rfc7515.xml

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<?rfc toc="yes"?>
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<rfc number="7515" category="std" ipr="trust200902" submissionType="IETF"
     consensus="yes">

  <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>
	<uri>http://www.thread-safe.com/</uri>
      </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>
	<uri>http://nat.sakimura.org/</uri>
      </address>
    </author>

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

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

    <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 Signature (JWS) represents
	content secured with digital signatures or
	Message Authentication Codes (MACs)
	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 an IANA registry defined by that specification.
	Related encryption capabilities are described in the separate
	JSON Web Encryption (JWE) specification.
      </t>
    </abstract>

  </front>

  <middle>
    <section title="Introduction" anchor="Introduction">
      <t>
	JSON Web Signature (JWS) represents
	content secured with digital signatures or
	Message Authentication Codes (MACs)
	using JSON-based <xref target="RFC7159"/>
	data structures.
	The JWS cryptographic mechanisms provide integrity protection for
	an arbitrary sequence of octets.
	See <xref target="SignaturesAndMacs"/> for a discussion on
	the differences between digital signatures and MACs.
      </t>
      <t>
	Two closely related serializations for JWSs are defined.
	The JWS Compact Serialization is a compact, URL-safe representation
	intended for space-constrained environments such as HTTP
	Authorization headers and URI query parameters.
	The JWS JSON Serialization represents JWSs as JSON objects and
	enables multiple signatures and/or MACs to be applied to the same content.
	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 an IANA registry defined by that specification.
	Related encryption capabilities are described in the separate
	JSON Web Encryption (JWE) <xref target="JWE" /> 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 <xref target="Terminology"/>.
	</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>
	These terms are defined by this specification:
      </t>

      <t>
	<list style="hanging">

          <t hangText="JSON Web Signature (JWS)">
	    <vspace/>
	    A data structure representing a digitally signed or MACed message.
	  </t>

          <t hangText="JOSE Header">
	    <vspace/>
	    JSON object containing the parameters
	    describing the cryptographic operations and parameters employed.
	    The JOSE (JSON Object Signing and Encryption) Header is comprised
	    of a set of Header Parameters.
	  </t>
          <t hangText="JWS Payload">
	    <vspace/>
	    The sequence of octets to be secured -- a.k.a. the message.
	    The payload can contain an arbitrary sequence of octets.
	  </t>
          <t hangText="JWS Signature">
	    <vspace/>
	    Digital signature or MAC over
	    the JWS Protected Header and the JWS Payload.
	  </t>

	  <t hangText="Header Parameter">
	    <vspace/>
	    A name/value pair that is member of the JOSE Header.
	  </t>

          <t hangText="JWS Protected Header">
	    <vspace/>
	    JSON object that contains the Header Parameters that are
	    integrity protected by
	    the JWS Signature digital signature or MAC operation.
	    For the JWS Compact Serialization, this comprises the entire JOSE Header.
	    For the JWS JSON Serialization, this is one component of the JOSE Header.
	  </t>
	  <t hangText="JWS Unprotected Header">
	    <vspace/>
	    JSON object that contains the Header Parameters that are not
	    integrity protected.
	    This can only be present when using the JWS JSON Serialization.
	  </t>

          <t hangText="Base64url Encoding">
	    <vspace/>
	    Base64 encoding using the URL- and filename-safe
	    character set defined in Section 5 of <xref target="RFC4648">RFC 4648</xref>,
	    with all trailing '=' characters omitted (as permitted by Section 3.2)
	    and without the inclusion of any line breaks, whitespace, or other additional characters.
	    Note that the base64url encoding of the empty octet sequence
	    is the empty string.
	    (See <xref target="base64urlnotes" /> for notes on
	    implementing base64url encoding without padding.)
	  </t>

	  <t hangText="JWS Signing Input">
	    <vspace/>
	    The input to the digital signature or MAC computation.
	    Its value is
	    ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)).
	  </t>

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

	  <t hangText="JWS JSON Serialization">
	    <vspace/>
	    A representation of the JWS as a JSON object.
	    Unlike the JWS Compact Serialization,
	    the JWS JSON Serialization
	    enables multiple digital signatures and/or MACs to
	    be applied to the same content.
	    This representation is neither optimized for compactness nor URL-safe.
	  </t>

	  <t hangText="Unsecured JWS">
	    <vspace/>
	    A JWS that provides no integrity protection.
	    Unsecured JWSs use the <spanx style="verb">alg</spanx>
	    value <spanx style="verb">none</spanx>.
	  </t>

	  <t hangText="Collision-Resistant Name">
	    <vspace/>
	    A name in a namespace that enables names to be allocated in a manner
	    such that they are highly unlikely to collide with other names.
	    Examples of collision-resistant namespaces include:
	    Domain Names,
	    Object Identifiers (OIDs) as defined in the ITU-T X.660
	    and X.670 Recommendation series, and
	    Universally Unique IDentifiers (UUIDs)
	    <xref target="RFC4122"/>.
	    When using an administratively delegated namespace,
	    the definer of a name needs to take
	    reasonable precautions to ensure they are in control of
	    the portion of the namespace they use to define the name.
	  </t>

	  <t hangText="StringOrURI">
	    <vspace/>
	    A JSON string value, with the additional requirement that
	    while arbitrary string values MAY be used, any value
	    containing a ":" character MUST be a URI
	    <xref target="RFC3986"/>.
	    StringOrURI values are compared as case-sensitive strings
	    with no transformations or canonicalizations applied.
	  </t>

        </list>
      </t>

      <t>
	The terms "JSON Web Encryption (JWE)",
        "JWE Compact Serialization",
        and "JWE JSON Serialization" are defined by
	the JWE specification <xref target="JWE"/>.
      </t>

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

    </section>

    <section title="JSON Web Signature (JWS) Overview" anchor="Overview">

      <t>
	JWS represents digitally signed or MACed 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 JWS 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>JWS Payload</t>
	  <t>JWS Signature</t>
	</list>
<?rfc subcompact="no"?>
      </t>
      <t>
	For a JWS,
	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>JWS Protected Header</t>
	  <t>JWS Unprotected Header</t>
	</list>
<?rfc subcompact="no"?>
      </t>
      <t>
	This document defines two serializations for JWSs:
	a compact, URL-safe serialization called the JWS Compact Serialization
	and a JSON serialization called the JWS JSON Serialization.
	In both serializations, the
	JWS Protected Header,
	JWS Payload, and
	JWS Signature
	are base64url encoded,
	since JSON lacks a way to directly represent arbitrary octet sequences.
      </t>

      <section title="JWS Compact Serialization Overview" anchor="CompactSerializationOverview">
	<t>
	  In the JWS Compact Serialization, no JWS Unprotected Header is used.
	  In this case, the JOSE Header and the JWS Protected Header are the same.
	</t>
	<t>
	  In the JWS Compact Serialization, a JWS is represented as the
	  concatenation:
	</t>
	<t>
	  <?rfc subcompact="yes"?>
	  <list style="empty">
	    <t>BASE64URL(UTF8(JWS Protected Header)) || '.' ||</t>
	    <t>BASE64URL(JWS Payload) || '.' ||</t>
	    <t>BASE64URL(JWS Signature)</t>
	  </list>
	  <?rfc subcompact="no"?>
	</t>
	<t>
	  See <xref target="CompactSerialization"/> for more information
	  about the JWS Compact Serialization.
	</t>
      </section>

      <section title="JWS JSON Serialization Overview" anchor="JSONSerializationOverview">
	<t>
	  In the JWS JSON Serialization, one or both of the JWS Protected Header
	  and JWS Unprotected Header MUST be present.
	  In this case, the members of the JOSE Header are the union of
	  the members of the JWS Protected Header and the JWS Unprotected Header
	  values that are present.
	</t>
	<t>
	  In the JWS JSON Serialization, a JWS is represented as a JSON object
	  containing some or all of these four members:

<?rfc subcompact="yes"?>
	  <list style="symbols">
	    <t><spanx style="verb">protected</spanx>, with the value BASE64URL(UTF8(JWS Protected Header))</t>
	    <t><spanx style="verb">header</spanx>, with the value JWS Unprotected Header</t>
	    <t><spanx style="verb">payload</spanx>, with the value BASE64URL(JWS Payload)</t>
	    <t><spanx style="verb">signature</spanx>, with the value
	    BASE64URL(JWS Signature)</t>
	  </list>
<?rfc subcompact="no"?>
	</t>
	<t>
	  The three base64url-encoded result strings
	  and the JWS Unprotected Header value
	  are represented as members within a JSON object.
	  The inclusion of some of these values is OPTIONAL.
	  The JWS JSON Serialization can also represent
	  multiple signature and/or MAC values, rather than just one.
	  See <xref target="JSONSerialization"/> for more information
	  about the JWS JSON Serialization.
	</t>
      </section>

      <section title="Example JWS" anchor="ExampleJWS">

	<t>
	  This section provides an example of a JWS.
	  Its computation is described in more detail in <xref target="HS256Example"/>,
	  including specifying the exact octet sequences representing the JSON values used
	  and the key value used.
	</t>
	<t>
	  The following example JWS Protected Header declares that the
	  encoded object is a JSON Web Token <xref target="JWT"/>
	  and the JWS Protected Header and the JWS Payload are
	  secured using the HMAC SHA-256
	  <xref target="RFC2104"/> <xref target="SHS"/>
	  algorithm:
	</t>

	<figure><artwork><![CDATA[
  {"typ":"JWT",
   "alg":"HS256"}
]]></artwork></figure>

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

	<figure><artwork><![CDATA[
  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
]]></artwork></figure>

	<t>
	  The UTF-8 representation of the following JSON object is used as the JWS Payload.
	  (Note that the payload can be any
	  content and need not be a representation of a JSON object.)
	</t>

	<figure><artwork><![CDATA[
  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}
]]></artwork></figure>

	<t>
	  Encoding this JWS Payload as
	  BASE64URL(JWS Payload) gives this value
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
]]></artwork></figure>

	<t>
	  Computing the HMAC of the JWS Signing Input
	  ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload))
	  with the HMAC SHA-256 algorithm
	  using the key specified in <xref target="HS256Example" />
	  and base64url-encoding the result
	  yields this BASE64URL(JWS Signature) value:
	</t>

	<figure><artwork><![CDATA[
  dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
]]></artwork></figure>

	<t>
	  Concatenating these values in the order
	  Header.Payload.Signature with period ('.') characters between the
	  parts yields this complete JWS representation
	  using the JWS Compact Serialization
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
  .
  dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
]]></artwork></figure>

	<t>
	  See <xref target="JWSExamples"/> for additional examples,
	  including examples using the JWS 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 JWS,
	the members of the JSON object(s) representing the JOSE Header describe the
	digital signature or MAC applied to the
	JWS Protected Header and the JWS Payload and optionally
	additional properties of the JWS.
	The Header Parameter names within the JOSE Header MUST be unique;
	JWS parsers MUST either reject JWSs with duplicate Header Parameter names
	or use a JSON parser that returns only the lexically last duplicate member name,
	as specified in Section 15.12 ("The JSON Object") of
	ECMAScript 5.1 <xref target="ECMAScript"/>.
      </t>
      <t>
	Implementations are required to understand
	the specific Header Parameters defined by this specification 
	that are designated as "MUST be understood"
	and process them in the manner defined in this specification.
	All other Header Parameters defined by this specification that
	are not so designated MUST be ignored when not understood.
	Unless listed as a critical Header Parameter, per <xref target="critDef"/>,
	all Header Parameters not defined by this specification
	MUST be ignored when not understood.
      </t>
      <t>
        There are three classes of Header Parameter names:
	Registered Header Parameter names, Public Header Parameter names,
	and Private Header Parameter names.
      </t>

      <section title="Registered Header Parameter Names" anchor="RegisteredHeaderParameterName">
	<t>
	  The following Header Parameter names for use in JWSs are registered
	  in the IANA
	  "JSON Web Signature and Encryption Header Parameters" registry
	  established by
	  <xref target="HdrReg"/>,
	  with meanings as defined in the subsections 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>
	    The <spanx style="verb">alg</spanx> (algorithm) Header Parameter
	    identifies the cryptographic algorithm used to
	    secure the JWS.
	    The JWS Signature value is not valid if the <spanx style="verb">alg</spanx>
	    value does not represent a supported algorithm or if there is not a
	    key for use with that algorithm associated with the
	    party that digitally signed or MACed the content.
	    <spanx style="verb">alg</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">alg</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">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 3.1 of 
	    <xref target="JWA"/>.
	  </t>
	</section>

	<section title='"jku" (JWK Set URL) Header Parameter' anchor="jkuDef">
	  <t>
	    The <spanx style="verb">jku</spanx> (JWK Set URL)
	    Header Parameter is a URI <xref target="RFC3986"/> that refers to a
	    resource for a set of JSON-encoded public keys, one of which
	    corresponds to the key
	    used to digitally sign the JWS.
	    The keys MUST be encoded as a JWK Set <xref target="JWK" />.
	    The protocol used to acquire the resource MUST provide
	    integrity protection; an HTTP GET request to retrieve the
	    JWK Set MUST use Transport Layer Security (TLS)
	    <xref target="RFC2818"/> <xref target="RFC5246"/>; and
	    the identity of the server MUST be validated, as per
	    Section 6 of <xref target="RFC6125">RFC 6125</xref>.
	    Also, see <xref target="TLS_requirements"/> on TLS requirements.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	</section>

	<section title='"jwk" (JSON Web Key) Header Parameter' anchor="jwkDef">
	  <t>
	    The <spanx style="verb">jwk</spanx> (JSON Web Key)
	    Header Parameter is the public key
	    that corresponds to the key
	    used to digitally sign the JWS.
	    This key is represented as a JSON Web Key <xref target="JWK" />.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	</section>

