rfc7516.xml

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<rfc category="std" ipr="trust200902" number="7516" submissionType="IETF" consensus="yes">

  <front>
    <title>JSON Web Encryption (JWE)</title>

    <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
      <organization>Microsoft</organization>
      <address>
        <email>mbj@microsoft.com</email>
        <uri>http://self-issued.info/</uri>
      </address>
    </author>

    <author fullname="Joe Hildebrand" initials="J." surname="Hildebrand">
      <organization abbrev="Cisco">Cisco Systems, Inc.</organization>
      <address>
        <email>jhildebr@cisco.com</email>
      </address>
    </author>

    <date month="May" year="2015"/>

    <area>Security</area>
    <workgroup>JOSE Working Group</workgroup>

    <keyword>RFC</keyword>
    <keyword>Request for Comments</keyword>
    <keyword>I-D</keyword>
    <keyword>Internet-Draft</keyword>
    <keyword>JavaScript Object Notation</keyword>
    <keyword>JSON</keyword>
    <keyword>JSON Object Signing and Encryption</keyword>
    <keyword>JOSE</keyword>
    <keyword>JSON Web Signature</keyword>
    <keyword>JWS</keyword>
    <keyword>JSON Web Encryption</keyword>
    <keyword>JWE</keyword>
    <keyword>JSON Web Key</keyword>
    <keyword>JWK</keyword>
    <keyword>JSON Web Algorithms</keyword>
    <keyword>JWA</keyword>

    <abstract>
      <t>
	JSON Web Encryption (JWE) represents encrypted content
	using JSON-based data structures.
	Cryptographic algorithms and identifiers for use with this
	specification are described in the separate
	JSON Web Algorithms (JWA) specification
	and IANA registries defined by that specification.
	Related digital signature and Message Authentication Code (MAC) 
        capabilities are described
	in the separate JSON Web Signature (JWS) specification.
      </t>
    </abstract>

  </front>

  <middle>
    <section title="Introduction" anchor="Introduction">
      <t>
	JSON Web Encryption (JWE) represents encrypted content
	using JSON-based data structures <xref target="RFC7159"/>.
	The JWE cryptographic mechanisms encrypt and provide integrity protection for
	an arbitrary sequence of octets.
      </t>
      <t>
	Two closely related serializations for JWEs are defined.
	The JWE Compact Serialization is a compact, URL-safe representation
	intended for space constrained environments such as HTTP
	Authorization headers and URI query parameters.
	The JWE JSON Serialization represents JWEs as JSON objects and
	enables the same content to be encrypted to multiple parties.
	Both share the same cryptographic underpinnings.
      </t>
      <t>
	Cryptographic algorithms and identifiers for use with this
	specification are described in the separate
	JSON Web Algorithms (JWA) <xref target="JWA" /> specification
	and IANA registries defined by that specification.
	Related digital signature and MAC capabilities are described
	in the separate JSON Web Signature (JWS) <xref target="JWS" />
	specification.
      </t>
      <t>
	Names defined by this specification are short because a core goal is
	for the resulting representations to be compact.
      </t>

      <section title="Notational Conventions" anchor="NotationalConventions">
        <t>
          The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
          "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "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" <xref target='RFC2119' />.
	  The interpretation should only be applied when the terms appear in all capital letters.
        </t>
	<t>
	  BASE64URL(OCTETS) denotes the base64url encoding of OCTETS,
	  per Section 2 of <xref target="JWS" />.
	</t>
	<t>
	  UTF8(STRING) denotes the octets of the
	  UTF-8 <xref target="RFC3629"/> representation of STRING,
	  where STRING is a sequence of zero or more Unicode <xref target="UNICODE"/> characters.
	</t>
	<t>
	  ASCII(STRING) denotes the octets of the
	  ASCII <xref target="RFC20"/> representation of STRING,
	  where STRING is a sequence of zero or more ASCII characters.
	</t>
	<t>
	  The concatenation of two values A and B
	  is denoted as A&nbsp;||&nbsp;B.
	</t>
      </section>

    </section>

    <section title="Terminology" anchor="Terminology">

      <t>
	The terms
	"JSON Web Signature (JWS)",
	"Base64url Encoding",
	"Collision-Resistant Name",
	"Header Parameter",
	"JOSE Header",
	and "StringOrURI" are defined by
	the JWS specification <xref target="JWS"/>.
      </t>

      <t>
	The terms 
	"Ciphertext",
	"Digital Signature", "Initialization Vector (IV)",
	"Message Authentication Code (MAC)",
	and "Plaintext" are defined by
	the <xref target="RFC4949">"Internet Security Glossary, Version 2"</xref>.
      </t>

      <t>
	These terms are defined by this specification:
      </t>

      <t>
	<list style="hanging">

          <t hangText="JSON Web Encryption (JWE)">
	    <vspace/>
	    A data structure representing an encrypted and integrity-protected message.
	  </t>

	  <t hangText="Authenticated Encryption with Associated Data (AEAD)">
	    <vspace/>
	    An AEAD algorithm is one that encrypts the plaintext,
	    allows Additional Authenticated Data to be specified,
	    and provides an integrated content integrity check
	    over the ciphertext and Additional Authenticated Data.
	    AEAD algorithms accept two inputs, the plaintext and the
	    Additional Authenticated Data value, and produce two outputs,
	    the ciphertext and the Authentication Tag value.
	    AES Galois/Counter Mode (GCM) is one such algorithm.
	  </t>

	  <t hangText="Additional Authenticated Data (AAD)">
	    <vspace/>
	    An input to an AEAD operation that
	    is integrity protected but not encrypted.
	  </t>
	  <t hangText="Authentication Tag">
	    <vspace/>
	    An output of an AEAD operation that
	    ensures the integrity of
	    the ciphertext
	    and the Additional Authenticated Data.
	    Note that some algorithms may not use an Authentication Tag,
	    in which case this value is the empty octet sequence.
	  </t>

	  <t hangText="Content Encryption Key (CEK)">
	    <vspace/>
	    A symmetric key for the AEAD algorithm
	    used to encrypt the plaintext
	    to produce the ciphertext and the Authentication Tag.
	  </t>

          <t hangText="JWE Encrypted Key">
	    <vspace/>
	    Encrypted Content Encryption Key value.
	    Note that for some algorithms, the JWE Encrypted Key
	    value is specified as being the empty octet sequence.
	  </t>
          <t hangText="JWE Initialization Vector">
	    <vspace/>
	    Initialization Vector value used
	    when encrypting the plaintext.
	    Note that some algorithms may not use an Initialization Vector,
	    in which case this value is the empty octet sequence.
	  </t>
	  <t hangText="JWE AAD">
	    <vspace/>
	    Additional value to be integrity protected by
	    the authenticated encryption operation.
	    This can only be present when using the JWE JSON Serialization.
	    (Note that this can also be achieved when using either
	    the JWE Compact Serialization or the JWE JSON Serialization
	    by including the AAD value as an integrity-protected Header Parameter value,
	    but at the cost of the value being double base64url encoded.)
	  </t>
          <t hangText="JWE Ciphertext">
	    <vspace/>
	    Ciphertext value resulting from
	    authenticated encryption of the plaintext with Additional Authenticated Data.
	  </t>
	  <t hangText="JWE Authentication Tag">
	    <vspace/>
	    Authentication Tag value resulting from
	    authenticated encryption of the plaintext with Additional Authenticated Data.
	  </t>

          <t hangText="JWE Protected Header">
	    <vspace/>
	    JSON object that contains the Header Parameters that
	    are integrity protected by the authenticated encryption operation.
	    These parameters apply to all recipients of the JWE.
	    For the JWE Compact Serialization, this comprises the entire JOSE Header.
	    For the JWE JSON Serialization, this is one component of the JOSE Header.
	  </t>
	  <t hangText="JWE Shared Unprotected Header">
	    <vspace/>
	    JSON object that contains the Header Parameters that
	    apply to all recipients of the JWE
	    that are not integrity protected.
	    This can only be present when using the JWE JSON Serialization.
	  </t>
	  <t hangText="JWE Per-Recipient Unprotected Header">
	    <vspace/>
	    JSON object that contains Header Parameters that
	    apply to a single recipient of the JWE.
	    These Header Parameter values are not integrity protected.
	    This can only be present when using the JWE JSON Serialization.
	  </t>

	  <t hangText="JWE Compact Serialization">
	    <vspace/>
	    A representation of the JWE as a compact, URL-safe string.
	  </t>

	  <t hangText="JWE JSON Serialization">
	    <vspace/>
	    A representation of the JWE as a JSON object.
	    The JWE JSON Serialization
	    enables the same content to be encrypted to multiple parties.
	    This representation is neither optimized for compactness nor URL safe.
	  </t>

	  <t hangText="Key Management Mode">
	    <vspace/>
	    A method of determining the Content Encryption Key value to
	    use. Each algorithm used for determining the CEK value uses a
	    specific Key Management Mode. 
	    Key Management Modes employed by this specification are
	    Key Encryption,
	    Key Wrapping,
	    Direct Key Agreement,
	    Key Agreement with Key Wrapping, and
	    Direct Encryption.
	  </t>

	  <t hangText="Key Encryption">
	    <vspace/>
	    A Key Management Mode in which the CEK value
	    is encrypted to the intended recipient using an asymmetric encryption algorithm.
	  </t>

	  <t hangText="Key Wrapping">
	    <vspace/>
	    A Key Management Mode in which the CEK value
	    is encrypted to the intended recipient using a symmetric key wrapping algorithm.
	  </t>

	  <t hangText="Direct Key Agreement">
	    <vspace/>
	    A Key Management Mode in which a key agreement algorithm is used to agree upon
	    the CEK value.
	  </t>

	  <t hangText="Key Agreement with Key Wrapping">
	    <vspace/>
	    A Key Management Mode in which a key agreement algorithm is used to agree upon
	    a symmetric key used to encrypt the CEK value
	    to the intended recipient using a symmetric key wrapping algorithm.
	  </t>

	  <t hangText="Direct Encryption">
	    <vspace/>
	    A Key Management Mode in which the CEK value
	    used is the secret symmetric key value shared between the parties.
	  </t>

        </list>
      </t>
    </section>

    <section title="JSON Web Encryption (JWE) Overview" anchor="Overview">

      <t>
	JWE represents encrypted content using JSON data
	structures and base64url encoding.
	These JSON data structures MAY contain whitespace and/or line breaks
	before or after any JSON values or structural characters,
	in accordance with Section 2 of <xref target="RFC7159">RFC 7159</xref>.
	A JWE represents these logical values
	(each of which is defined in <xref target="Terminology"/>):
      </t>
      <t>
	<?rfc subcompact="yes"?>
	<list style="symbols">
	  <t>JOSE Header</t>
          <t>JWE Encrypted Key</t>
          <t>JWE Initialization Vector</t>
	  <t>JWE AAD</t>
	  <t>JWE Ciphertext</t>
	  <t>JWE Authentication Tag</t>
	</list>
	<?rfc subcompact="no"?>
      </t>
      <t>
	For a JWE,
	the JOSE Header members are the union of the members of these values
	(each of which is defined in <xref target="Terminology"/>):
      </t>
      <t>
	<?rfc subcompact="yes"?>
	<list style="symbols">
	  <t>JWE Protected Header</t>
	  <t>JWE Shared Unprotected Header</t>
	  <t>JWE Per-Recipient Unprotected Header</t>
	</list>
	<?rfc subcompact="no"?>
      </t>
      <t>
	JWE utilizes authenticated encryption to ensure the confidentiality
	and integrity of the plaintext
	and the integrity of the JWE Protected Header and the JWE AAD.
      </t>
      <t>
	This document defines two serializations for JWEs:
	a compact, URL-safe serialization called the JWE Compact Serialization
	and a JSON serialization called the JWE JSON Serialization.
	In both serializations, the
	JWE Protected Header,
	JWE Encrypted Key,
	JWE Initialization Vector,
	JWE Ciphertext, and
	JWE Authentication Tag
	are base64url encoded,
	since JSON lacks a way to directly represent arbitrary octet sequences.
	When present, the JWE AAD is also base64url encoded.
      </t>

      <section title="JWE Compact Serialization Overview" anchor="CompactSerializationOverview">
	<t>
	  In the JWE Compact Serialization, no JWE Shared Unprotected Header or
	  JWE Per-Recipient Unprotected Header are used.
	  In this case, the JOSE Header and the JWE Protected Header are the same.
	</t>
	<t>
	  In the JWE Compact Serialization, a JWE is represented as the
	  concatenation:
	</t>
	<t>
	  <?rfc subcompact="yes"?>
	  <list style="empty">
	    <t>BASE64URL(UTF8(JWE Protected Header)) || '.' ||</t>
	    <t>BASE64URL(JWE Encrypted Key) || '.' ||</t>
	    <t>BASE64URL(JWE Initialization Vector) || '.' ||</t>
	    <t>BASE64URL(JWE Ciphertext) || '.' ||</t>
	    <t>BASE64URL(JWE Authentication Tag)</t>
	  </list>
	  <?rfc subcompact="no"?>
	</t>
	<t>
	  See <xref target="CompactSerialization"/> for more information
	  about the JWE Compact Serialization.
	</t>
      </section>

