4.1.  Security Threats

   The following list presents several common threats against protocols
   utilizing some form of tokens.  This list of threats is based on NIST
   Special Publication 800-63 [14].  We exclude a discussion of threats
   related to any form of registration and authentication.

   Token manufacture/modification:  An attacker may craft a fake token
      or modify the token content (such as the authentication or
      attribute statements), causing a resource server to grant
      inappropriate access to the attacker.  For example, an attacker
      may modify the token to extend the validity period or the scope to
      have extended access to information.

   Token disclosure:  Tokens may contain authentication and attribute
      statements that include sensitive information.

   Token redirect:  An attacker uses a token generated for consumption
      by one resource server to gain access to a different resource
      server that mistakenly believes the token to be for it.

   Token reuse:  An attacker attempts to use a token that has already
      been used with that resource server in the past.

4.2.  Threat Mitigation

   A large range of threats can be mitigated by protecting the contents
   of the access token by using a digital signature or a Message
   Authentication Code (MAC).  Consequently, the token integrity
   protection MUST be sufficient to prevent the token from being
   modified.

   To deal with token redirect, it is important for the authorization
   server to include the identity of the intended recipients (the
   audience), typically a single resource server (or a list of resource
   servers), in the token.  Restricting the use of the token to a
   specific scope is also RECOMMENDED.

   The authorization server MUST implement and use TLS.  Which
   version(s) ought to be implemented will vary over time, and depend on
   the widespread deployment and known security vulnerabilities at the
   time of implementation.  At the time of this writing, TLS version 1.2
   [8] is the most recent version.  The client MUST validate the TLS
   certificate chain when making requests to protected resources,
   including checking the Certificate Revocation List (CRL) [9].

   For the interaction between the client and the resource server this
   specification requires a TLS extension for usage with out-of-band

Bradley, et al.           Expires July 18, 2014                [Page 12]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   validation [5] to be used that allows clients to present raw public
   keys for asymmetric holder-of-the-key usage.

   With the usage of the holder-of-the-key concept it is not possible
   for any party other than the legitimate client to use an access token
   and to re-use it without knowing the corresponding asymmetric key
   pair.  This mechanism prevents against token disclosure.

   With the usage of the asymmetric holder-of-the-key concept the
   following deployment consideration needs to be taken into
   consideration.  In some deployments, including those utilizing load
   balancers, the TLS connection to the resource server terminates prior
   to the actual server that provides the resource.  This could leave
   the token unprotected between the front end server where the TLS
   connection terminates and the back end server that provides the
   resource.

   Client implementations must be carefully implemented to avoid leaking
   the ephemeral credentials (either the private key from the asymmetric
   credential or the shared secret).

   Token replay is also not possible since an eavesdropper will also
   have to obtain the corresponding private key or shared secret that is
   bound to the access token.  Nevertheless, it is good practice to
   limit the lifetime of the access token and therefore the lifetime of
   associated key.

4.3.  Summary of Recommendations

   The following three items represent the main recommendations:

   Safeguard the private key/shared secret:  Client implementations MUST
      ensure that the ephemeral private key / shared secret is not
      leaked to third parties, since those will be able to use the
      access token together with the keying material to gain access to
      protected resources.

   Switch keying material regularly:  Clients can at any time create a
      new ephemeral credential and associate it with an access token.
      For example, a client presents a new public key when requesting an
      access token with the help of a refresh token.  Nevertheless, the
      lifetime of these access token may be longer than the lifetime of
      bearer tokens.

   Issue scoped bearer tokens:  Token servers SHOULD issue bearer tokens
      that contain an audience restriction, scoping their use to the
      intended relying party or set of relying parties.

Bradley, et al.           Expires July 18, 2014                [Page 13]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

5.  IANA Considerations

   This document requires IANA to take the following actions.

5.1.  OAuth Parameters Registration

   This specification registers the following parameters in the OAuth
   Parameters Registry established by [3].

