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JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                       December 27, 2012
Expires: June 30, 2013


            JSON Web Encryption JSON Serialization (JWE-JS)
               draft-jones-jose-jwe-json-serialization-04

Abstract

   The JSON Web Encryption JSON Serialization (JWE-JS) is a means of
   representing encrypted content using JavaScript Object Notation
   (JSON) data structures.  This specification describes a means of
   representing secured content as a JSON data object (as opposed to the
   JWE specification, which uses a compact serialization with a URL-safe
   representation).  It enables the same content to be encrypted to
   multiple parties (unlike JWE).  Cryptographic algorithms and
   identifiers used with this specification are described in the
   separate JSON Web Algorithms (JWA) specification.  The JSON
   Serialization for related digital signature and MAC functionality is
   described in the separate JSON Web Signature JSON Serialization
   (JWS-JS) specification.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 30, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  JSON Serialization  . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Example JWE-JS  . . . . . . . . . . . . . . . . . . . . . . . . 5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . . . 7
   Appendix B.  Open Issues  . . . . . . . . . . . . . . . . . . . . . 7
   Appendix C.  Document History . . . . . . . . . . . . . . . . . . . 7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 9


























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1.  Introduction

   The JSON Web Encryption JSON Serialization (JWE-JS) is a format for
   representing encrypted content as a JavaScript Object Notation (JSON)
   [RFC4627] object.  It enables the same content to be encrypted to
   multiple parties (unlike JWE [JWE].)  The encryption mechanisms are
   independent of the type of content being encrypted.  Cryptographic
   algorithms and identifiers used with this specification are described
   in the separate JSON Web Algorithms (JWA) [JWA] specification.  The
   JSON Serialization for related digital signature and MAC
   functionality is described in the separate JSON Web Signature JSON
   Serialization (JWS-JS) [JWS-JS] specification.

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in Key words for use in
   RFCs to Indicate Requirement Levels [RFC2119].


2.  Terminology

   This specification uses the same terminology as the JSON Web
   Encryption (JWE) [JWE] specification.


3.  JSON Serialization

   The JSON Serialization represents encrypted content as a JSON object
   with a "recipients" member containing an array of per-recipient
   information, an "initialization_vector" member containing a shared
   Encoded JWE Initialization Vector value, and a "ciphertext" member
   containing a shared Encoded JWE Ciphertext value.  Each member of the
   "recipients" array is a JSON object with a "header" member containing
   an Encoded JWE Header value, an "encrypted_key" member containing an
   Encoded JWE Encrypted Key value, and an "integrity_value" member
   containing an Encoded JWE Integrity Value value.

   Unlike the compact serialization used by JWEs, content using the JSON
   Serialization MAY be encrypted to more than one recipient.  Each
   recipient requires:

   o  a JWE Header value specifying the cryptographic parameters used to
      encrypt the JWE Encrypted Key to that recipient and the parameters
      used to encrypt the plaintext to produce the JWE Ciphertext; this
      is represented as an Encoded JWE Header value in the "header"
      member of an object in the "recipients" array.



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   o  a JWE Encrypted Key value used to encrypt the ciphertext; this is
      represented as an Encoded JWE Encrypted Key value in the
      "encrypted_key" member of the same object in the "recipients"
      array.

   o  a JWE Integrity Value that ensures the integrity of the Ciphertext
      and the parameters used to create it; this is represented as an
      Encoded JWE Integrity Value value in the "integrity_value" member
      of the same object in the "recipients" array.

   Therefore, the syntax is:

     {"recipients":[
       {"header":"<header 1 contents>",
        "encrypted_key":"<encrypted key 1 contents>",
        "integrity_value":"<integrity value 1 contents>"},
       ...
       {"header":"<header N contents>",
        "encrypted_key":"<encrypted key N contents>",
        "integrity_value":"<integrity value N contents>"}],
      "initialization_vector":"<initialization vector contents>",
      "ciphertext":"<ciphertext contents>"
     }

   The contents of the Encoded JWE Header, Encoded JWE Encrypted Key,
   Encoded JWE Initialization Vector, Encoded JWE Ciphertext, and
   Encoded JWE Integrity Value values are exactly as specified in JSON
   Web Encryption (JWE) [JWE].  They are interpreted and validated in
   the same manner, with each corresponding "header", "encrypted_key",
   and "integrity_value" value being created and validated together.

   Each JWE Encrypted Key value and the corresponding JWE Integrity
   Value are computed using the parameters of the corresponding JWE
   Header value in the same manner described in the JWE specification.
   This has the desirable result that each Encoded JWE Encrypted Key
   value in the "recipients" array and each Encoded JWE Integrity Value
   in the same array element are identical to the values that would have
   been computed for the same parameters in a JWE, as is the shared JWE
   Ciphertext value.

   All recipients use the same JWE Ciphertext and JWE Initialization
   Vector values, resulting in potentially significant space savings if
   the message is large.  Therefore, all header parameters that specify
   the treatment of the JWE Ciphertext value MUST be the same for all
   recipients.  This primarily means that the "enc" (encryption method)
   header parameter value in the JWE Header for each recipient MUST be
   the same.




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4.  Example JWE-JS

   This section contains an example using the JWE JSON Serialization.
   This example demonstrates the capability for encrypting the same
   plaintext to multiple recipients.