      <section title="JWE JSON Serialization Overview" anchor="JSONSerializationOverview">
	<t>
	  In the JWE JSON Serialization, one or more of the JWE Protected Header,
	  JWE Shared Unprotected Header, and
	  JWE Per-Recipient Unprotected Header MUST be present.
	  In this case, the members of the JOSE Header are the union of
	  the members of the JWE Protected Header,
	  JWE Shared Unprotected Header, and
	  JWE Per-Recipient Unprotected Header
	  values that are present.
	</t>
	<t>
	  In the JWE JSON Serialization, a JWE is represented as a JSON object
	  containing some or all of these eight members:
	  <?rfc subcompact="yes"?>
	  <list style="empty">
	    <t><spanx style="verb">protected</spanx>, with the value BASE64URL(UTF8(JWE Protected Header))</t>
	    <t><spanx style="verb">unprotected</spanx>, with the value JWE Shared Unprotected Header</t>
	    <t><spanx style="verb">header</spanx>, with the value JWE Per-Recipient Unprotected Header</t>
	    <t><spanx style="verb">encrypted_key</spanx>, with the value BASE64URL(JWE Encrypted Key)</t>
	    <t><spanx style="verb">iv</spanx>, with the value BASE64URL(JWE Initialization Vector)</t>
	    <t><spanx style="verb">ciphertext</spanx>, with the value BASE64URL(JWE Ciphertext)</t>
	    <t><spanx style="verb">tag</spanx>, with the value BASE64URL(JWE Authentication Tag)</t>
	    <t><spanx style="verb">aad</spanx>, with the value BASE64URL(JWE AAD)</t>
	  </list>
	  <?rfc subcompact="no"?>
	</t>
	<t>
	  The six base64url-encoded result strings
	  and the two unprotected JSON object values
	  are represented as members within a JSON object.
	  The inclusion of some of these values is OPTIONAL.
	  The JWE JSON Serialization can also
	  encrypt the plaintext to multiple recipients.
	  See <xref target="JSONSerialization"/> for more information
	  about the JWE JSON Serialization.
	</t>
      </section>

      <section title="Example JWE" anchor="OAEPGCMIntro">
	<t>
	  This example encrypts the plaintext
	  "The true sign of intelligence is not knowledge but imagination."
	  to the recipient.
	</t>
	<t>
	  The following example JWE Protected Header declares that:
	  <list style="symbols">
	    <t>
	      The Content Encryption Key is encrypted to the recipient
	      using the RSAES-OAEP <xref target="RFC3447"/> algorithm to produce
	      the JWE Encrypted Key.
	    </t>
	    <t>
	      Authenticated encryption is performed on the plaintext
	      using the AES GCM
	      <xref target="AES"/> <xref target="NIST.800-38D"/>
	      algorithm with a 256-bit key
	      to produce the ciphertext and the Authentication Tag.
	    </t>
	  </list>
	</t>

	<figure><artwork><![CDATA[
  {"alg":"RSA-OAEP","enc":"A256GCM"}
]]></artwork></figure>

	<t>
	  Encoding this JWE Protected Header as
	  BASE64URL(UTF8(JWE Protected Header)) gives this value:
	</t>

	<figure><artwork><![CDATA[
  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ
]]></artwork></figure>
	
	<t>
	  The remaining steps to finish creating this JWE are:
	  <?rfc subcompact="yes"?>
	  <list style="symbols">
	    <t>
	      Generate a random Content Encryption Key (CEK).
	    </t>
	    <t>
	      Encrypt the CEK with the recipient's public key using the RSAES-OAEP
	      algorithm to produce the JWE Encrypted Key.
	    </t>
	    <t>
	      Base64url-encode the JWE Encrypted Key.
	    </t>
	    <t>
	      Generate a random JWE Initialization Vector.
	    </t>
	    <t>
	      Base64url-encode the JWE Initialization Vector.
	    </t>
	    <t>
	      Let the Additional Authenticated Data encryption parameter be
	      ASCII(BASE64URL(UTF8(JWE Protected Header))).
	    </t>
	    <t>
	      Perform authenticated encryption on the plaintext
	      with the AES GCM algorithm
	      using the CEK as the encryption key,
	      the JWE Initialization Vector,
	      and the Additional Authenticated Data value,
	      requesting a 128-bit Authentication Tag output.
	    </t>
	    <t>
	      Base64url-encode the ciphertext.
	    </t>
	    <t>
	      Base64url-encode the Authentication Tag.
	    </t>
	    <t>
	      Assemble the final representation:
	      The Compact Serialization of this result is the string
	      BASE64URL(UTF8(JWE Protected Header))
	      || '.' || BASE64URL(JWE Encrypted Key)
	      || '.' || BASE64URL(JWE Initialization Vector)
	      || '.' || BASE64URL(JWE Ciphertext)
	      || '.' || BASE64URL(JWE Authentication Tag).
	    </t>
	  </list>
	  <?rfc subcompact="no"?>
	</t>
	<t>
	  The final result in this example
	  (with line breaks for display purposes only) is:
	</t>
	<figure><artwork><![CDATA[
  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
  OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe
  ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb
  Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV
  mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8
  1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi
  6UklfCpIMfIjf7iGdXKHzg.
  48V1_ALb6US04U3b.
  5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji
  SdiwkIr3ajwQzaBtQD_A.
  XFBoMYUZodetZdvTiFvSkQ
]]></artwork></figure>

	<t>
	  See <xref target="OAEPGCMExample"/> for the complete details of computing this JWE.
	  See <xref target="JWEExamples"/> for additional examples,
	  including examples using the JWE JSON Serialization
	  in Sections <xref target="JSONSerializationExample" format="counter"/>
	  and <xref target="FlattenedJSONSerializationExample" format="counter"/>.
	</t>
      </section>

    </section>

    <section title="JOSE Header" anchor="Header">

      <t>
	For a JWE,
	the members of the JSON object(s) representing the JOSE Header
	describe the encryption applied to the plaintext and optionally
	additional properties of the JWE.
	The Header Parameter names within the JOSE Header MUST be unique,
	just as described in Section 4 of <xref target="JWS"/>.
	The rules about handling Header Parameters that are not understood
	by the implementation are also the same.
	The classes of Header Parameter names are likewise the same.
      </t>

      <section title="Registered Header Parameter Names" anchor="RegisteredHeaderParameterName">
	<t>
	  The following Header Parameter names for use in JWEs are registered
	  in the IANA
	  "JSON Web Signature and Encryption Header Parameters" registry
	  established by
	  <xref target="JWS"/>,
	  with meanings as defined below.
	</t>
	<t>
	  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.
	</t>

	<section title='"alg" (Algorithm) Header Parameter' anchor="algDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">alg</spanx> Header Parameter defined in
	    Section 4.1.1 of <xref target="JWS" />, except that
	    the Header Parameter identifies the cryptographic algorithm used to
	    encrypt or determine the value of the CEK.
	    The encrypted content is not usable if the <spanx style="verb">alg</spanx>
	    value does not represent a supported algorithm, or if the recipient does
	    not have a key that can be used with that algorithm.
	  </t>
	  <t>
	    A list of defined <spanx style="verb">alg</spanx> values
	    for this use can be found
	    in the IANA "JSON Web Signature and Encryption Algorithms" registry
	    established by
	    <xref target="JWA"/>;
	    the initial contents of this registry are the values defined in
	    Section 4.1 of
	    <xref target="JWA"/>.
	  </t>
	</section>

	<section title='"enc" (Encryption Algorithm) Header Parameter' anchor="encDef">
	  <t>
	    The <spanx style="verb">enc</spanx> (encryption algorithm)
	    Header Parameter identifies the content encryption algorithm
	    used to perform authenticated encryption on the plaintext
	    to produce the ciphertext and the Authentication Tag.
	    This algorithm MUST be an AEAD algorithm with a specified key length.
	    The encrypted content is not usable if the <spanx style="verb">enc</spanx>
	    value does not represent a supported algorithm.
	    <spanx style="verb">enc</spanx> values should either be
	    registered in the IANA
	    "JSON Web Signature and Encryption Algorithms" registry
	    established by
	    <xref target="JWA" /> or be
	    a value that contains a Collision-Resistant Name.
	    The <spanx style="verb">enc</spanx> value is a case-sensitive ASCII string
	    containing a StringOrURI value.
	    This Header Parameter MUST be present
	    and MUST be understood and processed by implementations.
	  </t>
	  <t>
	    A list of defined <spanx style="verb">enc</spanx> values
	    for this use can be found
	    in the IANA "JSON Web Signature and Encryption Algorithms" registry
	    established by
	    <xref target="JWA"/>;
	    the initial contents of this registry are the values defined in
	    Section 5.1 of
	    <xref target="JWA"/>.
	  </t>
	</section>

	<section title='"zip" (Compression Algorithm) Header Parameter' anchor="zipDef">
	  <t>
	    The <spanx style="verb">zip</spanx> (compression algorithm)
	    applied to the plaintext before encryption, if any.
	    The <spanx style="verb">zip</spanx> value defined by this specification is:
	  </t>
	  <t>
	    <?rfc subcompact="yes"?>
	    <list style='symbols'>
	      <t>
		<spanx style="verb">DEF</spanx>
		- Compression with the DEFLATE <xref target="RFC1951" /> algorithm
	      </t>
	    </list>
	    <?rfc subcompact="no"?>
	  </t>
	  <t>
	    Other values MAY be used.
	    Compression algorithm values can be registered in the IANA
	    "JSON Web Encryption Compression Algorithms" registry
	    established by
	    <xref target="JWA"/>.
	    The <spanx style="verb">zip</spanx> value is a case-sensitive string.
	    If no <spanx style="verb">zip</spanx> parameter is present,
	    no compression is applied to the plaintext before encryption.
	    When used, this Header Parameter MUST be integrity protected;
	    therefore, it MUST occur only within the JWE Protected Header.
	    Use of this Header Parameter is OPTIONAL.
	    This Header Parameter MUST be understood and processed by implementations.
	  </t>
	</section>

	<section title='"jku" (JWK Set URL) Header Parameter' anchor="jkuDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">jku</spanx> Header Parameter defined in
	    Section 4.1.2 of <xref target="JWS" />, except that
	    the JWK Set resource contains
	    the public key to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	  </t>
	</section>

	<section title='"jwk" (JSON Web Key) Header Parameter' anchor="jwkDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">jwk</spanx> Header Parameter defined in
	    Section 4.1.3 of <xref target="JWS" />, except that
	    the key is
	    the public key to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	  </t>
	</section>

	<section title='"kid" (Key ID) Header Parameter' anchor="kidDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">kid</spanx> Header Parameter defined in
	    Section 4.1.4 of <xref target="JWS" />, except that
	    the key hint references
	    the public key to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	    This parameter allows originators to explicitly signal a change of
	    key to JWE recipients.
	  </t>
	</section>

	<section title='"x5u" (X.509 URL) Header Parameter' anchor="x5uDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">x5u</spanx> Header Parameter defined in
	    Section 4.1.5 of <xref target="JWS" />, except that
	    the X.509 public key certificate or certificate chain
	    <xref target="RFC5280"/> contains the public key
	    to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	  </t>
	</section>

	<section title='"x5c" (X.509 Certificate Chain) Header Parameter' anchor="x5cDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">x5c</spanx> Header Parameter defined in
	    Section 4.1.6 of <xref target="JWS" />, except that
	    the X.509 public key certificate or certificate chain
	    <xref target="RFC5280"/> contains the public key
	    to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	  </t>
	  <t>
	    See Appendix B of <xref target="JWS"/> for an example
	    <spanx style="verb">x5c</spanx> value.
	  </t>
	</section>

	<section title='"x5t" (X.509 Certificate SHA-1 Thumbprint) Header Parameter' anchor="x5tDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">x5t</spanx> Header Parameter defined in
	    Section 4.1.7 of <xref target="JWS" />, except that
	    the certificate referenced by the thumbprint contains
	    the public key to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	    Note that certificate thumbprints are also sometimes known as certificate fingerprints.
	  </t>
	</section>

	<section title='"x5t#S256" (X.509 Certificate SHA-256 Thumbprint) Header Parameter' anchor="x5tS256Def">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">x5t#S256</spanx> Header Parameter defined in
	    Section 4.1.8 of <xref target="JWS" />, except that
	    the certificate referenced by the thumbprint contains
	    the public key to which the JWE was encrypted;
	    this can be used to determine the private key needed to decrypt the JWE.
	    Note that certificate thumbprints are also sometimes known as certificate fingerprints.
	  </t>
	</section>

	<section title='"typ" (Type) Header Parameter' anchor="typDef">

	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">typ</spanx> Header Parameter defined in
	    Section 4.1.9 of <xref target="JWS" />, except that
	    the type is that of this complete JWE.
	  </t>

	</section>

	<section title='"cty" (Content Type) Header Parameter' anchor="ctyDef">

	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">cty</spanx> Header Parameter defined in
	    Section 4.1.10 of <xref target="JWS" />, except that
	    the type is that of the secured content (the plaintext).
	  </t>

	</section>

	<section title='"crit" (Critical) Header Parameter' anchor="critDef">
	  <t>
	    This parameter has the same meaning, syntax, and processing rules as the
	    <spanx style="verb">crit</spanx> Header Parameter defined in
	    Section 4.1.11 of <xref target="JWS" />, except that
	    Header Parameters for a JWE are being referred to,
	    rather than Header Parameters for a JWS.
	  </t>
	</section>

