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Versions: (draft-jones-json-web-encryption) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

JOSE Working Group                                              M. Jones
Internet-Draft                                                 Microsoft
Intended status: Standards Track                             E. Rescorla
Expires: April 18, 2013                                             RTFM
                                                           J. Hildebrand
                                                                   Cisco
                                                        October 15, 2012


                       JSON Web Encryption (JWE)
                 draft-ietf-jose-json-web-encryption-06

Abstract

   JSON Web Encryption (JWE) is a means of representing encrypted
   content using JavaScript Object Notation (JSON) data structures.
   Cryptographic algorithms and identifiers for use with this
   specification are described in the separate JSON Web Algorithms (JWA)
   specification.  Related digital signature and MAC capabilities are
   described in the separate JSON Web Signature (JWS) 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 April 18, 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
   (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



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   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 . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.1.  Notational Conventions . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  JSON Web Encryption (JWE) Overview . . . . . . . . . . . . . .  7
     3.1.  Example JWE with an Integrated Integrity Check . . . . . .  8
     3.2.  Example JWE with a Separate Integrity Check  . . . . . . .  9
   4.  JWE Header . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.1.  Reserved Header Parameter Names  . . . . . . . . . . . . . 12
       4.1.1.  "alg" (Algorithm) Header Parameter . . . . . . . . . . 12
       4.1.2.  "enc" (Encryption Method) Header Parameter . . . . . . 12
       4.1.3.  "epk" (Ephemeral Public Key) Header Parameter  . . . . 13
       4.1.4.  "zip" (Compression Algorithm) Header Parameter . . . . 13
       4.1.5.  "jku" (JWK Set URL) Header Parameter . . . . . . . . . 13
       4.1.6.  "jwk" (JSON Web Key) Header Parameter  . . . . . . . . 13
       4.1.7.  "x5u" (X.509 URL) Header Parameter . . . . . . . . . . 13
       4.1.8.  "x5t" (X.509 Certificate Thumbprint) Header
               Parameter  . . . . . . . . . . . . . . . . . . . . . . 14
       4.1.9.  "x5c" (X.509 Certificate Chain) Header Parameter . . . 14
       4.1.10. "kid" (Key ID) Header Parameter  . . . . . . . . . . . 14
       4.1.11. "typ" (Type) Header Parameter  . . . . . . . . . . . . 15
       4.1.12. "cty" (Content Type) Header Parameter  . . . . . . . . 15
       4.1.13. "apu" (Agreement PartyUInfo) Header Parameter  . . . . 15
       4.1.14. "apv" (Agreement PartyVInfo) Header Parameter  . . . . 15
       4.1.15. "epu" (Encryption PartyUInfo) Header Parameter . . . . 15
       4.1.16. "epv" (Encryption PartyVInfo) Header Parameter . . . . 16
     4.2.  Public Header Parameter Names  . . . . . . . . . . . . . . 16
     4.3.  Private Header Parameter Names . . . . . . . . . . . . . . 16
   5.  Message Encryption . . . . . . . . . . . . . . . . . . . . . . 16
   6.  Message Decryption . . . . . . . . . . . . . . . . . . . . . . 18
   7.  CMK Encryption . . . . . . . . . . . . . . . . . . . . . . . . 19
   8.  Encrypting JWEs with Cryptographic Algorithms  . . . . . . . . 19
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 20
     9.1.  Registration of JWE Header Parameter Names . . . . . . . . 20
       9.1.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 20
     9.2.  JSON Web Signature and Encryption Type Values
           Registration . . . . . . . . . . . . . . . . . . . . . . . 21
       9.2.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 21
     9.3.  Media Type Registration  . . . . . . . . . . . . . . . . . 21
       9.3.1.  Registry Contents  . . . . . . . . . . . . . . . . . . 21
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 22



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   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 22
     11.2. Informative References . . . . . . . . . . . . . . . . . . 24
   Appendix A.  JWE Examples  . . . . . . . . . . . . . . . . . . . . 24
     A.1.  Example JWE using RSAES OAEP and AES GCM . . . . . . . . . 24
       A.1.1.  JWE Header . . . . . . . . . . . . . . . . . . . . . . 25
       A.1.2.  Encoded JWE Header . . . . . . . . . . . . . . . . . . 25
       A.1.3.  Content Master Key (CMK) . . . . . . . . . . . . . . . 25
       A.1.4.  Key Encryption . . . . . . . . . . . . . . . . . . . . 25
       A.1.5.  Encoded JWE Encrypted Key  . . . . . . . . . . . . . . 28
       A.1.6.  Initialization Vector  . . . . . . . . . . . . . . . . 28
       A.1.7.  "Additional Authenticated Data" Parameter  . . . . . . 28
       A.1.8.  Plaintext Encryption . . . . . . . . . . . . . . . . . 29
       A.1.9.  Encoded JWE Ciphertext . . . . . . . . . . . . . . . . 29
       A.1.10. Encoded JWE Integrity Value  . . . . . . . . . . . . . 30
       A.1.11. Complete Representation  . . . . . . . . . . . . . . . 30
       A.1.12. Validation . . . . . . . . . . . . . . . . . . . . . . 30
     A.2.  Example JWE using RSAES-PKCS1-V1_5 and AES CBC . . . . . . 30
       A.2.1.  JWE Header . . . . . . . . . . . . . . . . . . . . . . 31
       A.2.2.  Encoded JWE Header . . . . . . . . . . . . . . . . . . 31
       A.2.3.  Content Master Key (CMK) . . . . . . . . . . . . . . . 31
       A.2.4.  Key Encryption . . . . . . . . . . . . . . . . . . . . 31
       A.2.5.  Encoded JWE Encrypted Key  . . . . . . . . . . . . . . 34
       A.2.6.  Key Derivation . . . . . . . . . . . . . . . . . . . . 34
       A.2.7.  Initialization Vector  . . . . . . . . . . . . . . . . 34
       A.2.8.  Plaintext Encryption . . . . . . . . . . . . . . . . . 34
       A.2.9.  Encoded JWE Ciphertext . . . . . . . . . . . . . . . . 35
       A.2.10. Secured Input Value  . . . . . . . . . . . . . . . . . 35
       A.2.11. JWE Integrity Value  . . . . . . . . . . . . . . . . . 36
       A.2.12. Encoded JWE Integrity Value  . . . . . . . . . . . . . 36
       A.2.13. Complete Representation  . . . . . . . . . . . . . . . 36
       A.2.14. Validation . . . . . . . . . . . . . . . . . . . . . . 37
     A.3.  Example JWE using AES Key Wrap and AES GCM . . . . . . . . 37
       A.3.1.  JWE Header . . . . . . . . . . . . . . . . . . . . . . 37
       A.3.2.  Encoded JWE Header . . . . . . . . . . . . . . . . . . 38
       A.3.3.  Content Master Key (CMK) . . . . . . . . . . . . . . . 38
       A.3.4.  Key Encryption . . . . . . . . . . . . . . . . . . . . 38
       A.3.5.  Encoded JWE Encrypted Key  . . . . . . . . . . . . . . 38
       A.3.6.  Initialization Vector  . . . . . . . . . . . . . . . . 38
       A.3.7.  "Additional Authenticated Data" Parameter  . . . . . . 39
       A.3.8.  Plaintext Encryption . . . . . . . . . . . . . . . . . 39
       A.3.9.  Encoded JWE Ciphertext . . . . . . . . . . . . . . . . 39
       A.3.10. Encoded JWE Integrity Value  . . . . . . . . . . . . . 40
       A.3.11. Complete Representation  . . . . . . . . . . . . . . . 40
       A.3.12. Validation . . . . . . . . . . . . . . . . . . . . . . 40
     A.4.  Example Key Derivation for "enc" value "A128CBC+HS256" . . 40
       A.4.1.  CEK Generation . . . . . . . . . . . . . . . . . . . . 41
       A.4.2.  CIK Generation . . . . . . . . . . . . . . . . . . . . 42



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     A.5.  Example Key Derivation for "enc" value "A256CBC+HS512" . . 42
       A.5.1.  CEK Generation . . . . . . . . . . . . . . . . . . . . 43
       A.5.2.  CIK Generation . . . . . . . . . . . . . . . . . . . . 44
   Appendix B.  Acknowledgements  . . . . . . . . . . . . . . . . . . 45
   Appendix C.  Open Issues . . . . . . . . . . . . . . . . . . . . . 45
   Appendix D.  Document History  . . . . . . . . . . . . . . . . . . 46
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 49












































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1.  Introduction

   JSON Web Encryption (JWE) is a compact encryption format intended for
   space constrained environments such as HTTP Authorization headers and
   URI query parameters.  It represents this content using JavaScript
   Object Notation (JSON) [RFC4627] based data structures.  The JWE
   cryptographic mechanisms encrypt and provide integrity protection for
   arbitrary sequences of bytes.

   Cryptographic algorithms and identifiers for use with this
   specification are described in the separate JSON Web Algorithms (JWA)
   [JWA] specification.  Related digital signature and MAC capabilities
   are described in the separate JSON Web Signature (JWS) [JWS]
   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

   JSON Web Encryption (JWE)  A data structure representing an encrypted
      message.  The structure consists of five parts: the JWE Header,
      the JWE Encrypted Key, the JWE Initialization Vector, the JWE
      Ciphertext, and the JWE Integrity Value.

   Plaintext  The bytes to be encrypted -- a.k.a., the message.  The
      plaintext can contain an arbitrary sequence of bytes.

   Ciphertext  An encrypted representation of the Plaintext.

   Content Encryption Key (CEK)  A symmetric key used to encrypt the
      Plaintext for the recipient to produce the Ciphertext.

   Content Integrity Key (CIK)  A key used with a MAC function to ensure
      the integrity of the Ciphertext and the parameters used to create
      it.

   Content Master Key (CMK)  A key from which the CEK and CIK are
      derived.  When key wrapping or key encryption are employed, the
      CMK is randomly generated and encrypted to the recipient as the
      JWE Encrypted Key. When direct encryption with a shared symmetric
      key is employed, the CMK is the shared key.  When key agreement
      without key wrapping is employed, the CMK is the result of the key



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      agreement algorithm.

   JWE Header  A string representing a JSON object that describes the
      encryption operations applied to create the JWE Encrypted Key, the
      JWE Ciphertext, and the JWE Integrity Value.

   JWE Encrypted Key  When key wrapping or key encryption are employed,
      the Content Master Key (CMK) is encrypted with the intended
      recipient's key and the resulting encrypted content is recorded as
      a byte array, which is referred to as the JWE Encrypted Key.
      Otherwise, when direct encryption with a shared or agreed upon
      symmetric key is employed, the JWE Encrypted Key is the empty byte
      array.

   JWE Initialization Vector  A byte array containing the Initialization
      Vector used when encrypting the Plaintext.

   JWE Ciphertext  A byte array containing the Ciphertext.

   JWE Integrity Value  A byte array containing a MAC value that ensures
      the integrity of the Ciphertext and the parameters used to create
      it.

   Base64url Encoding  The URL- and filename-safe Base64 encoding
      described in RFC 4648 [RFC4648], Section 5, with the (non URL-
      safe) '=' padding characters omitted, as permitted by Section 3.2.
      (See Appendix C of [JWS] for notes on implementing base64url
      encoding without padding.)

   Encoded JWE Header  Base64url encoding of the bytes of the UTF-8
      [RFC3629] representation of the JWE Header.

   Encoded JWE Encrypted Key  Base64url encoding of the JWE Encrypted
      Key.

   Encoded JWE Initialization Vector  Base64url encoding of the JWE
      Initialization Vector.

   Encoded JWE Ciphertext  Base64url encoding of the JWE Ciphertext.

   Encoded JWE Integrity Value  Base64url encoding of the JWE Integrity
      Value.

   Header Parameter Name  The name of a member of the JSON object
      representing a JWE Header.






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   Header Parameter Value  The value of a member of the JSON object
      representing a JWE Header.

   JWE Compact Serialization  A representation of the JWE as the
      concatenation of the Encoded JWE Header, the Encoded JWE Encrypted
      Key, the Encoded JWE Initialization Vector, the Encoded JWE
      Ciphertext, and the Encoded JWE Integrity Value in that order,
      with the five strings being separated by four period ('.')
      characters.

   AEAD Algorithm  An Authenticated Encryption with Associated Data
      (AEAD) [RFC5116] encryption algorithm is one that provides an
      integrated content integrity check.  AES Galois/Counter Mode (GCM)
      is one such algorithm.