	<section title='"kid" (Key ID) Header Parameter' anchor="kidDef">
	  <t>
	    The <spanx style="verb">kid</spanx> (key ID) Header Parameter
	    is a hint indicating which key
	    was used to secure the JWS.
	    This parameter allows originators to explicitly signal a change of
	    key to recipients.
	    The structure of the
	    <spanx style="verb">kid</spanx> value is unspecified.
	    Its value MUST be a case-sensitive string.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	  <t>
	    When used with a JWK, the <spanx style="verb">kid</spanx>
	    value is used to match a JWK <spanx style="verb">kid</spanx> 
	    parameter value.
	  </t>
	</section>

	<section title='"x5u" (X.509 URL) Header Parameter' anchor="x5uDef">
	  <t>
	    The <spanx style="verb">x5u</spanx> (X.509 URL) Header Parameter
	    is a URI <xref target="RFC3986"/> that refers to a resource for
	    the X.509 public key certificate or certificate chain <xref target="RFC5280"/>
	    corresponding to the key
	    used to digitally sign the JWS.
	    The identified resource MUST provide a representation of
	    the certificate or certificate chain that conforms to
	    <xref target="RFC5280">RFC 5280</xref> in PEM-encoded form,
	    with each certificate delimited as specified in
	    Section 6.1 of <xref target="RFC4945">RFC 4945</xref>.
	    The certificate containing the public key
	    corresponding to the key
	    used to digitally sign the JWS
	    MUST be the first certificate.
	    This MAY be followed by additional certificates, with each
	    subsequent certificate being the one used to certify the
	    previous one.
	    The protocol used to acquire the resource MUST provide
	    integrity protection; an HTTP GET request to retrieve the
	    certificate MUST use TLS
	    <xref target="RFC2818"/> <xref target="RFC5246"/>; and
	    the identity of the server MUST be validated, as per
	    Section 6 of <xref target="RFC6125">RFC 6125</xref>.
	    Also, see <xref target="TLS_requirements"/> on TLS requirements.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	</section>

	<section title='"x5c" (X.509 Certificate Chain) Header Parameter' anchor="x5cDef">
	  <t>
	    The <spanx style="verb">x5c</spanx> (X.509 certificate chain)
	    Header Parameter contains the X.509 public key
	    certificate or certificate chain <xref target="RFC5280"/>
	    corresponding to the key
	    used to digitally sign the JWS.
	    The certificate or certificate chain is represented as
	    a JSON array of certificate value strings.
	    Each string in the array is a base64-encoded
	    (Section 4 of <xref target="RFC4648"/> -- not base64url-encoded)
	    DER <xref target="ITU.X690.2008"/> PKIX certificate value.
	    The certificate containing the public key
	    corresponding to the key
	    used to digitally sign the JWS
	    MUST be the first certificate.
	    This MAY be followed by additional certificates, with each
	    subsequent certificate being the one used to certify the
	    previous one.
	    The recipient MUST validate the certificate chain according
	    to <xref target="RFC5280">RFC 5280</xref> and
	    consider the certificate or certificate chain to be invalid if any
	    validation failure occurs.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	  <t>
	    See <xref target="x5cExample"/> 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>
	    The <spanx style="verb">x5t</spanx> (X.509 certificate SHA-1 thumbprint)
	    Header Parameter is a base64url-encoded
	    SHA-1 thumbprint (a.k.a. digest) of the DER encoding of
	    the X.509 certificate <xref target="RFC5280"/>
	    corresponding to the key
	    used to digitally sign the JWS.
	    Note that certificate thumbprints are also sometimes known as certificate fingerprints.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	</section>

	<section title='"x5t#S256" (X.509 Certificate SHA-256 Thumbprint) Header Parameter' anchor="x5tS256Def">
	  <t>
	    The <spanx style="verb">x5t#S256</spanx> (X.509 certificate SHA-256 thumbprint)
	    Header Parameter is a base64url-encoded
	    SHA-256 thumbprint (a.k.a. digest) of the DER encoding of
	    the X.509 certificate <xref target="RFC5280"/>
	    corresponding to the key
	    used to digitally sign the JWS.
	    Note that certificate thumbprints are also sometimes known as certificate fingerprints.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	</section>

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

	  <t>
	    The <spanx style="verb">typ</spanx> (type) Header Parameter
	    is used by JWS applications to declare the
	    media type <xref target="IANA.MediaTypes"/>
	    of this complete JWS.
	    This is intended for use by the application when
	    more than one kind of object could be present in
	    an application data structure that can contain a JWS;
	    the application can use this value to disambiguate among
	    the different kinds of objects that might be present.
	    It will typically not be used by applications when
	    the kind of object is already known.
	    This parameter is ignored by JWS implementations;
	    any processing of this parameter is performed by the JWS application.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	  <t>
	    Per <xref target="RFC2045">RFC 2045</xref>, all media type values,
	    subtype values, and parameter names are case insensitive.
	    However, parameter values are case sensitive unless
	    otherwise specified for the specific parameter.
	  </t>
	  <t>
	    To keep messages compact in common situations,
	    it is RECOMMENDED that producers omit an "application/" prefix
	    of a media type value in a <spanx style="verb">typ</spanx>
	    Header Parameter when no other '/' appears in the media type value.
	    A recipient using the media type value MUST treat it as if
	    "application/" were prepended to any
	    <spanx style="verb">typ</spanx> value not containing a '/'.
	    For instance, a <spanx style="verb">typ</spanx> value of
	    <spanx style="verb">example</spanx> SHOULD be used to represent
	    the <spanx style="verb">application/example</spanx> media type,
	    whereas the media type
	    <spanx style="verb">application/example;part="1/2"</spanx> cannot
	    be shortened to <spanx style="verb">example;part="1/2"</spanx>.
	  </t>
	  <t>
	    The <spanx style="verb">typ</spanx> value
	    <spanx style="verb">JOSE</spanx> can be used by applications
	    to indicate that this object is a JWS or JWE using
	    the JWS Compact Serialization or the JWE Compact Serialization.
	    The <spanx style="verb">typ</spanx> value
	    <spanx style="verb">JOSE+JSON</spanx> can be used by applications
	    to indicate that this object is a JWS or JWE using
	    the JWS JSON Serialization or the JWE JSON Serialization.
	    Other type values can also be used by applications.
	  </t>

	</section>

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

	  <t>
	    The <spanx style="verb">cty</spanx> (content type) Header Parameter
	    is used by JWS applications to declare the
	    media type <xref target="IANA.MediaTypes"/>
	    of the secured content (the payload).
	    This is intended for use by the application when
	    more than one kind of object could be present in
	    the JWS Payload;
	    the application can use this value to disambiguate among
	    the different kinds of objects that might be present.
	    It will typically not be used by applications when
	    the kind of object is already known.
	    This parameter is ignored by JWS implementations;
	    any processing of this parameter is performed by the JWS application.
	    Use of this Header Parameter is OPTIONAL.
	  </t>
	  <t>
	    Per <xref target="RFC2045">RFC 2045</xref>, all media type values,
	    subtype values, and parameter names are case insensitive.
	    However, parameter values are case sensitive unless
	    otherwise specified for the specific parameter.
	  </t>
	  <t>
	    To keep messages compact in common situations,
	    it is RECOMMENDED that producers omit an "application/" prefix
	    of a media type value in a <spanx style="verb">cty</spanx>
	    Header Parameter when no other '/' appears in the media type value.
	    A recipient using the media type value MUST treat it as if
	    "application/" were prepended to any
	    <spanx style="verb">cty</spanx> value not containing a '/'.
	    For instance, a <spanx style="verb">cty</spanx> value of
	    <spanx style="verb">example</spanx> SHOULD be used to represent
	    the <spanx style="verb">application/example</spanx> media type,
	    whereas the media type
	    <spanx style="verb">application/example;part="1/2"</spanx> cannot
	    be shortened to <spanx style="verb">example;part="1/2"</spanx>.
	  </t>

	</section>

	<section title='"crit" (Critical) Header Parameter' anchor="critDef">
	  <t>
	    The <spanx style="verb">crit</spanx> (critical) Header Parameter
	    indicates that extensions to 
	    this specification and/or <xref target="JWA"/> are being used
	    that MUST be understood and processed.
	    Its value is an array listing the Header Parameter names
	    present in the JOSE Header that use those extensions.
	    If any of the listed extension Header Parameters are not
	    understood and supported by the recipient, then the JWS is invalid.
	    Producers MUST NOT include Header Parameter names defined by
	    this specification or <xref target="JWA"/> for use with JWS,
	    duplicate names, or
	    names that do not occur as Header Parameter names within the JOSE Header
	    in the <spanx style="verb">crit</spanx> list.
	    Producers MUST NOT use the empty list <spanx style="verb">[]</spanx>
	    as the <spanx style="verb">crit</spanx> value.
	    Recipients MAY consider the JWS to be invalid if the critical list
	    contains any Header Parameter names defined by 
	    this specification or <xref target="JWA"/> for use with JWS
	    or if any other constraints on its use are violated.
	    When used, this Header Parameter MUST be integrity protected;
	    therefore, it MUST occur only within the JWS Protected Header.
	    Use of this Header Parameter is OPTIONAL.
	    This Header Parameter MUST be understood and processed by implementations.
	  </t>
	  <t>
	    <figure>
	      <preamble>
		An example use, along with a hypothetical
		<spanx style="verb">exp</spanx> (expiration time) field is:
	      </preamble>
	      <artwork><![CDATA[
  {"alg":"ES256",
   "crit":["exp"],
   "exp":1363284000
  }
]]></artwork>
	    </figure>
	  </t>
	</section>

      </section>

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

        <t>
	  Additional Header Parameter names can be defined by those
	  using JWSs. 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="HdrReg" /> 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 JWSs.
	</t>
      </section>

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

	<t>
	  A producer and consumer of a JWS 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 JWSs" anchor="JWSRules">

      <section title="Message Signature or MAC Computation" anchor="MessageSignature">
	<t>
	  To create a JWS, the following steps are performed.
	  The order of the steps is not significant in cases where
	  there are no dependencies between the inputs and outputs of the steps.

	  <list style="numbers">

	    <t>
	      Create the content to be used as the JWS Payload.
	    </t>
	    <t>
	      Compute the encoded payload value BASE64URL(JWS Payload).
	    </t>
	    <t>
	      Create the JSON object(s) containing the desired set of Header Parameters,
	      which together comprise the JOSE Header
	      (the JWS Protected Header and/or the JWS Unprotected Header).
	    </t>
	    <t>
	      Compute the encoded header value BASE64URL(UTF8(JWS Protected Header)).
	      If the JWS Protected Header is not present
	      (which can only happen when using the JWS JSON Serialization
	      and no <spanx style="verb">protected</spanx> member is present),
	      let this value be the empty string.
	    </t>
	    <t>
	      Compute the JWS Signature in the manner defined for
	      the particular algorithm being used over the JWS Signing Input
	      ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)).
	      The <spanx style="verb">alg</spanx> (algorithm) Header Parameter MUST be
	      present in the JOSE Header, with the algorithm value
	      accurately representing the algorithm used to construct
	      the JWS Signature.
	    </t>
	    <t>
	      Compute the encoded signature value BASE64URL(JWS Signature).
	    </t>
	    <t>
	      If the JWS JSON Serialization is being used, repeat this process
	      (steps 3-6)
	      for each digital signature or MAC operation being performed.
	    </t>
	    <t>
	      Create the desired serialized output.
	      The JWS Compact Serialization of this result is
	      BASE64URL(UTF8(JWS Protected Header))
	      || '.' || BASE64URL(JWS Payload)
	      || '.' || BASE64URL(JWS Signature).
	      The JWS JSON Serialization is described in <xref target="JSONSerialization"/>.
	    </t>
	  </list>
	</t>
      </section>

      <section title="Message Signature or MAC Validation" anchor="MessageValidation">
	<t>
	  When validating a JWS, the following steps are performed.
	  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 the listed steps fails, then the signature or MAC cannot be validated.
	</t>
	<t>
	  When there are multiple JWS Signature values,
	  it is an application decision which of the JWS Signature values
	  must successfully validate for the JWS to be accepted.
	  In some cases, all must successfully validate, or the JWS will be considered invalid.
	  In other cases, only a specific JWS Signature value
	  needs to be successfully validated.
	  However, in all cases, at least one JWS Signature value
	  MUST successfully validate, or the JWS MUST be considered invalid.
	</t>
	<t>
	  <list style="numbers">
	    <t>
	      Parse the JWS representation to extract the serialized values
	      for the components of the JWS.
	      When using the JWS Compact Serialization,
	      these components are
	      the base64url-encoded representations of
	      the JWS Protected Header,
	      the JWS Payload, and
	      the JWS Signature,
	      and when using the JWS JSON Serialization,
	      these components also include the unencoded JWS Unprotected Header value.
	      When using the JWS Compact Serialization,
	      the JWS Protected Header,
	      the JWS Payload, and
	      the JWS Signature
	      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 two delimiting period characters being used.
	      The JWS JSON Serialization
	      is described in <xref target="JSONSerialization"/>.
	    </t>
	    <t>
	      Base64url-decode the encoded representation of the
	      JWS Protected Header,
	      following the restriction that no line breaks, whitespace, or
	      other additional characters have been used.

