Nested JSON Web Token (JWT)
draft-yusef-oauth-nested-jwt-02

OAuth Working Group                                       R. Shekh-Yusef
Internet-Draft                                                     Avaya
Intended status: Standards Track                       September 2, 2019
Expires: March 5, 2020

                      Nested JSON Web Token (JWT)
                    draft-yusef-oauth-nested-jwt-02

Abstract

   This specification extends the scope of the Nested JSON Web Token
   (JWT) to allow the enclosing JWT to contain its own Claims Set in
   addition to the enclosed JWT.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Native App  . . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  STIR  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  JWT Content Type Header Parameter . . . . . . . . . . . . . .   4
   5.  JWT Content . . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Example . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   5
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   5
     10.2.  Informative References . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   JSON Web Token (JWT) is a mechanism that is used to transfer claims
   between two parties across security domains.  Nested JWT is a JWT in
   which the payload is another JWT.  The current specification does not
   define a means by which the enclosing JWT could have its own Claims
   Set, only the enclosed JWT would have claims.

   This specification extends the scope of the Nested JWT to allow the
   enclosing JWT to contain its own Claims Set in addition to the
   enclosed JWT.

1.1.  Terminology

   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 [RFC8174].

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2.  Overview

   RFC7519 defines Nested JWT as a JWT in which nested signing and/or
   encryption are employed.  In Nested JWTs, a JWT is used as the
   payload or plaintext value of an enclosing JWS or JWE structure,
   respectively.

   To indicate that the payload of an enclosing JWT is yet another JWT,
   the value of the Content Type Parameter of the JOSE header, i.e.
   "cty", must be set to "JWT", which means that the enclosing JWT
   cannot have its own claims.

   This document updates the enclosing JWT content to allow it to
   represent a Claims Set and an enclosed JWT, using JSON data
   structures, and updates the Content Type to indicate this new nested
   content.

3.  Use Cases

3.1.  Native App

   The use case is for a telephony application that is based on the
   "Native Apps Using the Browser" flow defined in RFC8252.  The Native
   App needs access to a telephony and non-telephony services that are
   controlled by different authorization servers, where the Native App
   can validate tokens issued by only one of these authorization
   servers.

   The Native App starts the process by interacting with a Client that
   requires the user to authenticate itself using a Browser.  The
   Browser starts by contacting an AS, which redirects it to an OP.  The
   user authenticates to the OP and obtains a Code, and then gets
   redirected back to AS.  The Native App gets access to the Code, then
   sends the Code to the AS, which then interacts with the OP to
   exchange the Code for an ID Token and OP Access Token.  Since the
   Native App has no way of validating the OP Access Token, when the AS
   creates an AS Access Token, it embeds the OP Access Token inside the
   AS Access Token, and returns it back to the Native App.  The Native
   App gets the AS Access Token and is able to validate it and extract
   the OP Access Token, and access the different services protected with
   these tokens.

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3.2.  STIR

   [RFC8225] defines a PASSporT, which is a JWT, that is used to verify
   the identity of a caller in an incoming call.

   The PASSporT Extension for Diverted Calls draft [STIR] uses a nested
   PASSporT to deliver the details of an incoming call that get
   redirected.  An authentication service acting for a retargeting
   entity generates new PASSporT and embeds the original PASSporT inside
   the new one.  When the new target receives the nested PASSporT it
   will be able to validate the enclosing PASSporT and use the details
   of the enclosed PASSporT to identify the origianl target.

4.  JWT Content Type Header Parameter

   The JOSE Header contains an optional parameter that could be used to
   indicate the type of the payload of a JWT.  With a typical Nested
   JWT, the value of the "cty" header must be "JWT".  To indicate that
   the payload contains a Claims Set in addition to the JWT, the value
   of the "cty" header must be "NJWT".

5.  JWT Content

   The payload of the enclosing JWT is JSON object that contains the
   Claims Set, and one new claim that is used to hold the enclosed JWT.

   This document defines a new claim, "njwt", that is used to contain
   the enclosed JWT.

6.  Example

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

   {
     "sub": "1234567890",
     "name": "John Doe",
     "iat": 1516239022,
     "njwt": "<njwt>"
   }

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7.  Security Considerations

   TODO

8.  IANA Considerations

   TODO

9.  Acknowledgments

   TODO

10.  References

10.1.  Normative References

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

10.2.  Informative References

   [RFC8225]  Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
              Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
              <https://www.rfc-editor.org/info/rfc8225>.

   [STIR]     Peterson, J., "PASSporT Extension for Diverted Calls",
              October 2018.

Author's Address

   Rifaat Shekh-Yusef
   Avaya
   425 Legget Drive
   Ottawa, Ontario
   Canada

   Phone: +1-613-595-9106
   EMail: rifaat.ietf@gmail.com

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