   Collision Resistant Namespace  A namespace that allows names to be
      allocated in a manner such that they are highly unlikely to
      collide with other names.  For instance, collision resistance can
      be achieved through administrative delegation of portions of the
      namespace or through use of collision-resistant name allocation
      functions.  Examples of Collision Resistant Namespaces include:
      Domain Names, Object Identifiers (OIDs) as defined in the ITU-T
      X.660 and X.670 Recommendation series, and Universally Unique
      IDentifiers (UUIDs) [RFC4122].  When using an administratively
      delegated namespace, the definer of a name needs to take
      reasonable precautions to ensure they are in control of the
      portion of the namespace they use to define the name.

   StringOrURI  A JSON string value, with the additional requirement
      that while arbitrary string values MAY be used, any value
      containing a ":" character MUST be a URI [RFC3986].  StringOrURI
      values are compared as case-sensitive strings with no
      transformations or canonicalizations applied.


3.  JSON Web Encryption (JWE) Overview

   JWE represents encrypted content using JSON data structures and
   base64url encoding.  The representation consists of five parts: the
   JWE Header, the JWE Encrypted Key, the JWE Initialization Vector, the
   JWE Ciphertext, and the JWE Integrity Value.  In the Compact
   Serialization, the five parts are base64url-encoded for transmission,
   and represented as the concatenation of the encoded strings in that
   order, with the five strings being separated by four period ('.')
   characters.  (A JSON Serialization for this information is defined in
   the separate JSON Web Encryption JSON Serialization (JWE-JS) [JWE-JS]
   specification.)




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   JWE utilizes encryption to ensure the confidentiality of the
   Plaintext.  JWE adds a content integrity check if not provided by the
   underlying encryption algorithm.

3.1.  Example JWE with an Integrated Integrity Check

   This example encrypts the plaintext "Live long and prosper." to the
   recipient using RSAES OAEP and AES GCM.  The AES GCM algorithm has an
   integrated integrity check.

   The following example JWE Header declares that:

   o  the Content Master Key is encrypted to the recipient using the
      RSAES OAEP algorithm to produce the JWE Encrypted Key and

   o  the Plaintext is encrypted using the AES GCM algorithm with a 256
      bit key to produce the Ciphertext.


     {"alg":"RSA-OAEP","enc":"A256GCM"}

   Base64url encoding the bytes of the UTF-8 representation of the JWE
   Header yields this Encoded JWE Header value:

     eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ

   The remaining steps to finish creating this JWE are:

   o  Generate a random Content Master Key (CMK)

   o  Encrypt the CMK with the recipient's public key using the RSAES
      OAEP algorithm to produce the JWE Encrypted Key

   o  Base64url encode the JWE Encrypted Key to produce the Encoded JWE
      Encrypted Key

   o  Generate a random JWE Initialization Vector

   o  Base64url encode the JWE Initialization Vector to produce the
      Encoded JWE Initialization Vector

   o  Concatenate the Encoded JWE Header value, a period character
      ('.'), the Encoded JWE Encrypted Key, a second period character
      ('.'), and the Encoded JWE Initialization Vector to create the
      "additional authenticated data" parameter for the AES GCM
      algorithm





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   o  Encrypt the Plaintext with AES GCM, using the CMK as the
      encryption key, the JWE Initialization Vector, and the "additional
      authenticated data" value above, requesting a 128 bit
      "authentication tag" output

   o  Base64url encode the resulting Ciphertext to create the Encoded
      JWE Ciphertext

   o  Base64url encode the resulting "authentication tag" to create the
      Encoded JWE Integrity Value

   o  Assemble the final representation: The Compact Serialization of
      this result is the concatenation of the Encoded JWE Header, the
      Encoded JWE Encrypted Key, the Encoded JWE Initialization Vector,
      the Encoded JWE Ciphertext, and the Encoded JWE Integrity Value in
      that order, with the five strings being separated by four period
      ('.') characters.

   The final result in this example (with line breaks for display
   purposes only) is:

     eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
     M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
     rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
     O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
     zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
     SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
     6BBBbR37pHcyzext9epOAQ.
     48V1_ALb6US04U3b.
     _e21tGGhac_peEFkLXr2dMPUZiUkrw.
     7V5ZDko0v_mf2PAc4JMiUg

   See Appendix A.1 for the complete details of computing this JWE.

3.2.  Example JWE with a Separate Integrity Check

   This example encrypts the plaintext "No matter where you go, there
   you are." to the recipient using RSAES-PKCS1-V1_5 and AES CBC.  AES
   CBC does not have an integrated integrity check, so a separate
   integrity check calculation is performed using HMAC SHA-256, with
   separate encryption and integrity keys being derived from a master
   key using the Concat KDF with the SHA-256 digest function.

   The following example JWE Header (with line breaks for display
   purposes only) declares that:

   o  the Content Master Key is encrypted to the recipient using the
      RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and



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   o  the Plaintext is encrypted using the AES CBC algorithm with a 128
      bit key to produce the Ciphertext, with the integrity of the
      Ciphertext and the parameters used to create it being secured
      using the HMAC SHA-256 algorithm.


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

   Base64url encoding the bytes of the UTF-8 representation of the JWE
   Header yields this Encoded JWE Header value:

     eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0

   The remaining steps to finish creating this JWE are like the previous
   example, but with an additional step to compute the separate
   integrity value:

   o  Generate a random Content Master Key (CMK)

   o  Encrypt the CMK with the recipient's public key using the RSAES-
      PKCS1-V1_5 algorithm to produce the JWE Encrypted Key

   o  Base64url encode the JWE Encrypted Key to produce the Encoded JWE
      Encrypted Key

   o  Generate a random JWE Initialization Vector

   o  Base64url encode the JWE Initialization Vector to produce the
      Encoded JWE Initialization Vector

   o  Use the Concat key derivation function to derive Content
      Encryption Key (CEK) and Content Integrity Key (CIK) values from
      the CMK

   o  Encrypt the Plaintext with AES CBC using the CEK and JWE
      Initialization Vector to produce the Ciphertext

   o  Base64url encode the resulting Ciphertext to create the Encoded
      JWE Ciphertext

   o  Concatenate the Encoded JWE Header value, a period character
      ('.'), the Encoded JWE Encrypted Key, a second period character
      ('.'), the Encoded JWE Initialization Vector, a third period ('.')
      character, and the Encoded JWE Ciphertext to create the value to
      integrity protect

   o  Compute the HMAC SHA-256 of this value using the CIK to create the
      JWE Integrity Value



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   o  Base64url encode the resulting JWE Integrity Value to create the
      Encoded JWE Integrity Value

   o  Assemble the final representation: The Compact Serialization of
      this result is the concatenation of the Encoded JWE Header, the
      Encoded JWE Encrypted Key, the Encoded JWE Initialization Vector,
      the Encoded JWE Ciphertext, and the Encoded JWE Integrity Value in
      that order, with the five strings being separated by four period
      ('.') characters.

   The final result in this example (with line breaks for display
   purposes only) is:

     eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
     O6AqXqgVlJJ4c4lp5sXZd7bpGHAw6ARkHUeXQxD1cAW4-X1x0qtj_AN0mukqEOl4
     Y6UOwJXIJY9-G1ELK-RQWrKH_StR-AM9H7GpKmSEji8QYOcMOjr-u9H1Lt_pBEie
     G802SxWz0rbFTXRcj4BWLxcpCtjUZ31AP-sc-L_eCZ5UNl0aSRNqFskuPkzRsFZR
     DJqSSJeVOyJ7pZCQ83fli19Vgi_3R7XMUqluQuuc7ZHOWixi47jXlBTlWRZ5iFxa
     S8G6J8wUrd4BKggAw3qX5XoIfXQVlQZE0Vmkq_zQSIo5LnFKyowooRcdsEuNh9B9
     Mkyt0ZQElG-jGdtHWjZSOA.
     AxY8DCtDaGlsbGljb3RoZQ.
     1eBWFgcrz40wC88cgv8rPgu3EfmC1p4zT0kIxxfSF2zDJcQ-iEHk1jQM95xAdr5Z.
     RBGhYzE8_cZLHjJqqHuLhzbgWgL_wV3LDSUrcbkOiIA

   See Appendix A.2 for the complete details of computing this JWE.


4.  JWE Header

   The members of the JSON object represented by the JWE Header describe
   the encryption applied to the Plaintext and optionally additional
   properties of the JWE.  The Header Parameter Names within this object
   MUST be unique; JWEs with duplicate Header Parameter Names MUST be
   rejected.  Implementations MUST understand the entire contents of the
   header; otherwise, the JWE MUST be rejected.

   There are two ways of distinguishing whether a header is a JWS Header
   or a JWE Header.  The first is by examining the "alg" (algorithm)
   header value.  If the value represents a digital signature or MAC
   algorithm, or is the value "none", it is for a JWS; if it represents
   an encryption or key agreement algorithm, it is for a JWE.  A second
   method is determining whether an "enc" (encryption method) member
   exists.  If the "enc" member exists, it is a JWE; otherwise, it is a
   JWS.  Both methods will yield the same result for all legal input
   values.

   There are three classes of Header Parameter Names: Reserved Header
   Parameter Names, Public Header Parameter Names, and Private Header



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   Parameter Names.

4.1.  Reserved Header Parameter Names

   The following header parameter names are reserved with meanings as
   defined below.  All the names are short because a core goal of JWE is
   for the representations to be compact.

   Additional reserved header parameter names MAY be defined via the
   IANA JSON Web Signature and Encryption Header Parameters registry
   [JWS].  As indicated by the common registry, JWSs and JWEs share a
   common header parameter space; when a parameter is used by both
   specifications, its usage must be compatible between the
   specifications.

4.1.1.  "alg" (Algorithm) Header Parameter

   The "alg" (algorithm) header parameter identifies the cryptographic
   algorithm used to encrypt or determine the value of the Content
   Master Key (CMK).  The algorithm specified by the "alg" value MUST be
   supported by the implementation and there MUST be a key for use with
   that algorithm associated with the intended recipient or the JWE MUST
   be rejected. "alg" values SHOULD either be registered in the IANA
   JSON Web Signature and Encryption Algorithms registry [JWA] or be a
   URI that contains a Collision Resistant Namespace.  The "alg" value
   is a case sensitive string containing a StringOrURI value.  This
   header parameter is REQUIRED.

   A list of defined "alg" values can be found in the IANA JSON Web
   Signature and Encryption Algorithms registry [JWA]; the initial
   contents of this registry are the values defined in Section 4.1 of
   the JSON Web Algorithms (JWA) [JWA] specification.

4.1.2.  "enc" (Encryption Method) Header Parameter

   The "enc" (encryption method) header parameter identifies the
   symmetric encryption algorithm used to encrypt the Plaintext to
   produce the Ciphertext.  The algorithm specified by the "enc" value
   MUST be supported by the implementation or the JWE MUST be rejected.
   "enc" values SHOULD either be registered in the IANA JSON Web
   Signature and Encryption Algorithms registry [JWA] or be a URI that
   contains a Collision Resistant Namespace.  The "enc" value is a case
   sensitive string containing a StringOrURI value.  This header
   parameter is REQUIRED.

   A list of defined "enc" values can be found in the IANA JSON Web
   Signature and Encryption Algorithms registry [JWA]; the initial
   contents of this registry are the values defined in Section 4.2 of



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   the JSON Web Algorithms (JWA) [JWA] specification.

4.1.3.  "epk" (Ephemeral Public Key) Header Parameter

   The "epk" (ephemeral public key) value created by the originator for
   the use in key agreement algorithms.  This key is represented as a
   JSON Web Key [JWK] value.  This header parameter is OPTIONAL,
   although its use is REQUIRED with some "alg" algorithms.

4.1.4.  "zip" (Compression Algorithm) Header Parameter

   The "zip" (compression algorithm) applied to the Plaintext before
   encryption, if any.  If present, the value of the "zip" header
   parameter MUST be the case sensitive string "DEF".  Compression is
   performed with the DEFLATE [RFC1951] algorithm.  If no "zip"
   parameter is present, no compression is applied to the Plaintext
   before encryption.  This header parameter is OPTIONAL.

4.1.5.  "jku" (JWK Set URL) Header Parameter

   The "jku" (JWK Set URL) header parameter is a URI [RFC3986] that
   refers to a resource for a set of JSON-encoded public keys, one of
   which corresponds to the key used to encrypt the JWE; this can be
   used to determine the private key needed to decrypt the JWE.  The
   keys MUST be encoded as a JSON Web Key Set (JWK Set) [JWK].  The
   protocol used to acquire the resource MUST provide integrity
   protection; an HTTP GET request to retrieve the certificate MUST use
   TLS [RFC2818] [RFC5246]; the identity of the server MUST be
   validated, as per Section 3.1 of HTTP Over TLS [RFC2818].  This
   header parameter is OPTIONAL.