	    </t>
	    <t>
	      Verify that the resulting octet sequence
	      is a UTF-8-encoded representation of
	      a completely valid JSON object
	      conforming to <xref target="RFC7159">RFC 7159</xref>;
	      let the JWS Protected Header be this JSON object.
	    </t>
	    <t>
	      If using the JWS Compact Serialization, let the JOSE Header be the
	      JWS Protected Header.
	      Otherwise, when using the JWS JSON Serialization,
	      let the JOSE Header be the union of
	      the members of the corresponding JWS Protected Header
	      and JWS 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 JWS 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 algorithm 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>
	      Base64url-decode the encoded representation of the
	      JWS Payload,
	      following the restriction that no line breaks, whitespace, or other additional characters have been used.
	    </t>
	    <t>
	      Base64url-decode the encoded representation of the
	      JWS Signature,
	      following the restriction that no line breaks, whitespace, or other additional characters have been used.
	    </t>
	    <t>
	      Validate the JWS Signature
	      against the JWS Signing Input
	      ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload))
	      in the manner defined for the algorithm being used, which
	      MUST be accurately represented by the value of the <spanx style="verb">alg</spanx> (algorithm)
	      Header Parameter, which MUST be present.
	      See <xref target="AlgValidation"/> for security considerations on algorithm validation.
	      Record whether the validation succeeded or not.
	    </t>
	    <t>
	      If the JWS JSON Serialization is being used, repeat this process
	      (steps 4-8)
	      for each digital signature or MAC value contained in the representation.
	    </t>
	    <t>
	      If none of the validations in step 9
	      succeeded, then the JWS MUST be considered invalid.
	      Otherwise, in the JWS JSON Serialization case, return a result to the application
	      indicating which of the validations succeeded and failed.
	      In the JWS Compact Serialization case, the result
	      can simply indicate whether or not the JWS was successfully validated.
	    </t>
	  </list>
	</t>
	<t>
	  Finally, note that it is an application decision which algorithms
	  may be used in a given context.
	  Even if a JWS can be successfully validated,
	  unless the algorithm(s) used in the JWS are acceptable
	  to the application, it SHOULD consider the JWS to be invalid.
	</t>
      </section>

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

	<t>
	  Processing a JWS inevitably requires comparing known strings
	  to members and values in JSON objects. For example, in checking what the
	  algorithm is, the Unicode string
	  <spanx style="verb">alg</spanx> will be
	  checked against the member names in the JOSE Header
	  to see if there is a matching Header Parameter name.
	  The same process is then used to determine if the value
	  of the <spanx style="verb">alg</spanx> Header Parameter
	  represents a supported algorithm.
	</t>
	<t>
	  The JSON rules for doing member name comparison are described in
	  Section 8.3 of <xref target="RFC7159">RFC 7159</xref>.
	  Since the only string comparison operations that are performed are
	  equality and inequality, the same rules can be used for comparing
	  both member names and member values against known strings.
	</t>
	<t>
	  These comparison rules MUST be used for all JSON string comparisons
	  except in cases where the definition of the member explicitly calls out that
	  a different comparison rule is to be used for that member value.
	  Only the <spanx style="verb">typ</spanx> and <spanx style="verb">cty</spanx>
	  member values defined in this specification do not use these comparison rules.
	</t>
	<t>
	  Some applications may include case-insensitive information in
	  a case-sensitive value, such as including a DNS name as part of
	  a <spanx style="verb">kid</spanx> (key ID) value.
	  In those cases, the application may need to define a convention
	  for the canonical case to use for representing the case-insensitive portions,
	  such as lowercasing them, if more than one party might need to
	  produce the same value so that they can be compared.
	  (However, if all other parties consume whatever value the producing party
	  emitted verbatim without attempting to compare it to an independently produced
	  value, then the case used by the producer will not matter.)
	</t>
	<t>
	  Also, see the JSON security considerations in <xref target="JSONSecCon"/> and
	  the Unicode security considerations in <xref target="UnicodeSecCon"/>.
	</t>
      </section>

    </section>

    <section title="Key Identification" anchor="IDingKeys">
      <t>
	It is necessary for the recipient of a JWS to be able to determine
	the key that was employed for the digital signature or MAC operation.
	The key employed can be identified using the
	Header Parameter methods described in <xref
	target="RegisteredHeaderParameterName" /> or can be identified
	using methods that are outside the scope of this specification.
	Specifically, the Header Parameters
	<spanx style="verb">jku</spanx>,
	<spanx style="verb">jwk</spanx>,
	<spanx style="verb">kid</spanx>,
	<spanx style="verb">x5u</spanx>,
	<spanx style="verb">x5c</spanx>,
	<spanx style="verb">x5t</spanx>,
	and <spanx style="verb">x5t#S256</spanx>
	can be used to identify the key used.
	These Header Parameters MUST be integrity protected if the
	information that they convey is to be utilized in a trust decision;
	however, if the only information used in the trust decision is a key,
	these parameters need not be integrity protected,
	since changing them in a way that causes a different key to be used
	will cause the validation to fail.
      </t>
      <t>
	The producer SHOULD include sufficient information in the Header Parameters
	to identify the key used, unless the application uses another means
	or convention to determine the key used.
	Validation of the signature or MAC fails when
	the algorithm used requires a key
	(which is true of all algorithms except for <spanx style="verb">none</spanx>) and
	the key used cannot be determined.
      </t>
      <t>
	The means of exchanging any shared symmetric keys used
	is outside the scope of this specification. 
      </t>
      <t>
	Also, see <xref target="KeySelectionNotes"/> for
	notes on possible key selection algorithms.
      </t>
    </section>

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

      <t>
	JWSs use one of two serializations: the
	JWS Compact Serialization
	or the
	JWS 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 JWS JSON Serialization is used,
	that only JWS JSON Serialization support for a single signature or MAC value is used,
	or that support for multiple signatures and/or MAC values is used.
	JWS implementations only need to implement the features needed
	for the applications they are designed to support.
      </t>

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

	<t>
	  The JWS Compact Serialization represents digitally signed or MACed
	  content as a compact, URL-safe string.
	  This string is:
	</t>
	<t>
	  <?rfc subcompact="yes"?>
	  <list style="empty">
	    <t>BASE64URL(UTF8(JWS Protected Header)) || '.' ||</t>
	    <t>BASE64URL(JWS Payload) || '.' ||</t>
	    <t>BASE64URL(JWS Signature)</t>
	  </list>
	  <?rfc subcompact="no"?>
	</t>
	<t>
	  Only one signature/MAC is supported by the JWS Compact Serialization
	  and it provides no syntax to represent a JWS Unprotected Header value.
	</t>

      </section>

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

	<t>
	  The JWS JSON Serialization represents digitally signed or MACed
	  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 JWS JSON Serialization:
	  a fully general syntax,
	  with which content can be secured with more than one
	  digital signature and/or MAC operation,
	  and a flattened syntax, which is optimized for
	  the single digital signature or MAC case.
	</t>

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

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

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

	      <t hangText="signatures">
		<vspace/>
		The <spanx style="verb">signatures</spanx> member value MUST be
		an array of JSON objects.
		Each object represents a signature or MAC over the JWS Payload
		and the JWS Protected Header.
	      </t>

	    </list>
	  </t>
	  <t>
	    The following members are defined for use in
	    the JSON objects that are elements of
	    the <spanx style="verb">signatures</spanx> array:
	  </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(JWS Protected Header)) when the JWS Protected Header
		value is non-empty; otherwise, it MUST be absent.
		These Header Parameter values are integrity protected.
	      </t>

	      <t hangText="header">
		<vspace/>
		The <spanx style="verb">header</spanx> member MUST be present and contain the value
		JWS Unprotected Header when the JWS 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="signature">
		<vspace/>
		The <spanx style="verb">signature</spanx> member MUST be present and contain the value
		BASE64URL(JWS Signature).
	      </t>

	    </list>
	  </t>

	  <t>
	    At least one of the
	    <spanx style="verb">protected</spanx> and
	    <spanx style="verb">header</spanx>
	    members MUST be present for each signature/MAC computation
	    so that an <spanx style="verb">alg</spanx>
	    Header Parameter value is conveyed.
	  </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>
	    The Header Parameter values used when creating or validating
	    individual signature or MAC values are
	    the union of the two sets of Header Parameter values that may be present:
	    (1) the JWS Protected Header
	    represented in the <spanx style="verb">protected</spanx>
	    member of the signature/MAC's array element, and
	    (2) the JWS Unprotected Header
	    in the <spanx style="verb">header</spanx>
	    member of the signature/MAC's array element.
	    The union of these sets of Header Parameters comprises the JOSE Header.
	    The Header Parameter names in the two locations MUST be disjoint.
	  </t>
	  <t>
	    Each JWS Signature value is computed using the
	    parameters of the corresponding JOSE Header value
	    in the same manner as for the JWS Compact Serialization.
	    This has the desirable property that each
	    JWS Signature value represented
	    in the <spanx style="verb">signatures</spanx> array
	    is identical to the value
	    that would have been computed for the same parameter
	    in the JWS Compact Serialization,
	    provided that the JWS Protected Header value
	    for that signature/MAC computation
	    (which represents the integrity-protected Header Parameter values)
	    matches that used in
	    the JWS Compact Serialization.
	  </t>

	  <figure>
	    <preamble>
	      In summary,
	      the syntax of a JWS using the general JWS JSON Serialization is as follows:
	    </preamble>
	    <artwork><![CDATA[
  {
   "payload":"<payload contents>",
   "signatures":[
    {"protected":"<integrity-protected header 1 contents>",
     "header":<non-integrity-protected header 1 contents>,
     "signature":"<signature 1 contents>"},
    ...
    {"protected":"<integrity-protected header N contents>",
     "header":<non-integrity-protected header N contents>,
     "signature":"<signature N contents>"}]
  }
]]></artwork>
	  </figure>

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

	</section>

	<section title="Flattened JWS JSON Serialization Syntax"
		 anchor="FlattenedJSONSerialization">
	  <t>
	    The flattened JWS JSON Serialization syntax is based upon
	    the general syntax but flattens it,
	    optimizing it for the single digital signature/MAC case.
	    It flattens it by removing
	    the <spanx style="verb">signatures</spanx> member and
	    instead placing those members defined for use in
	    the <spanx style="verb">signatures</spanx> array
	    (the <spanx style="verb">protected</spanx>,
	    <spanx style="verb">header</spanx>, and
	    <spanx style="verb">signature</spanx> members)
	    in the top-level JSON object
	    (at the same level as the <spanx style="verb">payload</spanx> member).
	  </t>
	  <t>
	    The <spanx style="verb">signatures</spanx> member MUST NOT
	    be present when using this syntax.
	    Other than this syntax difference, JWS 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 JWS using the flattened JWS JSON Serialization is as follows:
	    </preamble>
	    <artwork><![CDATA[
  {
   "payload":"<payload contents>",
   "protected":"<integrity-protected header contents>",
   "header":<non-integrity-protected header contents>,
   "signature":"<signature contents>"
  }
]]></artwork>
	  </figure>

	  <t>
	    See <xref target="FlattenedJSONSerializationExample"/> for an example
	    JWS using the flattened JWS JSON Serialization syntax.
	  </t>

	</section>

      </section>

    </section>

    <section anchor="TLS_requirements" title="TLS Requirements">
      <t>
	Implementations supporting the <spanx style="verb">jku</spanx> and/or
	<spanx style="verb">x5u</spanx> Header Parameters MUST support TLS.
	Which TLS version(s) ought to be implemented will vary over
	time and depend on the widespread deployment and known
	security vulnerabilities at the time of implementation.
	At the time of this writing,
	TLS version 1.2 <xref target='RFC5246' />
	is the most recent version.
      </t>
      <t>
	To protect against information disclosure and tampering,
	confidentiality protection MUST be applied using TLS
	with a ciphersuite that provides confidentiality and
	integrity protection.
	See current publications by the IETF TLS working group,
	including <xref target="RFC6176">RFC 6176</xref>,
	for guidance on the ciphersuites currently considered to be appropriate for use.
	Also, see <xref target="RFC7525">"Recommendations for Secure Use of
	Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)"</xref>
	for recommendations on improving the security of software and services using TLS.
      </t>
      <t>
	Whenever TLS is used, the identity of the service provider encoded
	in the TLS server certificate MUST be verified using the procedures
	described in Section 6 of <xref target="RFC6125">RFC 6125</xref>.
      </t>
    </section>

    <section title="IANA Considerations" anchor="IANA">
      <t>
	The following registration procedure is used for all the
	registries established by this specification.
      </t>
      <t>
	Values are registered on a Specification Required
	<xref target="RFC5226"/> basis 
  after a three-week review period on the jose-reg-review@ietf.org
  mailing list, on the advice of one or more Designated Experts.
  However, to allow for the allocation of values prior to publication,
  the Designated Experts may approve registration once they are
  satisfied that such a specification will be published.
      </t>
      <t>
Registration requests sent to the mailing list for review should use
an appropriate subject (e.g., "Request to register header parameter: example").
      </t>
      <t>
	Within the review period, the Designated Experts will either approve or
	deny the registration request, communicating this decision to the review list and IANA.
	Denials should include an explanation and, if applicable, suggestions as to how to make
	the request successful.
	Registration requests that are undetermined for
	a period longer than 21 days can be brought to the IESG's attention
	(using the iesg@ietf.org mailing list) for resolution.
      </t>
      <t>
	Criteria that should be applied by the Designated Experts includes
	determining whether the proposed registration duplicates existing functionality,
	whether it is likely to be of general applicability
	or useful only for a single application,
	and whether the registration description is clear.
      </t>
      <t>
	IANA must only accept registry updates from the Designated Experts and should direct
	all requests for registration to the review mailing list.
      </t>
      <t>
	It is suggested that multiple Designated Experts be appointed who are able to
	represent the perspectives of different applications using this specification,
	in order to enable broadly informed review of registration decisions.
	In cases where a registration decision could be perceived as
	creating a conflict of interest for a particular Expert,
	that Expert should defer to the judgment of the other Experts.
      </t>

      <section title="JSON Web Signature and Encryption Header Parameters Registry" anchor="HdrReg">
	<t>
	  This specification establishes the
	  IANA "JSON Web Signature and Encryption Header Parameters" registry
	  for Header Parameter names.
	  The registry records the Header Parameter name
	  and a reference to the specification that defines it.
	  The same Header Parameter name can be registered multiple times,
	  provided that the parameter usage is compatible
	  between the specifications.
	  Different registrations of the same Header Parameter name
	  will typically use different
	  Header Parameter Usage Locations values.
	</t>