      </section>

      <section title="Public Header Parameter Names" anchor="PublicHeaderParameterName">

        <t>
	  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
	  established by
	  <xref target="JWS" /> or be a Public Name:
	  a value that contains a Collision-Resistant Name.
	  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.
	</t>
	<t>
	  New Header Parameters should be introduced sparingly, as
	  they can result in non-interoperable JWEs.
	</t>
      </section>

      <section title="Private Header Parameter Names" anchor="PrivateHeaderParameterName">

	<t>
	  A producer and consumer of a JWE may agree to use Header Parameter names
	  that are Private Names:  names that are
	  not Registered Header Parameter names (<xref target="RegisteredHeaderParameterName"/>)
	  or Public Header Parameter names (<xref target="PublicHeaderParameterName"/>).
	  Unlike Public Header Parameter names,
	  Private Header Parameter names are subject to collision and
	  should be used with caution.
	</t>

      </section>
    </section>

    <section title="Producing and Consuming JWEs" anchor="JWERules">

      <section title="Message Encryption" anchor="Encryption">
	<t>
	  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.
	</t>

	<t>
	  <list style="numbers">
	    <t>
	      Determine the Key Management Mode employed by the algorithm
	      used to determine the Content Encryption Key value.
	      (This is the algorithm recorded in the
	      <spanx style="verb">alg</spanx> (algorithm)
	      Header Parameter of the resulting JWE.)
	    </t>
	    <t>
	      When Key Wrapping, Key Encryption,
	      or Key Agreement with Key Wrapping are employed,
	      generate a random CEK value.
	      See <xref target="RFC4086">RFC 4086</xref> for
	      considerations on generating random values.
	      The CEK MUST have a length equal to that
	      required for the content encryption algorithm.
	    </t>
	    <t>
	      When Direct Key Agreement or Key Agreement with Key Wrapping
	      are employed, use the key agreement algorithm
	      to compute the value of the agreed upon key.
	      When Direct Key Agreement is employed,
	      let the CEK be the agreed upon key.
	      When Key Agreement with Key Wrapping is employed,
	      the agreed upon key will be used to wrap the CEK.
	    </t>
	    <t>
	      When Key Wrapping, Key Encryption,
	      or Key Agreement with Key Wrapping are employed,
	      encrypt the CEK to the recipient and let the result be the
	      JWE Encrypted Key.
	    </t>
	    <t>
	      When Direct Key Agreement or Direct Encryption are employed,
	      let the JWE Encrypted Key be the empty octet sequence.
	    </t>
	    <t>
	      When Direct Encryption is employed,
	      let the CEK be the shared symmetric key.
	    </t>
	    <t>
	      Compute the encoded key value BASE64URL(JWE Encrypted Key).
	    </t>
	    <t>
	      If the JWE JSON Serialization is being used, repeat this process
	      (steps 1-7)
	      for each recipient.
	    </t>
	    <t>
	      Generate a random JWE Initialization Vector of the correct size
	      for the content encryption algorithm (if required for the algorithm);
	      otherwise, let the JWE Initialization Vector be the empty octet sequence.
	    </t>
	    <t>
	      Compute the encoded Initialization Vector value
	      BASE64URL(JWE Initialization Vector).
	    </t>
	    <t>
	      If a <spanx style="verb">zip</spanx> parameter was included,
	      compress the plaintext using the specified compression algorithm
	      and let M be the octet sequence representing the compressed plaintext;
	      otherwise, let M be the octet sequence representing the plaintext.
	    </t>
	    <t>
	      Create the JSON object(s) containing the desired set of Header Parameters,
	      which together comprise the JOSE Header: one or more of the JWE Protected 
              Header, the JWE Shared Unprotected
              Header, and the JWE Per-Recipient Unprotected Header.
	    </t>
	    <t>
	      Compute the Encoded Protected Header value
	      BASE64URL(UTF8(JWE Protected Header)).
	      If the JWE Protected Header is not present
	      (which can only happen when using the JWE JSON Serialization
	      and no <spanx style="verb">protected</spanx> member is present),
	      let this value be the empty string.
	    </t>
	    <t>
	      Let the Additional Authenticated Data encryption parameter be
	      ASCII(Encoded Protected Header).
	      However, if a JWE AAD value is present
	      (which can only be the case when using the JWE JSON Serialization),
	      instead let the Additional Authenticated Data encryption parameter be
	      ASCII(Encoded Protected Header || '.' || BASE64URL(JWE AAD)).
	    </t>
	    <t>
	      Encrypt M using the CEK, the JWE Initialization Vector, and
	      the Additional Authenticated Data value
	      using the specified content encryption algorithm
	      to create the JWE Ciphertext value and the JWE Authentication Tag
	      (which is the Authentication Tag output from the encryption operation).
	    </t>
	    <t>
	      Compute the encoded ciphertext value BASE64URL(JWE Ciphertext).
	    </t>
	    <t>
	      Compute the encoded Authentication Tag value
	      BASE64URL(JWE Authentication Tag).
	    </t>
	    <t>
	      If a JWE AAD value is present,
	      compute the encoded AAD value BASE64URL(JWE AAD).
	    </t>

	    <t>
	      Create the desired serialized output.
	      The Compact Serialization of this result is the string
	      BASE64URL(UTF8(JWE Protected Header))
	      || '.' || BASE64URL(JWE Encrypted Key)
	      || '.' || BASE64URL(JWE Initialization Vector)
	      || '.' || BASE64URL(JWE Ciphertext)
	      || '.' || BASE64URL(JWE Authentication Tag).
	      The JWE JSON Serialization is described in <xref target="JSONSerialization"/>.
	    </t>
	  </list>
	</t>
      </section>

      <section title="Message Decryption" anchor="Decryption">
	<t>
	  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 fail, the encrypted content cannot be validated.
	</t>
	<t>
	  When there are multiple recipients,
	  it is an application decision which of the recipients' encrypted content
	  must successfully validate for the JWE to be accepted.
	  In some cases, encrypted content for all recipients must successfully validate
	  or the JWE will be considered invalid.
	  In other cases, only the encrypted content for a single recipient
	  needs to be successfully validated.
	  However, in all cases, the encrypted content for at least one recipient
	  MUST successfully validate or the JWE MUST be considered invalid.
	</t>
	<t>
	  <list style="numbers">
	    <t>
	      Parse the JWE representation to extract the serialized values
	      for the components of the JWE.
	      When using the JWE Compact Serialization,
	      these components are
	      the base64url-encoded representations of
	      the JWE Protected Header,
	      the JWE Encrypted Key,
	      the JWE Initialization Vector,
	      the JWE Ciphertext, and
	      the JWE Authentication Tag,
	      and when using the JWE JSON Serialization,
	      these components also include the base64url-encoded representation of
	      the JWE AAD and the unencoded
	      JWE Shared Unprotected Header and
	      JWE Per-Recipient Unprotected Header values.
	      When using the JWE Compact Serialization,
	      the JWE Protected Header,
	      the JWE Encrypted Key,
	      the JWE Initialization Vector,
	      the JWE Ciphertext, and
	      the JWE Authentication Tag
	      are represented as base64url-encoded values in that order,
	      with each value being separated from the next by a single period ('.') character,
	      resulting in exactly four delimiting period characters being used.
	      The JWE JSON Serialization
	      is described in <xref target="JSONSerialization"/>.
	    </t>
	    <t>
	      Base64url decode the encoded representations of
	      the JWE Protected Header,
	      the JWE Encrypted Key,
	      the JWE Initialization Vector,
	      the JWE Ciphertext,
	      the JWE Authentication Tag, and
	      the JWE AAD,
	      following the restriction that no line breaks, whitespace, or other additional characters have been used.
	    </t>
	    <t>
	      Verify that the octet sequence resulting from decoding the encoded JWE Protected Header
	      is a UTF-8-encoded representation of
	      a completely valid JSON object
	      conforming to <xref target="RFC7159">RFC 7159</xref>;
	      let the JWE Protected Header be this JSON object.
	    </t>
	    <t>
	      If using the JWE Compact Serialization, let the JOSE Header be the
	      JWE Protected Header.
	      Otherwise, when using the JWE JSON Serialization,
	      let the JOSE Header be the union of
	      the members of the JWE Protected Header,
	      the JWE Shared Unprotected Header and
	      the corresponding JWE Per-Recipient Unprotected Header,
	      all of which must be completely valid JSON objects.
	      During this step,
	      verify that the resulting JOSE Header does not contain duplicate
	      Header Parameter names.
	      When using the JWE JSON Serialization, this restriction includes
	      that the same Header Parameter name also MUST NOT occur in
	      distinct JSON object values that together comprise the JOSE Header.
	    </t>
	    <t>
	      Verify that the implementation understands and can process
	      all fields that it is required to support,
	      whether required by this specification,
	      by the algorithms being used,
	      or by the <spanx style="verb">crit</spanx> Header Parameter value,
	      and that the values of those parameters are also understood and supported.
	    </t>
	    <t>
	      Determine the Key Management Mode employed by the algorithm
	      specified by the
	      <spanx style="verb">alg</spanx> (algorithm) Header Parameter.
	    </t>
	    <t>
	      Verify that the JWE uses a key known to the recipient.
	    </t>
	    <t>
	      When Direct Key Agreement or Key Agreement with Key Wrapping
	      are employed, use the key agreement algorithm
	      to compute the value of the agreed upon key.
	      When Direct Key Agreement is employed,
	      let the CEK 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.
	    </t>
	    <t>
	      When Key Wrapping, Key Encryption,
	      or Key Agreement with Key Wrapping are employed,
	      decrypt the JWE Encrypted Key to produce the CEK.
	      The CEK MUST have a length equal to that
	      required for the content encryption algorithm.
	      Note that when there are multiple recipients,
	      each recipient will only be able to decrypt JWE Encrypted Key values
	      that were encrypted to a key in that recipient's possession.
	      It is therefore normal to only be able to decrypt one of the
	      per-recipient JWE Encrypted Key values to obtain the CEK value.
	      Also, see <xref target="TimingAttacks"/> for security considerations
	      on mitigating timing attacks.
	    </t>
	    <t>
	      When Direct Key Agreement or Direct Encryption are employed,
	      verify that the JWE Encrypted Key value is an empty octet sequence.
	    </t>
	    <t>
	      When Direct Encryption is employed,
	      let the CEK be the shared symmetric key.
	    </t>
	    <t>
	      Record whether the CEK could be successfully determined for this recipient or not.
	    </t>
	    <t>
	      If the JWE JSON Serialization is being used, repeat this process
	      (steps 4-12)
	      for each recipient contained in the representation.
	    </t>
	    <t>
	      Compute the Encoded Protected Header value
	      BASE64URL(UTF8(JWE Protected Header)).
	      If the JWE Protected Header is not present
	      (which can only happen when using the JWE JSON Serialization
	      and no <spanx style="verb">protected</spanx> member is present),
	      let this value be the empty string.
	    </t>
	    <t>
	      Let the Additional Authenticated Data encryption parameter be
	      ASCII(Encoded Protected Header).
	      However, if a JWE AAD value is present
	      (which can only be the case when using the JWE JSON Serialization),
	      instead let the Additional Authenticated Data encryption parameter be
	      ASCII(Encoded Protected Header || '.' || BASE64URL(JWE AAD)).
	    </t>
	    <t>
	      Decrypt the JWE Ciphertext using the CEK, the JWE Initialization Vector,
	      the Additional Authenticated Data value,
	      and the JWE Authentication Tag
	      (which is the Authentication Tag input to the calculation)
	      using the specified content encryption algorithm,
	      returning the decrypted plaintext and validating the JWE Authentication Tag
	      in the manner specified for the algorithm,
	      rejecting the input without emitting any decrypted output
	      if the JWE Authentication Tag is incorrect.
	    </t>
	    <t>
	      If a <spanx style="verb">zip</spanx> parameter was included,
	      uncompress the decrypted plaintext using the specified compression algorithm.
	    </t>
	    <t>
	      If there was no recipient for which all of the decryption steps succeeded,
	      then the JWE MUST be considered invalid.
	      Otherwise, output the plaintext.
	      In the JWE JSON Serialization case, also return a result to the application
	      indicating for which of the recipients the decryption succeeded and failed.
	    </t>
	  </list>
	</t>
	<t>
	  Finally, note that it is an application decision which algorithms
	  may be used in a given context.
	  Even if a JWE can be successfully decrypted,
	  unless the algorithms used in the JWE are acceptable
	  to the application, it SHOULD consider the JWE to be invalid.
	</t>
      </section>

      <section title="String Comparison Rules" anchor="StringComparison">

	<t>
	  The string comparison rules for this specification are the same as
	  those defined in
	  Section 5.3 of <xref target="JWS" />.
	</t>
      </section>

    </section>

    <section title="Key Identification" anchor="IDingKeys">
      <t>
	The key identification methods for this specification are the same as
	those defined in
	Section 6 of <xref target="JWS" />, except that
	the key being identified is
	the public key to which the JWE was encrypted.
      </t>
    </section>