4.1.6.  "jwk" (JSON Web Key) Header Parameter

   The "jwk" (JSON Web Key) header parameter is a public key that
   corresponds to the key used to encrypt the JWE; this can be used to
   determine the private key needed to decrypt the JWE.  This key is
   represented as a JSON Web Key [JWK].  This header parameter is
   OPTIONAL.

4.1.7.  "x5u" (X.509 URL) Header Parameter

   The "x5u" (X.509 URL) header parameter is a URI [RFC3986] that refers
   to a resource for the X.509 public key certificate or certificate
   chain [RFC5280] corresponding to the key used to encrypt the JWE;
   this can be used to determine the private key needed to decrypt the
   JWE.  The identified resource MUST provide a representation of the
   certificate or certificate chain that conforms to RFC 5280 [RFC5280]
   in PEM encoded form [RFC1421].  The certificate containing the public



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   key of the entity that encrypted the JWE MUST be the first
   certificate.  This MAY be followed by additional certificates, with
   each subsequent certificate being the one used to certify the
   previous one.  The protocol used to acquire the resource MUST provide
   integrity protection; an HTTP GET request to retrieve the certificate
   MUST use TLS [RFC2818] [RFC5246]; the identity of the server MUST be
   validated, as per Section 3.1 of HTTP Over TLS [RFC2818].  This
   header parameter is OPTIONAL.

4.1.8.  "x5t" (X.509 Certificate Thumbprint) Header Parameter

   The "x5t" (X.509 Certificate Thumbprint) header parameter provides a
   base64url encoded SHA-1 thumbprint (a.k.a. digest) of the DER
   encoding of the X.509 certificate [RFC5280] corresponding to the key
   used to encrypt the JWE; this can be used to determine the private
   key needed to decrypt the JWE.  This header parameter is OPTIONAL.

   If, in the future, certificate thumbprints need to be computed using
   hash functions other than SHA-1, it is suggested that additional
   related header parameters be defined for that purpose.  For example,
   it is suggested that a new "x5t#S256" (X.509 Certificate Thumbprint
   using SHA-256) header parameter could be defined by registering it in
   the IANA JSON Web Signature and Encryption Header Parameters registry
   [JWS].

4.1.9.  "x5c" (X.509 Certificate Chain) Header Parameter

   The "x5c" (X.509 Certificate Chain) header parameter contains the
   X.509 public key certificate or certificate chain [RFC5280]
   corresponding to the key used to encrypt the JWE; this can be used to
   determine the private key needed to decrypt the JWE.  The certificate
   or certificate chain is represented as an array of certificate value
   strings.  Each string is a base64 encoded ([RFC4648] Section 4 -- not
   base64url encoded) DER [ITU.X690.1994] PKIX certificate value.  The
   certificate containing the public key of the entity that encrypted
   the JWE MUST be the first certificate.  This MAY be followed by
   additional certificates, with each subsequent certificate being the
   one used to certify the previous one.  The recipient MUST verify the
   certificate chain according to [RFC5280] and reject the JWE if any
   validation failure occurs.  This header parameter is OPTIONAL.

   See Appendix B of [JWS] for an example "x5c" value.

4.1.10.  "kid" (Key ID) Header Parameter

   The "kid" (key ID) header parameter is a hint indicating which key
   was used to encrypt the JWE; this can be used to determine the
   private key needed to decrypt the JWE.  This parameter allows



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   originators to explicitly signal a change of key to recipients.
   Should the recipient be unable to locate a key corresponding to the
   "kid" value, they SHOULD treat that condition as an error.  The
   interpretation of the "kid" value is unspecified.  Its value MUST be
   a string.  This header parameter is OPTIONAL.

   When used with a JWK, the "kid" value MAY be used to match a JWK
   "kid" parameter value.

4.1.11.  "typ" (Type) Header Parameter

   The "typ" (type) header parameter is used to declare the type of this
   object.  The type value "JWE" MAY be used to indicate that this
   object is a JWE.  The "typ" value is a case sensitive string.  This
   header parameter is OPTIONAL.

   MIME Media Type [RFC2046] values MAY be used as "typ" values.

   "typ" values SHOULD either be registered in the IANA JSON Web
   Signature and Encryption Type Values registry [JWS] or be a URI that
   contains a Collision Resistant Namespace.

4.1.12.  "cty" (Content Type) Header Parameter

   The "cty" (content type) header parameter is used to declare the type
   of the encrypted content (the Plaintext).  The "cty" value is a case
   sensitive string.  This header parameter is OPTIONAL.

   The values used for the "cty" header parameter come from the same
   value space as the "typ" header parameter, with the same rules
   applying.

4.1.13.  "apu" (Agreement PartyUInfo) Header Parameter

   The "apu" (agreement PartyUInfo) value for key agreement algorithms
   using it (such as "ECDH-ES"), represented as a base64url encoded
   string.  This header parameter is OPTIONAL.

4.1.14.  "apv" (Agreement PartyVInfo) Header Parameter

   The "apv" (agreement PartyVInfo) value for key agreement algorithms
   using it (such as "ECDH-ES"), represented as a base64url encoded
   string.  This header parameter is OPTIONAL.

4.1.15.  "epu" (Encryption PartyUInfo) Header Parameter

   The "epu" (encryption PartyUInfo) value for plaintext encryption
   algorithms using it (such as "A128CBC+HS256"), represented as a



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   base64url encoded string.  This header parameter is OPTIONAL.

4.1.16.  "epv" (Encryption PartyVInfo) Header Parameter

   The "epv" (encryption PartyVInfo) value for plaintext encryption
   algorithms using it (such as "A128CBC+HS256"), represented as a
   base64url encoded string.  This header parameter is OPTIONAL.

4.2.  Public Header Parameter Names

   Additional header parameter names can be defined by those using JWEs.
   However, in order to prevent collisions, any new header parameter
   name SHOULD either be registered in the IANA JSON Web Signature and
   Encryption Header Parameters registry [JWS] or be a URI that contains
   a Collision Resistant Namespace.  In each case, the definer of the
   name or value needs to take reasonable precautions to make sure they
   are in control of the part of the namespace they use to define the
   header parameter name.

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

4.3.  Private Header Parameter Names

   A producer and consumer of a JWE may agree to any header parameter
   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.


5.  Message Encryption

   The message encryption process is as follows.  The order of the steps
   is not significant in cases where there are no dependencies between
   the inputs and outputs of the steps.

   1.   When key wrapping, key encryption, or key agreement with key
        wrapping are employed, generate a random Content Master Key
        (CMK).  See RFC 4086 [RFC4086] for considerations on generating
        random values.  The CMK MUST have a length equal to that
        required for the block encryption algorithm.

   2.   When key agreement is employed, use the key agreement algorithm
        to compute the value of the agreed upon key.  When key agreement
        without key wrapping is employed, let the Content Master Key
        (CMK) be the agreed upon key.  When key agreement with key
        wrapping is employed, the agreed upon key will be used to wrap
        the CMK.



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   3.   When key wrapping, key encryption, or key agreement with key
        wrapping are employed, encrypt the CMK for the recipient (see
        Section 7) and let the result be the JWE Encrypted Key.
        Otherwise, when direct encryption with a shared or agreed upon
        symmetric key is employed, let the JWE Encrypted Key be the
        empty byte array.

   4.   When direct encryption with a shared symmetric key is employed,
        let the Content Master Key (CMK) be the shared key.

   5.   Base64url encode the JWE Encrypted Key to create the Encoded JWE
        Encrypted Key.

   6.   Generate a random JWE Initialization Vector of the correct size
        for the block encryption algorithm (if required for the
        algorithm); otherwise, let the JWE Initialization Vector be the
        empty byte string.

   7.   Base64url encode the JWE Initialization Vector to create the
        Encoded JWE Initialization Vector.

   8.   Compress the Plaintext if a "zip" parameter was included.

   9.   Serialize the (compressed) Plaintext into a byte sequence M.

   10.  Create a JWE Header containing the encryption parameters used.
        Note that white space is explicitly allowed in the
        representation and no canonicalization need be performed before
        encoding.

   11.  Base64url encode the bytes of the UTF-8 representation of the
        JWE Header to create the Encoded JWE Header.

   12.  Encrypt M using the CMK, the JWE Initialization Vector, and the
        other parameters required for the specified block encryption
        algorithm to create the JWE Ciphertext value and the JWE
        Integrity Value.

   13.  Base64url encode the JWE Ciphertext to create the Encoded JWE
        Ciphertext.

   14.  Base64url encode the JWE Integrity Value to create the Encoded
        JWE Integrity Value.

   15.  The five encoded parts, taken together, are the result.

   16.  The Compact Serialization of this result is the concatenation of
        the Encoded JWE Header, the Encoded JWE Encrypted Key, the



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        Encoded JWE Initialization Vector, the Encoded JWE Ciphertext,
        and the Encoded JWE Integrity Value in that order, with the five
        strings being separated by four period ('.') characters.


6.  Message Decryption

   The message decryption process is the reverse of the encryption
   process.  The order of the steps is not significant in cases where
   there are no dependencies between the inputs and outputs of the
   steps.  If any of these steps fails, the JWE MUST be rejected.

   1.   Determine the Encoded JWE Header, the Encoded JWE Encrypted Key,
        the Encoded JWE Initialization Vector, the Encoded JWE
        Ciphertext, and the Encoded JWE Integrity Value values contained
        in the JWE.  When using the Compact Serialization, these five
        values are represented in that order, separated by four period
        ('.') characters.

   2.   The Encoded JWE Header, the Encoded JWE Encrypted Key, the
        Encoded JWE Initialization Vector, the Encoded JWE Ciphertext,
        and the Encoded JWE Integrity Value MUST be successfully
        base64url decoded following the restriction that no padding
        characters have been used.

   3.   The resulting JWE Header MUST be completely valid JSON syntax
        conforming to RFC 4627 [RFC4627].

   4.   The resulting JWE Header MUST be validated to only include
        parameters and values whose syntax and semantics are both
        understood and supported.

   5.   Verify that the JWE uses a key known to the recipient.

   6.   When key agreement is employed, use the key agreement algorithm
        to compute the value of the agreed upon key.  When key agreement
        without key wrapping is employed, let the Content Master Key
        (CMK) be the agreed upon key.  When key agreement with key
        wrapping is employed, the agreed upon key will be used to
        decrypt the JWE Encrypted Key.

   7.   When key wrapping, key encryption, or key agreement with key
        wrapping are employed, decrypt the JWE Encrypted Key to produce
        the Content Master Key (CMK).  The CMK MUST have a length equal
        to that required for the block encryption algorithm.

   8.   When direct encryption with a shared symmetric key is employed,
        let the Content Master Key (CMK) be the shared key.



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   9.   Decrypt the JWE Ciphertext using the CMK, the JWE Initialization
        Vector, and the other parameters required for the specified
        block encryption algorithm, returning the decrypted plaintext
        and verifying the JWE Integrity Value in the manner specified
        for the algorithm.

   10.  Uncompress the decrypted plaintext if a "zip" parameter was
        included.

   11.  Output the resulting Plaintext.


7.  CMK Encryption

   JWE supports three forms of Content Master Key (CMK) encryption:

   o  Asymmetric encryption under the recipient's public key.

   o  Symmetric encryption under a key shared between the sender and
      receiver.

   o  Symmetric encryption under a key agreed upon between the sender
      and receiver.

   See the algorithms registered for "enc" usage in the IANA JSON Web
   Signature and Encryption Algorithms registry [JWA] and Section 4.1 of
   the JSON Web Algorithms (JWA) [JWA] specification for lists of
   encryption algorithms that can be used for CMK encryption.


8.  Encrypting JWEs with Cryptographic Algorithms

   JWE uses cryptographic algorithms to encrypt the Plaintext and the
   Content Encryption Key (CMK) and to provide integrity protection for
   the JWE Header, JWE Encrypted Key, and JWE Ciphertext.  The JSON Web
   Algorithms (JWA) [JWA] specification specifies a set of cryptographic
   algorithms and identifiers to be used with this specification and
   defines registries for additional such algorithms.  Specifically,
   Section 4.1 specifies a set of "alg" (algorithm) header parameter
   values and Section 4.2 specifies a set of "enc" (encryption method)
   header parameter values intended for use this specification.  It also
   describes the semantics and operations that are specific to these
   algorithms and algorithm families.

   Public keys employed for encryption can be identified using the
   Header Parameter methods described in Section 4.1 or can be
   distributed using methods that are outside the scope of this
   specification.



