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<modulesynopsis>
<name>mod_auth_digest</name>
<description>User authentication using MD5
    Digest Authentication.</description>
<status>Experimental</status>
<sourcefile>mod_auth_digest.c</sourcefile>
<identifier>auth_digest_module</identifier>

<summary>
    <p>This module implements HTTP Digest Authentication.  However, it
    has not been extensively tested and is therefore marked
    experimental.</p>
</summary>

<seealso><directive module="core">AuthName</directive></seealso>
<seealso><directive module="core">AuthType</directive></seealso>
<seealso><directive module="core">Require</directive></seealso>
<seealso><directive module="core">Satisfy</directive></seealso>

<section><title>Using Digest Authentication</title>

    <p>Using MD5 Digest authentication is very simple. Simply set
    up authentication normally, using "AuthType Digest" and
    "AuthDigestFile" instead of the normal "AuthType Basic" and
    "AuthUserFile"; also, replace any "AuthGroupFile" with
    "AuthDigestGroupFile". Then add a "AuthDigestDomain" directive
    containing at least the root URI(s) for this protection space.
    Example:</p>
<example>
  &lt;Location /private/&gt;<br />
  AuthType Digest<br />
  AuthName "private area"<br />
  AuthDigestDomain /private/ http://mirror.my.dom/private2/<br />
  AuthDigestFile /web/auth/.digest_pw<br />
  Require valid-user<br />
  &lt;/Location&gt;
</example>

<note><title>Note</title> 
    
    <p>Digest authentication provides a more secure password system
    than Basic authentication, but only works with supporting
    browsers. As of July 2002, the major browsers that support digest
    authentication are <a href="http://www.opera.com/">Opera</a>, <a
    href="http://www.microsoft.com/windows/ie/">MS Internet
    Explorer</a> (fails when used with a query string), <a
    href="http://www.w3.org/Amaya/">Amaya</a> and <a
    href="http://www.mozilla.org">Mozilla</a>.  Since digest
    authentication is not as widely implemented as basic
    authentication, you should use it only in controlled settings.</p>

</note>
</section>

<directivesynopsis>
<name>AuthDigestFile</name>
<description>Location of the text file containing the list
of users and encoded passwords for digest authentication</description>
<syntax>AuthDigestFile <em>file-path</em></syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDigestFile</directive> directive sets the
    name of a textual file containing the list of users and encoded
    passwords for digest authentication. <em>File-path</em> is the
    absolute path to the user file.</p>

    <p>The digest file uses a special format. Files in this format
    can be created using the <a
    href="../programs/htdigest.html">htdigest</a> utility found in
    the support/ subdirectory of the Apache distribution.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestGroupFile</name>
<description>Name of the text file containing the list of groups
for digest authentication</description>
<syntax>AuthDigestGroupFile <em>file-path</em></syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDigestGroupFile</directive> directive sets
    the name of a textual file containing the list of groups and their
    members (user names). <em>File-path</em> is the absolute path to
    the group file.</p>

    <p>Each line of the group file contains a groupname followed by
    a colon, followed by the member usernames separated by spaces.
    Example:</p>

<example>mygroup: bob joe anne</example>

    <p>Note that searching large text files is <em>very</em>
    inefficient.</p>

    <p>Security: make sure that the AuthGroupFile is stored outside
    the document tree of the web-server; do <em>not</em> put it in
    the directory that it protects. Otherwise, clients will be able
    to download the AuthGroupFile.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestQop</name>
<description>Determines the quality-of-protection to use in digest
authentication</description>
<syntax>AuthDigestQop none|auth|auth-int [auth|auth-int]</syntax>
<default>AuthDigestQop auth</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDigestQop</directive> directive determines
    the quality-of-protection to use. <em>auth</em> will only do
    authentication (username/password); <em>auth-int</em> is
    authentication plus integrity checking (an MD5 hash of the entity
    is also computed and checked); <em>none</em> will cause the module
    to use the old RFC-2069 digest algorithm (which does not include
    integrity checking). Both <em>auth</em> and <em>auth-int</em> may
    be specified, in which the case the browser will choose which of
    these to use. <em>none</em> should only be used if the browser for
    some reason does not like the challenge it receives otherwise.</p>