   Two recipients are present in this example: the first using the
   RSAES-PKCS1-V1_5 algorithm to encrypt the Content Master Key (CMK)
   and the second using RSAES OAEP to encrypt the CMK.  The Plaintext is
   encrypted using the AES CBC algorithm and the same block encryption
   parameters to produce the common JWE Ciphertext value.  The two
   Decoded JWE Header Segments used are:

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

   and:

     {"alg":"RSA-OAEP","enc":"A128CBC+HS256"}

   The keys used for the first recipient are the same as those in
   Appendix A.2 of [JWE], as is the plaintext used.  The asymmetric
   encryption key used for the second recipient is the same as that used
   in Appendix A.1 of [JWE]; the block encryption keys and parameters
   for the second recipient are the same as those for the first
   recipient (which must be the case, since the initialization vector
   and ciphertext are shared).

   The complete JSON Web Encryption JSON Serialization (JWE-JS) for
   these values is as follows (with line breaks for display purposes
   only):





















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     {"recipients":[
       {"header":
         "eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0",
        "encrypted_key":
         "ZmnlqWgjXyqwjr7cXHys8F79anIUI6J2UWdAyRQEcGBU-KPHsePM910_RoTDG
          u1IW40Dn0dvcdVEjpJcPPNIbzWcMxDi131Ejeg-b8ViW5YX5oRdYdiR4gMSDD
          B3mbkInMNUFT-PK5CuZRnHB2rUK5fhPuF6XFqLLZCG5Q_rJm6Evex-XLcNQAJ
          Na1-6CIU12Wj3mPExxw9vbnsQDU7B4BfmhdyiflLA7Ae5ZGoVRl3A__yLPXxR
          jHFhpOeDp_adx8NyejF5cz9yDKULugNsDMdlHeJQOMGVLYaSZt3KP6aWNSqFA
          1PHDg-10ceuTEtq_vPE4-Gtev4N4K4Eudlj4Q",
        "integrity_value":
         "8LXqMd0JLGsxMaB5uoNaMpg7uUW_p40RlaZHCwMIyzk"},
       {"header":
         "eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhDQkMrSFMyNTYifQ",
        "encrypted_key":
         "nxwnYB86zEvVRofSxnDuFAE9-Gi2JtCy5eMyYedowjfGlkoA-Y0JyfwWXE_EU
          vhq6WS_DM3a18You2Qsah3BvvSRPZ8-TNYX3_4QCEO-V8EVbF1eGoJFs9ODmC
          cOiuMl1xLnSAYlwEDDnhwEkXv8o6MZEvh-msqTY6NyFGd6mhjpu9P4o2F2hOe
          Nt6FthcR4cNpAVSbydEEBszsrp27nB-JwfmLjnSYQO1JBwbgUJXHZyIJcQa7i
          43Vko02HkWTxBta0q5Zr_Jd7V2l-6HLYIuNc7fZH1DSJSTBTotcugumR5zNX_
          uxQyMoWOQ-SsQ7HxqrrFbo5FNoLPZiuNYuCdQ",
        "integrity_value":
         "QbYksTWNZTcMfJMLoGB_aTCA0-IuNObm19_VdpabviM"}],
      "initialization_vector":
       "AxY8DCtDaGlsbGljb3RoZQ",
      "ciphertext":
       "Rxsjg6PIExcmGSF7LnSEkDqWIKfAw1wZz2XpabV5PwQsolKwEauWYZNE9Q1hZJE
        Z"
     }


5.  IANA Considerations

   This specification makes no requests of IANA.


6.  Security Considerations

   The security considerations for this specification are the same as
   those for the JSON Web Encryption (JWE) [JWE] specification.


7.  References

7.1.  Normative References

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



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              December 2012.

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

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

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

7.2.  Informative References

   [I-D.rescorla-jsms]
              Rescorla, E. and J. Hildebrand, "JavaScript Message
              Security Format", draft-rescorla-jsms-00 (work in
              progress), March 2011.

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

   [JWS-JS]   Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature JSON Serialization (JWS-JS)",
              draft-jones-jose-jws-json-serialization (work in
              progress), December 2012.


Appendix A.  Acknowledgements

   JSON serializations for encrypted content were previously explored by
   JSON Simple Encryption [JSE] and JavaScript Message Security Format
   [I-D.rescorla-jsms].


Appendix B.  Open Issues

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

   The following items remain to be considered or done in this draft:

   o  Track changes that occur in the JWE spec.


Appendix C.  Document History

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




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   -04

   o  Added seriesInfo information to Internet Draft references.

   -03

   o  Updated values for example AES CBC calculations.

   -02

   o  Changed to use an array of structures for per-recipient values,
      rather than a set of parallel arrays.

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

   -01

   o  Added a complete JWE-JS example.

   o  Generalized language to refer to Message Authentication Codes
      (MACs) rather than Hash-based Message Authentication Codes
      (HMACs).

   -00

   o  Renamed draft-jones-json-web-encryption-json-serialization to
      draft-jones-jose-jwe-json-serialization to have "jose" be in the
      document name so it can be included in the Related Documents list
      at http://datatracker.ietf.org/wg/jose/.  No normative changes.

   draft-jones-json-web-encryption-json-serialization-02

   o  Updated examples to track updated algorithm properties in the JWA
      spec.

   o  Tracked editorial changes made to the JWE spec.

   draft-jones-json-web-encryption-json-serialization-01

   o  Tracked changes between JOSE JWE draft -00 and -01, which added an
      integrity check for non-Authenticated Encryption algorithms.

   draft-jones-json-web-encryption-json-serialization-00



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   o  Created the initial version incorporating JOSE working group input
      and drawing from the JSON Serialization previously proposed in
      draft-jones-json-web-token-01.


Author's Address

   Michael B. Jones
   Microsoft

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







































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