   Parameter name:  pk_info

   Parameter usage location:  token request

   Change controller:  IETF

   Specification document(s):  [[ this document ]]

   Related information:  None

   Parameter name:  token_type

   Parameter usage location:  token request, token response,
      authorization response

   Change controller:  IETF

   Specification document(s):  [[ this document ]]

   Related information:  None

   Parameter name:  profile

   Parameter usage location:  token request, token response,
      authorization response

   Change controller:  IETF

   Specification document(s):  [[ this document ]]

   Related information:  None

   Parameter name:  id

   Parameter usage location:  token response, authorization response

   Change controller:  IETF

   Specification document(s):  [[ this document ]]

Bradley, et al.           Expires July 18, 2014                [Page 14]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   Related information:  None

   Parameter name:  key

   Parameter usage location:  token response, authorization response

   Change controller:  IETF

   Specification document(s):  [[ this document ]]

   Related information:  None

5.2.  The 'hotk' JSON Web Token Claims

   [6] established the IANA JSON Web Token Claims registry for reserved
   JWT Claim Names and this document adds the 'hotk' name to that
   registry.

5.3.  The 'hotk' OAuth Access Token Type

   Section 11.1 of [3] defines the OAuth Access Token Type Registry and
   this document adds another token type to this registry.

   Type name:  hotk

   Additional Token Endpoint Response Parameters:  (none)

   HTTP Authentication Scheme(s):  Holder of the key confirmation using
      TLS

   Change controller:  IETF

   Specification document(s):  [[ this document ]]

5.4.  Profile Registry

   This document asks IANA to create a registry for profiles of
   symmetric key-based holder-of-the-key mechanisms.  The policy for
   adding new entries to the registry is "Specification Required".  IANA
   is asked to populate the registry with the following values:

   o  Profile name: jws

   o  Change controller: IETF

   o  Specification document(s): [[ this document ]]

   o  Profile name: mac

Bradley, et al.           Expires July 18, 2014                [Page 15]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   o  Change controller: IETF

   o  Specification document(s): [[ this document ]]

6.  Acknowledgements

   The author would like to thank the OAuth working group and
   participants of the Internet Identity Workshop for their discussion
   input that lead to this document.

7.  References

7.1.  Normative References

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

   [2]        Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [3]        Hardt, D., "The OAuth 2.0 Authorization Framework", draft-
              ietf-oauth-v2-31 (work in progress), August 2012.

   [4]        Jones, M., "JSON Web Key (JWK)", draft-ietf-jose-json-web-
              key-19 (work in progress), December 2013.

   [5]        Wouters, P., Tschofenig, H., Gilmore, J., Weiler, S., and
              T. Kivinen, "Using Raw Public Keys in Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", draft-ietf-tls-oob-pubkey-10 (work in progress),
              October 2013.

   [6]        Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", draft-ietf-oauth-json-web-token-14 (work in
              progress), December 2013.

   [7]        Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", draft-ietf-jose-json-web-signature-19
              (work in progress), December 2013.

   [8]        Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [9]        Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

Bradley, et al.           Expires July 18, 2014                [Page 16]
Internet-Draft         OAuth 2.0 HOTK Token Usage           January 2014

   [10]       Richer, J., Mills, W., Tschofenig, H., and P. Hunt, "OAuth
              2.0 Message Authentication Code (MAC) Tokens", draft-ietf-
              oauth-v2-http-mac-04 (work in progress), July 2013.

7.2.  Informative References

   [11]       Campbell, B., Mortimore, C., Jones, M., and Y. Goland,
              "Assertion Framework for OAuth 2.0 Client Authentication
              and Authorization Grants", draft-ietf-oauth-assertions-13
              (work in progress), December 2013.

   [12]       Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
              Framework: Bearer Token Usage", draft-ietf-
              oauth-v2-bearer-23 (work in progress), August 2012.

   [13]       Hammer-Lahav, E., "The OAuth 1.0 Protocol", RFC 5849,
              April 2010.

   [14]       Burr, W., Dodson, D., Perlner, R., Polk, T., Gupta, S.,
              and E. Nabbus, "NIST Special Publication 800-63-1,
              INFORMATION SECURITY", December 2008.

Authors' Addresses

   John Bradley
   Ping Identity

   Email: ve7jtb@ve7jtb.com

   Phil Hunt
   Oracle Corporation

   Email: phil.hunt@yahoo.com

   Tony Nadalin
   Microsoft

   Email: tonynad@microsoft.com

   Hannes Tschofenig

   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at

Bradley, et al.           Expires July 18, 2014                [Page 17]