    <section title="Serializations" anchor="Serializations">

      <t>
	JWEs use one of two serializations: the
	JWE Compact Serialization
	or the
	JWE JSON Serialization.
	Applications using this specification need to specify what serialization
	and serialization features are used for that application.
	For instance, applications might specify
	that only the JWE JSON Serialization is used,
	that only JWE JSON Serialization support for a single recipient is used,
	or that support for multiple recipients is used.
	JWE implementations only need to implement the features needed
	for the applications they are designed to support.
      </t>

      <section title="JWE Compact Serialization" anchor="CompactSerialization">

	<t>
	  The JWE Compact Serialization represents encrypted
	  content as a compact, URL-safe string.
	  This string is:
	</t>
	<t>
	  <?rfc subcompact="yes"?>
	  <list style="empty">
	    <t>BASE64URL(UTF8(JWE Protected Header)) || '.' ||</t>
	    <t>BASE64URL(JWE Encrypted Key) || '.' ||</t>
	    <t>BASE64URL(JWE Initialization Vector) || '.' ||</t>
	    <t>BASE64URL(JWE Ciphertext) || '.' ||</t>
	    <t>BASE64URL(JWE Authentication Tag)</t>
	  </list>
	  <?rfc subcompact="no"?>
	</t>
	<t>
	  Only one recipient is supported by the JWE Compact Serialization
	  and it provides no syntax to represent
	  JWE Shared Unprotected Header,
	  JWE Per-Recipient Unprotected Header,
	  or JWE AAD values.
	</t>

      </section>

      <section title="JWE JSON Serialization" anchor="JSONSerialization">

	<t>
	  The JWE JSON Serialization represents encrypted
	  content as a JSON object.
	  This representation is neither optimized for compactness nor URL safe.
	</t>
	<t>
	  Two closely related syntaxes are defined for the JWE JSON Serialization:
	  a fully general syntax,
	  with which content can be encrypted to more than one recipient,
	  and a flattened syntax, which is optimized for
	  the single-recipient case.
	</t>

	<section title="General JWE JSON Serialization Syntax"
		 anchor="GeneralJSONSerialization">

	  <t>
	    The following members are defined for use in
	    top-level JSON objects used for the
	    fully general JWE JSON Serialization syntax:
	  </t>
	  <t>
	    <list style="hanging">

	      <t hangText="protected">
		<vspace/>
		The <spanx style="verb">protected</spanx> member MUST be present and contain the value
		BASE64URL(UTF8(JWE Protected Header)) when the JWE Protected Header
		value is non-empty; otherwise, it MUST be absent.
		These Header Parameter values are integrity protected.
	      </t>

	      <t hangText="unprotected">
		<vspace/>
		The <spanx style="verb">unprotected</spanx> member MUST be present and contain the value
		JWE Shared Unprotected Header when the JWE Shared Unprotected Header
		value is non-empty; otherwise, it MUST be absent.
		This value is represented as an unencoded JSON object,
		rather than as a string.
		These Header Parameter values are not integrity protected.
	      </t>

	      <t hangText="iv">
		<vspace/>
		The <spanx style="verb">iv</spanx> member MUST be present and contain the value
		BASE64URL(JWE Initialization Vector) when the JWE Initialization Vector
		value is non-empty; otherwise, it MUST be absent.
	      </t>

	      <t hangText="aad">
		<vspace/>
		The <spanx style="verb">aad</spanx> member MUST be present and contain the value
		BASE64URL(JWE AAD)) when the JWE AAD
		value is non-empty; otherwise, it MUST be absent.
		A JWE AAD value
		can be included to supply a base64url-encoded value
		to be integrity protected but not encrypted.
	      </t>

	      <t hangText="ciphertext">
		<vspace/>
		The <spanx style="verb">ciphertext</spanx> member MUST be present and contain the value
		BASE64URL(JWE Ciphertext).
	      </t>

	      <t hangText="tag">
		<vspace/>
		The <spanx style="verb">tag</spanx> member MUST be present and contain the value
		BASE64URL(JWE Authentication Tag) when the JWE Authentication Tag
		value is non-empty; otherwise, it MUST be absent.
	      </t>

	      <t hangText="recipients">
		<vspace/>
		The <spanx style="verb">recipients</spanx> member value MUST be
		an array of JSON objects.
		Each object contains information specific to a single recipient.
		This member MUST be present with exactly one array element per recipient,
		even if some or all of the array element values are the empty JSON object
		<spanx style="verb">{}</spanx>
		(which can happen when all Header Parameter values are shared
		between all recipients and when no encrypted key is used,
		such as when doing Direct Encryption).
	      </t>

	    </list>
	  </t>
	  <t>
	    The following members are defined for use in
	    the JSON objects that are elements of
	    the <spanx style="verb">recipients</spanx> array:
	  </t>
	  <t>
	    <list style="hanging">

	      <t hangText="header">
		<vspace/>
		The <spanx style="verb">header</spanx> member MUST be present and contain the value
		JWE Per-Recipient Unprotected Header when the JWE Per-Recipient Unprotected Header
		value is non-empty; otherwise, it MUST be absent.
		This value is represented as an unencoded JSON object,
		rather than as a string.
		These Header Parameter values are not integrity protected.
	      </t>

	      <t hangText="encrypted_key">
		<vspace/>
		The <spanx style="verb">encrypted_key</spanx> member MUST be present and contain the value
		BASE64URL(JWE Encrypted Key) when the JWE Encrypted Key
		value is non-empty; otherwise, it MUST be absent.
	      </t>

	    </list>
	  </t>

	  <t>
	    At least one of the
	    <spanx style="verb">header</spanx>,
	    <spanx style="verb">protected</spanx>,
	    and <spanx style="verb">unprotected</spanx>
	    members MUST be present so that <spanx style="verb">alg</spanx>
	    and <spanx style="verb">enc</spanx>
	    Header Parameter values are conveyed for each recipient computation.
	  </t>
	  <t>
	    Additional members can be present in both the JSON objects defined above;
	    if not understood by implementations encountering them, they MUST be ignored.
	  </t>
	  <t>
	    Some Header Parameters, including the <spanx style="verb">alg</spanx>
	    parameter, can be shared among all recipient computations.
	    Header Parameters in the JWE Protected Header and
	    JWE Shared Unprotected Header values are shared among all recipients.
	  </t>
	  <t>
	    The Header Parameter values used when creating or validating
	    per-recipient ciphertext and Authentication Tag values are
	    the union of the three sets of Header Parameter values that may be present:
	    (1) the JWE Protected Header represented in the
	    <spanx style="verb">protected</spanx> member,
	    (2) the JWE Shared Unprotected Header represented in the
	    <spanx style="verb">unprotected</spanx> member, and
	    (3) the JWE Per-Recipient Unprotected Header represented in the
	    <spanx style="verb">header</spanx>
	    member of the recipient's array element.
	    The union of these sets of Header Parameters comprises the JOSE Header.
	    The Header Parameter names in the three locations MUST be disjoint.
	  </t>
	  <t>
	    Each JWE Encrypted Key value is computed using the
	    parameters of the corresponding JOSE Header value
	    in the same manner as for the JWE Compact Serialization.
	    This has the desirable property that each
	    JWE Encrypted Key value
	    in the <spanx style="verb">recipients</spanx> array
	    is identical to the value
	    that would have been computed for the same parameter
	    in the JWE Compact Serialization.
	    Likewise, the JWE Ciphertext and JWE Authentication Tag values
	    match those produced for the JWE Compact Serialization,
	    provided that the JWE Protected Header value
	    (which represents the integrity-protected Header Parameter values)
	    matches that used in
	    the JWE Compact Serialization.
	  </t>
	  <t>
	    All recipients use the same
	    JWE Protected Header,
	    JWE Initialization Vector,
	    JWE Ciphertext,
	    and JWE Authentication Tag values,
	    when present, resulting in
	    potentially significant space savings if the message is large.
	    Therefore, all Header Parameters that specify the treatment of
	    the plaintext value MUST be the same for all recipients.
	    This primarily means that the <spanx
	    style="verb">enc</spanx> (encryption algorithm) Header Parameter
	    value in the JOSE Header for each recipient
	    and any parameters of that algorithm MUST be the same.
	  </t>

	  <figure>
	    <preamble>
	      In summary,
	      the syntax of a JWE using the general JWE JSON Serialization is as follows:
	    </preamble>
	    <artwork><![CDATA[
  {
   "protected":"<integrity-protected shared header contents>",
   "unprotected":<non-integrity-protected shared header contents>,
   "recipients":[
    {"header":<per-recipient unprotected header 1 contents>,
     "encrypted_key":"<encrypted key 1 contents>"},
    ...
    {"header":<per-recipient unprotected header N contents>,
     "encrypted_key":"<encrypted key N contents>"}],
   "aad":"<additional authenticated data contents>",
   "iv":"<initialization vector contents>",
   "ciphertext":"<ciphertext contents>",
   "tag":"<authentication tag contents>"
  }
]]></artwork>
	  </figure>

	  <t>
	    See <xref target="JSONSerializationExample"/> for an example
	    JWE using the general JWE JSON Serialization syntax.
	  </t>

	</section>

	<section title="Flattened JWE JSON Serialization Syntax"
		 anchor="FlattenedJSONSerialization">
	  <t>
	    The flattened JWE JSON Serialization syntax is based upon
	    the general syntax, but flattens it,
	    optimizing it for the single-recipient case.
	    It flattens it by removing
	    the <spanx style="verb">recipients</spanx> member and
	    instead placing those members defined for use in
	    the <spanx style="verb">recipients</spanx> array
	    (the <spanx style="verb">header</spanx> and
	    <spanx style="verb">encrypted_key</spanx> members)
	    in the top-level JSON object
	    (at the same level as the <spanx style="verb">ciphertext</spanx> member).
	  </t>
	  <t>
	    The <spanx style="verb">recipients</spanx> member MUST NOT
	    be present when using this syntax.
	    Other than this syntax difference, JWE JSON Serialization objects
	    using the flattened syntax are processed identically to those
	    using the general syntax.
	  </t>

	  <figure>
	    <preamble>
	      In summary,
	      the syntax of a JWE using the flattened JWE JSON Serialization is as follows:
	    </preamble>
	    <artwork><![CDATA[
  {
   "protected":"<integrity-protected header contents>",
   "unprotected":<non-integrity-protected header contents>,
   "header":<more non-integrity-protected header contents>,
   "encrypted_key":"<encrypted key contents>",
   "aad":"<additional authenticated data contents>",
   "iv":"<initialization vector contents>",
   "ciphertext":"<ciphertext contents>",
   "tag":"<authentication tag contents>"
  }
]]></artwork>
	  </figure>

	  <t>
	    Note that when using the flattened syntax,
	    just as when using the general syntax,
	    any unprotected Header Parameter values can reside in either
	    the <spanx style="verb">unprotected</spanx> member or
	    the <spanx style="verb">header</spanx> member, or in both.
	  </t>
	  <t>
	    See <xref target="FlattenedJSONSerializationExample"/> for an example
	    JWE using the flattened JWE JSON Serialization syntax.
	  </t>

	</section>

      </section>

    </section>

     <section anchor="TLS_requirements" title="TLS Requirements">

      <t>
	The Transport Layer Security (TLS) requirements for this specification are the same as
	those defined in
	Section 8 of <xref target="JWS" />.
      </t>
    </section>

    <section title="Distinguishing between JWS and JWE Objects" anchor="Distinguishing">

      <t>
	There are several ways of distinguishing whether an object is a
	JWS or JWE.
	All these methods will yield the same result for all legal input values;
	they may yield different results for malformed inputs.