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9.  IANA Considerations

9.1.  Registration of JWE Header Parameter Names

   This specification registers the Header Parameter Names defined in
   Section 4.1 in the IANA JSON Web Signature and Encryption Header
   Parameters registry [JWS].

9.1.1.  Registry Contents

   o  Header Parameter Name: "alg"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.1 of [[ this document ]]

   o  Header Parameter Name: "enc"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.2 of [[ this document ]]

   o  Header Parameter Name: "epk"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.3 of [[ this document ]]

   o  Header Parameter Name: "zip"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.4 of [[ this document ]]

   o  Header Parameter Name: "jku"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.5 of [[ this document ]]

   o  Header Parameter Name: "jwk"
   o  Change Controller: IETF
   o  Specification document(s): Section 4.1.6 of [[ this document ]]

   o  Header Parameter Name: "x5u"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.7 of [[ this document ]]

   o  Header Parameter Name: "x5t"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.8 of [[ this document ]]

   o  Header Parameter Name: "x5c"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.9 of [[ this document ]]






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   o  Header Parameter Name: "kid"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.10 of [[ this document ]]

   o  Header Parameter Name: "typ"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.11 of [[ this document ]]

   o  Header Parameter Name: "cty"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.12 of [[ this document ]]

   o  Header Parameter Name: "apu"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.13 of [[ this document ]]

   o  Header Parameter Name: "apv"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.14 of [[ this document ]]

   o  Header Parameter Name: "epu"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.15 of [[ this document ]]

   o  Header Parameter Name: "epv"
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.16 of [[ this document ]]

9.2.  JSON Web Signature and Encryption Type Values Registration

9.2.1.  Registry Contents

   This specification registers the "JWE" type value in the IANA JSON
   Web Signature and Encryption Type Values registry [JWS]:

   o  "typ" Header Parameter Value: "JWE"
   o  Abbreviation for MIME Type: application/jwe
   o  Change Controller: IETF
   o  Specification Document(s): Section 4.1.11 of [[ this document ]]

9.3.  Media Type Registration

9.3.1.  Registry Contents

   This specification registers the "application/jwe" Media Type
   [RFC2046] in the MIME Media Type registry [RFC4288] to indicate that
   the content is a JWE using the Compact Serialization.




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   o  Type Name: application
   o  Subtype Name: jwe
   o  Required Parameters: n/a
   o  Optional Parameters: n/a
   o  Encoding considerations: JWE values are encoded as a series of
      base64url encoded values (some of which may be the empty string)
      separated by period ('.') characters
   o  Security Considerations: See the Security Considerations section
      of this document
   o  Interoperability Considerations: n/a
   o  Published Specification: [[ this document ]]
   o  Applications that use this media type: OpenID Connect and other
      applications using encrypted JWTs
   o  Additional Information: Magic number(s): n/a, File extension(s):
      n/a, Macintosh file type code(s): n/a
   o  Person & email address to contact for further information: Michael
      B. Jones, mbj@microsoft.com
   o  Intended Usage: COMMON
   o  Restrictions on Usage: none
   o  Author: Michael B. Jones, mbj@microsoft.com
   o  Change Controller: IETF


10.  Security Considerations

   All of the security issues faced by any cryptographic application
   must be faced by a JWS/JWE/JWK agent.  Among these issues are
   protecting the user's private key, preventing various attacks, and
   helping the user avoid mistakes such as inadvertently encrypting a
   message for the wrong recipient.  The entire list of security
   considerations is beyond the scope of this document, but some
   significant concerns are listed here.

   All the security considerations in the JWS specification also apply
   to this specification.  Likewise, all the security considerations in
   XML Encryption 1.1 [W3C.CR-xmlenc-core1-20120313] also apply to JWE,
   other than those that are XML specific.


11.  References

11.1.  Normative References

   [ITU.X690.1994]
              International Telecommunications Union, "Information
              Technology - ASN.1 encoding rules: Specification of Basic
              Encoding Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER)", ITU-T Recommendation



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              X.690, 1994.

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

   [JWK]      Jones, M., "JSON Web Key (JWK)", October 2012.

   [JWS]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", October 2012.

   [RFC1421]  Linn, J., "Privacy Enhancement for Internet Electronic
              Mail: Part I: Message Encryption and Authentication
              Procedures", RFC 1421, February 1993.

   [RFC1951]  Deutsch, P., "DEFLATE Compressed Data Format Specification
              version 1.3", RFC 1951, May 1996.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

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

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [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.

   [RFC4086]  Eastlake, D., Schiller, J., and S. Crocker, "Randomness
              Requirements for Security", BCP 106, RFC 4086, June 2005.

   [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and
              Registration Procedures", BCP 13, RFC 4288, December 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.

   [RFC5116]  McGrew, D., "An Interface and Algorithms for Authenticated
              Encryption", RFC 5116, January 2008.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security



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              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5280]  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.

   [W3C.CR-xmlenc-core1-20120313]
              Eastlake, D., Reagle, J., Hirsch, F., and T. Roessler,
              "XML Encryption Syntax and Processing Version 1.1", World
              Wide Web Consortium CR CR-xmlenc-core1-20120313,
              March 2012,
              <http://www.w3.org/TR/2012/CR-xmlenc-core1-20120313>.

11.2.  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.

   [JWE-JS]   Jones, M., "JSON Web Encryption JSON Serialization
              (JWE-JS)", October 2012.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              July 2005.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, September 2009.


Appendix A.  JWE Examples

   This section provides examples of JWE computations.

A.1.  Example JWE using RSAES OAEP and AES GCM

   This example encrypts the plaintext "Live long and prosper." to the
   recipient using RSAES OAEP and AES GCM.  The AES GCM algorithm has an
   integrated integrity check.  The representation of this plaintext is:

   [76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32,
   112, 114, 111, 115, 112, 101, 114, 46]




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A.1.1.  JWE Header

   The following example JWE Header declares that:

   o  the Content Master Key is encrypted to the recipient using the
      RSAES OAEP algorithm to produce the JWE Encrypted Key and

   o  the Plaintext is encrypted using the AES GCM algorithm with a 256
      bit key to produce the Ciphertext.


     {"alg":"RSA-OAEP","enc":"A256GCM"}

A.1.2.  Encoded JWE Header

   Base64url encoding the bytes of the UTF-8 representation of the JWE
   Header yields this Encoded JWE Header value:

     eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ

A.1.3.  Content Master Key (CMK)

   Generate a 256 bit random Content Master Key (CMK).  In this example,
   the value is:

   [177, 161, 244, 128, 84, 143, 225, 115, 63, 180, 3, 255, 107, 154,
   212, 246, 138, 7, 110, 91, 112, 46, 34, 105, 47, 130, 203, 46, 122,
   234, 64, 252]

A.1.4.  Key Encryption

   Encrypt the CMK with the recipient's public key using the RSAES OAEP
   algorithm to produce the JWE Encrypted Key. In this example, the RSA
   key parameters are:

















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   +-----------+-------------------------------------------------------+
   | Parameter | Value                                                 |
   | Name      |                                                       |
   +-----------+-------------------------------------------------------+
   | Modulus   | [161, 168, 84, 34, 133, 176, 208, 173, 46, 176, 163,  |
   |           | 110, 57, 30, 135, 227, 9, 31, 226, 128, 84, 92, 116,  |
   |           | 241, 70, 248, 27, 227, 193, 62, 5, 91, 241, 145, 224, |
   |           | 205, 141, 176, 184, 133, 239, 43, 81, 103, 9, 161,    |
   |           | 153, 157, 179, 104, 123, 51, 189, 34, 152, 69, 97,    |
   |           | 69, 78, 93, 140, 131, 87, 182, 169, 101, 92, 142, 3,  |
   |           | 22, 167, 8, 212, 56, 35, 79, 210, 222, 192, 208, 252, |
   |           | 49, 109, 138, 173, 253, 210, 166, 201, 63, 102, 74,   |
   |           | 5, 158, 41, 90, 144, 108, 160, 79, 10, 89, 222, 231,  |
   |           | 172, 31, 227, 197, 0, 19, 72, 81, 138, 78, 136, 221,  |
   |           | 121, 118, 196, 17, 146, 10, 244, 188, 72, 113, 55,    |
   |           | 221, 162, 217, 171, 27, 57, 233, 210, 101, 236, 154,  |
   |           | 199, 56, 138, 239, 101, 48, 198, 186, 202, 160, 76,   |
   |           | 111, 234, 71, 57, 183, 5, 211, 171, 136, 126, 64, 40, |
   |           | 75, 58, 89, 244, 254, 107, 84, 103, 7, 236, 69, 163,  |
   |           | 18, 180, 251, 58, 153, 46, 151, 174, 12, 103, 197,    |
   |           | 181, 161, 162, 55, 250, 235, 123, 110, 17, 11, 158,   |
   |           | 24, 47, 133, 8, 199, 235, 107, 126, 130, 246, 73,     |
   |           | 195, 20, 108, 202, 176, 214, 187, 45, 146, 182, 118,  |
   |           | 54, 32, 200, 61, 201, 71, 243, 1, 255, 131, 84, 37,   |
   |           | 111, 211, 168, 228, 45, 192, 118, 27, 197, 235, 232,  |
   |           | 36, 10, 230, 248, 190, 82, 182, 140, 35, 204, 108,    |
   |           | 190, 253, 186, 186, 27]                               |
   | Exponent  | [1, 0, 1]                                             |























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   | Private   | [144, 183, 109, 34, 62, 134, 108, 57, 44, 252, 10,    |
   | Exponent  | 66, 73, 54, 16, 181, 233, 92, 54, 219, 101, 42, 35,   |
   |           | 178, 63, 51, 43, 92, 119, 136, 251, 41, 53, 23, 191,  |
   |           | 164, 164, 60, 88, 227, 229, 152, 228, 213, 149, 228,  |
   |           | 169, 237, 104, 71, 151, 75, 88, 252, 216, 77, 251,    |
   |           | 231, 28, 97, 88, 193, 215, 202, 248, 216, 121, 195,   |
   |           | 211, 245, 250, 112, 71, 243, 61, 129, 95, 39, 244,    |
   |           | 122, 225, 217, 169, 211, 165, 48, 253, 220, 59, 122,  |
   |           | 219, 42, 86, 223, 32, 236, 39, 48, 103, 78, 122, 216, |
   |           | 187, 88, 176, 89, 24, 1, 42, 177, 24, 99, 142, 170,   |
   |           | 1, 146, 43, 3, 108, 64, 194, 121, 182, 95, 187, 134,  |
   |           | 71, 88, 96, 134, 74, 131, 167, 69, 106, 143, 121, 27, |
   |           | 72, 44, 245, 95, 39, 194, 179, 175, 203, 122, 16,     |
   |           | 112, 183, 17, 200, 202, 31, 17, 138, 156, 184, 210,   |
   |           | 157, 184, 154, 131, 128, 110, 12, 85, 195, 122, 241,  |
   |           | 79, 251, 229, 183, 117, 21, 123, 133, 142, 220, 153,  |
   |           | 9, 59, 57, 105, 81, 255, 138, 77, 82, 54, 62, 216,    |
   |           | 38, 249, 208, 17, 197, 49, 45, 19, 232, 157, 251,     |
   |           | 131, 137, 175, 72, 126, 43, 229, 69, 179, 117, 82,    |
   |           | 157, 213, 83, 35, 57, 210, 197, 252, 171, 143, 194,   |
   |           | 11, 47, 163, 6, 253, 75, 252, 96, 11, 187, 84, 130,   |
   |           | 210, 7, 121, 78, 91, 79, 57, 251, 138, 132, 220, 60,  |
   |           | 224, 173, 56, 224, 201]                               |
   +-----------+-------------------------------------------------------+

   The resulting JWE Encrypted Key value is:

   [51, 101, 241, 165, 179, 145, 41, 236, 202, 75, 60, 208, 47, 255,
   121, 248, 104, 226, 185, 212, 65, 78, 169, 255, 162, 100, 188, 207,
   220, 96, 161, 22, 251, 47, 66, 112, 229, 75, 4, 111, 25, 173, 200,
   121, 246, 79, 189, 102, 173, 146, 228, 142, 14, 12, 167, 200, 27,
   133, 138, 37, 180, 249, 4, 56, 123, 192, 162, 156, 246, 231, 235,
   217, 240, 45, 158, 213, 195, 154, 2, 142, 86, 61, 198, 210, 34, 225,
   92, 7, 128, 227, 4, 227, 55, 183, 69, 0, 59, 162, 71, 145, 98, 238,
   0, 70, 40, 123, 159, 37, 115, 18, 16, 157, 236, 138, 117, 166, 18,
   45, 181, 125, 112, 170, 168, 82, 129, 80, 166, 242, 150, 97, 17, 217,
   109, 251, 51, 35, 39, 236, 107, 95, 43, 154, 4, 227, 206, 187, 75,
   13, 51, 231, 115, 79, 67, 72, 145, 54, 225, 164, 60, 195, 120, 188,
   69, 113, 3, 182, 21, 189, 79, 82, 122, 46, 196, 199, 254, 252, 7,
   119, 5, 32, 144, 143, 173, 11, 99, 205, 120, 106, 231, 51, 231, 77,
   73, 252, 197, 221, 142, 254, 151, 7, 6, 203, 65, 108, 117, 121, 15,
   95, 43, 111, 13, 94, 242, 226, 150, 94, 121, 72, 144, 251, 69, 93,
   137, 178, 13, 216, 8, 227, 125, 110, 180, 157, 250, 207, 184, 232,
   222, 164, 193, 70, 232, 16, 65, 109, 29, 251, 164, 119, 50, 205, 236,
   109, 245, 234, 78, 1]






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A.1.5.  Encoded JWE Encrypted Key

   Base64url encode the JWE Encrypted Key to produce the Encoded JWE
   Encrypted Key. This result (with line breaks for display purposes
   only) is:

     M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
     rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
     O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
     zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
     SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
     6BBBbR37pHcyzext9epOAQ

A.1.6.  Initialization Vector

   Generate a random 96 bit JWE Initialization Vector.  In this example,
   the value is:

   [227, 197, 117, 252, 2, 219, 233, 68, 180, 225, 77, 219]

   Base64url encoding this value yields the Encoded JWE Initialization
   Vector value:

     48V1_ALb6US04U3b

A.1.7.  "Additional Authenticated Data" Parameter

   Concatenate the Encoded JWE Header value, a period character ('.'),
   the Encoded JWE Encrypted Key, a second period character ('.'), and
   the Encoded JWE Initialization Vector to create the "additional
   authenticated data" parameter for the AES GCM algorithm.  This result
   (with line breaks for display purposes only) is:

     eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
     M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
     rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
     O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
     zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
     SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
     6BBBbR37pHcyzext9epOAQ.
     48V1_ALb6US04U3b

   The representation of this value is:

   [101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 48, 69,
   116, 84, 48, 70, 70, 85, 67, 73, 115, 73, 109, 86, 117, 89, 121, 73,
   54, 73, 107, 69, 121, 78, 84, 90, 72, 81, 48, 48, 105, 102, 81, 46,
   77, 50, 88, 120, 112, 98, 79, 82, 75, 101, 122, 75, 83, 122, 122, 81,



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   76, 95, 57, 53, 45, 71, 106, 105, 117, 100, 82, 66, 84, 113, 110, 95,
   111, 109, 83, 56, 122, 57, 120, 103, 111, 82, 98, 55, 76, 48, 74,
   119, 53, 85, 115, 69, 98, 120, 109, 116, 121, 72, 110, 50, 84, 55,
   49, 109, 114, 90, 76, 107, 106, 103, 52, 77, 112, 56, 103, 98, 104,
   89, 111, 108, 116, 80, 107, 69, 79, 72, 118, 65, 111, 112, 122, 50,
   53, 45, 118, 90, 56, 67, 50, 101, 49, 99, 79, 97, 65, 111, 53, 87,
   80, 99, 98, 83, 73, 117, 70, 99, 66, 52, 68, 106, 66, 79, 77, 51,
   116, 48, 85, 65, 79, 54, 74, 72, 107, 87, 76, 117, 65, 69, 89, 111,
   101, 53, 56, 108, 99, 120, 73, 81, 110, 101, 121, 75, 100, 97, 89,
   83, 76, 98, 86, 57, 99, 75, 113, 111, 85, 111, 70, 81, 112, 118, 75,
   87, 89, 82, 72, 90, 98, 102, 115, 122, 73, 121, 102, 115, 97, 49, 56,
   114, 109, 103, 84, 106, 122, 114, 116, 76, 68, 84, 80, 110, 99, 48,
   57, 68, 83, 74, 69, 50, 52, 97, 81, 56, 119, 51, 105, 56, 82, 88, 69,
   68, 116, 104, 87, 57, 84, 49, 74, 54, 76, 115, 84, 72, 95, 118, 119,
   72, 100, 119, 85, 103, 107, 73, 45, 116, 67, 50, 80, 78, 101, 71,
   114, 110, 77, 45, 100, 78, 83, 102, 122, 70, 51, 89, 55, 45, 108,
   119, 99, 71, 121, 48, 70, 115, 100, 88, 107, 80, 88, 121, 116, 118,
   68, 86, 55, 121, 52, 112, 90, 101, 101, 85, 105, 81, 45, 48, 86, 100,
   105, 98, 73, 78, 50, 65, 106, 106, 102, 87, 54, 48, 110, 102, 114,
   80, 117, 79, 106, 101, 112, 77, 70, 71, 54, 66, 66, 66, 98, 82, 51,
   55, 112, 72, 99, 121, 122, 101, 120, 116, 57, 101, 112, 79, 65, 81,
   46, 52, 56, 86, 49, 95, 65, 76, 98, 54, 85, 83, 48, 52, 85, 51, 98]

A.1.8.  Plaintext Encryption

   Encrypt the Plaintext with AES GCM using the CMK as the encryption
   key, the JWE Initialization Vector, and the "additional authenticated
   data" value above, requesting a 128 bit "authentication tag" output.
   The resulting Ciphertext is:

   [253, 237, 181, 180, 97, 161, 105, 207, 233, 120, 65, 100, 45, 122,
   246, 116, 195, 212, 102, 37, 36, 175]

   The resulting "authentication tag" value is:

   [237, 94, 89, 14, 74, 52, 191, 249, 159, 216, 240, 28, 224, 147, 34,
   82]

A.1.9.  Encoded JWE Ciphertext

   Base64url encode the resulting Ciphertext to create the Encoded JWE
   Ciphertext.  This result is:

     _e21tGGhac_peEFkLXr2dMPUZiUkrw







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A.1.10.  Encoded JWE Integrity Value

   Base64url encode the resulting "authentication tag" to create the
   Encoded JWE Integrity Value.  This result is:

     7V5ZDko0v_mf2PAc4JMiUg

A.1.11.  Complete Representation

   Assemble the final representation: The Compact Serialization of this
   result is the concatenation of the Encoded JWE Header, the Encoded
   JWE Encrypted Key, the Encoded JWE Initialization Vector, the Encoded
   JWE Ciphertext, and the Encoded JWE Integrity Value in that order,
   with the five strings being separated by four period ('.')
   characters.

   The final result in this example (with line breaks for display
   purposes only) is:

     eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
     M2XxpbORKezKSzzQL_95-GjiudRBTqn_omS8z9xgoRb7L0Jw5UsEbxmtyHn2T71m
     rZLkjg4Mp8gbhYoltPkEOHvAopz25-vZ8C2e1cOaAo5WPcbSIuFcB4DjBOM3t0UA
     O6JHkWLuAEYoe58lcxIQneyKdaYSLbV9cKqoUoFQpvKWYRHZbfszIyfsa18rmgTj
     zrtLDTPnc09DSJE24aQ8w3i8RXEDthW9T1J6LsTH_vwHdwUgkI-tC2PNeGrnM-dN
     SfzF3Y7-lwcGy0FsdXkPXytvDV7y4pZeeUiQ-0VdibIN2AjjfW60nfrPuOjepMFG
     6BBBbR37pHcyzext9epOAQ.
     48V1_ALb6US04U3b.
     _e21tGGhac_peEFkLXr2dMPUZiUkrw.
     7V5ZDko0v_mf2PAc4JMiUg

A.1.12.  Validation

   This example illustrates the process of creating a JWE with an AEAD
   algorithm.  These results can be used to validate JWE decryption
   implementations for these algorithms.  Note that since the RSAES OAEP
   computation includes random values, the encryption results above will
   not be completely reproducible.  However, since the AES GCM
   computation is deterministic, the JWE Encrypted Ciphertext values
   will be the same for all encryptions performed using these inputs.

A.2.  Example JWE using RSAES-PKCS1-V1_5 and AES CBC

   This example encrypts the plaintext "No matter where you go, there
   you are." to the recipient using RSAES-PKCS1-V1_5 and AES CBC.  AES
   CBC does not have an integrated integrity check, so a separate
   integrity check calculation is performed using HMAC SHA-256, with
   separate encryption and integrity keys being derived from a master
   key using the Concat KDF with the SHA-256 digest function.  The



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   representation of this plaintext is:

   [78, 111, 32, 109, 97, 116, 116, 101, 114, 32, 119, 104, 101, 114,
   101, 32, 121, 111, 117, 32, 103, 111, 44, 32, 116, 104, 101, 114,
   101, 32, 121, 111, 117, 32, 97, 114, 101, 46]

A.2.1.  JWE Header

   The following example JWE Header (with line breaks for display
   purposes only) declares that:

   o  the Content Master Key is encrypted to the recipient using the
      RSAES-PKCS1-V1_5 algorithm to produce the JWE Encrypted Key and

   o  the Plaintext is encrypted using the AES CBC algorithm with a 128
      bit key to produce the Ciphertext, with the integrity of the
      Ciphertext and the parameters used to create it being secured with
      the HMAC SHA-256 algorithm.


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

A.2.2.  Encoded JWE Header

   Base64url encoding the bytes of the UTF-8 representation of the JWE
   Header yields this Encoded JWE Header value:

     eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0

A.2.3.  Content Master Key (CMK)

   Generate a 256 bit random Content Master Key (CMK).  In this example,
   the key value is:

   [4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106,
   206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156,
   44, 207]

A.2.4.  Key Encryption

   Encrypt the CMK with the recipient's public key using the RSAES-
   PKCS1-V1_5 algorithm to produce the JWE Encrypted Key. In this
   example, the RSA key parameters are:








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   +-----------+-------------------------------------------------------+
   | Parameter | Value                                                 |
   | Name      |                                                       |
   +-----------+-------------------------------------------------------+
   | Modulus   | [177, 119, 33, 13, 164, 30, 108, 121, 207, 136, 107,  |
   |           | 242, 12, 224, 19, 226, 198, 134, 17, 71, 173, 75, 42, |
   |           | 61, 48, 162, 206, 161, 97, 108, 185, 234, 226, 219,   |
   |           | 118, 206, 118, 5, 169, 224, 60, 181, 90, 85, 51, 123, |
   |           | 6, 224, 4, 122, 29, 230, 151, 12, 244, 127, 121, 25,  |
   |           | 4, 85, 220, 144, 215, 110, 130, 17, 68, 228, 129,     |
   |           | 138, 7, 130, 231, 40, 212, 214, 17, 179, 28, 124,     |
   |           | 151, 178, 207, 20, 14, 154, 222, 113, 176, 24, 198,   |
   |           | 73, 211, 113, 9, 33, 178, 80, 13, 25, 21, 25, 153,    |
   |           | 212, 206, 67, 154, 147, 70, 194, 192, 183, 160, 83,   |
   |           | 98, 236, 175, 85, 23, 97, 75, 199, 177, 73, 145, 50,  |
   |           | 253, 206, 32, 179, 254, 236, 190, 82, 73, 67, 129,    |
   |           | 253, 252, 220, 108, 136, 138, 11, 192, 1, 36, 239,    |
   |           | 228, 55, 81, 113, 17, 25, 140, 63, 239, 146, 3, 172,  |
   |           | 96, 60, 227, 233, 64, 255, 224, 173, 225, 228, 229,   |
   |           | 92, 112, 72, 99, 97, 26, 87, 187, 123, 46, 50, 90,    |
   |           | 202, 117, 73, 10, 153, 47, 224, 178, 163, 77, 48, 46, |
   |           | 154, 33, 148, 34, 228, 33, 172, 216, 89, 46, 225,     |
   |           | 127, 68, 146, 234, 30, 147, 54, 146, 5, 133, 45, 78,  |
   |           | 254, 85, 55, 75, 213, 86, 194, 218, 215, 163, 189,    |
   |           | 194, 54, 6, 83, 36, 18, 153, 53, 7, 48, 89, 35, 66,   |
   |           | 144, 7, 65, 154, 13, 97, 75, 55, 230, 132, 3, 13,     |
   |           | 239, 71]                                              |
   | Exponent  | [1, 0, 1]                                             |























