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<div id="preamble"><h1>Apache Module mod_auth_digest</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/mod/mod_auth_digest.html" title="English">&nbsp;en&nbsp;</a> |
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>User authentication using MD5
    Digest Authentication</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>auth_digest_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_auth_digest.c</td></tr></table>
<h3>Summary</h3>

    <p>This module implements HTTP Digest Authentication
    (<a href="http://www.faqs.org/rfcs/rfc2617.html">RFC2617</a>), and
    provides an alternative to <code class="module"><a href="../mod/mod_auth_basic.html">mod_auth_basic</a></code> where the
    password is not transmitted as cleartext. However, this does
    <strong>not</strong> lead to a significant security advantage over
    basic authentication. On the other hand, the password storage on the
    server is much less secure with digest authentication than with
    basic authentication. Therefore, using basic auth and encrypting the
    whole connection using <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code> is a much better
    alternative.</p>
</div>
<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><h3>Topics</h3>
<ul id="topics">
<li><img alt="" src="../images/down.gif" /> <a href="#using">Using Digest Authentication</a></li>
</ul><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif" /> <a href="#authdigestalgorithm">AuthDigestAlgorithm</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#authdigestdomain">AuthDigestDomain</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#authdigestnoncelifetime">AuthDigestNonceLifetime</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#authdigestprovider">AuthDigestProvider</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#authdigestqop">AuthDigestQop</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#authdigestshmemsize">AuthDigestShmemSize</a></li>
</ul>
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_auth_digest">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_auth_digest">Report a bug</a></li></ul><h3>See also</h3>
<ul class="seealso">
<li><code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code></li>
<li><code class="directive"><a href="../mod/mod_authn_core.html#authtype">AuthType</a></code></li>
<li><code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code></li>
<li><a href="../howto/auth.html">Authentication howto</a></li>
<li><a href="#comments_section">Comments</a></li></ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="using" id="using">Using Digest Authentication</a></h2>

    <p>To use MD5 Digest authentication, configure the location to be
    protected as shown in the below example:</p>

    <div class="example"><h3>Example:</h3><pre class="prettyprint lang-config">&lt;Location "/private/"&gt;
    AuthType Digest
    AuthName "private area"
    AuthDigestDomain "/private/" "http://mirror.my.dom/private2/"
    
    AuthDigestProvider file
    AuthUserFile "/web/auth/.digest_pw"
    Require valid-user
&lt;/Location&gt;</pre>
</div>

    <p><code class="directive"><a href="#authdigestdomain">AuthDigestDomain</a></code>
    should list the locations that will be protected by this
    configuration.</p>

    <p>The password file referenced in the <code class="directive"><a href="#authuserfile">AuthUserFile</a></code> directive may be
    created and managed using the <code class="program"><a href="../programs/htdigest.html">htdigest</a></code> tool.</p>


    <div class="note"><h3>Note</h3>
    <p>Digest authentication was intended to be more secure than basic
    authentication, but no longer fulfills that design goal. A
    man-in-the-middle attacker can trivially force the browser to downgrade
    to basic authentication. And even a passive eavesdropper can brute-force
    the password using today's graphics hardware, because the hashing
    algorithm used by digest authentication is too fast. Another problem is
    that the storage of the passwords on the server is insecure. The contents
    of a stolen htdigest file can be used directly for digest authentication.
    Therefore using <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code> to encrypt the whole connection is
    strongly recommended.</p>
    <p><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code> only works properly on platforms
      where APR supports shared memory.</p>
    </div>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="AuthDigestAlgorithm" id="AuthDigestAlgorithm">AuthDigestAlgorithm</a> <a name="authdigestalgorithm" id="authdigestalgorithm">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Selects the algorithm used to calculate the challenge and
response hashes in digest authentication</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AuthDigestAlgorithm MD5|MD5-sess</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AuthDigestAlgorithm MD5</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_auth_digest</td></tr>
</table>
    <p>The <code class="directive">AuthDigestAlgorithm</code> directive
    selects the algorithm used to calculate the challenge and response
    hashes.</p>

    <div class="note">
      <code>MD5-sess</code> is not correctly implemented yet.
    </div>
    

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="AuthDigestDomain" id="AuthDigestDomain">AuthDigestDomain</a> <a name="authdigestdomain" id="authdigestdomain">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>URIs that are in the same protection space for digest
authentication</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AuthDigestDomain <var>URI</var> [<var>URI</var>] ...</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_auth_digest</td></tr>
</table>
    <p>The <code class="directive">AuthDigestDomain</code> directive allows
    you to specify one or more URIs which are in the same protection
    space (<em>i.e.</em> use the same realm and username/password info).
    The specified URIs are prefixes; the client will assume
    that all URIs "below" these are also protected by the same
    username/password. The URIs may be either absolute URIs (<em>i.e.</em>
    including a scheme, host, port, etc.) or relative URIs.</p>