	<list style='symbols'>
	  <t>
	    If the object is using the JWS Compact Serialization or
	    the JWE Compact Serialization, the number of base64url-encoded segments
	    separated by period ('.') characters differs for JWSs and JWEs.
	    JWSs have three segments separated by two period ('.') characters.
	    JWEs have five segments separated by four period ('.') characters.
	  </t>
	  <t>
	    If the object is using the JWS JSON Serialization or
	    the JWE JSON Serialization, the members used will be different.
	    JWSs have a <spanx style="verb">payload</spanx> member and JWEs do not.
	    JWEs have a <spanx style="verb">ciphertext</spanx> member and JWSs do not.
	  </t>
	  <t>
	    The JOSE Header for a JWS can be distinguished from
	    the JOSE Header for a JWE by
	    examining the <spanx style="verb">alg</spanx>
	    (algorithm) Header Parameter value.
	    If the value represents a digital signature or MAC algorithm,
	    or is the value <spanx style="verb">none</spanx>, it is for a JWS;
	    if it represents a Key Encryption, Key Wrapping, Direct Key Agreement,
	    Key Agreement with Key Wrapping, or Direct Encryption algorithm, it is for a JWE.
	    (Extracting the <spanx style="verb">alg</spanx> value to examine is
	    straightforward when using the JWS Compact Serialization or
	    the JWE Compact Serialization and may be more difficult when
	    using the JWS JSON Serialization or the JWE JSON Serialization.)
	  </t>
	  <t>
	    The JOSE Header for a JWS can also be distinguished from
	    the JOSE Header for a JWE by
	    determining whether an
	    <spanx style="verb">enc</spanx> (encryption algorithm) member exists.
	    If the <spanx style="verb">enc</spanx> member exists, it is a JWE;
	    otherwise, it is a JWS.
	  </t>
	</list>
      </t>
    </section>

    <section title="IANA Considerations" anchor="IANA">

      <section title="JSON Web Signature and Encryption Header Parameters Registration" anchor="HdrReg">
	<t>
	  This section registers the Header Parameter names defined in
	  <xref target="RegisteredHeaderParameterName"/> in the IANA
	  "JSON Web Signature and Encryption Header Parameters" registry
	  established by
	  <xref target="JWS" />.
	</t>

        <section title="Registry Contents" anchor="HdrContents">
          <t> <?rfc subcompact="yes"?>
            <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">alg</spanx>
              </t>
              <t>
                Header Parameter Description: Algorithm
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="algDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
            <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">enc</spanx>
              </t>
              <t>
                Header Parameter Description: Encryption Algorithm
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="encDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
            <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">zip</spanx>
              </t>
              <t>
                Header Parameter Description: Compression Algorithm
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="zipDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">jku</spanx>
              </t>
              <t>
                Header Parameter Description: JWK Set URL
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="jkuDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">jwk</spanx>
              </t>
              <t>
                Header Parameter Description: JSON Web Key
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="jwkDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">kid</spanx>
              </t>
              <t>
                Header Parameter Description: Key ID
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="kidDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">x5u</spanx>
              </t>
              <t>
                Header Parameter Description: X.509 URL
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5uDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">x5c</spanx>
              </t>
              <t>
                Header Parameter Description: X.509 Certificate Chain
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5cDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">x5t</spanx>
              </t>
              <t>
                Header Parameter Description: X.509 Certificate SHA-1 Thumbprint
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5tDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">x5t#S256</spanx>
              </t>
              <t>
                Header Parameter Description: X.509 Certificate SHA-256 Thumbprint
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5tS256Def"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">typ</spanx>
              </t>
              <t>
                Header Parameter Description: Type
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="typDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">cty</spanx>
              </t>
              <t>
                Header Parameter Description: Content Type
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="ctyDef"/> of RFC 7516
              </t>
            </list>
	  </t>
	  <t>
	    <list style='symbols'>
              <t>
                Header Parameter Name: <spanx style="verb">crit</spanx>
              </t>
              <t>
                Header Parameter Description: Critical
              </t>
	      <t>
		Header Parameter Usage Location(s): JWE
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="critDef"/> of RFC 7516
              </t>
            </list>
          </t>
	</section>
	<?rfc subcompact="no"?>
      </section>

    </section>

    <section title="Security Considerations" anchor="Security">
      <t>
	All of the security issues that are pertinent to any cryptographic application
	must be addressed by JWS/JWE/JWK agents.  Among these issues are protecting
	the user's asymmetric private and symmetric secret keys and
	employing countermeasures to various attacks.
      </t>
      <t>
	All the security considerations in the JWS specification
	also apply to this specification.
	Likewise, all the security considerations in
	<xref target="W3C.REC-xmlenc-core1-20130411">XML Encryption 1.1</xref>
	also apply, other than those that are XML specific.
      </t>

      <section title="Key Entropy and Random Values" anchor="KeyEntropy">
	<t>
	  See Section 10.1 of <xref target="JWS"/> for security considerations on
	  key entropy and random values.
	  In addition to the uses of random values listed there, note that
	  random values are also used for
	  Content Encryption Keys (CEKs) and Initialization Vectors (IVs)
	  when performing encryption.
	</t>
      </section>

      <section title="Key Protection" anchor="KeyProtection">
	<t>
	  See Section 10.2 of <xref target="JWS"/> for security considerations on
	  key protection.
	  In addition to the keys listed there that must be protected,
	  implementations performing encryption must protect
	  the key encryption key and the Content Encryption Key.
	  Compromise of the key encryption key may result
	  in the disclosure of all contents protected with that key.
	  Similarly, compromise of the Content Encryption Key may result in
	  disclosure of the associated encrypted content.
	</t>
      </section>

      <section title="Using Matching Algorithm Strengths" anchor="MatchingStrengths">
	<t>
	  Algorithms of matching strengths should be used together whenever possible.
	  For instance, when AES Key Wrap is used with a given key size,
	  using the same key size is recommended when AES GCM is also used.
	  If the key encryption and content encryption algorithms are different,
	  the effective security is determined by the weaker of the two algorithms.
	</t>
	<t>
	  Also, see <xref target="RFC3766">RFC 3766</xref> for information on
	  determining strengths for public keys used for exchanging symmetric keys.
	</t>
      </section>

      <section title="Adaptive Chosen-Ciphertext Attacks" anchor="Chosen-Ciphertext">
	<t>
	  When decrypting, particular care must be taken not to allow
	  the JWE recipient to be used as an oracle for decrypting messages.
	  <xref target="RFC3218">RFC 3218</xref> should be consulted for specific
	  countermeasures to attacks on RSAES-PKCS1-v1_5.
	  An attacker might modify the contents of the <spanx style="verb">alg</spanx>
	  Header Parameter from <spanx style="verb">RSA-OAEP</spanx> to
	  <spanx style="verb">RSA1_5</spanx> in order to generate a
	  formatting error that can be detected and used to recover the CEK
	  even if RSAES-OAEP was used to encrypt the CEK.
	  It is therefore particularly important to report all
	  formatting errors to the CEK, Additional Authenticated Data,
	  or ciphertext as a single error when the encrypted content is rejected.
	</t>
	<t>
	  Additionally, this type of attack can be prevented by
	  restricting the use of a key to a limited set of algorithms
	  -- usually one.
	  This means, for instance, that if the key is marked as being for
	  <spanx style="verb">RSA&nbhy;OAEP</spanx> only, any attempt to decrypt a message
	  using the <spanx style="verb">RSA1_5</spanx> algorithm with that key should
	  fail immediately due to invalid use of the key.
	</t>
      </section>

      <section title="Timing Attacks" anchor="TimingAttacks">
	<t>
	  To mitigate the attacks described in <xref target="RFC3218">RFC 3218</xref>,
	  the recipient MUST NOT distinguish between format, padding, and
	  length errors of encrypted keys.  It is strongly recommended,
	  in the event of receiving an improperly formatted key,
	  that the recipient substitute a randomly generated
	  CEK and proceed to the next step, to mitigate timing attacks.
	</t>
      </section>

    </section>
  </middle>

  <back>
    <references title="Normative References">
      <?rfc include='reference.RFC.1951.xml' ?>
      <?rfc include='reference.RFC.2119.xml' ?>
      <?rfc include='reference.RFC.3629.xml' ?>
      <?rfc include='reference.RFC.4949.xml' ?>
      <?rfc include='reference.RFC.5280.xml' ?>
      <?rfc include='reference.RFC.7159.xml' ?>

      <reference anchor="RFC20" target="http://www.rfc-editor.org/info/rfc20">
	<front>
	  <title>ASCII format for Network Interchange</title>
	  <author fullname="Vint Cerf" surname="Cerf" initials="V.">
	    <organization>University California Los Angeles (UCLA)</organization>
	  </author>
	  <date month="October" year="1969"/>
	</front>
	<seriesInfo name="STD" value="80"/>
	<seriesInfo name="RFC" value="20"/>
      </reference>

      <reference anchor="UNICODE" target="http://www.unicode.org/versions/latest/">
	<front>
	  <title abbrev="Unicode">The Unicode Standard</title>
	  <author>
	    <organization>The Unicode Consortium</organization>
	    <address />
	  </author>
	  <date/>
	</front>
      </reference>

      <reference anchor="JWS" target="http://www.rfc-editor.org/info/rfc7515">
        <front>
          <title>JSON Web Signature (JWS)</title>
	  <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
	    <organization>Microsoft</organization>
	    <address>
	      <email>mbj@microsoft.com</email>
	      <uri>http://self-issued.info/</uri>
	    </address>
	  </author>
	  <author fullname="John Bradley" initials="J." surname="Bradley">
	    <organization abbrev="Ping Identity">Ping Identity</organization>
	    <address>
	      <email>ve7jtb@ve7jtb.com</email>
	    </address>
	  </author>
	  <author fullname="Nat Sakimura" initials="N." surname="Sakimura">
	    <organization abbrev="NRI">Nomura Research Institute</organization>
	    <address>
	      <email>n-sakimura@nri.co.jp</email>
	    </address>
	  </author>
	  <date month="May" year="2015"/>
        </front>
        <seriesInfo name="RFC" value="7515" />
      </reference>

      <reference anchor="JWK" target="http://www.rfc-editor.org/info/rfc7517">
        <front>
	  <title>JSON Web Key (JWK)</title>
	  <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
	    <organization>Microsoft</organization>
	    <address>
	      <email>mbj@microsoft.com</email>
	      <uri>http://self-issued.info/</uri>
	    </address>
	  </author>
	  <date month="May" year="2015"/>
        </front>
        <seriesInfo name="RFC" value="7517"/>
      </reference>

      <reference anchor="JWA" target="http://www.rfc-editor.org/info/rfc7518">
        <front>
	  <title>JSON Web Algorithms (JWA)</title>
	  <author fullname="Michael B. Jones" initials="M.B." surname="Jones">
	    <organization>Microsoft</organization>
	    <address>
	      <email>mbj@microsoft.com</email>
	      <uri>http://self-issued.info/</uri>
	    </address>
	  </author>
	  <date month="May" year="2015"/>
        </front>
        <seriesInfo name="RFC" value="7518"/>
      </reference>
    </references>

    <references title="Informative References">
      <?rfc include='reference.RFC.3218.xml' ?>
      <?rfc include='reference.RFC.3447.xml' ?>
      <?rfc include='reference.RFC.3766.xml' ?>
      <?rfc include='reference.RFC.4086.xml' ?>
      <?rfc include='reference.RFC.5652.xml' ?>

<!--draft-rescorla-jsms-00, Expired-->
<reference anchor='JSMS'>
<front>
<title>JavaScript Message Security Format</title>
<author initials='E' surname='Rescorla' fullname='Eric Rescorla'>
    <organization />
</author>
<author initials='J' surname='Hildebrand' fullname='Joe Hildebrand'>
    <organization />
</author>
<date month='March' year='2011' />
</front>
<seriesInfo name='Work in Progress,' value='draft-rescorla-jsms-00' />
</reference>

      <reference target="http://www.w3.org/TR/2013/REC-xmlenc-core1-20130411/" anchor="W3C.REC-xmlenc-core1-20130411">
	<front>
	  <title>XML Encryption Syntax and Processing Version 1.1</title>
	  <author fullname="Donald Eastlake" surname="Eastlake" initials="D."><organization/></author>
	  <author fullname="Joseph Reagle" surname="Reagle" initials="J."><organization/></author>
	  <author fullname="Frederick Hirsch" surname="Hirsch" initials="F."><organization/></author>
	  <author fullname="Thomas Roessler" surname="Roessler" initials="T."><organization/></author>
	  <date year="2013" month="April"/>
	</front>
	<seriesInfo value="REC-xmlenc-core1-20130411" name="World Wide Web Consortium Recommendation"/>
      </reference>

      <reference anchor="AES" target="http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf">
        <front>
          <title>Advanced Encryption Standard (AES)</title>
          <author>
            <organization>National Institute of Standards and Technology (NIST)
            </organization>
          </author>
          <date month="November" year="2001" />
        </front>
        <seriesInfo name="FIPS" value="PUB 197" />
      </reference>

      <reference anchor="NIST.800-38D" target="http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf">
        <front>
          <title>Recommendation for Block Cipher Modes of Operation:
	  Galois/Counter Mode (GCM) and GMAC</title>
          <author>
            <organization>National Institute of Standards and Technology (NIST)
            </organization>
          </author>
          <date month="November" year="2007" />
        </front>
        <seriesInfo name="NIST" value="PUB 800-38D" />
      </reference>

      <reference anchor="JSE" target="http://jsonenc.info/enc/1.0/">
        <front>
          <title>JSON Simple Encryption</title>
	  <author fullname="John Bradley" initials="J." surname="Bradley">
	    <organization>independent</organization>
	  </author>
	  <author fullname="Nat Sakimura (editor)" initials="N. " surname="Sakimura (editor)">
	    <organization abbrev="NRI">Nomura Research Institute</organization>
	  </author>
          <date month="September" year="2010" />
        </front>
      </reference>
    </references>


    <section title="JWE Examples" anchor="JWEExamples">

      <t>
	This section provides examples of JWE computations.
      </t>


      <section title="Example JWE using RSAES-OAEP and AES GCM" anchor="OAEPGCMExample">
	<t>
	  This example encrypts the plaintext
	  "The true sign of intelligence is not knowledge but imagination."
	  to the recipient using RSAES-OAEP for key encryption
	  and AES GCM for content encryption.
	  The representation of this plaintext (using JSON array notation) is:
	</t>
	<t>
[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]
	</t>

	<section title="JOSE Header" anchor="OAEPGCMHeader">
	  <t>
	    The following example JWE Protected Header declares that:
	    <list style="symbols">
	      <t>
		The Content Encryption Key is encrypted to the recipient
		using the RSAES-OAEP algorithm to produce
		the JWE Encrypted Key.
	      </t>
	      <t>
		Authenticated encryption is performed on the plaintext
		using the AES GCM algorithm with a 256-bit key
		to produce the ciphertext and the Authentication Tag.
	      </t>
	    </list>
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"RSA-OAEP","enc":"A256GCM"}
]]></artwork></figure>