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   | Private   | [84, 80, 150, 58, 165, 235, 242, 123, 217, 55, 38,    |
   | Exponent  | 154, 36, 181, 221, 156, 211, 215, 100, 164, 90, 88,   |
   |           | 40, 228, 83, 148, 54, 122, 4, 16, 165, 48, 76, 194,   |
   |           | 26, 107, 51, 53, 179, 165, 31, 18, 198, 173, 78, 61,  |
   |           | 56, 97, 252, 158, 140, 80, 63, 25, 223, 156, 36, 203, |
   |           | 214, 252, 120, 67, 180, 167, 3, 82, 243, 25, 97, 214, |
   |           | 83, 133, 69, 16, 104, 54, 160, 200, 41, 83, 164, 187, |
   |           | 70, 153, 111, 234, 242, 158, 175, 28, 198, 48, 211,   |
   |           | 45, 148, 58, 23, 62, 227, 74, 52, 117, 42, 90, 41,    |
   |           | 249, 130, 154, 80, 119, 61, 26, 193, 40, 125, 10,     |
   |           | 152, 174, 227, 225, 205, 32, 62, 66, 6, 163, 100, 99, |
   |           | 219, 19, 253, 25, 105, 80, 201, 29, 252, 157, 237,    |
   |           | 69, 1, 80, 171, 167, 20, 196, 156, 109, 249, 88, 0,   |
   |           | 3, 152, 38, 165, 72, 87, 6, 152, 71, 156, 214, 16,    |
   |           | 71, 30, 82, 51, 103, 76, 218, 63, 9, 84, 163, 249,    |
   |           | 91, 215, 44, 238, 85, 101, 240, 148, 1, 82, 224, 91,  |
   |           | 135, 105, 127, 84, 171, 181, 152, 210, 183, 126, 24,  |
   |           | 46, 196, 90, 173, 38, 245, 219, 186, 222, 27, 240,    |
   |           | 212, 194, 15, 66, 135, 226, 178, 190, 52, 245, 74,    |
   |           | 65, 224, 81, 100, 85, 25, 204, 165, 203, 187, 175,    |
   |           | 84, 100, 82, 15, 11, 23, 202, 151, 107, 54, 41, 207,  |
   |           | 3, 136, 229, 134, 131, 93, 139, 50, 182, 204, 93,     |
   |           | 130, 89]                                              |
   +-----------+-------------------------------------------------------+

   The resulting JWE Encrypted Key value is:

   [59, 160, 42, 94, 168, 21, 148, 146, 120, 115, 137, 105, 230, 197,
   217, 119, 182, 233, 24, 112, 48, 232, 4, 100, 29, 71, 151, 67, 16,
   245, 112, 5, 184, 249, 125, 113, 210, 171, 99, 252, 3, 116, 154, 233,
   42, 16, 233, 120, 99, 165, 14, 192, 149, 200, 37, 143, 126, 27, 81,
   11, 43, 228, 80, 90, 178, 135, 253, 43, 81, 248, 3, 61, 31, 177, 169,
   42, 100, 132, 142, 47, 16, 96, 231, 12, 58, 58, 254, 187, 209, 245,
   46, 223, 233, 4, 72, 158, 27, 205, 54, 75, 21, 179, 210, 182, 197,
   77, 116, 92, 143, 128, 86, 47, 23, 41, 10, 216, 212, 103, 125, 64,
   63, 235, 28, 248, 191, 222, 9, 158, 84, 54, 93, 26, 73, 19, 106, 22,
   201, 46, 62, 76, 209, 176, 86, 81, 12, 154, 146, 72, 151, 149, 59,
   34, 123, 165, 144, 144, 243, 119, 229, 139, 95, 85, 130, 47, 247, 71,
   181, 204, 82, 169, 110, 66, 235, 156, 237, 145, 206, 90, 44, 98, 227,
   184, 215, 148, 20, 229, 89, 22, 121, 136, 92, 90, 75, 193, 186, 39,
   204, 20, 173, 222, 1, 42, 8, 0, 195, 122, 151, 229, 122, 8, 125, 116,
   21, 149, 6, 68, 209, 89, 164, 171, 252, 208, 72, 138, 57, 46, 113,
   74, 202, 140, 40, 161, 23, 29, 176, 75, 141, 135, 208, 125, 50, 76,
   173, 209, 148, 4, 148, 111, 163, 25, 219, 71, 90, 54, 82, 56]







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A.2.5.  Encoded JWE Encrypted Key

   Base64url encode the JWE Encrypted Key to produce the Encoded JWE
   Encrypted Key. This result (with line breaks for display purposes
   only) is:

     O6AqXqgVlJJ4c4lp5sXZd7bpGHAw6ARkHUeXQxD1cAW4-X1x0qtj_AN0mukqEOl4
     Y6UOwJXIJY9-G1ELK-RQWrKH_StR-AM9H7GpKmSEji8QYOcMOjr-u9H1Lt_pBEie
     G802SxWz0rbFTXRcj4BWLxcpCtjUZ31AP-sc-L_eCZ5UNl0aSRNqFskuPkzRsFZR
     DJqSSJeVOyJ7pZCQ83fli19Vgi_3R7XMUqluQuuc7ZHOWixi47jXlBTlWRZ5iFxa
     S8G6J8wUrd4BKggAw3qX5XoIfXQVlQZE0Vmkq_zQSIo5LnFKyowooRcdsEuNh9B9
     Mkyt0ZQElG-jGdtHWjZSOA

A.2.6.  Key Derivation

   Use the Concat key derivation function to derive Content Encryption
   Key (CEK) and Content Integrity Key (CIK) values from the CMK.  The
   details of this derivation are shown in Appendix A.4.  The resulting
   CEK value is:

   [37, 245, 125, 247, 113, 155, 238, 98, 228, 206, 62, 65, 81, 153, 79,
   91]

   The resulting CIK value is:

   [203, 194, 197, 180, 120, 46, 123, 202, 78, 12, 33, 116, 214, 247,
   128, 41, 175, 53, 181, 164, 224, 223, 56, 146, 179, 193, 18, 223,
   146, 85, 244, 127]

A.2.7.  Initialization Vector

   Generate a random 128 bit JWE Initialization Vector.  In this
   example, the value is:

   [3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104,
   101]

   Base64url encoding this value yields the Encoded JWE Initialization
   Vector value:

     AxY8DCtDaGlsbGljb3RoZQ

A.2.8.  Plaintext Encryption

   Encrypt the Plaintext with AES CBC using the CEK and the JWE
   Initialization Vector to produce the Ciphertext.  The resulting
   Ciphertext is:




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   [213, 224, 86, 22, 7, 43, 207, 141, 48, 11, 207, 28, 130, 255, 43,
   62, 11, 183, 17, 249, 130, 214, 158, 51, 79, 73, 8, 199, 23, 210, 23,
   108, 195, 37, 196, 62, 136, 65, 228, 214, 52, 12, 247, 156, 64, 118,
   190, 89]

A.2.9.  Encoded JWE Ciphertext

   Base64url encode the resulting Ciphertext to create the Encoded JWE
   Ciphertext.  This result is:

     1eBWFgcrz40wC88cgv8rPgu3EfmC1p4zT0kIxxfSF2zDJcQ-iEHk1jQM95xAdr5Z

A.2.10.  Secured Input Value

   Concatenate the Encoded JWE Header value, a period character ('.'),
   the Encoded JWE Encrypted Key, a second period character, the Encoded
   JWE Initialization Vector, a third period ('.') character, and the
   Encoded JWE Ciphertext to create the value to integrity protect.
   This result (with line breaks for display purposes only) is:

     eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
     O6AqXqgVlJJ4c4lp5sXZd7bpGHAw6ARkHUeXQxD1cAW4-X1x0qtj_AN0mukqEOl4
     Y6UOwJXIJY9-G1ELK-RQWrKH_StR-AM9H7GpKmSEji8QYOcMOjr-u9H1Lt_pBEie
     G802SxWz0rbFTXRcj4BWLxcpCtjUZ31AP-sc-L_eCZ5UNl0aSRNqFskuPkzRsFZR
     DJqSSJeVOyJ7pZCQ83fli19Vgi_3R7XMUqluQuuc7ZHOWixi47jXlBTlWRZ5iFxa
     S8G6J8wUrd4BKggAw3qX5XoIfXQVlQZE0Vmkq_zQSIo5LnFKyowooRcdsEuNh9B9
     Mkyt0ZQElG-jGdtHWjZSOA.
     AxY8DCtDaGlsbGljb3RoZQ.
     1eBWFgcrz40wC88cgv8rPgu3EfmC1p4zT0kIxxfSF2zDJcQ-iEHk1jQM95xAdr5Z

   The representation of this value is:

   [101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 48, 69,
   120, 88, 122, 85, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105,
   74, 66, 77, 84, 73, 52, 81, 48, 74, 68, 75, 48, 104, 84, 77, 106, 85,
   50, 73, 110, 48, 46, 79, 54, 65, 113, 88, 113, 103, 86, 108, 74, 74,
   52, 99, 52, 108, 112, 53, 115, 88, 90, 100, 55, 98, 112, 71, 72, 65,
   119, 54, 65, 82, 107, 72, 85, 101, 88, 81, 120, 68, 49, 99, 65, 87,
   52, 45, 88, 49, 120, 48, 113, 116, 106, 95, 65, 78, 48, 109, 117,
   107, 113, 69, 79, 108, 52, 89, 54, 85, 79, 119, 74, 88, 73, 74, 89,
   57, 45, 71, 49, 69, 76, 75, 45, 82, 81, 87, 114, 75, 72, 95, 83, 116,
   82, 45, 65, 77, 57, 72, 55, 71, 112, 75, 109, 83, 69, 106, 105, 56,
   81, 89, 79, 99, 77, 79, 106, 114, 45, 117, 57, 72, 49, 76, 116, 95,
   112, 66, 69, 105, 101, 71, 56, 48, 50, 83, 120, 87, 122, 48, 114, 98,
   70, 84, 88, 82, 99, 106, 52, 66, 87, 76, 120, 99, 112, 67, 116, 106,
   85, 90, 51, 49, 65, 80, 45, 115, 99, 45, 76, 95, 101, 67, 90, 53, 85,
   78, 108, 48, 97, 83, 82, 78, 113, 70, 115, 107, 117, 80, 107, 122,
   82, 115, 70, 90, 82, 68, 74, 113, 83, 83, 74, 101, 86, 79, 121, 74,



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   55, 112, 90, 67, 81, 56, 51, 102, 108, 105, 49, 57, 86, 103, 105, 95,
   51, 82, 55, 88, 77, 85, 113, 108, 117, 81, 117, 117, 99, 55, 90, 72,
   79, 87, 105, 120, 105, 52, 55, 106, 88, 108, 66, 84, 108, 87, 82, 90,
   53, 105, 70, 120, 97, 83, 56, 71, 54, 74, 56, 119, 85, 114, 100, 52,
   66, 75, 103, 103, 65, 119, 51, 113, 88, 53, 88, 111, 73, 102, 88, 81,
   86, 108, 81, 90, 69, 48, 86, 109, 107, 113, 95, 122, 81, 83, 73, 111,
   53, 76, 110, 70, 75, 121, 111, 119, 111, 111, 82, 99, 100, 115, 69,
   117, 78, 104, 57, 66, 57, 77, 107, 121, 116, 48, 90, 81, 69, 108, 71,
   45, 106, 71, 100, 116, 72, 87, 106, 90, 83, 79, 65, 46, 65, 120, 89,
   56, 68, 67, 116, 68, 97, 71, 108, 115, 98, 71, 108, 106, 98, 51, 82,
   111, 90, 81, 46, 49, 101, 66, 87, 70, 103, 99, 114, 122, 52, 48, 119,
   67, 56, 56, 99, 103, 118, 56, 114, 80, 103, 117, 51, 69, 102, 109,
   67, 49, 112, 52, 122, 84, 48, 107, 73, 120, 120, 102, 83, 70, 50,
   122, 68, 74, 99, 81, 45, 105, 69, 72, 107, 49, 106, 81, 77, 57, 53,
   120, 65, 100, 114, 53, 90]

A.2.11.  JWE Integrity Value

   Compute the HMAC SHA-256 of this value using the CIK to create the
   JWE Integrity Value.  This result is:

   [68, 17, 161, 99, 49, 60, 253, 198, 75, 30, 50, 106, 168, 123, 139,
   135, 54, 224, 90, 2, 255, 193, 93, 203, 13, 37, 43, 113, 185, 14,
   136, 128]

A.2.12.  Encoded JWE Integrity Value

   Base64url encode the resulting JWE Integrity Value to create the
   Encoded JWE Integrity Value.  This result is:

     RBGhYzE8_cZLHjJqqHuLhzbgWgL_wV3LDSUrcbkOiIA

A.2.13.  Complete Representation

   Assemble the final representation: The Compact Serialization of this
   result is the concatenation of the Encoded JWE Header, the Encoded
   JWE Encrypted Key, the Encoded JWE Initialization Vector, the Encoded
   JWE Ciphertext, and the Encoded JWE Integrity Value in that order,
   with the five strings being separated by four period ('.')
   characters.