        <section title="Registration Template" anchor="HdrTemplate">
          <t>
            <list style='hanging'>
              <t hangText='Header Parameter Name:'>
		<vspace/>
                The name requested (e.g., "kid").
		Because a core goal of this specification is for the resulting
		representations to be compact, it is RECOMMENDED that the name be short
		-- not to exceed 8 characters without a compelling reason to do so.
		This name is case sensitive.
		Names may not match other registered names in a case-insensitive manner
		unless the Designated Experts state that there is a compelling reason
		to allow an exception.
              </t>
              <t hangText='Header Parameter Description:'>
		<vspace/>
                Brief description of the Header Parameter (e.g., "Key ID").
              </t>
              <t hangText='Header Parameter Usage Location(s):'>
                <vspace/>
                The Header Parameter usage locations, which should be one or more of the values
		<spanx style="verb">JWS</spanx> or
		<spanx style="verb">JWE</spanx>.
              </t>
              <t hangText='Change Controller:'>
                <vspace/>
                For Standards Track RFCs, list the "IESG". For others, give the name of the
                responsible party. Other details (e.g., postal address, email address, home page
                URI) may also be included.
              </t>
              <t hangText='Specification Document(s):'>
                <vspace/>
                Reference to the document or documents that specify the parameter,
		preferably including URIs that
                can be used to retrieve copies of the documents.
		An indication of the relevant
                sections may also be included but is not required.
              </t>
            </list>
          </t>
        </section>

        <section title="Initial Registry Contents" anchor="HdrContents">
	  <t>
	    This section registers the Header Parameter names defined in
	    <xref target="RegisteredHeaderParameterName"/> in this registry.
	  </t>
	  <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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="algDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="jkuDef"/> of RFC 7515
              </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): JWS
	      </t>
	      <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="jwkDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="kidDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5uDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5cDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5tDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="x5tS256Def"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="typDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="ctyDef"/> of RFC 7515
              </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): JWS
	      </t>
              <t>
                Change Controller: IESG
              </t>
              <t>
                Specification Document(s): <xref target="critDef"/> of RFC 7515
              </t>
            </list>
          </t>
	</section>
	<?rfc subcompact="no"?>
      </section>

      <section title="Media Type Registration" anchor="MediaReg">
	<section title="Registry Contents" anchor="MediaContents">
	  <t>
	    This section registers the
	    <spanx style="verb">application/jose</spanx>
	    media type <xref target="RFC2046"/>
	    in the "Media Types" registry <xref target="IANA.MediaTypes"/>
	    in the manner described in <xref target="RFC6838">RFC 6838</xref>,
	    which can be used to indicate that the content is
	    a JWS or JWE using
	    the JWS Compact Serialization or the JWE Compact
	    Serialization. This section also registers
	    the
	    <spanx style="verb">application/jose+json</spanx>
	    media type in the "Media Types" registry,
	    which can be used to indicate that the content is
	    a JWS or JWE using
	    the JWS JSON Serialization or the JWE JSON Serialization.
	  </t>
	  <t> <?rfc subcompact="yes"?>
	    <list style="symbols">
	      <t>
		Type name: application
	      </t>
	      <t>
		Subtype name: jose
	      </t>
	      <t>
		Required parameters: n/a
	      </t>
	      <t>
		Optional parameters: n/a
	      </t>
	      <t>
		Encoding considerations: 8bit;
		application/jose values are encoded as a
		series of base64url-encoded values (some of which may be the
		empty string), each separated from the next by a single period ('.') character.
	      </t>
	      <t>
		Security considerations: See the Security Considerations
		section of RFC 7515.
	      </t>
	      <t>
		Interoperability considerations: n/a
	      </t>
	      <t>
		Published specification: RFC 7515
	      </t>
	      <t>
		Applications that use this media type:
		OpenID Connect, Mozilla Persona, Salesforce, Google, Android,
		Windows Azure, Xbox One, Amazon Web Services,
		and numerous others that use JWTs
	      </t>
	      <t>
		Fragment identifier considerations: n/a
	      </t>
	      <t>
		Additional information:<list style="empty">
		<t>Magic number(s): n/a</t>
		<t>File extension(s): n/a</t>
		<t>Macintosh file type code(s): n/a</t></list>
<vspace/>
	      </t>
	      <t>
		Person &amp; email address to contact for further information:
<vspace/>
		Michael B.&nbsp;Jones, mbj@microsoft.com
	      </t>
	      <t>
		Intended usage: COMMON
	      </t>
	      <t>
		Restrictions on usage: none
	      </t>
	      <t>
		Author: Michael B.&nbsp;Jones, mbj@microsoft.com
	      </t>
	      <t>
		Change Controller: IESG
	      </t>
	      <t>
		Provisional registration? No
	      </t>
	    </list>
	  </t>
	  <t>
	    <list style="symbols">
	      <t>
		Type name: application
	      </t>
	      <t>
		Subtype name: jose+json
	      </t>
	      <t>
		Required parameters: n/a
	      </t>
	      <t>
		Optional parameters: n/a
	      </t>
	      <t>
		Encoding considerations: 8bit;
		application/jose+json values are represented as a JSON Object;
		UTF-8 encoding SHOULD be employed for the JSON object.
	      </t>
	      <t>
		Security considerations: See the Security Considerations
		section of RFC 7515
	      </t>
	      <t>
		Interoperability considerations: n/a
	      </t>
	      <t>
		Published specification: RFC 7515
	      </t>
	      <t>
		Applications that use this media type:
		Nimbus JOSE + JWT library
	      </t>
	      <t>
		Fragment identifier considerations: n/a
	      </t>
	      <t>
		Additional information:<list style="empty">
		<t>Magic number(s): n/a</t>
		<t>File extension(s): n/a</t>
		<t>Macintosh file type code(s): n/a</t></list>
<vspace/>
	      </t>
	      <t>
		Person &amp; email address to contact for further information:
<vspace/>
		Michael B.&nbsp;Jones, mbj@microsoft.com
	      </t>
	      <t>
		Intended usage: COMMON
	      </t>
	      <t>
		Restrictions on usage: none
	      </t>
	      <t>
		Author: Michael B.&nbsp;Jones, mbj@microsoft.com
	      </t>
	      <t>
		Change Controller: IESG
	      </t>
	      <t>
		Provisional registration? No
	      </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
	<xref target="W3C.NOTE-xmldsig-core2-20130411">"XML Signature
              Syntax and Processing Version 2.0"</xref>,
	also apply to this specification, other than those that are XML specific.
	Likewise, many of the best practices documented in
	<xref target="W3C.NOTE-xmldsig-bestpractices-20130411">"XML Signature Best Practices"</xref>
	also apply to this specification,
	other than those that are XML specific.
      </t>

      <section title="Key Entropy and Random Values" anchor="KeyEntropy">
	<t>
	  Keys are only as strong as the amount of entropy used to
	  generate them.  A minimum of 128 bits of entropy should be
	  used for all keys, and depending upon the application context,
	  more may be required.
	</t>
	<t>
	  Implementations must randomly generate public/private key pairs,
	  MAC keys, and padding values.
	  The use of inadequate pseudorandom number
	  generators (PRNGs) to generate cryptographic keys can result in
	  little or no security.  An attacker may find it much easier to
	  reproduce the PRNG environment that produced the keys, searching the
	  resulting small set of possibilities rather than brute-force
	  searching the whole key space.  The generation of quality random
	  numbers is difficult.
	  <xref target="RFC4086">RFC 4086</xref> offers important guidance in
	  this area.
	</t>
      </section>

      <section title="Key Protection" anchor="KeyProtection">
	<t>
	  Implementations must protect the signer's private key.  Compromise of
	  the signer's private key permits an attacker to masquerade as the signer.
	</t>
	<t>
	  Implementations must protect the MAC key.
	  Compromise of the MAC key may result in undetectable
	  modification of the authenticated content.
	</t>
      </section>

      <section title="Key Origin Authentication" anchor="KeyOrigin">
	<t>
	  The key management technique employed to obtain public keys
	  must authenticate the origin of the key;
	  otherwise, it is unknown what party signed the message.
	</t>
	<t>
	  Likewise, the key management technique employed to distribute MAC
	  keys must provide data origin authentication;
	  otherwise, the contents are delivered with integrity from an unknown
	  source.
	</t>
      </section>

      <section title="Cryptographic Agility" anchor="CryptoAgility">
	<t>
	  See Section 8.1 of <xref target="JWA"/> for security considerations on
	  cryptographic agility.
	</t>
      </section>

      <section title="Differences between Digital Signatures and MACs"
	       anchor="SignaturesAndMacs">
	<t>
	  While MACs and digital signatures can both be used for
	  integrity checking, there are some significant differences between
	  the security properties that each of them provides.
	  These need to be taken into consideration when designing protocols and
	  selecting the algorithms to be used in protocols.
	</t>
	<t>
	  Both signatures and MACs provide for integrity checking -- verifying that
	  the message has not been modified since the integrity value was computed.
	  However, MACs provide for origination identification only under
	  specific circumstances.
	  It can normally be assumed that a private key used for a signature
	  is only in the hands of a single entity
	  (although perhaps a distributed entity, in the case of replicated servers);
	  however, a MAC key needs to be in the hands of all the entities that use it
	  for integrity computation and checking.
	  Validation of a MAC only provides corroboration that the message
	  was generated by one of the parties that knows the symmetric MAC key.
	  This means that origination can only be determined if a MAC key is known only
	  to two entities and the recipient knows that it did not create the message.
	  MAC validation cannot be used to prove origination to a third party.
	</t>
      </section>

      <section title="Algorithm Validation" anchor="AlgValidation">
	<t>
	  The digital signature representations for some algorithms include
	  information about the algorithm used inside the signature value.
	  For instance, signatures produced with RSASSA-PKCS1-v1_5
	  <xref target="RFC3447"/>
	  encode the hash function used, and many libraries
	  actually use the hash algorithm specified inside the signature
	  when validating the signature.
	  When using such libraries, as part of the algorithm validation
	  performed, implementations MUST ensure
	  that the algorithm information encoded in the signature
	  corresponds to that specified with the
	  <spanx style="verb">alg</spanx> Header Parameter.
	  If this is not done, an attacker could claim to have used
	  a strong hash algorithm while actually using a weak one
	  represented in the signature value.
	</t>
      </section>

      <section title="Algorithm Protection" anchor="AlgProtection">
	<t>
	  In some usages of JWS, there is a risk of algorithm substitution attacks,
	  in which an attacker can use an existing digital signature value with a different
	  signature algorithm to make it appear that a signer has signed something
	  that it has not.  These attacks have been discussed in detail in the
	  context of Cryptographic Message Syntax (CMS) <xref target="RFC6211"/>.
	  This risk arises when all of the following are true:
	</t>
	<t>
<?rfc subcompact="no"?>
	  <list style="symbols">
	    <t>
	      Verifiers of a signature support multiple algorithms.
	    </t>
	    <t>
	      Given an existing signature, an attacker can find another payload
	      that produces the same signature value with a different algorithm.
	    </t>
	    <t>
	      The payload crafted by the attacker is valid in the application context.
	    </t>
	  </list>
	</t>
	<t>
	  There are several ways for an application to mitigate algorithm substitution attacks:
	</t>
	<t>
	  <list style="symbols">
	    <t>
	      Use only digital signature algorithms that are not vulnerable to substitution attacks.
	      Substitution attacks are only feasible if an attacker can compute
	      pre-images for a hash function accepted by the recipient.
	      All JWA-defined signature algorithms use SHA-2 hashes, for which there are
	      no known pre-image attacks, as of the time of this writing.
	    </t>
	    <t>
	      Require that the <spanx style="verb">alg</spanx> Header Parameter be
	      carried in the JWS Protected Header.
	      (This is always the case when using the JWS Compact Serialization
	      and is the approach taken by CMS <xref target="RFC6211"/>.)
	    </t>
	    <t>
	      Include a field containing the algorithm in the application payload,
	      and require that it be matched with the <spanx style="verb">alg</spanx>
	      Header Parameter during verification.
	      (This is the approach taken by PKIX <xref target="RFC5280"/>.)
	    </t>
	  </list>
	</t>
      </section>

      <section title="Chosen Plaintext Attacks" anchor="ChosenPlaintext">
	<t>
	  Creators of JWSs should not allow third parties to insert
	  arbitrary content into the message without adding entropy
	  not controlled by the third party.
	</t>
      </section>

      <section title="Timing Attacks" anchor="TimingAttacks">
	<t>
	  When cryptographic algorithms are implemented in such a way
	  that successful operations take a different amount of time
	  than unsuccessful operations, attackers may be able to
	  use the time difference to obtain information about the keys
	  employed.  Therefore, such timing differences must be avoided.
	</t>
      </section>

      <section title="Replay Protection" anchor="ReplayProtection">
	<t>
	  While not directly in scope for this specification, note that
	  applications using JWS (or JWE) objects can thwart replay attacks
	  by including a unique message identifier as integrity-protected content
	  in the JWS (or JWE) message and having the recipient verify that
	  the message has not been previously received or acted upon.
	</t>
      </section>

      <section title="SHA-1 Certificate Thumbprints" anchor="SHA-1x5t">
	<t>
	  A SHA-1 hash is used when computing
	  <spanx style="verb">x5t</spanx> (X.509 certificate SHA-1 thumbprint) values,
	  for compatibility reasons.  Should an effective means of producing
	  SHA-1 hash collisions be developed and should an attacker wish to
	  interfere with the use of a known certificate on a given system,
	  this could be accomplished by creating another certificate whose
	  SHA-1 hash value is the same and adding it to the certificate
	  store used by the intended victim.  A prerequisite to this
	  attack succeeding is the attacker having write access to the
	  intended victim's certificate store.
	</t>
	<t>
	  Alternatively, the <spanx style="verb">x5t#S256</spanx>
	  (X.509 certificate SHA-256 thumbprint) Header Parameter
	  could be used instead of <spanx style="verb">x5t</spanx>.
	  However, at the time of this writing, no development platform
	  is known to support SHA-256 certificate thumbprints.
	</t>
      </section>