	  <t>
	    Encoding this JWE Protected Header as
	    BASE64URL(UTF8(JWE Protected Header)) gives this value:
	  </t>

	  <figure><artwork><![CDATA[
  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ
]]></artwork></figure>
	</section>

	<section title="Content Encryption Key (CEK)" anchor="OAEPGCMCEK">
	  <t>
	    Generate a 256-bit random CEK.
	    In this example, the value (using JSON array notation) is:
	  </t>
	  <t>
[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]
	  </t>
	</section>

	<section title="Key Encryption" anchor="OAEPGCEKeyEncryption">
	  <t>
	    Encrypt the CEK with the recipient's public key using the RSAES&nbhy;OAEP
	    algorithm to produce the JWE Encrypted Key.
	    This example uses the RSA key
	    represented in JSON Web Key <xref target="JWK" /> format below
	    (with line breaks within values for display purposes only):
	  </t>
	  <figure><artwork><![CDATA[
  {"kty":"RSA",
   "n":"oahUIoWw0K0usKNuOR6H4wkf4oBUXHTxRvgb48E-BVvxkeDNjbC4he8rUW
        cJoZmds2h7M70imEVhRU5djINXtqllXI4DFqcI1DgjT9LewND8MW2Krf3S
        psk_ZkoFnilakGygTwpZ3uesH-PFABNIUYpOiN15dsQRkgr0vEhxN92i2a
        sbOenSZeyaxziK72UwxrrKoExv6kc5twXTq4h-QChLOln0_mtUZwfsRaMS
        tPs6mS6XrgxnxbWhojf663tuEQueGC-FCMfra36C9knDFGzKsNa7LZK2dj
        YgyD3JR_MB_4NUJW_TqOQtwHYbxevoJArm-L5StowjzGy-_bq6Gw",
   "e":"AQAB",
   "d":"kLdtIj6GbDks_ApCSTYQtelcNttlKiOyPzMrXHeI-yk1F7-kpDxY4-WY5N
        WV5KntaEeXS1j82E375xxhWMHXyvjYecPT9fpwR_M9gV8n9Hrh2anTpTD9
        3Dt62ypW3yDsJzBnTnrYu1iwWRgBKrEYY46qAZIrA2xAwnm2X7uGR1hghk
        qDp0Vqj3kbSCz1XyfCs6_LehBwtxHIyh8Ripy40p24moOAbgxVw3rxT_vl
        t3UVe4WO3JkJOzlpUf-KTVI2Ptgm-dARxTEtE-id-4OJr0h-K-VFs3VSnd
        VTIznSxfyrj8ILL6MG_Uv8YAu7VILSB3lOW085-4qE3DzgrTjgyQ",
   "p":"1r52Xk46c-LsfB5P442p7atdPUrxQSy4mti_tZI3Mgf2EuFVbUoDBvaRQ-
        SWxkbkmoEzL7JXroSBjSrK3YIQgYdMgyAEPTPjXv_hI2_1eTSPVZfzL0lf
        fNn03IXqWF5MDFuoUYE0hzb2vhrlN_rKrbfDIwUbTrjjgieRbwC6Cl0",
   "q":"wLb35x7hmQWZsWJmB_vle87ihgZ19S8lBEROLIsZG4ayZVe9Hi9gDVCOBm
        UDdaDYVTSNx_8Fyw1YYa9XGrGnDew00J28cRUoeBB_jKI1oma0Orv1T9aX
        IWxKwd4gvxFImOWr3QRL9KEBRzk2RatUBnmDZJTIAfwTs0g68UZHvtc",
   "dp":"ZK-YwE7diUh0qR1tR7w8WHtolDx3MZ_OTowiFvgfeQ3SiresXjm9gZ5KL
        hMXvo-uz-KUJWDxS5pFQ_M0evdo1dKiRTjVw_x4NyqyXPM5nULPkcpU827
        rnpZzAJKpdhWAgqrXGKAECQH0Xt4taznjnd_zVpAmZZq60WPMBMfKcuE",
   "dq":"Dq0gfgJ1DdFGXiLvQEZnuKEN0UUmsJBxkjydc3j4ZYdBiMRAy86x0vHCj
        ywcMlYYg4yoC4YZa9hNVcsjqA3FeiL19rk8g6Qn29Tt0cj8qqyFpz9vNDB
        UfCAiJVeESOjJDZPYHdHY8v1b-o-Z2X5tvLx-TCekf7oxyeKDUqKWjis",
   "qi":"VIMpMYbPf47dT1w_zDUXfPimsSegnMOA1zTaX7aGk_8urY6R8-ZW1FxU7
        AlWAyLWybqq6t16VFd7hQd0y6flUK4SlOydB61gwanOsXGOAOv82cHq0E3
        eL4HrtZkUuKvnPrMnsUUFlfUdybVzxyjz9JF_XyaY14ardLSjf4L_FNY"
  }
]]></artwork></figure>

	  <t>
	    The resulting JWE Encrypted Key value is:
	  </t>
	  <t>
[56, 163, 154, 192, 58, 53, 222, 4, 105, 218, 136, 218, 29, 94, 203, 22,
 150, 92, 129, 94, 211, 232, 53, 89, 41, 60, 138, 56, 196, 216, 82, 98,
 168, 76, 37, 73, 70, 7, 36, 8, 191, 100, 136, 196, 244, 220, 145, 158,
 138, 155, 4, 117, 141, 230, 199, 247, 173, 45, 182, 214, 74, 177, 107, 211,
 153, 11, 205, 196, 171, 226, 162, 128, 171, 182, 13, 237, 239, 99, 193, 4,
 91, 219, 121, 223, 107, 167, 61, 119, 228, 173, 156, 137, 134, 200, 80, 219,
 74, 253, 56, 185, 91, 177, 34, 158, 89, 154, 205, 96, 55, 18, 138, 43,
 96, 218, 215, 128, 124, 75, 138, 243, 85, 25, 109, 117, 140, 26, 155, 249,
 67, 167, 149, 231, 100, 6, 41, 65, 214, 251, 232, 87, 72, 40, 182, 149,
 154, 168, 31, 193, 126, 215, 89, 28, 111, 219, 125, 182, 139, 235, 195, 197,
 23, 234, 55, 58, 63, 180, 68, 202, 206, 149, 75, 205, 248, 176, 67, 39,
 178, 60, 98, 193, 32, 238, 122, 96, 158, 222, 57, 183, 111, 210, 55, 188,
 215, 206, 180, 166, 150, 166, 106, 250, 55, 229, 72, 40, 69, 214, 216, 104,
 23, 40, 135, 212, 28, 127, 41, 80, 175, 174, 168, 115, 171, 197, 89, 116,
 92, 103, 246, 83, 216, 182, 176, 84, 37, 147, 35, 45, 219, 172, 99, 226,
 233, 73, 37, 124, 42, 72, 49, 242, 35, 127, 184, 134, 117, 114, 135, 206]
	  </t>

	  <t>
	    Encoding this JWE Encrypted Key as
	    BASE64URL(JWE Encrypted Key) gives this value
	    (with line breaks for display purposes only):
	  </t>
<figure><artwork><![CDATA[
  OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe
  ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb
  Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV
  mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8
  1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi
  6UklfCpIMfIjf7iGdXKHzg
]]></artwork></figure>
	</section>

	<section title="Initialization Vector" anchor="OAEPGCMIV">
	  <t>
	    Generate a random 96-bit JWE Initialization Vector.
	    In this example, the value is:
	  </t>
	  <t>
	    [227, 197, 117, 252, 2, 219, 233, 68, 180, 225, 77, 219]
	  </t>
	  <t>
	    Encoding this JWE Initialization Vector as
	    BASE64URL(JWE Initialization Vector) gives this value:
	  </t>
<figure><artwork><![CDATA[
  48V1_ALb6US04U3b
]]></artwork></figure>
	</section>

	<section title='Additional Authenticated Data' anchor="OAEPGCMAAD">
	  <t>
	    Let the Additional Authenticated Data encryption parameter be
	    ASCII(BASE64URL(UTF8(JWE Protected Header))).
	    This value is:
	  </t>
	  <t>
[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]
	  </t>
	</section>

	<section title="Content Encryption" anchor="OAEPGCMEncryption">
	  <t>
	    Perform authenticated encryption on the plaintext
	    with the AES GCM algorithm
	    using the CEK 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:
	  </t>
	  <t>
[229, 236, 166, 241, 53, 191, 115, 196, 174, 43, 73, 109, 39, 122, 233, 96,
 140, 206, 120, 52, 51, 237, 48, 11, 190, 219, 186, 80, 111, 104, 50, 142,
 47, 167, 59, 61, 181, 127, 196, 21, 40, 82, 242, 32, 123, 143, 168, 226,
 73, 216, 176, 144, 138, 247, 106, 60, 16, 205, 160, 109, 64, 63, 192]
	  </t>
	  <t>
	    The resulting Authentication Tag value is:
	  </t>
	  <t>
[92, 80, 104, 49, 133, 25, 161, 215, 173, 101, 219, 211, 136, 91, 210, 145]
	  </t>

	  <t>
	    Encoding this JWE Ciphertext as
	    BASE64URL(JWE Ciphertext) gives this value
	    (with line breaks for display purposes only):
	  </t>
<figure><artwork><![CDATA[
  5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji
  SdiwkIr3ajwQzaBtQD_A
]]></artwork></figure>

	  <t>
	    Encoding this JWE Authentication Tag as
	    BASE64URL(JWE Authentication Tag) gives this value:
	  </t>
<figure><artwork><![CDATA[
  XFBoMYUZodetZdvTiFvSkQ
]]></artwork></figure>
	</section>

	<section title="Complete Representation" anchor="OAEPGCMComplete">
	  <t>
	    Assemble the final representation:
	    The Compact Serialization of this result is the string
	    BASE64URL(UTF8(JWE Protected Header))
	    || '.' || BASE64URL(JWE Encrypted Key)
	    || '.' || BASE64URL(JWE Initialization Vector)
	    || '.' || BASE64URL(JWE Ciphertext)
	    || '.' || BASE64URL(JWE Authentication Tag).
	  </t>
	  <t>
	    The final result in this example
	    (with line breaks for display purposes only) is:
	  </t>
	  <figure><artwork><![CDATA[
  eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ.
  OKOawDo13gRp2ojaHV7LFpZcgV7T6DVZKTyKOMTYUmKoTCVJRgckCL9kiMT03JGe
  ipsEdY3mx_etLbbWSrFr05kLzcSr4qKAq7YN7e9jwQRb23nfa6c9d-StnImGyFDb
  Sv04uVuxIp5Zms1gNxKKK2Da14B8S4rzVRltdYwam_lDp5XnZAYpQdb76FdIKLaV
  mqgfwX7XWRxv2322i-vDxRfqNzo_tETKzpVLzfiwQyeyPGLBIO56YJ7eObdv0je8
  1860ppamavo35UgoRdbYaBcoh9QcfylQr66oc6vFWXRcZ_ZT2LawVCWTIy3brGPi
  6UklfCpIMfIjf7iGdXKHzg.
  48V1_ALb6US04U3b.
  5eym8TW_c8SuK0ltJ3rpYIzOeDQz7TALvtu6UG9oMo4vpzs9tX_EFShS8iB7j6ji
  SdiwkIr3ajwQzaBtQD_A.
  XFBoMYUZodetZdvTiFvSkQ
]]></artwork></figure>
	</section>

	<section title="Validation" anchor="OAEPGCMValidation">
	  <t>
	    This example illustrates the process of creating a JWE with
	    RSAES&nbhy;OAEP for key encryption
	    and AES GCM for content encryption.
	    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.
	  </t>
	</section>
      </section>


      <section title="Example JWE using RSAES-PKCS1-v1_5 and AES_128_CBC_HMAC_SHA_256" anchor="RSACBCExample">
	<t>
	  This example encrypts the plaintext
	  "Live long and prosper."
	  to the recipient using RSAES-PKCS1-v1_5 for key encryption
	  and AES_128_CBC_HMAC_SHA_256 for content encryption.
	  The representation of this plaintext (using JSON array notation) is:
	</t>
	<t>
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114,
 111, 115, 112, 101, 114, 46]
	</t>

	<section title="JOSE Header" anchor="RSACBCHeader">
	  <t>
	    The following example JWE Protected Header declares that:
	    <list style="symbols">
	      <t>
		The Content Encryption Key is encrypted to the recipient
		using the RSAES-PKCS1-v1_5 algorithm to produce
		the JWE Encrypted Key.
	      </t>
	      <t>
		Authenticated encryption is performed on the plaintext
		using the AES_128_CBC_HMAC_SHA_256 algorithm
		to produce the ciphertext and the Authentication Tag.
	      </t>
	    </list>
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"RSA1_5","enc":"A128CBC-HS256"}
]]></artwork></figure>

	  <t>
	    Encoding this JWE Protected Header as
	    BASE64URL(UTF8(JWE Protected Header)) gives this value:
	  </t>

	  <figure><artwork><![CDATA[
  eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0
]]></artwork></figure>
	</section>

	<section title="Content Encryption Key (CEK)" anchor="RSACBCCEK">
	  <t>
	    Generate a 256-bit random CEK.
	    In this example, the key value is:
	  </t>
	  <t>
[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]
	  </t>
	</section>