   The final result in this example (with line breaks for display
   purposes only) is:








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     eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDK0hTMjU2In0.
     O6AqXqgVlJJ4c4lp5sXZd7bpGHAw6ARkHUeXQxD1cAW4-X1x0qtj_AN0mukqEOl4
     Y6UOwJXIJY9-G1ELK-RQWrKH_StR-AM9H7GpKmSEji8QYOcMOjr-u9H1Lt_pBEie
     G802SxWz0rbFTXRcj4BWLxcpCtjUZ31AP-sc-L_eCZ5UNl0aSRNqFskuPkzRsFZR
     DJqSSJeVOyJ7pZCQ83fli19Vgi_3R7XMUqluQuuc7ZHOWixi47jXlBTlWRZ5iFxa
     S8G6J8wUrd4BKggAw3qX5XoIfXQVlQZE0Vmkq_zQSIo5LnFKyowooRcdsEuNh9B9
     Mkyt0ZQElG-jGdtHWjZSOA.
     AxY8DCtDaGlsbGljb3RoZQ.
     1eBWFgcrz40wC88cgv8rPgu3EfmC1p4zT0kIxxfSF2zDJcQ-iEHk1jQM95xAdr5Z.
     RBGhYzE8_cZLHjJqqHuLhzbgWgL_wV3LDSUrcbkOiIA

A.2.14.  Validation

   This example illustrates the process of creating a JWE with a
   composite AEAD algorithm created from a non-AEAD algorithm by adding
   a separate integrity check calculation.  These results can be used to
   validate JWE decryption implementations for these algorithms.  Note
   that since the RSAES-PKCS1-V1_5 computation includes random values,
   the encryption results above will not be completely reproducible.
   However, since the AES CBC computation is deterministic, the JWE
   Encrypted Ciphertext values will be the same for all encryptions
   performed using these inputs.

A.3.  Example JWE using AES Key Wrap and AES GCM

   This example encrypts the plaintext "The true sign of intelligence is
   not knowledge but imagination." to the recipient using AES Key Wrap
   and AES GCM.  The representation of this plaintext is:

   [84, 104, 101, 32, 116, 114, 117, 101, 32, 115, 105, 103, 110, 32,
   111, 102, 32, 105, 110, 116, 101, 108, 108, 105, 103, 101, 110, 99,
   101, 32, 105, 115, 32, 110, 111, 116, 32, 107, 110, 111, 119, 108,
   101, 100, 103, 101, 32, 98, 117, 116, 32, 105, 109, 97, 103, 105,
   110, 97, 116, 105, 111, 110, 46]

A.3.1.  JWE Header

   The following example JWE Header declares that:

   o  the Content Master Key is encrypted to the recipient using the AES
      Key Wrap algorithm with a 128 bit key to produce the JWE Encrypted
      Key and

   o  the Plaintext is encrypted using the AES GCM algorithm with a 128
      bit key to produce the Ciphertext.


     {"alg":"A128KW","enc":"A128GCM"}



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A.3.2.  Encoded JWE Header

   Base64url encoding the bytes of the UTF-8 representation of the JWE
   Header yields this Encoded JWE Header value:

     eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIn0

A.3.3.  Content Master Key (CMK)

   Generate a 128 bit random Content Master Key (CMK).  In this example,
   the value is:

   [64, 154, 239, 170, 64, 40, 195, 99, 19, 84, 192, 142, 192, 238, 207,
   217]

A.3.4.  Key Encryption

   Encrypt the CMK with the shared symmetric key using the AES Key Wrap
   algorithm to produce the JWE Encrypted Key. In this example, the
   shared symmetric key value is:

   [25, 172, 32, 130, 225, 114, 26, 181, 138, 106, 254, 192, 95, 133,
   74, 82]

   The resulting JWE Encrypted Key value is:

   [164, 255, 251, 1, 64, 200, 65, 200, 34, 197, 81, 143, 43, 211, 240,
   38, 191, 161, 181, 117, 119, 68, 44, 80]

A.3.5.  Encoded JWE Encrypted Key

   Base64url encode the JWE Encrypted Key to produce the Encoded JWE
   Encrypted Key. This result is:

     pP_7AUDIQcgixVGPK9PwJr-htXV3RCxQ

A.3.6.  Initialization Vector

   Generate a random 96 bit JWE Initialization Vector.  In this example,
   the value is:

   [253, 220, 80, 25, 166, 152, 178, 168, 97, 99, 67, 89]

   Base64url encoding this value yields the Encoded JWE Initialization
   Vector value:

     _dxQGaaYsqhhY0NZ




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A.3.7.  "Additional Authenticated Data" Parameter

   Concatenate the Encoded JWE Header value, a period character ('.'),
   the Encoded JWE Encrypted Key, a second period character ('.'), and
   the Encoded JWE Initialization Vector to create the "additional
   authenticated data" parameter for the AES GCM algorithm.  This result
   (with line breaks for display purposes only) is:

     eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIn0.
     pP_7AUDIQcgixVGPK9PwJr-htXV3RCxQ.
     _dxQGaaYsqhhY0NZ

   The representation of this value is:

   [101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 66, 77, 84, 73, 52,
   83, 49, 99, 105, 76, 67, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66,
   77, 84, 73, 52, 82, 48, 78, 78, 73, 110, 48, 46, 112, 80, 95, 55, 65,
   85, 68, 73, 81, 99, 103, 105, 120, 86, 71, 80, 75, 57, 80, 119, 74,
   114, 45, 104, 116, 88, 86, 51, 82, 67, 120, 81, 46, 95, 100, 120, 81,
   71, 97, 97, 89, 115, 113, 104, 104, 89, 48, 78, 90]

A.3.8.  Plaintext Encryption

   Encrypt the Plaintext with AES GCM using the CMK as the encryption
   key, the JWE Initialization Vector, and the "additional authenticated
   data" value above, requesting a 128 bit "authentication tag" output.
   The resulting Ciphertext is:

   [227, 12, 89, 132, 185, 16, 248, 93, 145, 87, 53, 130, 95, 115, 62,
   104, 138, 96, 109, 71, 124, 211, 165, 103, 202, 99, 21, 193, 4, 226,
   84, 229, 254, 106, 144, 241, 39, 86, 148, 132, 160, 104, 88, 232,
   228, 109, 85, 7, 86, 80, 134, 106, 166, 24, 92, 199, 210, 188, 153,
   187, 218, 69, 227]

   The resulting "authentication tag" value is:

   [154, 35, 80, 107, 37, 148, 81, 6, 103, 4, 60, 206, 171, 165, 113,
   67]

A.3.9.  Encoded JWE Ciphertext

   Base64url encode the resulting Ciphertext to create the Encoded JWE
   Ciphertext.  This result (with line breaks for display purposes only)
   is:

     4wxZhLkQ-F2RVzWCX3M-aIpgbUd806VnymMVwQTiVOX-apDxJ1aUhKBoWOjkbVUH
     VlCGaqYYXMfSvJm72kXj




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A.3.10.  Encoded JWE Integrity Value

   Base64url encode the resulting "authentication tag" to create the
   Encoded JWE Integrity Value.  This result is:

     miNQayWUUQZnBDzOq6VxQw

A.3.11.  Complete Representation

   Assemble the final representation: The Compact Serialization of this
   result is the concatenation of the Encoded JWE Header, the Encoded
   JWE Encrypted Key, the Encoded JWE Initialization Vector, the Encoded
   JWE Ciphertext, and the Encoded JWE Integrity Value in that order,
   with the five strings being separated by four period ('.')
   characters.

   The final result in this example (with line breaks for display
   purposes only) is:

     eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIn0.
     pP_7AUDIQcgixVGPK9PwJr-htXV3RCxQ.
     _dxQGaaYsqhhY0NZ.
     4wxZhLkQ-F2RVzWCX3M-aIpgbUd806VnymMVwQTiVOX-apDxJ1aUhKBoWOjkbVUH
     VlCGaqYYXMfSvJm72kXj.
     miNQayWUUQZnBDzOq6VxQw

A.3.12.  Validation

   This example illustrates the process of creating a JWE with symmetric
   key wrap and an AEAD algorithm.  These results can be used to
   validate JWE decryption implementations for these algorithms.  Also,
   since both the AES Key Wrap and AES GCM computations are
   deterministic, the resulting JWE value will be the same for all
   encryptions performed using these inputs.  Since the computation is
   reproducible, these results can also be used to validate JWE
   encryption implementations for these algorithms.

A.4.  Example Key Derivation for "enc" value "A128CBC+HS256"

   This example uses the Concat KDF to derive the Content Encryption Key
   (CEK) and Content Integrity Key (CIK) from the Content Master Key
   (CMK) in the manner described in Section 4.8.1 of [JWA].  In this
   example, a 256 bit CMK is used to derive a 128 bit CEK and a 256 bit
   CIK.

   The CMK value used is:

   [4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106,



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   206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156,
   44, 207]

A.4.1.  CEK Generation

   These values are concatenated to produce the round 1 hash input:

   o  the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),

   o  the CMK value (as above),

   o  the output bit size 128 as a 32 bit big endian number ([0, 0, 0,
      128]),

   o  the bytes of the UTF-8 representation of the "enc" value
      "A128CBC+HS256" -- [65, 49, 50, 56, 67, 66, 67, 43, 72, 83, 50,
      53, 54],

   o  (no bytes are included for the "epu" (encryption PartyUInfo) and
      "epv" (encryption PartyVInfo) parameters because they are absent,
      but if present, the base64url decoded values of them would have
      been included here),

   o  the bytes of the ASCII representation of the label "Encryption" --
      [69, 110, 99, 114, 121, 112, 116, 105, 111, 110].

   Thus the round 1 hash input is:

   [0, 0, 0, 1, 4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250,
   63, 170, 106, 206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0,
   240, 143, 156, 44, 207, 0, 0, 0, 128, 65, 49, 50, 56, 67, 66, 67, 43,
   72, 83, 50, 53, 54, 69, 110, 99, 114, 121, 112, 116, 105, 111, 110]

   The SHA-256 hash of this value, which is the round 1 hash output, is:

   [37, 245, 125, 247, 113, 155, 238, 98, 228, 206, 62, 65, 81, 153, 79,
   91, 225, 37, 250, 101, 198, 63, 51, 182, 5, 242, 241, 169, 162, 232,
   103, 155]

   Given that 128 bits are needed for the CEK and the hash has produced
   256 bits, the CEK value is the first 128 bits of that value:

   [37, 245, 125, 247, 113, 155, 238, 98, 228, 206, 62, 65, 81, 153, 79,
   91]







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A.4.2.  CIK Generation

   These values are concatenated to produce the round 1 hash input:

   o  the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),

   o  the CMK value (as above),

   o  the output bit size 256 as a 32 bit big endian number ([0, 0, 1,
      0]),

   o  the bytes of the UTF-8 representation of the "enc" value
      "A128CBC+HS256" -- [65, 49, 50, 56, 67, 66, 67, 43, 72, 83, 50,
      53, 54],

   o  (no bytes are included for the "epu" (encryption PartyUInfo) and
      "epv" (encryption PartyVInfo) parameters because they are absent,
      but if present, the base64url decoded values of them would have
      been included here),

   o  the bytes of the ASCII representation of the label "Integrity" --
      [73, 110, 116, 101, 103, 114, 105, 116, 121].

   Thus the round 1 hash input is:

   [0, 0, 0, 1, 4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250,
   63, 170, 106, 206, 107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0,
   240, 143, 156, 44, 207, 0, 0, 1, 0, 65, 49, 50, 56, 67, 66, 67, 43,
   72, 83, 50, 53, 54, 73, 110, 116, 101, 103, 114, 105, 116, 121]

   The SHA-256 hash of this value, which is the round 1 hash output, is:

   [203, 194, 197, 180, 120, 46, 123, 202, 78, 12, 33, 116, 214, 247,
   128, 41, 175, 53, 181, 164, 224, 223, 56, 146, 179, 193, 18, 223,
   146, 85, 244, 127]

   Given that 256 bits are needed for the CIK and the hash has produced
   256 bits, the CIK value is that same value:

   [203, 194, 197, 180, 120, 46, 123, 202, 78, 12, 33, 116, 214, 247,
   128, 41, 175, 53, 181, 164, 224, 223, 56, 146, 179, 193, 18, 223,
   146, 85, 244, 127]

A.5.  Example Key Derivation for "enc" value "A256CBC+HS512"

   This example uses the Concat KDF to derive the Content Encryption Key
   (CEK) and Content Integrity Key (CIK) from the Content Master Key
   (CMK) in the manner described in Section 4.8.1 of [JWA].  In this



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   example, a 512 bit CMK is used to derive a 256 bit CEK and a 512 bit
   CIK.