      <section title="JSON Security Considerations" anchor="JSONSecCon">
	<t>
	  Strict JSON <xref target="RFC7159"/> validation is a security requirement.
	  If malformed JSON is received, then the intent of the producer
	  is impossible to reliably discern.
	  Ambiguous and potentially exploitable situations could arise
	  if the JSON parser used does not reject malformed JSON syntax.
	  In particular, any JSON inputs not conforming to the JSON-text syntax
	  defined in RFC 7159 MUST be rejected in their entirety by JSON parsers.
	</t>
	<t>
	  Section 4 of "The JavaScript Object Notation (JSON) Data Interchange Format"
	  <xref target="RFC7159"/> states, "The names
	  within an object SHOULD be unique", whereas this specification states that

<list><t>
        The Header Parameter names within the JOSE Header MUST be unique;
	JWS parsers MUST either reject JWSs with duplicate Header Parameter
	names                        
        or use a JSON parser that returns only the lexically last duplicate
	member name,                 
        as specified in Section 15.12 ("The JSON Object") of
	ECMAScript 5.1 <xref target="ECMAScript"/>.
</t>
</list>
	  Thus, this specification requires that the "SHOULD" in Section 4 of
	  <xref target="RFC7159"/>
	  be treated as a "MUST" by producers
	  and that it be either treated as a "MUST" or treated in the manner specified in
	  ECMAScript 5.1 by consumers.
	  Ambiguous and potentially exploitable situations could arise
	  if the JSON parser used does not enforce the uniqueness of member names
	  or returns an unpredictable value for duplicate member names.
	</t>
	<t>
	  Some JSON parsers might not reject input that contains extra
	  significant characters after a valid input.  For instance,
	  the input <spanx style="verb">{"tag":"value"}ABCD</spanx>
	  contains a valid JSON-text object followed by
	  the extra characters <spanx style="verb">ABCD</spanx>.
	  Implementations MUST consider JWSs containing such input to be invalid.
	</t>
      </section>

      <section title="Unicode Comparison Security Considerations" anchor="UnicodeSecCon">
        <t>
	  Header Parameter names and algorithm names are Unicode strings.  For
	  security reasons, the representations of these names must be
	  compared verbatim after performing any escape processing (as
	  per Section 8.3 of <xref target="RFC7159">RFC 7159</xref>).
	  This means, for instance, that these JSON strings must
	  compare as being equal ("sig", "\u0073ig"), whereas these
	  must all compare as being not equal to the first set or to
	  each other ("SIG", "Sig", "si\u0047").
	</t>
	<t>
	  JSON strings can contain characters outside the Unicode
	  Basic Multilingual Plane.  For instance, the G clef
	  character (U+1D11E) may be represented in a JSON string as
	  "\uD834\uDD1E".  Ideally, JWS implementations SHOULD ensure
	  that characters outside the Basic Multilingual Plane are
	  preserved and compared correctly; alternatively, if this is
	  not possible due to these characters exercising limitations
	  present in the underlying JSON implementation, then input
	  containing them MUST be rejected.
	</t>

      </section>

    </section>
  </middle>

  <back>
    <references title="Normative References">

<?rfc include="reference.RFC.2119"?>
<?rfc include="reference.RFC.2045"?>
<?rfc include="reference.RFC.2046"?>
<?rfc include="reference.RFC.2818"?>
<?rfc include="reference.RFC.3629"?>
<?rfc include="reference.RFC.3986"?>
<?rfc include="reference.RFC.4648"?>
<?rfc include="reference.RFC.4945"?>
<?rfc include="reference.RFC.4949"?>
<?rfc include="reference.RFC.5246"?>
<?rfc include="reference.RFC.5280"?>
<?rfc include="reference.RFC.6125"?>
<?rfc include="reference.RFC.6176"?>
<?rfc include="reference.RFC.7159"?>

      <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="ITU.X690.2008">
<front>
<title>Information Technology - ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished
Encoding Rules (DER)</title>
<author>
<organization>International Telecommunications Union</organization>
</author>
<date month="" year="2008" />
</front>

<seriesInfo name="ITU-T" value="Recommendation X.690" />

</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>
	<!--
	  Note that this reference is to the latest version of Unicode,
	  rather than to a specific release.  It is not expected that future changes in
	  the UNICODE specification will impact the syntax of JSON or the UTF-8 encoding.
	-->
      </reference>


<!-- draft-ietf-jose-json-web-key RFC 7517 -->
      <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>

<!-- draft-ietf-jose-json-web-algorithms RFC 7518 -->
      <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>

      <reference anchor="ECMAScript" target="http://www.ecma-international.org/ecma-262/5.1/ECMA-262.pdf">
	<front>
	  <title>ECMAScript Language Specification, 5.1 Edition</title>
	  <author>
	    <organization>Ecma International</organization>
	  </author>
	  <date month="June" year="2011"/>
	</front>
	<seriesInfo name="ECMA" value="262"/>
	<format target="http://www.ecma-international.org/ecma-262/5.1/" type="HTML" />
	<format target="http://www.ecma-international.org/ecma-262/5.1/ECMA-262.pdf" type="PDF" />
      </reference>

      <reference anchor="IANA.MediaTypes" target="http://www.iana.org/assignments/media-types">
        <front>
          <title>Media Types</title>
          <author>
            <organization>IANA</organization>
          </author>
	  <date/>
        </front>
	<format target="http://www.iana.org/assignments/media-types"
		type="HTML" />
      </reference>

    </references>

    <references title="Informative References">

<?rfc include="reference.RFC.2104"?>
<?rfc include="reference.RFC.3447"?>
<?rfc include="reference.RFC.4086"?>
<?rfc include="reference.RFC.4122"?>
<?rfc include="reference.RFC.5226"?>
<?rfc include="reference.RFC.6211"?>
<?rfc include="reference.RFC.6838"?>

<!-- draft-ietf-uta-tls-bcp now RFC 7525 -->
<?rfc include="reference.RFC.7525"?>

      <reference
	  target="http://www.w3.org/TR/2013/NOTE-xmldsig-core2-20130411/"
	  anchor="W3C.NOTE-xmldsig-core2-20130411">
	<front>
	  <title>XML Signature Syntax and Processing Version 2.0</title>
	  <author fullname="Donald Eastlake" surname="Eastlake" initials="D."><organization/></author>
	  <author fullname="Joseph Reagle" surname="Reagle" initials="J."><organization/></author>
	  <author fullname="David Solo" surname="Solo" initials="D."><organization/></author>
	  <author fullname="Frederick Hirsch" surname="Hirsch" initials="F."><organization/></author>
	  <author fullname="Thomas Roessler" surname="Roessler" initials="T."><organization/></author>
	  <author fullname="Kelvin Yiu" surname="Yiu" initials="K."><organization/></author>
	  <author fullname="Pratik Datta" surname="Datta" initials="P."><organization/></author>
	  <author fullname="Scott Cantor" surname="Cantor" initials="S."><organization/></author>
	  <date year="2013" day="11" month="April"/>
	</front>
	<seriesInfo value="NOTE-xmldsig-core2-20130411"
		    name="World Wide Web Consortium Note"/>
	<format target="http://www.w3.org/TR/2013/NOTE-xmldsig-core2-20130411/" type="HTML"/>
      </reference>


      <reference target="http://www.w3.org/TR/2013/NOTE-xmldsig-bestpractices-20130411/" anchor="W3C.NOTE-xmldsig-bestpractices-20130411">
	<front>
	  <title>XML Signature Best Practices</title>
	  <author fullname="Frederick Hirsch" surname="Hirsch" initials="F."><organization/></author>
	  <author fullname="Pratik Datta" surname="Datta" initials="P."><organization/></author>
	  <date year="2013" day="11" month="April"/>
	</front>
	<seriesInfo value="NOTE-xmldsig-bestpractices-20130411"
		    name="World Wide Web Consortium Note"/>
	<format target="http://www.w3.org/TR/2013/NOTE-xmldsig-bestpractices-20130411/" type="HTML"/>
      </reference>

      <reference anchor="JWT" target='http://www.rfc-editor.org/info/rfc7519'>
        <front>
          <title>JSON Web Token (JWT)</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>
	      <uri>http://www.thread-safe.com/</uri>
	    </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>
	      <uri>http://nat.sakimura.org/</uri>
	    </address>
	  </author>

	  <date month="May" year="2015"/>
        </front>
        <seriesInfo name="RFC" value="7519" />
      </reference>

      <reference anchor="SHS" target="http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf">
        <front>
          <title>Secure Hash Standard (SHS)</title>

          <author>
            <organization>National Institute of Standards and
            Technology</organization>
          </author>

          <date month="March" year="2012" />
        </front>
        <seriesInfo name="FIPS" value="PUB 180-4" />
        <format target="http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf" type="PDF" />
      </reference>

      <reference anchor="MagicSignatures" target="http://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html">
        <front>
          <title>Magic Signatures</title>

          <author fullname="John Panzer" initials="J."
		  surname="Panzer" role="editor"></author>

          <author fullname="Ben Laurie" initials="B." surname="Laurie"></author>

          <author fullname="Dirk Balfanz" initials="D." surname="Balfanz"></author>

          <date day="7" month="January" year="2011" />
        </front>
        <format target="http://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html" type="HTML" />
      </reference>


      <reference anchor="JSS" target="http://jsonenc.info/jss/1.0/">
        <front>
          <title>JSON Simple Sign</title>

	  <author fullname="John Bradley" initials="J." surname="Bradley">
	    <organization>independent</organization>
	  </author>

	  <author fullname="Nat Sakimura" initials="N. "
		  surname="Sakimura" role="editor">
	    <organization abbrev="NRI">Nomura Research Institute</organization>
	  </author>

          <date month="September" year="2010" />
        </front>
        <format target="http://jsonenc.info/jss/1.0/" type="HTML" />
      </reference>

      <reference anchor="CanvasApp" target="http://developers.facebook.com/docs/authentication/canvas">
        <front>
          <title>Canvas Applications</title>

          <author><organization>Facebook
          </organization></author>

          <date/>
        </front>
        <format target="http://developers.facebook.com/docs/authentication/canvas" type="HTML" />
      </reference>

      <reference anchor="JWE" target="http://www.rfc-editor.org/info/rfc7516">
        <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"/>
        </front>
        <seriesInfo name="RFC" value="7516" />
      </reference>
    </references>

    <section title="JWS Examples" anchor="JWSExamples">

      <t>
	This section provides several examples of JWSs.
	While the first three
	examples all represent JSON Web Tokens (JWTs) <xref
	target="JWT" />, the payload can be any
	octet sequence, as shown in <xref target="ES512Example"/>.
      </t>

      <section title="Example JWS Using HMAC SHA-256" anchor="HS256Example">
	<section title="Encoding" anchor="HS256Encoding">
	  <t>
	    The following example JWS Protected Header declares that the
	    data structure is a JWT <xref target="JWT"/>
	    and the JWS Signing Input is secured using
	    the HMAC SHA-256 algorithm.
	  </t>

	  <figure><artwork><![CDATA[
  {"typ":"JWT",
   "alg":"HS256"}
]]></artwork></figure>

	  <t>
	    To remove potential ambiguities in the representation of the JSON object above,
	    the actual octet sequence representing UTF8(JWS Protected Header) used in this example
	    is also included below.
	    (Note that ambiguities can arise due to
	    differing platform representations of line breaks (CRLF versus LF),
	    differing spacing at the beginning and ends of lines,
	    whether the last line has a terminating line break or not,
	    and other causes.
	    In the representation used in this example,
	    the first line has no leading or trailing spaces,
	    a CRLF line break (13, 10) occurs between the first and second lines,
	    the second line has one leading space (32) and no trailing spaces,
	    and the last line does not have a terminating line break.)
	    The octets representing UTF8(JWS Protected Header) in this example
	    (using JSON array notation) are:
	  </t>
	  <t>

[123, 34, 116, 121, 112, 34, 58, 34, 74, 87, 84, 34, 44, 13, 10, 32, 34, 97, 108, 103, 34, 58, 34, 72, 83, 50, 53, 54, 34, 125]

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

	  <figure><artwork><![CDATA[
  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
]]></artwork></figure>

	  <t>
	    The JWS Payload used in this example
	    is the octets of the UTF-8 representation of the JSON object below.
	    (Note that the payload can be any base64url-encoded octet
	    sequence and need not be a base64url-encoded JSON
	    object.)
	  </t>

	  <figure><artwork><![CDATA[
  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}
]]></artwork></figure>

	  <t>
	    The following octet sequence, which is the UTF-8 representation
	    used in this example for the JSON object above, is the JWS Payload:
	  </t>
	  <t>

[123, 34, 105, 115, 115, 34, 58, 34, 106, 111, 101, 34, 44, 13, 10, 32, 34, 101, 120, 112, 34, 58, 49, 51, 48, 48, 56, 49, 57, 51, 56, 48, 44, 13, 10, 32, 34, 104, 116, 116, 112, 58, 47, 47, 101, 120, 97, 109, 112, 108, 101, 46, 99, 111, 109, 47, 105, 115, 95, 114, 111, 111, 116, 34, 58, 116, 114, 117, 101, 125]

	  </t>
	  <t>
Encoding this JWS Payload as BASE64URL(UTF8(JWS Payload))
gives this value
	    (with line breaks for display purposes only):
	  </t>

          <figure><artwork><![CDATA[
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
]]></artwork></figure>

	  <t>
	    Combining these as
	    BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)
	    gives this string
	    (with line breaks for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
]]></artwork></figure>

	  <t>
	    The resulting JWS Signing Input value,
	    which is the ASCII representation of above string,
	    is the following octet sequence (using JSON array notation):
	  </t>
	  <t>

[101, 121, 74, 48, 101, 88, 65, 105, 79, 105, 74, 75, 86, 49, 81, 105, 76, 65, 48, 75, 73, 67, 74, 104, 98, 71, 99, 105, 79, 105, 74, 73, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]

	  </t>
	  <t>
	    HMACs are generated using keys.
	    This example uses the symmetric 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":"oct",
   "k":"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75
        aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
  }
]]></artwork></figure>
	  <t>
	    Running the HMAC SHA-256 algorithm on
	    the JWS Signing Input
	    with this key yields this JWS Signature octet sequence:
	  </t>
	  <t>