	<section title="Key Encryption" anchor="RSACBCKeyEncryption">
	  <t>
	    Encrypt the CEK with the recipient's public key using the RSAES&nbhy;PKCS1&nbhy;v1_5
	    algorithm to produce the JWE Encrypted Key.
	    This example uses the RSA key
	    represented in JSON Web Key <xref target="JWK" /> format below
	    (with line breaks within values for display purposes only):
	  </t>
	  <figure><artwork><![CDATA[
  {"kty":"RSA",
   "n":"sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl
        UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre
        cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_
        7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI
        Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU
        7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw",
   "e":"AQAB",
   "d":"VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq
        1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry
        nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_
        0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj
        -VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj
        T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ",
   "p":"9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68
        ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP
        krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM",
   "q":"uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y
        BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN
        -3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0",
   "dp":"w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv
        ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra
        Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs",
   "dq":"o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff
        7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_
        odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU",
   "qi":"eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC
        tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ
        B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo"
  }
]]></artwork></figure>

	  <t>
	    The resulting JWE Encrypted Key value is:
	  </t>
	  <t>
[80, 104, 72, 58, 11, 130, 236, 139, 132, 189, 255, 205, 61, 86, 151, 176,
 99, 40, 44, 233, 176, 189, 205, 70, 202, 169, 72, 40, 226, 181, 156, 223,
 120, 156, 115, 232, 150, 209, 145, 133, 104, 112, 237, 156, 116, 250, 65, 102,
 212, 210, 103, 240, 177, 61, 93, 40, 71, 231, 223, 226, 240, 157, 15, 31,
 150, 89, 200, 215, 198, 203, 108, 70, 117, 66, 212, 238, 193, 205, 23, 161,
 169, 218, 243, 203, 128, 214, 127, 253, 215, 139, 43, 17, 135, 103, 179, 220,
 28, 2, 212, 206, 131, 158, 128, 66, 62, 240, 78, 186, 141, 125, 132, 227,
 60, 137, 43, 31, 152, 199, 54, 72, 34, 212, 115, 11, 152, 101, 70, 42,
 219, 233, 142, 66, 151, 250, 126, 146, 141, 216, 190, 73, 50, 177, 146, 5,
 52, 247, 28, 197, 21, 59, 170, 247, 181, 89, 131, 241, 169, 182, 246, 99,
 15, 36, 102, 166, 182, 172, 197, 136, 230, 120, 60, 58, 219, 243, 149, 94,
 222, 150, 154, 194, 110, 227, 225, 112, 39, 89, 233, 112, 207, 211, 241, 124,
 174, 69, 221, 179, 107, 196, 225, 127, 167, 112, 226, 12, 242, 16, 24, 28,
 120, 182, 244, 213, 244, 153, 194, 162, 69, 160, 244, 248, 63, 165, 141, 4,
 207, 249, 193, 79, 131, 0, 169, 233, 127, 167, 101, 151, 125, 56, 112, 111,
 248, 29, 232, 90, 29, 147, 110, 169, 146, 114, 165, 204, 71, 136, 41, 252]
	  </t>

	  <t>
	    Encoding this JWE Encrypted Key as
	    BASE64URL(JWE Encrypted Key) gives this value
	    (with line breaks for display purposes only):
	  </t>
<figure><artwork><![CDATA[
  UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm
  1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc
  HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF
  NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8
  rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv
  -B3oWh2TbqmScqXMR4gp_A
]]></artwork></figure>
	</section>

	<section title="Initialization Vector" anchor="RSACBCIV">
	  <t>
	    Generate a random 128-bit JWE Initialization Vector.
	    In this example, the value is:
	  </t>
	  <t>
	    [3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]
	  </t>
	  <t>
	    Encoding this JWE Initialization Vector as
	    BASE64URL(JWE Initialization Vector) gives this value:
	  </t>
<figure><artwork><![CDATA[
  AxY8DCtDaGlsbGljb3RoZQ
]]></artwork></figure>
	</section>

	<section title='Additional Authenticated Data' anchor="RSACBCAAD">
	  <t>
	    Let the Additional Authenticated Data encryption parameter be
	    ASCII(BASE64URL(UTF8(JWE Protected Header))).
	    This value is:
	  </t>
	  <t>
[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, 76, 85, 104, 84, 77, 106, 85, 50,
 73, 110, 48]
	  </t>
	</section>

	<section title="Content Encryption" anchor="RSACBCEncryption">
	  <t>
	    Perform authenticated encryption on the plaintext
	    with the AES_128_CBC_HMAC_SHA_256 algorithm
	    using the CEK as the encryption key,
	    the JWE Initialization Vector,
	    and the Additional Authenticated Data value above.
	    The steps for doing this using the values from <xref target="WrapExample"/>
	    are detailed in <xref target="CBC_HMAC_Example"/>.
	    The resulting ciphertext is:
	  </t>
	  <t>
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
	  </t>
	  <t>
	    The resulting Authentication Tag value is:
	  </t>
	  <t>
[246, 17, 244, 190, 4, 95, 98, 3, 231, 0, 115, 157, 242, 203, 100, 191]
	  </t>

	  <t>
	    Encoding this JWE Ciphertext as
	    BASE64URL(JWE Ciphertext) gives this value:
	  </t>
<figure><artwork><![CDATA[
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY
]]></artwork></figure>

	  <t>
	    Encoding this JWE Authentication Tag as
	    BASE64URL(JWE Authentication Tag) gives this value:
	  </t>
<figure><artwork><![CDATA[
  9hH0vgRfYgPnAHOd8stkvw
]]></artwork></figure>
	</section>

	<section title="Complete Representation" anchor="RSACBCComplete">
	  <t>
	    Assemble the final representation:
	    The Compact Serialization of this result is the string
	    BASE64URL(UTF8(JWE Protected Header))
	    || '.' || BASE64URL(JWE Encrypted Key)
	    || '.' || BASE64URL(JWE Initialization Vector)
	    || '.' || BASE64URL(JWE Ciphertext)
	    || '.' || BASE64URL(JWE Authentication Tag).
	  </t>
	  <t>
	    The final result in this example
	    (with line breaks for display purposes only) is:
	  </t>
	  <figure><artwork><![CDATA[
  eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.
  UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm
  1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc
  HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF
  NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8
  rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv
  -B3oWh2TbqmScqXMR4gp_A.
  AxY8DCtDaGlsbGljb3RoZQ.
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.
  9hH0vgRfYgPnAHOd8stkvw
]]></artwork></figure>
	</section>

	<section title="Validation" anchor="RSACBCValidation">
	  <t>
	    This example illustrates the process of creating a JWE with
	    RSAES&nbhy;PKCS1&nbhy;v1_5 for key encryption
	    and AES_CBC_HMAC_SHA2 for content encryption.
	    These results can be used to validate JWE decryption implementations for these algorithms.
	    Note that since the RSAES&nbhy;PKCS1&nbhy;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.
	  </t>
	</section>
      </section>


      <section title="Example JWE Using AES Key Wrap and AES_128_CBC_HMAC_SHA_256" anchor="WrapExample">
	<t>
	  This example encrypts the plaintext
	  "Live long and prosper."
	  to the recipient using AES Key Wrap for key encryption
	  and AES_128_CBC_HMAC_SHA_256 for content encryption.
	  The representation of this plaintext (using JSON array notation) is:
	</t>
	<t>
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114,
 111, 115, 112, 101, 114, 46]
	</t>

	<section title="JOSE Header" anchor="WrapHeader">
	  <t>
	    The following example JWE Protected Header declares that:
	    <list style="symbols">
	      <t>
		The Content Encryption Key is encrypted to the recipient
		using the AES Key Wrap algorithm with a 128-bit key to produce
		the JWE Encrypted Key.
	      </t>
	      <t>
		Authenticated encryption is performed on the plaintext
		using the AES_128_CBC_HMAC_SHA_256 algorithm
		to produce the ciphertext and the Authentication Tag.
	      </t>
	    </list>
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"A128KW","enc":"A128CBC-HS256"}
]]></artwork></figure>

	  <t>
	    Encoding this JWE Protected Header as
	    BASE64URL(UTF8(JWE Protected Header)) gives this value:
	  </t>

	  <figure><artwork><![CDATA[
  eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0
]]></artwork></figure>
	</section>

	<section title="Content Encryption Key (CEK)" anchor="WrapCEK">
	  <t>
	    Generate a 256-bit random CEK.
	    In this example, the value is:
	  </t>
	  <t>
[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]
	  </t>
	</section>

	<section title="Key Encryption" anchor="WrapKeyEncryption">
	  <t>
	    Encrypt the CEK with the shared symmetric key using the AES Key Wrap
	    algorithm to produce the JWE Encrypted Key.
	    This example uses the symmetric key
	    represented in JSON Web Key <xref target="JWK" /> format below:
	  </t>
	  <figure><artwork><![CDATA[
  {"kty":"oct",
   "k":"GawgguFyGrWKav7AX4VKUg"
  }
]]></artwork></figure>

	  <t>
	    The resulting JWE Encrypted Key value is:
	  </t>
	  <t>
[232, 160, 123, 211, 183, 76, 245, 132, 200, 128, 123, 75, 190, 216, 22, 67,
 201, 138, 193, 186, 9, 91, 122, 31, 246, 90, 28, 139, 57, 3, 76, 124,
 193, 11, 98, 37, 173, 61, 104, 57]
	  </t>

	  <t>
	    Encoding this JWE Encrypted Key as
	    BASE64URL(JWE Encrypted Key) gives this value:
	  </t>
<figure><artwork><![CDATA[
  6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ
]]></artwork></figure>
	</section>

	<section title="Initialization Vector" anchor="WrapIV">
	  <t>
	    Generate a random 128-bit JWE Initialization Vector.
	    In this example, the value is:
	  </t>
	  <t>
	    [3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]
	  </t>
	  <t>
	    Encoding this JWE Initialization Vector as
	    BASE64URL(JWE Initialization Vector) gives this value:
	  </t>
<figure><artwork><![CDATA[
  AxY8DCtDaGlsbGljb3RoZQ
]]></artwork></figure>
	</section>

	<section title='Additional Authenticated Data' anchor="WrapAAD">
	  <t>
	    Let the Additional Authenticated Data encryption parameter be
	    ASCII(BASE64URL(UTF8(JWE Protected Header))).
	    This value is:
	  </t>
	  <t>
[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, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
 73, 110, 48]
	  </t>
	</section>

	<section title="Content Encryption" anchor="WrapEncryption">
	  <t>
	    Perform authenticated encryption on the plaintext
	    with the AES_128_CBC_HMAC_SHA_256 algorithm
	    using the CEK as the encryption key,
	    the JWE Initialization Vector,
	    and the Additional Authenticated Data value above.
	    The steps for doing this using the values from this example
	    are detailed in <xref target="CBC_HMAC_Example"/>.
	    The resulting ciphertext is:
	  </t>
	  <t>
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
	  </t>
	  <t>
	    The resulting Authentication Tag value is:
	  </t>
	  <t>
[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85]
	  </t>

	  <t>
	    Encoding this JWE Ciphertext as
	    BASE64URL(JWE Ciphertext) gives this value:
	  </t>
<figure><artwork><![CDATA[
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY
]]></artwork></figure>

	  <t>
	    Encoding this JWE Authentication Tag as
	    BASE64URL(JWE Authentication Tag) gives this value:
	  </t>
<figure><artwork><![CDATA[
  U0m_YmjN04DJvceFICbCVQ
]]></artwork></figure>
	</section>

	<section title="Complete Representation" anchor="WrapComplete">
	  <t>
	    Assemble the final representation:
	    The Compact Serialization of this result is the string
	    BASE64URL(UTF8(JWE Protected Header))
	    || '.' || BASE64URL(JWE Encrypted Key)
	    || '.' || BASE64URL(JWE Initialization Vector)
	    || '.' || BASE64URL(JWE Ciphertext)
	    || '.' || BASE64URL(JWE Authentication Tag).
	  </t>
	  <t>
	    The final result in this example
	    (with line breaks for display purposes only) is:
	  </t>
	  <figure><artwork><![CDATA[
  eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.
  6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.
  AxY8DCtDaGlsbGljb3RoZQ.
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.
  U0m_YmjN04DJvceFICbCVQ
]]></artwork></figure>
	</section>

	<section title="Validation" anchor="WrapValidation">
	  <t>
	    This example illustrates the process of creating a JWE with
	    AES Key Wrap for key encryption
	    and AES GCM for content encryption.
	    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.
	  </t>
	</section>
      </section>

      <section title="Example JWE Using General JWE JSON Serialization"
	       anchor="JSONSerializationExample">
	<t>
	  This section contains an example using the general JWE JSON Serialization syntax.
	  This example demonstrates the capability for
	  encrypting the same plaintext to multiple recipients.
	</t>
	<t>
	  Two recipients are present in this example.
	  The algorithm and key used for the first recipient
	  are the same as that used in <xref target="RSACBCExample"/>.
	  The algorithm and key used for the second recipient
	  are the same as that used in <xref target="WrapExample"/>.
	  The resulting JWE Encrypted Key values are therefore the same;
	  those computations are not repeated here.
	</t>
	<t>
	  The plaintext, the CEK, JWE Initialization Vector,
	  and JWE Protected Header are shared by all recipients
	  (which must be the case, since the ciphertext and
	  Authentication Tag are also shared).
	</t>