    <p><strong><em>auth-int</em> is not implemented
    yet</strong>.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestNonceLifetime</name>
<description>How long the server nonce is valid</description>
<syntax>AuthDigestNonceLifetime <em>seconds</em></syntax>
<default>AuthDigestNonceLifetime 300</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDigestNonceLifetime</directive> 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 <em>seconds</em> 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 <em>seconds</em> is less than 0 then the nonce never
    expires. <!-- Not implemented yet If <EM>seconds</EM> is 0 then
    the nonce may be used exactly once by the client. Note that while
    one-time-nonces provide higher security against replay attacks,
    they also have significant performance implications, as the
    browser cannot pipeline or multiple connections for the
    requests. Because browsers cannot easily detect that
    one-time-nonces are being used, this may lead to browsers trying
    to pipeline requests and receiving 401 responses for all but the
    first request, requiring the browser to resend the requests. Note
    also that the protection against reply attacks only makes sense
    for dynamically generated content and things like POST requests;
    for static content the attacker may already have the complete
    response, so one-time-nonces do not make sense here.  -->
    </p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestNonceFormat</name>
<description>Determines how the nonce is generated</description>
<syntax>???</syntax>
<default>???</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p><strong>Not implemented yet.</strong> <!--
            <P>The AuthDigestNonceFormat directive determines how the nonce is
            generated.
            -->
    </p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestNcCheck</name>
<description>Enables or disables checking of the nonce-count sent by the
server</description>
<syntax>AuthDigestNcCheck On|Off</syntax>
<default>AuthDigestNcCheck Off</default>
<contextlist><context>server config</context></contextlist>

<usage>
    <p><strong>Not implemented yet.</strong> <!--
            <P>The AuthDigestNcCheck directive enables or disables the checking of the
            nonce-count sent by the server.

            <P>While recommended from a security standpoint, turning this directive
            On has one important performance implication. To check the nonce-count
            *all* requests (which have an Authorization header, irrespective of
            whether they require digest authentication) must be serialized through
            a critical section. If the server is handling a large number of
            requests which contain the Authorization header then this may noticeably
            impact performance.
            -->
    </p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestAlgorithm</name>
<description>Selects the algorithm used to calculate the challenge and
response hases in digest authentication</description>
<syntax>AuthDigestAlgorithm MD5|MD5-sess</syntax>
<default>AuthDigestAlgorithm MD5</default>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDigestAlgorithm</directive> directive
    selects the algorithm used to calculate the challenge and response
    hashes.</p>

    <p><strong><em>MD5-sess</em> is not correctly implemented
    yet</strong>. <!--
            <P>To use <EM>MD5-sess</EM> you must first code up the
            <VAR>get_userpw_hash()</VAR> function in <VAR>mod_auth_digest.c</VAR> .
            -->
    </p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>AuthDigestDomain</name>
<description>URIs that are in the same protection space for digest
authentication</description>
<syntax>AuthDigestDomain <em>URI</em> [<em>URI</em>] ...</syntax>
<contextlist><context>directory</context><context>.htaccess</context>
</contextlist>
<override>AuthConfig</override>

<usage>
    <p>The <directive>AuthDigestDomain</directive> directive allows
    you to specify one or more URIs which are in the same protection
    space (i.e. use the same realm and username/password info). The
    specified URIs are prefixes, i.e. the client will assume that all
    URIs "below" these are also protected by the same
    username/password. The URIs may be either absolute URIs
    (i.e. inluding 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. Apart from increasing the size of the request, it may
    also have a detrimental effect on performance if
    "AuthDigestNcCheck" is on.</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>
</usage>
</directivesynopsis>

</modulesynopsis>