[116, 24, 223, 180, 151, 153, 224, 37, 79, 250, 96, 125, 216, 173, 187, 186, 22, 212, 37, 77, 105, 214, 191, 240, 91, 88, 5, 88, 83, 132, 141, 121]

	  </t>
	  <t>
	    Encoding this JWS Signature as
	    BASE64URL(JWS Signature) gives this value:
	  </t>

	  <figure><artwork><![CDATA[
  dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
]]></artwork></figure>

	<t>
	  Concatenating these values in the order
	  Header.Payload.Signature with period ('.') characters between the
	  parts yields this complete JWS representation
	  using the JWS Compact Serialization
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
  .
  dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
]]></artwork></figure>

	</section>

	<section title="Validating" anchor="HS256Validating">

	  <t>
	    Since the <spanx style="verb">alg</spanx> Header Parameter
	    is <spanx style="verb">HS256</spanx>, we validate the HMAC SHA-256
	    value contained in the JWS Signature.
	  </t>
          <t>
	    To validate the HMAC value, we repeat the previous process
	    of using the correct key and
	    the JWS Signing Input
	    (which is the initial substring of the JWS Compact Serialization
	    representation up until but not including the second period character)
	    as input to the HMAC SHA-256 function
	    and then taking the output and determining if it matches
	    the JWS Signature
	    (which is base64url decoded from the value encoded in the JWS representation).
	    If it matches exactly, the HMAC has been validated.
	  </t>
	</section>
      </section>

      <section title="Example JWS Using RSASSA-PKCS1-v1_5 SHA-256" anchor="RS256Example">

	<section title="Encoding" anchor="RS256Encoding">
	  <t>
	    The JWS Protected Header in this example is different
	    from the previous example in two ways.  First, because a
	    different algorithm is being used, the <spanx style="verb">alg</spanx> value is
	    different.  Second, for illustration purposes only, the
	    optional <spanx style="verb">typ</spanx> (type) Header Parameter is not used.
	    (This difference is
	    not related to the algorithm employed.)  The
	    JWS Protected Header used is:
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"RS256"}
]]></artwork></figure>

	  <t>
	    The octets representing UTF8(JWS Protected Header) in this example (using JSON array notation) are:
	  </t>
	  <t>

[123, 34, 97, 108, 103, 34, 58, 34, 82, 83, 50, 53, 54, 34, 125]

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

	  <figure><artwork><![CDATA[
  eyJhbGciOiJSUzI1NiJ9
]]></artwork></figure>

	  <t>
	    The JWS Payload used in this example, which
	    follows, is the same as in the previous example.  Since
	    the BASE64URL(JWS Payload) value will therefore be the same, its
	    computation is not repeated here.
	  </t>

	  <figure><artwork><![CDATA[
  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}
]]></artwork></figure>

	  <t>
	    Combining these as
	    BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)
	    gives this string
	    (with line breaks for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  eyJhbGciOiJSUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
]]></artwork></figure>

	  <t>
	    The resulting JWS Signing Input value,
	    which is the ASCII representation of above string,
	    is the following octet sequence:
	  </t>
	  <t>

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]

	  </t>

	  <t>
	    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":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
        HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
        D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
        SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
        MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
        NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ",
   "e":"AQAB",
   "d":"Eq5xpGnNCivDflJsRQBXHx1hdR1k6Ulwe2JZD50LpXyWPEAeP88vLNO97I
        jlA7_GQ5sLKMgvfTeXZx9SE-7YwVol2NXOoAJe46sui395IW_GO-pWJ1O0
        BkTGoVEn2bKVRUCgu-GjBVaYLU6f3l9kJfFNS3E0QbVdxzubSu3Mkqzjkn
        439X0M_V51gfpRLI9JYanrC4D4qAdGcopV_0ZHHzQlBjudU2QvXt4ehNYT
        CBr6XCLQUShb1juUO1ZdiYoFaFQT5Tw8bGUl_x_jTj3ccPDVZFD9pIuhLh
        BOneufuBiB4cS98l2SR_RQyGWSeWjnczT0QU91p1DhOVRuOopznQ",
   "p":"4BzEEOtIpmVdVEZNCqS7baC4crd0pqnRH_5IB3jw3bcxGn6QLvnEtfdUdi
        YrqBdss1l58BQ3KhooKeQTa9AB0Hw_Py5PJdTJNPY8cQn7ouZ2KKDcmnPG
        BY5t7yLc1QlQ5xHdwW1VhvKn-nXqhJTBgIPgtldC-KDV5z-y2XDwGUc",
   "q":"uQPEfgmVtjL0Uyyx88GZFF1fOunH3-7cepKmtH4pxhtCoHqpWmT8YAmZxa
        ewHgHAjLYsp1ZSe7zFYHj7C6ul7TjeLQeZD_YwD66t62wDmpe_HlB-TnBA
        -njbglfIsRLtXlnDzQkv5dTltRJ11BKBBypeeF6689rjcJIDEz9RWdc",
   "dp":"BwKfV3Akq5_MFZDFZCnW-wzl-CCo83WoZvnLQwCTeDv8uzluRSnm71I3Q
        CLdhrqE2e9YkxvuxdBfpT_PI7Yz-FOKnu1R6HsJeDCjn12Sk3vmAktV2zb
        34MCdy7cpdTh_YVr7tss2u6vneTwrA86rZtu5Mbr1C1XsmvkxHQAdYo0",
   "dq":"h_96-mK1R_7glhsum81dZxjTnYynPbZpHziZjeeHcXYsXaaMwkOlODsWa
        7I9xXDoRwbKgB719rrmI2oKr6N3Do9U0ajaHF-NKJnwgjMd2w9cjz3_-ky
        NlxAr2v4IKhGNpmM5iIgOS1VZnOZ68m6_pbLBSp3nssTdlqvd0tIiTHU",
   "qi":"IYd7DHOhrWvxkwPQsRM2tOgrjbcrfvtQJipd-DlcxyVuuM9sQLdgjVk2o
        y26F0EmpScGLq2MowX7fhd_QJQ3ydy5cY7YIBi87w93IKLEdfnbJtoOPLU
        W0ITrJReOgo1cq9SbsxYawBgfp_gh6A5603k2-ZQwVK0JKSHuLFkuQ3U"
  }
]]></artwork></figure>

	  <t>
	    The RSA private key is then passed to the RSA
	    signing function, which also takes the hash type, SHA-256,
	    and the JWS Signing Input
	    as inputs.  The result of the digital signature is an octet sequence,
	    which represents a big-endian integer.  In this example, it
	    is:
	  </t>
	  <t>
[112, 46, 33, 137, 67, 232, 143, 209, 30, 181, 216, 45, 191, 120, 69, 243, 65, 6, 174, 27, 129, 255, 247, 115, 17, 22, 173, 209, 113, 125, 131, 101, 109, 66, 10, 253, 60, 150, 238, 221, 115, 162, 102, 62, 81, 102, 104, 123, 0, 11, 135, 34, 110, 1, 135, 237, 16, 115, 249, 69, 229, 130, 173, 252, 239, 22, 216, 90, 121, 142, 232, 198, 109, 219, 61, 184, 151, 91, 23, 208, 148, 2, 190, 237, 213, 217, 217, 112, 7, 16, 141, 178, 129, 96, 213, 248, 4, 12, 167, 68, 87, 98, 184, 31, 190, 127, 249, 217, 46, 10, 231, 111, 36, 242, 91, 51, 187, 230, 244, 74, 230, 30, 177, 4, 10, 203, 32, 4, 77, 62, 249, 18, 142, 212, 1, 48, 121, 91, 212, 189, 59, 65, 238, 202, 208, 102, 171, 101, 25, 129, 253, 228, 141, 247, 127, 55, 45, 195, 139, 159, 175, 221, 59, 239, 177, 139, 93, 163, 204, 60, 46, 176, 47, 158, 58, 65, 214, 18, 202, 173, 21, 145, 18, 115, 160, 95, 35, 185, 232, 56, 250, 175, 132, 157, 105, 132, 41, 239, 90, 30, 136, 121, 130, 54, 195, 212, 14, 96, 69, 34, 165, 68, 200, 242, 122, 122, 45, 184, 6, 99, 209, 108, 247, 202, 234, 86, 222, 64, 92, 178, 33, 90, 69, 178, 194, 85, 102, 181, 90, 193, 167, 72, 160, 112, 223, 200, 163, 42, 70, 149, 67, 208, 25, 238, 251, 71]
	  </t>
	  <t>
	    Encoding the signature as
	    BASE64URL(JWS Signature) produces this value
	    (with line breaks for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7
  AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4
  BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K
  0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv
  hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB
  p0igcN_IoypGlUPQGe77Rw
]]></artwork></figure>

	<t>
	  Concatenating these values in the order
	  Header.Payload.Signature with period ('.') characters between the
	  parts yields this complete JWS representation
	  using the JWS Compact Serialization
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJhbGciOiJSUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
  .
  cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7
  AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4
  BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K
  0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv
  hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB
  p0igcN_IoypGlUPQGe77Rw
]]></artwork></figure>

	</section>

	<section title="Validating" anchor="RS256Validating">

	  <t>
	    Since the <spanx style="verb">alg</spanx> Header Parameter
	    is <spanx style="verb">RS256</spanx>, we
	    validate the RSASSA-PKCS1-v1_5 SHA-256 digital signature contained in the JWS Signature.
	  </t>
	  <t>
	    Validating the JWS Signature is a bit different
	    from the previous example.
	    We pass the public key (n, e),
	    the JWS Signature
	    (which is base64url decoded from the value encoded in the JWS representation), and
	    the JWS Signing Input
	    (which is the initial substring of the JWS Compact Serialization
	    representation up until but not including the second period character)
	    to an RSASSA-PKCS1-v1_5 signature verifier that has
	    been configured to use the SHA-256 hash function.
	  </t>

	</section>
      </section>

      <section title="Example JWS Using ECDSA P-256 SHA-256" anchor="ES256Example">
	<section title="Encoding" anchor="ES256Encoding">
	  <t>
	    The JWS Protected Header for this example differs from
	    the previous example because a different algorithm is
	    being used.  The JWS Protected Header used is:
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"ES256"}
]]></artwork></figure>

	  <t>
	    The octets representing UTF8(JWS Protected Header) in this example (using JSON array notation) are:
	  </t>
	  <t>

[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 50, 53, 54, 34, 125]

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

	  <figure><artwork><![CDATA[
  eyJhbGciOiJFUzI1NiJ9
]]></artwork></figure>

	  <t>
	    The JWS Payload used in this example, which
	    follows, is the same as in the previous examples.  Since
	    the BASE64URL(JWS Payload) value will therefore be the same, its
	    computation is not repeated here.
	  </t>

	  <figure><artwork><![CDATA[
  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}
]]></artwork></figure>

	  <t>
	    Combining these as
	    BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)
	    gives this string
	    (with line breaks for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  eyJhbGciOiJFUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
]]></artwork></figure>

	  <t>
	    The resulting JWS Signing Input value,
	    which is the ASCII representation of above string,
	    is the following octet sequence:
	  </t>
	  <t>

[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]

	  </t>

	  <t>
	    This example uses the Elliptic Curve key
	    represented in JSON Web Key <xref target="JWK" /> format below:
	  </t>
	  <figure><artwork><![CDATA[
  {"kty":"EC",
   "crv":"P-256",
   "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
   "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",
   "d":"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI"
  }
]]></artwork></figure>

	  <t>
	    The Elliptic Curve Digital Signature Algorithm (ECDSA) private part d is then passed to an ECDSA
	    signing function, which also takes the curve type, P-256,
	    the hash type, SHA-256, and
	    the JWS Signing Input
	    as inputs.  The result of the
	    digital signature is the Elliptic Curve (EC) point (R, S), where R and S are
	    unsigned integers.  In this example, the R and S values,
	    given as octet sequences representing big-endian integers are:
	  </t>

	  <texttable>
	    <ttcol align="left">Result Name</ttcol>
	    <ttcol align="left">Value</ttcol>

	    <c>R</c>
	    <c>

[14, 209, 33, 83, 121, 99, 108, 72, 60, 47, 127, 21, 88, 7, 212, 2, 163, 178, 40, 3, 58, 249, 124, 126, 23, 129, 154, 195, 22, 158, 166, 101]

	    </c>

	    <c>S</c>
	    <c>

[197, 10, 7, 211, 140, 60, 112, 229, 216, 241, 45, 175, 8, 74, 84, 128, 166, 101, 144, 197, 242, 147, 80, 154, 143, 63, 127, 138, 131, 163, 84, 213]

	    </c>
	  </texttable>

	  <t>
	    The JWS Signature is the value R || S.
	    Encoding the signature as
	    BASE64URL(JWS Signature) produces this value
	    (with line breaks for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA
  pmWQxfKTUJqPP3-Kg6NU1Q
]]></artwork></figure>

	<t>
	  Concatenating these values in the order
	  Header.Payload.Signature with period ('.') characters between the
	  parts yields this complete JWS representation
	  using the JWS Compact Serialization
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJhbGciOiJFUzI1NiJ9
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
  .
  DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA
  pmWQxfKTUJqPP3-Kg6NU1Q
]]></artwork></figure>

	</section>

	<section title="Validating" anchor="ES256Validating">

	  <t>
	    Since the <spanx style="verb">alg</spanx> Header Parameter
	    is <spanx style="verb">ES256</spanx>, we
	    validate the ECDSA P-256 SHA-256 digital signature contained in
	    the JWS Signature.
	  </t>
	  <t>
	    Validating the JWS Signature is a bit different
	    from the previous examples.
	    We need to split the 64 member octet sequence of the JWS Signature
	    (which is base64url decoded from the value encoded in the JWS representation)
	    into two 32 octet sequences, the first representing R and the second S. We
	    then pass the public key (x, y), the signature (R, S), and 
	    the JWS Signing Input
	    (which is the initial substring of the JWS Compact Serialization
	    representation up until but not including the second period character)
	    to an ECDSA signature verifier that
	    has been configured to use the P-256 curve with the
	    SHA-256 hash function.
	  </t>