   The CMK value used is:

   [148, 116, 199, 126, 2, 117, 233, 76, 150, 149, 89, 193, 61, 34, 239,
   226, 109, 71, 59, 160, 192, 140, 150, 235, 106, 204, 49, 176, 68,
   119, 13, 34, 49, 19, 41, 69, 5, 20, 252, 145, 104, 129, 137, 138, 67,
   23, 153, 83, 81, 234, 82, 247, 48, 211, 41, 130, 35, 124, 45, 156,
   249, 7, 225, 168]

A.5.1.  CEK Generation

   These values are concatenated to produce the round 1 hash input:

   o  the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),

   o  the CMK value (as above),

   o  the output bit size 256 as a 32 bit big endian number ([0, 0, 1,
      0]),

   o  the bytes of the UTF-8 representation of the "enc" value
      "A256CBC+HS512" -- [65, 50, 53, 54, 67, 66, 67, 43, 72, 83, 53,
      49, 50],

   o  (no bytes are included for the "epu" (encryption PartyUInfo) and
      "epv" (encryption PartyVInfo) parameters because they are absent,
      but if present, the base64url decoded values of them would have
      been included here),

   o  the bytes of the ASCII representation of the label "Encryption" --
      [69, 110, 99, 114, 121, 112, 116, 105, 111, 110].

   Thus the round 1 hash input is:

   [0, 0, 0, 1, 148, 116, 199, 126, 2, 117, 233, 76, 150, 149, 89, 193,
   61, 34, 239, 226, 109, 71, 59, 160, 192, 140, 150, 235, 106, 204, 49,
   176, 68, 119, 13, 34, 49, 19, 41, 69, 5, 20, 252, 145, 104, 129, 137,
   138, 67, 23, 153, 83, 81, 234, 82, 247, 48, 211, 41, 130, 35, 124,
   45, 156, 249, 7, 225, 168, 0, 0, 1, 0, 65, 50, 53, 54, 67, 66, 67,
   43, 72, 83, 53, 49, 50, 69, 110, 99, 114, 121, 112, 116, 105, 111,
   110]

   The SHA-512 hash of this value, which is the round 1 hash output, is:

   [95, 112, 19, 252, 0, 97, 200, 188, 108, 84, 27, 116, 192, 169, 42,
   165, 25, 246, 115, 235, 226, 198, 148, 211, 94, 143, 240, 226, 89,



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   226, 79, 13, 178, 80, 124, 251, 55, 114, 30, 115, 179, 64, 107, 213,
   222, 225, 12, 169, 245, 116, 231, 83, 227, 233, 20, 164, 249, 148,
   62, 92, 43, 5, 1, 97]

   Given that 256 bits are needed for the CEK and the hash has produced
   512 bits, the CEK value is the first 256 bits of that value:

   [95, 112, 19, 252, 0, 97, 200, 188, 108, 84, 27, 116, 192, 169, 42,
   165, 25, 246, 115, 235, 226, 198, 148, 211, 94, 143, 240, 226, 89,
   226, 79, 13]

A.5.2.  CIK Generation

   These values are concatenated to produce the round 1 hash input:

   o  the round number 1 as a 32 bit big endian integer ([0, 0, 0, 1]),

   o  the CMK value (as above),

   o  the output bit size 512 as a 32 bit big endian number ([0, 0, 2,
      0]),

   o  the bytes of the UTF-8 representation of the "enc" value
      "A256CBC+HS512" -- [65, 50, 53, 54, 67, 66, 67, 43, 72, 83, 53,
      49, 50],

   o  (no bytes are included for the "epu" (encryption PartyUInfo) and
      "epv" (encryption PartyVInfo) parameters because they are absent,
      but if present, the base64url decoded values of them would have
      been included here),

   o  the bytes of the ASCII representation of the label "Integrity" --
      [73, 110, 116, 101, 103, 114, 105, 116, 121].

   Thus the round 1 hash input is:

   [0, 0, 0, 1, 148, 116, 199, 126, 2, 117, 233, 76, 150, 149, 89, 193,
   61, 34, 239, 226, 109, 71, 59, 160, 192, 140, 150, 235, 106, 204, 49,
   176, 68, 119, 13, 34, 49, 19, 41, 69, 5, 20, 252, 145, 104, 129, 137,
   138, 67, 23, 153, 83, 81, 234, 82, 247, 48, 211, 41, 130, 35, 124,
   45, 156, 249, 7, 225, 168, 0, 0, 2, 0, 65, 50, 53, 54, 67, 66, 67,
   43, 72, 83, 53, 49, 50, 73, 110, 116, 101, 103, 114, 105, 116, 121]

   The SHA-512 hash of this value, which is the round 1 hash output, is:

   [203, 188, 104, 71, 177, 60, 21, 10, 255, 157, 56, 214, 254, 87, 32,
   115, 194, 36, 117, 162, 226, 93, 50, 220, 191, 219, 41, 56, 80, 197,
   18, 173, 250, 145, 215, 178, 235, 51, 251, 122, 212, 193, 48, 227,



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   126, 89, 253, 101, 143, 252, 124, 157, 147, 200, 175, 164, 253, 92,
   204, 122, 218, 77, 105, 146]

   Given that 512 bits are needed for the CIK and the hash has produced
   512 bits, the CIK value is that same value:

   [203, 188, 104, 71, 177, 60, 21, 10, 255, 157, 56, 214, 254, 87, 32,
   115, 194, 36, 117, 162, 226, 93, 50, 220, 191, 219, 41, 56, 80, 197,
   18, 173, 250, 145, 215, 178, 235, 51, 251, 122, 212, 193, 48, 227,
   126, 89, 253, 101, 143, 252, 124, 157, 147, 200, 175, 164, 253, 92,
   204, 122, 218, 77, 105, 146]


Appendix B.  Acknowledgements

   Solutions for encrypting JSON content were also explored by JSON
   Simple Encryption [JSE] and JavaScript Message Security Format
   [I-D.rescorla-jsms], both of which significantly influenced this
   draft.  This draft attempts to explicitly reuse as many of the
   relevant concepts from XML Encryption 1.1
   [W3C.CR-xmlenc-core1-20120313] and RFC 5652 [RFC5652] as possible,
   while utilizing simple compact JSON-based data structures.

   Special thanks are due to John Bradley and Nat Sakimura for the
   discussions that helped inform the content of this specification and
   to Eric Rescorla and Joe Hildebrand for allowing the reuse of text
   from [I-D.rescorla-jsms] in this document.

   Thanks to Axel Nennker, Emmanuel Raviart, Brian Campbell, and Edmund
   Jay for validating the examples in this specification.

   Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
   Sean Turner and Stephen Farrell served as Security area directors
   during the creation of this specification.


Appendix C.  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  Should we define optional nonce, timestamp, and/or uninterpreted
      string header parameter(s)?







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Appendix D.  Document History

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

   -06

   o  Removed the "int" and "kdf" parameters and defined the new
      composite AEAD algorithms "A128CBC+HS256" and "A256CBC+HS512" to
      replace the former uses of AES CBC, which required the use of
      separate integrity and key derivation functions.

   o  Included additional values in the Concat KDF calculation -- the
      desired output size and the algorithm value, and optionally
      PartyUInfo and PartyVInfo values.  Added the optional header
      parameters "apu" (agreement PartyUInfo), "apv" (agreement
      PartyVInfo), "epu" (encryption PartyUInfo), and "epv" (encryption
      PartyVInfo).  Updated the KDF examples accordingly.

   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.

   o  Changed "x5c" (X.509 Certificate Chain) representation from being
      a single string to being an array of strings, each containing a
      single base64 encoded DER certificate value, representing elements
      of the certificate chain.

   o  Added an AES Key Wrap example.

   o  Reordered the encryption steps so CMK creation is first, when
      required.

   o  Correct statements in examples about which algorithms produce
      reproducible results.

   -05

   o  Support both direct encryption using a shared or agreed upon
      symmetric key, and the use of a shared or agreed upon symmetric
      key to key wrap the CMK.

   o  Added statement that "StringOrURI values are compared as case-
      sensitive strings with no transformations or canonicalizations
      applied".




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   o  Updated open issues.

   o  Indented artwork elements to better distinguish them from the body
      text.

   -04

   o  Refer to the registries as the primary sources of defined values
      and then secondarily reference the sections defining the initial
      contents of the registries.

   o  Normatively reference XML Encryption 1.1
      [W3C.CR-xmlenc-core1-20120313] for its security considerations.

   o  Reference draft-jones-jose-jwe-json-serialization instead of
      draft-jones-json-web-encryption-json-serialization.

   o  Described additional open issues.

   o  Applied editorial suggestions.

   -03

   o  Added the "kdf" (key derivation function) header parameter to
      provide crypto agility for key derivation.  The default KDF
      remains the Concat KDF with the SHA-256 digest function.

   o  Reordered encryption steps so that the Encoded JWE Header is
      always created before it is needed as an input to the AEAD
      "additional authenticated data" parameter.

   o  Added the "cty" (content type) header parameter for declaring type
      information about the secured content, as opposed to the "typ"
      (type) header parameter, which declares type information about
      this object.

   o  Moved description of how to determine whether a header is for a
      JWS or a JWE from the JWT spec to the JWE spec.

   o  Added complete encryption examples for both AEAD and non-AEAD
      algorithms.

   o  Added complete key derivation examples.

   o  Added "Collision Resistant Namespace" to the terminology section.

   o  Reference ITU.X690.1994 for DER encoding.




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   o  Added Registry Contents sections to populate registry values.

   o  Numerous editorial improvements.

   -02

   o  When using AEAD algorithms (such as AES GCM), use the "additional
      authenticated data" parameter to provide integrity for the header,
      encrypted key, and ciphertext and use the resulting
      "authentication tag" value as the JWE Integrity Value.

   o  Defined KDF output key sizes.

   o  Generalized text to allow key agreement to be employed as an
      alternative to key wrapping or key encryption.

   o  Changed compression algorithm from gzip to DEFLATE.

   o  Clarified that it is an error when a "kid" value is included and
      no matching key is found.

   o  Clarified that JWEs with duplicate Header Parameter Names MUST be
      rejected.

   o  Clarified the relationship between "typ" header parameter values
      and MIME types.

   o  Registered application/jwe MIME type and "JWE" typ header
      parameter value.

   o  Simplified JWK terminology to get replace the "JWK Key Object" and
      "JWK Container Object" terms with simply "JSON Web Key (JWK)" and
      "JSON Web Key Set (JWK Set)" and to eliminate potential confusion
      between single keys and sets of keys.  As part of this change, the
      header parameter name for a public key value was changed from
      "jpk" (JSON Public Key) to "jwk" (JSON Web Key).

   o  Added suggestion on defining additional header parameters such as
      "x5t#S256" in the future for certificate thumbprints using hash
      algorithms other than SHA-1.

   o  Specify RFC 2818 server identity validation, rather than RFC 6125
      (paralleling the same decision in the OAuth specs).

   o  Generalized language to refer to Message Authentication Codes
      (MACs) rather than Hash-based Message Authentication Codes (HMACs)
      unless in a context specific to HMAC algorithms.




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   o  Reformatted to give each header parameter its own section heading.

   -01

   o  Added an integrity check for non-AEAD algorithms.

   o  Added "jpk" and "x5c" header parameters for including JWK public
      keys and X.509 certificate chains directly in the header.

   o  Clarified that this specification is defining the JWE Compact
      Serialization.  Referenced the new JWE-JS spec, which defines the
      JWE JSON Serialization.

   o  Added text "New header parameters should be introduced sparingly
      since an implementation that does not understand a parameter MUST
      reject the JWE".

   o  Clarified that the order of the encryption and decryption steps is
      not significant in cases where there are no dependencies between
      the inputs and outputs of the steps.

   o  Made other editorial improvements suggested by JOSE working group
      participants.

   -00

   o  Created the initial IETF draft based upon
      draft-jones-json-web-encryption-02 with no normative changes.

   o  Changed terminology to no longer call both digital signatures and
      HMACs "signatures".


Authors' Addresses

   Michael B. Jones
   Microsoft

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


   Eric Rescorla
   RTFM, Inc.

   Email: ekr@rtfm.com





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   Joe Hildebrand
   Cisco Systems, Inc.

   Email: jhildebr@cisco.com















































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