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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
]>
<document url="credentialhandler.html">

  &project;

  <properties>
    <title>The CredentialHandler Component</title>
  </properties>

<body>

<section name="Table of Contents">
<toc />
</section>

<section name="Introduction">

  <p>The <strong>CredentialHandler</strong> element represents the component
  used by a <a href="realm.html">Realm</a> to compare a provided credential such
  as a password with the version of the credential stored by the
  <a href="realm.html">Realm</a>. The <strong>CredentialHandler</strong> can
  also be used to generate a new stored version of a given credential that would
  be required, for example, when adding a new user to a
  <a href="realm.html">Realm</a> or when changing a user&apos;s password.</p>

  <p>A <strong>CredentialHadler</strong> element MUST be nested inside a
  <a href="realm.html">Realm</a> component.  If it is not included,
  a default <strong>CredentialHadler</strong> will be created using the
  <strong>MessageDigestCredentialHandler</strong>.</p>

</section>


<section name="Attributes">

  <subsection name="Common Attributes">

    <p>All implementations of <strong>CredentialHandler</strong> support the
    following attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use. This class must
        implement the <code>org.apache.catalina.CredentialHandler</code>
        interface.</p>
      </attribute>

    </attributes>

    <p>Unlike most Catalina components, there are several standard
    <strong>CredentialHandler</strong> implementations available.  As a result,
    if a <strong>CredentialHandler</strong> element is present then the
    <code>className</code> attribute MUST be used to select the implementation
    you wish to use.</p>

  </subsection>


  <subsection name="MessageDigestCredentialHandler">

    <p>The <strong>MessageDigestCredentialHandler</strong> is used when stored
    passwords are protected by a message digest. This credential handler
    supports the following forms of stored passwords:</p>
    <ul>
      <li><strong>plainText</strong> - the plain text credentials if no
      algorithm is specified</li>
      <li><strong>encodedCredential</strong> - a hex encoded digest of the
      password digested using the configured digest</li>
      <li><strong>{MD5}encodedCredential</strong> - a Base64 encoded MD5
      digest of the password</li>
      <li><strong>{SHA}encodedCredential</strong> - a Base64 encoded SHA1 digest
      of the password</li>
      <li><strong>{SSHA}encodedCredential</strong> - 20 character salt followed
      by the salted SHA1 digest Base64 encoded</li>
      <li><strong>salt$iterationCount$encodedCredential</strong> - a hex encoded
      salt, iteration code and a hex encoded credential, each separated by
      $</li>
    </ul>

    <p>If the stored password form does not include an iteration count then an
    iteration count of 1 is used.</p>

    <p>If the stored password form does not include salt then no salt is
    used.</p>

    <attributes>

      <attribute name="algorithm" required="false">
        <p>The name of the <code>java.security.MessageDigest</code> algorithm
        used to encode user passwords stored in the database.  If not specified,
        user passwords are assumed to be stored in clear-text.</p>
      </attribute>

      <attribute name="encoding" required="false">
        <p>Digesting the password requires that it is converted to bytes. This
        attribute determines the character encoding to use for conversions
        between characters and bytes. If not specified, UTF-8 will be used.</p>
      </attribute>

      <attribute name="iterations" required="false">
        <p>The number of iterations to use when creating a new stored credential
        from a clear text credential.</p>
      </attribute>

      <attribute name="saltLength" required="false">
        <p>The length of the randomly generated salt to use when creating a
        new stored credential from a clear text credential.</p>
      </attribute>

    </attributes>

  </subsection>

  <subsection name="NestedCredentialHandler">

    <p>The <strong>NestedCredentialHandler</strong> is an implementation of
    <strong>CredentialHandler</strong> that delegates to one or more
    sub-CredentialHandlers.</p>

    <p>Using the <strong>NestedCredentialHandler</strong> gives the developer
    the ability to combine multiple <strong>CredentialHandler</strong>s of the
    same or different types.</p>

    <p>Sub-CredentialHandlers are defined by nesting CredentialHandler elements
    inside the <code>CredentialHandler</code> element that defines the
    NestedCredentialHandler. Credentials will be matched against each
    <code>CredentialHandler</code> in the order they are listed. A match against
    any CredentialHandler will be sufficient for the credentials to be
    considered matched.</p>

  </subsection>

  <subsection name="SecretKeyCredentialHandler">

    <p>The <strong>SecretKeyCredentialHandler</strong> is used when stored
    passwords are built using <code>javax.crypto.SecretKeyFactory</code>. This
    credential handler supports the following forms of stored passwords:</p>
    <ul>
      <li><strong>salt$iterationCount$encodedCredential</strong> - a hex encoded
      salt, iteration code and a hex encoded credential, each separated by
      $</li>
    </ul>

    <p>If the stored password form does not include an iteration count then an
    iteration count of 1 is used.</p>

    <p>If the stored password form does not include salt then no salt is
    used.</p>

    <attributes>

      <attribute name="algorithm" required="false">
        <p>The name of the secret key algorithm used to encode user passwords
        stored in the database.  If not specified, a default of
        <code>PBKDF2WithHmacSHA1</code> is used.</p>
      </attribute>

      <attribute name="keyLength" required="false">
        <p>The length of key to generate for the stored credential. If not
        specified, a default of <code>160</code> is used.</p>
      </attribute>

      <attribute name="iterations" required="false">
        <p>The number of iterations to use when creating a new stored credential
        from a clear text credential.</p>
      </attribute>

      <attribute name="saltLength" required="false">
        <p>The length of the randomly generated salt to use when creating a
        new stored credential from a clear text credential.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Nested Components">

  <p>If you are using the <em>NestedCredentialHandler Implementation</em> or a
  CredentialHandler that extends the NestedCredentialHandler one or more
  <strong>&lt;CredentialHandler&gt;</strong> elements may be nested inside it.
  </p>

</section>


<section name="Special Features">

  <p>No special features are associated with a
  <strong>CredentialHandler</strong> element.</p>

</section>

</body>

</document>