	<section title="JWE Per-Recipient Unprotected Headers" anchor="JSRecipientHeaders">
	  <t>
	    The first recipient uses the RSAES-PKCS1-v1_5 algorithm
	    to encrypt the CEK.
	    The second uses AES Key Wrap to encrypt the CEK.
	    Key ID values are supplied for both keys.
	    The two JWE Per-Recipient Unprotected Header values used to represent
	    these algorithms and key IDs are:
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"RSA1_5","kid":"2011-04-29"}
]]></artwork></figure>

	  <t>
	    and
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"A128KW","kid":"7"}
]]></artwork></figure>
	</section>

	<section title="JWE Protected Header" anchor="JSProtectedHeader">
	  <t>
	    Authenticated encryption is performed on the plaintext
	    using the AES_128_CBC_HMAC_SHA_256 algorithm
	    to produce the common JWE Ciphertext and JWE Authentication Tag values.
	    The JWE Protected Header value representing this is:
	  </t>

	  <figure><artwork><![CDATA[
  {"enc":"A128CBC-HS256"}
]]></artwork></figure>

	  <t>
	    Encoding this JWE Protected Header as
	    BASE64URL(UTF8(JWE Protected Header)) gives this value:
	  </t>

	  <figure><artwork><![CDATA[
  eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0
]]></artwork></figure>

	</section>

	<section title="JWE Shared Unprotected Header" anchor="JSUnprotectedHeader">
	  <t>
	    This JWE uses the <spanx style="verb">jku</spanx> Header Parameter
	    to reference a JWK Set.
	    This is represented in the following JWE Shared Unprotected Header value as:
	  </t>

	  <figure><artwork><![CDATA[
  {"jku":"https://server.example.com/keys.jwks"}
]]></artwork></figure>

	</section>

	<section title="Complete JOSE Header Values" anchor="JSHeader">
	  <t>
	    Combining the JWE Per-Recipient Unprotected Header,
	    JWE Protected Header, and JWE Shared Unprotected Header values
	    supplied, the JOSE Header values used for the first and second recipient,
	    respectively, are:
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"RSA1_5",
   "kid":"2011-04-29",
   "enc":"A128CBC-HS256",
   "jku":"https://server.example.com/keys.jwks"}
]]></artwork></figure>

	  <t>
	    and
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"A128KW",
   "kid":"7",
   "enc":"A128CBC-HS256",
   "jku":"https://server.example.com/keys.jwks"}
]]></artwork></figure>

	</section>

	<section title='Additional Authenticated Data' anchor="JSAAD">
	  <t>
	    Let the Additional Authenticated Data encryption parameter be
	    ASCII(BASE64URL(UTF8(JWE Protected Header))).
	    This value is:
	  </t>
	  <t>
	    [101, 121, 74, 108, 98, 109, 77, 105, 79, 105, 74, 66, 77, 84, 73, 52,
	    81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50, 73, 110, 48]
	  </t>
	</section>

	<section title="Content Encryption" anchor="JSEncryption">
	  <t>
	    Perform authenticated encryption on the plaintext
	    with the AES_128_CBC_HMAC_SHA_256 algorithm
	    using the CEK as the encryption key,
	    the JWE Initialization Vector,
	    and the Additional Authenticated Data value above.
	    The steps for doing this using the values from <xref target="WrapExample"/>
	    are detailed in <xref target="CBC_HMAC_Example"/>.
	    The resulting ciphertext is:
	  </t>
	  <t>
	    [40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
	    129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
	  </t>
	  <t>
	    The resulting Authentication Tag value is:
	  </t>
	  <t>
	    [51, 63, 149, 60, 252, 148, 225, 25, 92, 185, 139, 245, 35, 2, 47, 207]
	  </t>

	  <t>
	    Encoding this JWE Ciphertext as
	    BASE64URL(JWE Ciphertext) gives this value:
	  </t>
	  <figure><artwork><![CDATA[
  KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY
]]></artwork></figure>

	  <t>
	    Encoding this JWE Authentication Tag as
	    BASE64URL(JWE Authentication Tag) gives this value:
	  </t>
	  <figure><artwork><![CDATA[
  Mz-VPPyU4RlcuYv1IwIvzw
]]></artwork></figure>
	</section>

	<section title="Complete JWE JSON Serialization Representation" anchor="JSComplete">

	  <t>
	    The complete JWE JSON Serialization
	    for these values is as follows
	    (with line breaks within values for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  {
   "protected":
    "eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",
   "unprotected":
    {"jku":"https://server.example.com/keys.jwks"},
   "recipients":[
    {"header":
      {"alg":"RSA1_5","kid":"2011-04-29"},
     "encrypted_key":
      "UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-
       kFm1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKx
       GHZ7PcHALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3
       YvkkysZIFNPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPh
       cCdZ6XDP0_F8rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPg
       wCp6X-nZZd9OHBv-B3oWh2TbqmScqXMR4gp_A"},
    {"header":
      {"alg":"A128KW","kid":"7"},
     "encrypted_key":
      "6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ"}],
   "iv":
    "AxY8DCtDaGlsbGljb3RoZQ",
   "ciphertext":
    "KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY",
   "tag":
    "Mz-VPPyU4RlcuYv1IwIvzw"
  }
]]></artwork></figure>
	</section>

      </section>

      <section title="Example JWE Using Flattened JWE JSON Serialization"
	       anchor="FlattenedJSONSerializationExample">
	<t>
	  This section contains an example using the flattened JWE JSON Serialization syntax.
	  This example demonstrates the capability for
	  encrypting the plaintext to a single recipient
	  in a flattened JSON structure.
	</t>
	<t>
	  The values in this example are the same as those for the second recipient
	  of the previous example in <xref target="JSONSerializationExample"/>.
	</t>

	<t>
	  The complete JWE JSON Serialization
	  for these values is as follows
	  (with line breaks within values for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  {
   "protected":
    "eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",
   "unprotected":
    {"jku":"https://server.example.com/keys.jwks"},
   "header":
    {"alg":"A128KW","kid":"7"},
   "encrypted_key":
    "6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ",
   "iv":
    "AxY8DCtDaGlsbGljb3RoZQ",
   "ciphertext":
    "KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY",
   "tag":
    "Mz-VPPyU4RlcuYv1IwIvzw"
  }
]]></artwork></figure>

      </section>

    </section>

    <section title="Example AES_128_CBC_HMAC_SHA_256 Computation"
	     anchor="CBC_HMAC_Example">
      <t>
	This example shows the steps in the AES_128_CBC_HMAC_SHA_256
	authenticated encryption computation using the values from
	the example in <xref target="WrapExample"/>.
	As described where this algorithm is defined in
	Sections 5.2 and 5.2.3 of JWA, the AES_CBC_HMAC_SHA2 family
	of algorithms are implemented using
	Advanced Encryption Standard (AES) in Cipher Block Chaining (CBC) mode with Public-Key 
        Cryptography Standards (PKCS) #7 padding
	to perform the encryption and
	an HMAC SHA-2 function to perform the integrity calculation
	-- in this case, HMAC SHA-256.
      </t>

      <section title="Extract MAC_KEY and ENC_KEY from Key" anchor="ExtractKeys">
	<t>
	  The 256 bit AES_128_CBC_HMAC_SHA_256 key K used in this example (using JSON array notation) is:
	</t>
	<t>
	  [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]
	</t>
	<t>
	  Use the first 128 bits of this key as the HMAC SHA-256 key MAC_KEY, which is:
	</t>
	<t>
	  [4, 211, 31, 197, 84, 157, 252, 254, 11, 100, 157, 250, 63, 170, 106, 206]
	</t>
	<t>
	  Use the last 128 bits of this key as the AES-CBC key ENC_KEY, which is:
	</t>
	<t>
	  [107, 124, 212, 45, 111, 107, 9, 219, 200, 177, 0, 240, 143, 156, 44, 207]
	</t>
	<t>
	  Note that the MAC key comes before the encryption key in the input key K;
	  this is in the opposite order of the algorithm names in
	  the identifiers "AES_128_CBC_HMAC_SHA_256" and
	  <spanx style="verb">A128CBC-HS256</spanx>.
	</t>
      </section>

      <section title="Encrypt Plaintext to Create Ciphertext"
	       anchor="EncryptWithCBC">
	<t>
	  Encrypt the plaintext with
	  AES in CBC mode using PKCS #7 padding
	  using the ENC_KEY above.
	  The plaintext in this example is:
	</t>
	<t>
[76, 105, 118, 101, 32, 108, 111, 110, 103, 32, 97, 110, 100, 32, 112, 114,
 111, 115, 112, 101, 114, 46]
	</t>
	<t>
	  The encryption result is as follows, which is the ciphertext output:
	</t>
	<t>
[40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152, 230, 6, 75,
 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143, 112, 56, 102]
	</t>
      </section>

      <section title="64-Bit Big-Endian Representation of AAD Length"
	       anchor="CreateAL">
	<t>
	  The Additional Authenticated Data (AAD) in this example is:
	</t>
	<t>
[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, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
 73, 110, 48]
	</t>
	<t>
	  This AAD is 51-bytes long, which is 408-bits long.
	  The octet string AL, which is the number of bits in AAD
	  expressed as a big-endian 64-bit unsigned integer is:
	</t>
	<t>
	  [0, 0, 0, 0, 0, 0, 1, 152]
	</t>
      </section>

      <section title="Initialization Vector Value" anchor="IVValue">
	<t>
	  The Initialization Vector value used in this example is:
	</t>
	<t>
[3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111, 116, 104, 101]
	</t>
      </section>

      <section title="Create Input to HMAC Computation" anchor="HMACInput">
	<t>
	  Concatenate
	  the AAD,
	  the Initialization Vector,
	  the ciphertext,
	  and the AL value.
	  The result of this concatenation is:
	</t>
	<t>
[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, 81, 48, 74, 68, 76, 85, 104, 84, 77, 106, 85, 50,
 73, 110, 48, 3, 22, 60, 12, 43, 67, 104, 105, 108, 108, 105, 99, 111,
 116, 104, 101, 40, 57, 83, 181, 119, 33, 133, 148, 198, 185, 243, 24, 152,
 230, 6, 75, 129, 223, 127, 19, 210, 82, 183, 230, 168, 33, 215, 104, 143,
 112, 56, 102, 0, 0, 0, 0, 0, 0, 1, 152]
	</t>
      </section>

      <section title="Compute HMAC Value" anchor="DoHMAC">
	<t>
	  Compute the HMAC SHA-256 of the concatenated value above.  This result M is:
	</t>
	<t>
[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85,
 9, 84, 229, 201, 219, 135, 44, 252, 145, 102, 179, 140, 105, 86, 229, 116]
	</t>
      </section>

      <section title="Truncate HMAC Value to Create Authentication Tag"
	       anchor="DoTruncate">
	<t>
	  Use the first half (128 bits) of the HMAC output M as
	  the Authentication Tag output T. This truncated value is:
	</t>
	<t>
[83, 73, 191, 98, 104, 205, 211, 128, 201, 189, 199, 133, 32, 38, 194, 85]
	</t>
      </section>
    
    </section>


    <section title="Acknowledgements" anchor="Acknowledgements" numbered="no">

      <t>
	Solutions for encrypting JSON content were also explored by
	<xref target="JSE">"JSON Simple Encryption"</xref> and
	<xref target="JSMS">"JavaScript Message Security
	Format"</xref>, both of which significantly influenced this document.
	This document attempts to explicitly reuse as many of the relevant concepts from
	<xref target="W3C.REC-xmlenc-core1-20130411">XML Encryption 1.1</xref>
	and <xref target="RFC5652">RFC 5652</xref> as possible,
	while utilizing simple, compact JSON-based data structures.
      </t>
      <t>
	Special thanks are due to John Bradley, Eric Rescorla, and Nat Sakimura for
	the discussions that helped inform the content of this
	specification; to Eric Rescorla and Joe Hildebrand for
	allowing the reuse of text from <xref
	target="JSMS"/> in this document;
	and to Eric Rescorla for co-authoring many drafts of this specification.
      </t>
      <t>
	Thanks to Axel Nennker, Emmanuel Raviart, Brian Campbell, and Edmund Jay
	for validating the examples in this specification.
      </t>
      <t>
        This specification is the work of the JOSE working group,
	which includes dozens of active and dedicated participants.
	In particular, the following individuals contributed ideas,
        feedback, and wording that influenced this specification:
      </t>
      <t>
	Richard Barnes,
	John Bradley,
	Brian Campbell,
	Alissa Cooper,
	Breno de Medeiros,
	Stephen Farrell,
	Dick Hardt,
	Jeff Hodges,
	Russ Housley,
	Edmund Jay,
	Scott Kelly,
	Stephen Kent,
	Barry Leiba,
	James Manger,
	Matt Miller,
	Kathleen Moriarty,
	Tony Nadalin,
	Hideki Nara,
	Axel Nennker,
	Ray Polk,
	Emmanuel Raviart,
	Eric Rescorla,
	Pete Resnick,
	Nat Sakimura,
	Jim Schaad,
	Hannes Tschofenig,
	and Sean Turner.
      </t>
      <t>
	Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
	Sean Turner, Stephen Farrell, and Kathleen Moriarty served as Security Area Directors
	during the creation of this specification.
      </t>
    </section>
  </back>
</rfc>