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JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                           July 16, 2012
Expires: January 17, 2013


            JSON Web Encryption JSON Serialization (JWE-JS)
               draft-jones-jose-jwe-json-serialization-01

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 17, 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
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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.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . . . 7
   Appendix B.  Document History . . . . . . . . . . . . . . . . . . . 7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 8


























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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 members for each of four constituent parts: a "headers" member
   whose value is a non-empty array of Encoded JWE Header values, an
   "encrypted_keys" member whose value is a non-empty array of Encoded
   JWE Encrypted Key values, a "ciphertext" member whose value is an
   Encoded JWE Ciphertext value, and an "integrity_values" member whose
   value is a non-empty array of Encoded JWE Integrity Value values.
   The number of elements in each of the arrays MUST be the same.

   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; these
      values are represented as Encoded JWE Header values that are
      elements of the non-empty array contained in the "headers" member.




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   o  a JWE Encrypted Key value; these values are represented as Encoded
      JWE Encrypted Key values that are corresponding elements of the
      non-empty array contained in the "encrypted_keys" member.

   o  a JWE Integrity Value that ensures the integrity of the Ciphertext
      and the parameters used to create it; these values are represented
      as Encoded JWE Integrity Value values that are corresponding
      elements of the non-empty array contained in the
      "integrity_values" member.

   Therefore, the syntax is:

     {"headers":["<header 1 contents>",...,"<header N contents>"],
      "encrypted_keys":["<key 1 contents>",...,"<key N contents>"],
      "ciphertext":"<ciphertext contents>",
      "integrity_values":["<value 1 contents>",...,"<value N contents>"]
     }

   The contents of the Encoded JWE Header, Encoded JWE Encrypted Key,
   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
   "headers", "encrypted_keys", and "integrity_values" value being
   created or validated together.  The arrays MUST have the same number
   of elements.

   The i'th JWE Encrypted Key value and the i'th JWE Integrity Value are
   computed using the parameters of i'th 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
   "encrypted_keys" array and each Encoded JWE Integrity Value in the
   "integrity_values" array are identical to the values that would have
   been computed for the same header and payload in a JWE, as is the JWE
   Ciphertext value.

   All recipients use the same JWE Ciphertext value, 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.  In
   particular, this means that the "enc" (encryption method) header
   parameter value in the JWE Header for each recipient MUST be the
   same, as MUST be the "iv" (initialization vector) value, the "int"
   (integrity algorithm) value, and the "kdf" (key derivation function)
   value, when present.







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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","int":"HS256","iv":"AxY8DCtDaGlsbGljb3RoZQ"}

   and:

  {"alg":"RSA-OAEP","enc":"A128CBC","int":"HS256","iv":"AxY8DCtDaGlsbGljb3RoZQ"}

   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 ciphertext is 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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     {"headers":[
       "eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDIiwiaW50IjoiSFMyNTYiLCJp
        diI6IkF4WThEQ3REYUdsc2JHbGpiM1JvWlEifQ",
       "eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhDQkMiLCJpbnQiOiJIUzI1NiIs
        Iml2IjoiQXhZOERDdERhR2xzYkdsamIzUm9aUSJ9"],
      "encrypted_keys":[
       "IPI_z172hSWHMFgED8EG9DM6hIXU_6NaO1DImCn0vNeuoBq847Sl6qw_GHSYHJUQ
        XtXJq7S_CxWVrI82wjrOyaQca5tLZRZc45BfKHeqByThKI261QevEK56SyAwwXfK
        KZjSvkQ5dwTFSgfy76rMSUvVynHYEhdCatBF9HWTAiXPx7hgZixG1FeP_QCmOylz
        2VClVyYFCbjKREOwBFf-puNYfO75S3LNlJUtTsGGQL2oTKpMsEiUTdefkje91VX9
        h8g7908lFsggbjV7NicJsufuXxnTj1fcWIrRDeNIOmakiPEODi0gTSz0ou-W-LWK
        -3T1zYlOIiIKBjsExQKZ-w",
       "gyhQHQYGyPZQP21Oxd6TdJjrmNkals3Jin2631_eaW-8tPEZxjeNA1lJD7gi2tAQ
        X9ERZkbD8-9-8Gq9HkpJIhINX4TkqmCynmT8kQfjiv5t8KuTI_OjhD-I0CfvWs3T
        7yf2W6_vQcs1ezsapKPGj92i6Z1xpWgtDuK5YwU3PLAEfNeAgBK0fM9x9DkIuhBN
        7O9LWRtP6FnYKaygc5-tzR_O9nTJ0u4ImsBPGaHHQEfvzMBtQgAPQCdkDiITxSdJ
        OdvBQVmg7uGKOybF42R-gzP63lxAqiYmp6DVPlPYydIEB2lCZxGUJIsmEM0qwXt1
        GEmj_aYGhCUrkPSidvE6Ag"],
      "ciphertext":"_Z_djlIoC4MDSCKireWS2beti4Q6iSG2UjFujQvdz-_PQdUcFNkO
       ulegD6BgjgdFLjeB4HHOO7UHvP8PEDu0a0sA2a_-CI0w2YQQ2QQe35M",
      "integrity_values":[
       "c41k4T4eAgCCt63m8ZNmiOinMciFFypOFpvid7i6D0k",
       "NX62w-GLPhXVJuQxXnbWrBKLkt9j14IULcMdJ9kzeF0"]
     }


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.  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.


8.  References




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8.1.  Normative References

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

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

8.2.  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)", July 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.  Document History

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

   -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




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   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-AEAD algorithms.

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

   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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