    <p>This directive <em>should</em> always be specified and
    contain at least the (set of) root URI(s) for this space.
    Omitting to do so will cause the client to send the
    Authorization header for <em>every request</em> sent to this
    server.</p>

    <p>The URIs specified can also point to different servers, in
    which case clients (which understand this) will then share
    username/password info across multiple servers without
    prompting the user each time. </p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="AuthDigestNonceLifetime" id="AuthDigestNonceLifetime">AuthDigestNonceLifetime</a> <a name="authdigestnoncelifetime" id="authdigestnoncelifetime">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>How long the server nonce is valid</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AuthDigestNonceLifetime <var>seconds</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AuthDigestNonceLifetime 300</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_auth_digest</td></tr>
</table>
    <p>The <code class="directive">AuthDigestNonceLifetime</code> directive
    controls how long the server nonce is valid. When the client
    contacts the server using an expired nonce the server will send
    back a 401 with <code>stale=true</code>. If <var>seconds</var> is
    greater than 0 then it specifies the amount of time for which the
    nonce is valid; this should probably never be set to less than 10
    seconds. If <var>seconds</var> is less than 0 then the nonce never
    expires. 
    </p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="AuthDigestProvider" id="AuthDigestProvider">AuthDigestProvider</a> <a name="authdigestprovider" id="authdigestprovider">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the authentication provider(s) for this location</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AuthDigestProvider <var>provider-name</var>
[<var>provider-name</var>] ...</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AuthDigestProvider file</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_auth_digest</td></tr>
</table>
    <p>The <code class="directive">AuthDigestProvider</code> directive sets
    which provider is used to authenticate the users for this location.
    The default <code>file</code> provider is implemented
    by the <code class="module"><a href="../mod/mod_authn_file.html">mod_authn_file</a></code> module.  Make sure
    that the chosen provider module is present in the server.</p>

    <p>See <code class="module"><a href="../mod/mod_authn_dbm.html">mod_authn_dbm</a></code>, <code class="module"><a href="../mod/mod_authn_file.html">mod_authn_file</a></code>,
    <code class="module"><a href="../mod/mod_authn_dbd.html">mod_authn_dbd</a></code> and <code class="module"><a href="../mod/mod_authn_socache.html">mod_authn_socache</a></code>
    for providers.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="AuthDigestQop" id="AuthDigestQop">AuthDigestQop</a> <a name="authdigestqop" id="authdigestqop">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the quality-of-protection to use in digest
authentication</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AuthDigestQop none|auth|auth-int [auth|auth-int]</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AuthDigestQop auth</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_auth_digest</td></tr>
</table>
    <p>The <code class="directive">AuthDigestQop</code> directive determines
    the <dfn>quality-of-protection</dfn> to use. <code>auth</code> will
    only do authentication (username/password); <code>auth-int</code> is
    authentication plus integrity checking (an MD5 hash of the entity
    is also computed and checked); <code>none</code> will cause the module
    to use the old RFC-2069 digest algorithm (which does not include
    integrity checking). Both <code>auth</code> and <code>auth-int</code> may
    be specified, in which the case the browser will choose which of
    these to use. <code>none</code> should only be used if the browser for
    some reason does not like the challenge it receives otherwise.</p>

    <div class="note">
      <code>auth-int</code> is not implemented yet.
    </div>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="AuthDigestShmemSize" id="AuthDigestShmemSize">AuthDigestShmemSize</a> <a name="authdigestshmemsize" id="authdigestshmemsize">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The amount of shared memory to allocate for keeping track
of clients</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AuthDigestShmemSize <var>size</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AuthDigestShmemSize 1000</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_auth_digest</td></tr>
</table>
    <p>The <code class="directive">AuthDigestShmemSize</code> directive defines
    the amount of shared memory, that will be allocated at the server
    startup for keeping track of clients. Note that the shared memory
    segment cannot be set less than the space that is necessary for
    tracking at least <em>one</em> client. This value is dependent on your
    system. If you want to find out the exact value, you may simply
    set <code class="directive">AuthDigestShmemSize</code> to the value of
    <code>0</code> and read the error message after trying to start the
    server.</p>

    <p>The <var>size</var> is normally expressed in Bytes, but you
    may follow the number with a <code>K</code> or an <code>M</code> to
    express your value as KBytes or MBytes. For example, the following
    directives are all equivalent:</p>

<pre class="prettyprint lang-config">AuthDigestShmemSize 1048576
AuthDigestShmemSize 1024K
AuthDigestShmemSize 1M</pre>


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