	</section>
      </section>


      <section title="Example JWS Using ECDSA P-521 SHA-512" anchor="ES512Example">
	<section title="Encoding" anchor="ES512Encoding">
	  <t>
	    The JWS Protected Header for this example differs from
	    the previous example because different ECDSA curves
	    and hash functions are used.  The JWS Protected Header used is:
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"ES512"}
]]></artwork></figure>

	  <t>
	    The octets representing UTF8(JWS Protected Header) in this example (using JSON array notation) are:
	  </t>
	  <t>

[123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 53, 49, 50, 34, 125]

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

	  <figure><artwork><![CDATA[
  eyJhbGciOiJFUzUxMiJ9
]]></artwork></figure>

	  <t>
	    The JWS Payload used in this example is the ASCII string "Payload".
	    The representation of this string is the following octet sequence:
	  </t>
	  <t>
[80, 97, 121, 108, 111, 97, 100]
	  </t>
	  <t>
	    Encoding this JWS Payload as
	    BASE64URL(JWS Payload) gives this value:
	  </t>

	  <figure><artwork><![CDATA[
  UGF5bG9hZA
]]></artwork></figure>

	  <t>
	    Combining these as
	    BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload)
	    gives this string:
	  </t>

	  <figure><artwork><![CDATA[
  eyJhbGciOiJFUzUxMiJ9.UGF5bG9hZA
]]></artwork></figure>

	  <t>
	    The resulting JWS Signing Input value,
	    which is the ASCII representation of above string,
	    is the following octet sequence:
	  </t>
	  <t>
[101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 85, 120, 77, 105, 74, 57, 46, 85, 71, 70, 53, 98, 71, 57, 104, 90, 65]
	  </t>

	  <t>
	    This example uses the Elliptic Curve 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":"EC",
   "crv":"P-521",
   "x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_
        NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk",
   "y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDl
        y79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2",
   "d":"AY5pb7A0UFiB3RELSD64fTLOSV_jazdF7fLYyuTw8lOfRhWg6Y6rUrPA
        xerEzgdRhajnu0ferB0d53vM9mE15j2C"
  }
]]></artwork></figure>

	  <t>
	    The ECDSA private part d is then passed to an ECDSA
	    signing function, which also takes the curve type, P-521,
	    the hash type, SHA-512, and
	    the JWS Signing Input
	    as inputs.  The result of the
	    digital signature is the EC point (R, S), where R and S are
	    unsigned integers.  In this example, the R and S values,
	    given as octet sequences representing big-endian integers are:
	  </t>

	  <texttable>
	    <ttcol align="left">Result Name</ttcol>
	    <ttcol align="left">Value</ttcol>

	    <c>R</c>
	    <c>
[1, 220, 12, 129, 231, 171, 194, 209, 232, 135, 233, 117, 247, 105, 122, 210,
 26, 125, 192, 1, 217, 21, 82, 91, 45, 240, 255, 83, 19, 34, 239, 71,
 48, 157, 147, 152, 105, 18, 53, 108, 163, 214, 68, 231, 62, 153, 150, 106,
 194, 164, 246, 72, 143, 138, 24, 50, 129, 223, 133, 206, 209, 172, 63, 237,
 119, 109]
	    </c>

	    <c>S</c>
	    <c>
[0, 111, 6, 105, 44, 5, 41, 208, 128, 61, 152, 40, 92, 61,
 152, 4, 150, 66, 60, 69, 247, 196, 170, 81, 193, 199, 78, 59, 194, 169,
 16, 124, 9, 143, 42, 142, 131, 48, 206, 238, 34, 175, 83, 203, 220, 159,
 3, 107, 155, 22, 27, 73, 111, 68, 68, 21, 238, 144, 229, 232, 148, 188,
 222, 59, 242, 103]
	    </c>
	  </texttable>

	  <t>
	    The JWS Signature is the value R || S.
	    Encoding the signature as
	    BASE64URL(JWS Signature) produces this value
	    (with line breaks for display purposes only):
	  </t>

	  <figure><artwork><![CDATA[
  AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq
  wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp
  EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn
]]></artwork></figure>

	<t>
	  Concatenating these values in the order
	  Header.Payload.Signature with period ('.') characters between the
	  parts yields this complete JWS representation
	  using the JWS Compact Serialization
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJhbGciOiJFUzUxMiJ9
  .
  UGF5bG9hZA
  .
  AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq
  wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp
  EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn
]]></artwork></figure>

	</section>

	<section title="Validating" anchor="ES512Validating">

	  <t>
	    Since the <spanx style="verb">alg</spanx> Header Parameter
	    is <spanx style="verb">ES512</spanx>, we
	    validate the ECDSA P-521 SHA-512 digital signature contained in
	    the JWS Signature.
	  </t>
	  <t>
	    Validating this JWS Signature is very similar to the previous example.
	    We need to split the 132-member octet sequence of the JWS Signature
	    into two 66-octet sequences, the first representing R and the second S. We
	    then pass the public key (x, y), the signature (R, S), and
	    the JWS Signing Input
	    to an ECDSA signature verifier that
	    has been configured to use the P-521 curve with the
	    SHA-512 hash function.
	  </t>

	</section>
      </section>

      <section title="Example Unsecured JWS" anchor="ExampleUnsecuredJWS">

	<t>
	  The following example JWS Protected Header declares that the
	  encoded object is an Unsecured JWS:
	</t>

	<figure><artwork><![CDATA[
  {"alg":"none"}
]]></artwork></figure>

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

	<figure><artwork><![CDATA[
  eyJhbGciOiJub25lIn0
]]></artwork></figure>

	<t>
	  The JWS Payload used in this example, which
	  follows, is the same as in the previous examples.  Since
	  the BASE64URL(JWS Payload) value will therefore be the same, its
	  computation is not repeated here.
	</t>

	<figure><artwork><![CDATA[
  {"iss":"joe",
   "exp":1300819380,
   "http://example.com/is_root":true}
]]></artwork></figure>

	<t>
	  The JWS Signature is the empty octet string
	  and BASE64URL(JWS Signature) is the empty string.
	</t>

	<t>
	  Concatenating these values in the order
	  Header.Payload.Signature with period ('.') characters between the
	  parts yields this complete JWS representation
	  using the JWS Compact Serialization
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJhbGciOiJub25lIn0
  .
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
  .
]]></artwork></figure>
      </section>

      <section title="Example JWS Using General JWS JSON Serialization"
	       anchor="JSONSerializationExample">
	<t>
	  This section contains an example using the general JWS JSON Serialization syntax.
	  This example demonstrates the capability for
	  conveying multiple digital signatures and/or MACs for the
	  same payload.
	</t>
	<t>
	  The JWS Payload used in this example is the same as
	  that used in the examples in <xref target="RS256Example"/>
	  and <xref target="ES256Example"/>
	  (with line breaks for display purposes only):
	</t>

	<figure><artwork><![CDATA[
  eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
  cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
]]></artwork></figure>

	<t>
	  Two digital signatures are used in this example:
	  the first using RSASSA-PKCS1-v1_5 SHA-256 and
	  the second using ECDSA P-256 SHA-256.
	  For the first, the JWS Protected Header and key
	  are the same as in <xref target="RS256Example"/>,
	  resulting in the same JWS Signature value;
	  therefore, its computation is not repeated here.
	  For the second, the JWS Protected Header and key
	  are the same as in <xref target="ES256Example"/>,
	  resulting in the same JWS Signature value;
	  therefore, its computation is not repeated here.
	</t>

	<section title="JWS Per-Signature Protected Headers" anchor="JSProtectedHeaders">

	  <t>
	    The JWS Protected Header value used for the first signature is:
	  </t>
	  
	  <figure><artwork><![CDATA[
  {"alg":"RS256"}
]]></artwork></figure>

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

	  <figure><artwork><![CDATA[
  eyJhbGciOiJSUzI1NiJ9
]]></artwork></figure>

	  <t>
	    The JWS Protected Header value used for the second signature is:
	  </t>
	  
	  <figure><artwork><![CDATA[
  {"alg":"ES256"}
]]></artwork></figure>

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

	  <figure><artwork><![CDATA[
  eyJhbGciOiJFUzI1NiJ9
]]></artwork></figure>
	</section>

	<section title="JWS Per-Signature Unprotected Headers" anchor="JSRecipientHeaders">
	  <t>
	    Key ID values are supplied for both keys using per-signature
	    Header Parameters.
	    The two JWS Unprotected Header values used to represent these key IDs are:
	  </t>

	  <figure><artwork><![CDATA[
  {"kid":"2010-12-29"}
]]></artwork></figure>

	  <t>
	    and
	  </t>

	  <figure><artwork><![CDATA[
  {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}
]]></artwork></figure>
	</section>

	<section title="Complete JOSE Header Values" anchor="JSHeader">
	  <t>
	    Combining the JWS Protected Header and JWS Unprotected Header values
	    supplied, the JOSE Header values used for the first and second
	    signatures, respectively, are:
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"RS256",
   "kid":"2010-12-29"}
]]></artwork></figure>

	  <t>
	    and
	  </t>

	  <figure><artwork><![CDATA[
  {"alg":"ES256",
   "kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}
]]></artwork></figure>

	</section>


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

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

	  <figure><artwork><![CDATA[
  {
   "payload":
    "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
     tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ",
   "signatures":[
    {"protected":"eyJhbGciOiJSUzI1NiJ9",
     "header":
      {"kid":"2010-12-29"},
     "signature":
      "cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZ
       mh7AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjb
       KBYNX4BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHl
       b1L07Qe7K0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZES
       c6BfI7noOPqvhJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AX
       LIhWkWywlVmtVrBp0igcN_IoypGlUPQGe77Rw"},
    {"protected":"eyJhbGciOiJFUzI1NiJ9",
     "header":
      {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"},
     "signature":
      "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8IS
       lSApmWQxfKTUJqPP3-Kg6NU1Q"}]
  }
]]></artwork></figure>
	</section>

      </section>

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

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

	<figure><artwork><![CDATA[
  {
   "payload":
    "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
     tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ",
   "protected":"eyJhbGciOiJFUzI1NiJ9",
   "header":
    {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"},
   "signature":
    "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8IS
     lSApmWQxfKTUJqPP3-Kg6NU1Q"
  }
]]></artwork></figure>

      </section>

    </section>

    <section title='"x5c" (X.509 Certificate Chain) Example' anchor="x5cExample">
      <t>
	The JSON array below is an example of a certificate chain
	that could be used as the value of an
	<spanx style="verb">x5c</spanx> (X.509 certificate chain) Header Parameter,
	per <xref target="x5cDef"/>
	(with line breaks within values for display purposes only):
      </t>

      <figure><artwork><![CDATA[
  ["MIIE3jCCA8agAwIBAgICAwEwDQYJKoZIhvcNAQEFBQAwYzELMAkGA1UEBhMCVVM
    xITAfBgNVBAoTGFRoZSBHbyBEYWRkeSBHcm91cCwgSW5jLjExMC8GA1UECxMoR2
    8gRGFkZHkgQ2xhc3MgMiBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTAeFw0wNjExM
    TYwMTU0MzdaFw0yNjExMTYwMTU0MzdaMIHKMQswCQYDVQQGEwJVUzEQMA4GA1UE
    CBMHQXJpem9uYTETMBEGA1UEBxMKU2NvdHRzZGFsZTEaMBgGA1UEChMRR29EYWR
    keS5jb20sIEluYy4xMzAxBgNVBAsTKmh0dHA6Ly9jZXJ0aWZpY2F0ZXMuZ29kYW
    RkeS5jb20vcmVwb3NpdG9yeTEwMC4GA1UEAxMnR28gRGFkZHkgU2VjdXJlIENlc
    nRpZmljYXRpb24gQXV0aG9yaXR5MREwDwYDVQQFEwgwNzk2OTI4NzCCASIwDQYJ
    KoZIhvcNAQEBBQADggEPADCCAQoCggEBAMQt1RWMnCZM7DI161+4WQFapmGBWTt
    wY6vj3D3HKrjJM9N55DrtPDAjhI6zMBS2sofDPZVUBJ7fmd0LJR4h3mUpfjWoqV
    Tr9vcyOdQmVZWt7/v+WIbXnvQAjYwqDL1CBM6nPwT27oDyqu9SoWlm2r4arV3aL
    GbqGmu75RpRSgAvSMeYddi5Kcju+GZtCpyz8/x4fKL4o/K1w/O5epHBp+YlLpyo
    7RJlbmr2EkRTcDCVw5wrWCs9CHRK8r5RsL+H0EwnWGu1NcWdrxcx+AuP7q2BNgW
    JCJjPOq8lh8BJ6qf9Z/dFjpfMFDniNoW1fho3/Rb2cRGadDAW/hOUoz+EDU8CAw
    EAAaOCATIwggEuMB0GA1UdDgQWBBT9rGEyk2xF1uLuhV+auud2mWjM5zAfBgNVH
    SMEGDAWgBTSxLDSkdRMEXGzYcs9of7dqGrU4zASBgNVHRMBAf8ECDAGAQH/AgEA
    MDMGCCsGAQUFBwEBBCcwJTAjBggrBgEFBQcwAYYXaHR0cDovL29jc3AuZ29kYWR
    keS5jb20wRgYDVR0fBD8wPTA7oDmgN4Y1aHR0cDovL2NlcnRpZmljYXRlcy5nb2
    RhZGR5LmNvbS9yZXBvc2l0b3J5L2dkcm9vdC5jcmwwSwYDVR0gBEQwQjBABgRVH
    SAAMDgwNgYIKwYBBQUHAgEWKmh0dHA6Ly9jZXJ0aWZpY2F0ZXMuZ29kYWRkeS5j
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    BANKGwOy9+aG2Z+5mC6IGOgRQjhVyrEp0lVPLN8tESe8HkGsz2ZbwlFalEzAFPI
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    5CkKSkB2XIsKd83ASe8T+5o0yGPwLPk9Qnt0hCqU7S+8MxZC9Y7lhyVJEnfzuz9
    p0iRFEUOOjZv2kWzRaJBydTXRE4+uXR21aITVSzGh6O1mawGhId/dQb8vxRMDsx
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    EjYx8WnM25sgVjOuH0aBsXBTWVU+4=",
   "MIIE+zCCBGSgAwIBAgICAQ0wDQYJKoZIhvcNAQEFBQAwgbsxJDAiBgNVBAcTG1Z
    hbGlDZXJ0IFZhbGlkYXRpb24gTmV0d29yazEXMBUGA1UEChMOVmFsaUNlcnQsIE
    luYy4xNTAzBgNVBAsTLFZhbGlDZXJ0IENsYXNzIDIgUG9saWN5IFZhbGlkYXRpb
    24gQXV0aG9yaXR5MSEwHwYDVQQDExhodHRwOi8vd3d3LnZhbGljZXJ0LmNvbS8x
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    yMFoXDTI0MDYyOTE3MDYyMFowYzELMAkGA1UEBhMCVVMxITAfBgNVBAoTGFRoZS
    BHbyBEYWRkeSBHcm91cCwgSW5jLjExMC8GA1UECxMoR28gRGFkZHkgQ2xhc3MgM
    iBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTCCASAwDQYJKoZIhvcNAQEBBQADggEN
    ADCCAQgCggEBAN6d1+pXGEmhW+vXX0iG6r7d/+TvZxz0ZWizV3GgXne77ZtJ6XC
    APVYYYwhv2vLM0D9/AlQiVBDYsoHUwHU9S3/Hd8M+eKsaA7Ugay9qK7HFiH7Eux
    6wwdhFJ2+qN1j3hybX2C32qRe3H3I2TqYXP2WYktsqbl2i/ojgC95/5Y0V4evLO
    tXiEqITLdiOr18SPaAIBQi2XKVlOARFmR6jYGB0xUGlcmIbYsUfb18aQr4CUWWo
    riMYavx4A6lNf4DD+qta/KFApMoZFv6yyO9ecw3ud72a9nmYvLEHZ6IVDd2gWMZ
    Eewo+YihfukEHU1jPEX44dMX4/7VpkI+EdOqXG68CAQOjggHhMIIB3TAdBgNVHQ
    4EFgQU0sSw0pHUTBFxs2HLPaH+3ahq1OMwgdIGA1UdIwSByjCBx6GBwaSBvjCBu
    zEkMCIGA1UEBxMbVmFsaUNlcnQgVmFsaWRhdGlvbiBOZXR3b3JrMRcwFQYDVQQK
    Ew5WYWxpQ2VydCwgSW5jLjE1MDMGA1UECxMsVmFsaUNlcnQgQ2xhc3MgMiBQb2x
    pY3kgVmFsaWRhdGlvbiBBdXRob3JpdHkxITAfBgNVBAMTGGh0dHA6Ly93d3cudm
    FsaWNlcnQuY29tLzEgMB4GCSqGSIb3DQEJARYRaW5mb0B2YWxpY2VydC5jb22CA
    QEwDwYDVR0TAQH/BAUwAwEB/zAzBggrBgEFBQcBAQQnMCUwIwYIKwYBBQUHMAGG
    F2h0dHA6Ly9vY3NwLmdvZGFkZHkuY29tMEQGA1UdHwQ9MDswOaA3oDWGM2h0dHA
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    09VZw==",
   "MIIC5zCCAlACAQEwDQYJKoZIhvcNAQEFBQAwgbsxJDAiBgNVBAcTG1ZhbGlDZXJ
    0IFZhbGlkYXRpb24gTmV0d29yazEXMBUGA1UEChMOVmFsaUNlcnQsIEluYy4xNT
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    P7RfZHM047QSv4dk+NoS/zcnwbNDu+97bi5p9wIDAQABMA0GCSqGSIb3DQEBBQU
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    C1u+mNr0HZDzTuIYEZoDJJKPTEjlbVUjP9UNV+mWwD5MlM/Mtsq2azSiGM5bUMM
    j4QssxsodyamEwCW/POuZ6lcg5Ktz885hZo+L7tdEy8W9ViH0Pd"]
]]></artwork></figure>
    </section>


    <section title="Notes on Implementing base64url Encoding without Padding" anchor="base64urlnotes">

      <t>
	This appendix describes how to implement base64url encoding
	and decoding functions without padding based upon standard
	base64 encoding and decoding functions that do use padding.
      </t>
      <t>
	To be concrete, example C# code implementing these functions
	is shown below.  Similar code could be used in other
	languages.
      </t>

      <figure><artwork><![CDATA[
  static string base64urlencode(byte [] arg)
  {
    string s = Convert.ToBase64String(arg); // Regular base64 encoder
    s = s.Split('=')[0]; // Remove any trailing '='s
    s = s.Replace('+', '-'); // 62nd char of encoding
    s = s.Replace('/', '_'); // 63rd char of encoding
    return s;
  }

  static byte [] base64urldecode(string arg)
  {
    string s = arg;
    s = s.Replace('-', '+'); // 62nd char of encoding
    s = s.Replace('_', '/'); // 63rd char of encoding
    switch (s.Length % 4) // Pad with trailing '='s
    {
      case 0: break; // No pad chars in this case
      case 2: s += "=="; break; // Two pad chars
      case 3: s += "="; break; // One pad char
      default: throw new System.Exception(
        "Illegal base64url string!");
    }
    return Convert.FromBase64String(s); // Standard base64 decoder
  }
]]></artwork></figure>

      <t>
	As per the example code above, the number of '=' padding
	characters that needs to be added to the end of a base64url-encoded
	string without padding to turn it into one with
	padding is a deterministic function of the length of the
	encoded string.  Specifically,

	if the length mod 4 is 0, no padding is added;
	if the length mod 4 is 2, two '=' padding characters are added;
	if the length mod 4 is 3, one '=' padding character is added;
	if the length mod 4 is 1, the input is malformed.
      </t>
      <t>
	An example correspondence between unencoded and encoded values
	follows.  The octet sequence below encodes into the string
	below, which when decoded, reproduces the octet sequence.
      </t>

      <figure><artwork>3 236 255 224 193
A-z_4ME</artwork></figure>
    </section>

    <section title="Notes on Key Selection" anchor="KeySelectionNotes">
      <t>
	This appendix describes a set of possible algorithms for selecting the key
	to be used to validate the digital signature or MAC of a JWS
	or for selecting the key to be used to decrypt a JWE.
	This guidance describes a family of possible algorithms
	rather than a single algorithm,
	because in different contexts, not all the sources of keys will be used,
	they can be tried in different orders,
	and sometimes not all the collected keys will be tried;
	hence, different algorithms will be used in different application contexts.
      </t>
      <t>
	The steps below are described for illustration purposes only;
	specific applications can and are likely to use different algorithms
	or perform some of the steps in different orders.
	Specific applications will frequently have a much simpler method
	of determining the keys to use, as there may be one or two key selection
	methods that are profiled for the application's use. 
	This appendix supplements the normative information on key location
	in <xref target="IDingKeys"/>.
      </t>
      <t>
	These algorithms include the following steps.
	Note that the steps can be performed in any order
	and do not need to be treated as distinct.
	For example, keys can be tried as soon as they are found,
	rather than collecting all the keys before trying any.

	<list style="numbers">
	  <t>
	    Collect the set of potentially applicable keys.
	    Sources of keys may include:

	    <list style="symbols">
	      <t>
		Keys supplied by the application protocol being used.
	      </t>
	      <t>
		Keys referenced by the <spanx style="verb">jku</spanx> (JWK Set URL)
		Header Parameter.
	      </t>
	      <t>
		The key provided by the <spanx style="verb">jwk</spanx> (JSON Web Key)
		Header Parameter.
	      </t>
	      <t>
		The key referenced by the <spanx style="verb">x5u</spanx> (X.509 URL)
		Header Parameter.
	      </t>
	      <t>
		The key provided by the
		<spanx style="verb">x5c</spanx> (X.509 certificate chain)
		Header Parameter.
	      </t>
	      <t>
		Other applicable keys available to the application.
	      </t>
	    </list>

	    The order for collecting and trying keys from different key sources
	    is typically application dependent.
	    For example, frequently, all keys from a one set of locations,
	    such as local caches,
	    will be tried before collecting and trying keys from other locations.
	  </t>
	  <t>
	    Filter the set of collected keys.
	    For instance, some applications will use only keys referenced by
	    <spanx style="verb">kid</spanx> (key ID) or
	    <spanx style="verb">x5t</spanx> (X.509 certificate SHA-1 thumbprint)
	    parameters.
	    If the application uses the JWK
	    <spanx style="verb">alg</spanx> (algorithm),
	    <spanx style="verb">use</spanx> (public key use), or
	    <spanx style="verb">key_ops</spanx> (key operations) parameters,
	    keys with inappropriate values of those parameters
	    would be excluded.
	    Additionally, keys might be filtered to include or exclude keys
	    with certain other member values in an application-specific manner.
	    For some applications, no filtering will be applied.
	  </t>
	  <t>
	    Order the set of collected keys.
	    For instance, keys referenced by
	    <spanx style="verb">kid</spanx> (key ID) or
	    <spanx style="verb">x5t</spanx> (X.509 certificate SHA-1 thumbprint)
	    parameters might be tried before keys with neither of these values.
	    Likewise, keys with certain member values
	    might be ordered before keys with other member values.
	    For some applications, no ordering will be applied.
	  </t>
	  <t>
	    Make trust decisions about the keys.
	    Signatures made with 
	    keys not meeting the application's trust criteria would not be accepted.
	    Such criteria might include, but is not limited to,
	    the source of the key,
	    whether the TLS certificate validates for keys retrieved from URLs,
	    whether a key in an X.509 certificate is backed by a valid certificate chain,
	    and other information known by the application.
	  </t>
	  <t>
	    Attempt signature or MAC validation for a JWS
	    or decryption of a JWE with
	    some or all of the collected and possibly filtered and/or ordered keys.
	    A limit on the number of keys to be tried might be applied.
	    This process will normally terminate following a successful validation
	    or decryption.
	  </t>
	</list>
      </t>
      <t>
	Note that it is reasonable for some applications to perform
	signature or MAC validation prior to making a trust decision about a key,
	since keys for which the validation fails need no trust decision.
      </t>
    </section>

    <section title='Negative Test Case for "crit" Header Parameter' anchor="critTest">
      <t>
	Conforming implementations must reject input containing critical extensions
	that are not understood or cannot be processed.  The following JWS must
	be rejected by all implementations, because it uses an extension
	Header Parameter name <spanx style="verb">http://example.invalid/UNDEFINED</spanx>
	that they do not understand.
	Any other similar input, in which the use of the value
	<spanx style="verb">http://example.invalid/UNDEFINED</spanx> is substituted for
	any other Header Parameter name not understood by the implementation,
	must also be rejected.

	<figure>
	  <preamble>
	    The JWS Protected Header value for this JWS is:
	  </preamble>
	  <artwork><![CDATA[
  {"alg":"none",
   "crit":["http://example.invalid/UNDEFINED"],
   "http://example.invalid/UNDEFINED":true
  }
]]></artwork>
	</figure>

	<figure>
	  <preamble>
	    The complete JWS that must be rejected is as follows
	    (with line breaks for display purposes only):
	  </preamble>
	  <artwork><![CDATA[
  eyJhbGciOiJub25lIiwNCiAiY3JpdCI6WyJodHRwOi8vZXhhbXBsZS5jb20vVU5ERU
  ZJTkVEIl0sDQogImh0dHA6Ly9leGFtcGxlLmNvbS9VTkRFRklORUQiOnRydWUNCn0.
  RkFJTA.
]]></artwork>
	</figure>
      </t>
    </section>

    <section anchor="DetachedContent" title="Detached Content">
      <t>
	In some contexts, it is useful to integrity-protect content that
	is not itself contained in a JWS.
	One way to do this is to create a JWS in the normal fashion using
	a representation of the content as the payload
	but then delete the payload representation from the JWS
	and send this modified object to the recipient rather than the JWS.
	When using the JWS Compact Serialization, the deletion is accomplished
	by replacing the second field (which contains BASE64URL(JWS Payload)) value
	with the empty string;
	when using the JWS JSON Serialization, the deletion is accomplished
	by deleting the <spanx style="verb">payload</spanx> member.
	This method assumes that the recipient can reconstruct
	the exact payload used in the JWS.
	To use the modified object, the recipient reconstructs the JWS
	by re-inserting the payload representation into the modified object
	and uses the resulting JWS in the usual manner.
	Note that this method needs no support from JWS libraries, as applications
	can use this method by modifying the inputs and outputs of standard JWS libraries.
      </t>
    </section>


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

      <t>
	Solutions for signing JSON content were previously explored by
	<xref target="MagicSignatures">Magic Signatures</xref>, <xref
	target="JSS">JSON Simple Sign</xref>, and <xref
	target="CanvasApp">Canvas Applications</xref>, all of which
	influenced this document.
      </t>
      <t>
	Thanks to Axel Nennker for his early implementation
	and feedback on the JWS and JWE specifications.
      </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>
	Dirk Balfanz,
	Richard Barnes,
	Brian Campbell,
	Alissa Cooper,
	Breno de Medeiros,
	Stephen Farrell,
        Yaron Y.&nbsp;Goland,	
	Dick Hardt,
	Joe Hildebrand,
	Jeff Hodges,
	Russ Housley,
	Edmund Jay,
	Tero Kivinen,
	Ben Laurie,
	Ted Lemon,
	James Manger,
	Matt Miller,
	Kathleen Moriarty,
	Tony Nadalin,
	Hideki Nara,
	Axel Nennker,
	John Panzer,
	Ray Polk,
	Emmanuel Raviart,
	Eric Rescorla,
	Pete Resnick,
	Jim Schaad,
	Paul Tarjan,
	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>