2 <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
3 <?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
6 <name>mod_auth_digest</name>
7 <description>User authentication using MD5
8 Digest Authentication.</description>
9 <status>Experimental</status>
10 <sourcefile>mod_auth_digest.c</sourcefile>
11 <identifier>auth_digest_module</identifier>
14 <p>This module implements HTTP Digest Authentication. However, it
15 has not been extensively tested and is therefore marked
19 <seealso><directive module="core">AuthName</directive></seealso>
20 <seealso><directive module="core">AuthType</directive></seealso>
21 <seealso><directive module="core">Require</directive></seealso>
22 <seealso><directive module="core">Satisfy</directive></seealso>
24 <section id="using"><title>Using Digest Authentication</title>
26 <p>Using MD5 Digest authentication is very simple. Simply set
27 up authentication normally, using "AuthType Digest" and
28 "AuthDigestFile" instead of the normal "AuthType Basic" and
29 "AuthUserFile"; also, replace any "AuthGroupFile" with
30 "AuthDigestGroupFile". Then add a "AuthDigestDomain" directive
31 containing at least the root URI(s) for this protection space.
35 <Location /private/><br />
38 AuthName "private area"<br />
39 AuthDigestDomain /private/ http://mirror.my.dom/private2/<br />
40 AuthDigestFile /web/auth/.digest_pw<br />
41 Require valid-user<br />
46 <note><title>Note</title>
47 <p>Digest authentication provides a more secure password system
48 than Basic authentication, but only works with supporting
49 browsers. As of July 2002, the major browsers that support digest
50 authentication are <a href="http://www.opera.com/">Opera</a>, <a
51 href="http://www.microsoft.com/windows/ie/">MS Internet
52 Explorer</a> (fails when used with a query string), <a
53 href="http://www.w3.org/Amaya/">Amaya</a> and <a
54 href="http://www.mozilla.org">Mozilla</a>. Since digest
55 authentication is not as widely implemented as basic
56 authentication, you should use it only in controlled settings.</p>
61 <name>AuthDigestFile</name>
62 <description>Location of the text file containing the list
63 of users and encoded passwords for digest authentication</description>
64 <syntax>AuthDigestFile <var>file-path</var></syntax>
65 <contextlist><context>directory</context><context>.htaccess</context>
67 <override>AuthConfig</override>
70 <p>The <directive>AuthDigestFile</directive> directive sets the
71 name of a textual file containing the list of users and encoded
72 passwords for digest authentication. <var>File-path</var> is the
73 absolute path to the user file.</p>
75 <p>The digest file uses a special format. Files in this format
76 can be created using the <a
77 href="../programs/htdigest.html">htdigest</a> utility found in
78 the support/ subdirectory of the Apache distribution.</p>
83 <name>AuthDigestGroupFile</name>
84 <description>Name of the text file containing the list of groups
85 for digest authentication</description>
86 <syntax>AuthDigestGroupFile <var>file-path</var></syntax>
87 <contextlist><context>directory</context><context>.htaccess</context>
89 <override>AuthConfig</override>
92 <p>The <directive>AuthDigestGroupFile</directive> directive sets
93 the name of a textual file containing the list of groups and their
94 members (user names). <var>File-path</var> is the absolute path to
97 <p>Each line of the group file contains a groupname followed by
98 a colon, followed by the member usernames separated by spaces.
101 <example>mygroup: bob joe anne</example>
103 <p>Note that searching large text files is <em>very</em>
106 <p>Security: make sure that the AuthGroupFile is stored outside
107 the document tree of the web-server; do <em>not</em> put it in
108 the directory that it protects. Otherwise, clients will be able
109 to download the AuthGroupFile.</p>
114 <name>AuthDigestQop</name>
115 <description>Determines the quality-of-protection to use in digest
116 authentication</description>
117 <syntax>AuthDigestQop none|auth|auth-int [auth|auth-int]</syntax>
118 <default>AuthDigestQop auth</default>
119 <contextlist><context>directory</context><context>.htaccess</context>
121 <override>AuthConfig</override>
124 <p>The <directive>AuthDigestQop</directive> directive determines
125 the quality-of-protection to use. <code>auth</code> will only do
126 authentication (username/password); <code>auth-int</code> is
127 authentication plus integrity checking (an MD5 hash of the entity
128 is also computed and checked); <code>none</code> will cause the module
129 to use the old RFC-2069 digest algorithm (which does not include
130 integrity checking). Both <code>auth</code> and <code>auth-int</code> may
131 be specified, in which the case the browser will choose which of
132 these to use. <code>none</code> should only be used if the browser for
133 some reason does not like the challenge it receives otherwise.</p>
136 <code>auth-int</code> is not implemented yet.
142 <name>AuthDigestNonceLifetime</name>
143 <description>How long the server nonce is valid</description>
144 <syntax>AuthDigestNonceLifetime <var>seconds</var></syntax>
145 <default>AuthDigestNonceLifetime 300</default>
146 <contextlist><context>directory</context><context>.htaccess</context>
148 <override>AuthConfig</override>
151 <p>The <directive>AuthDigestNonceLifetime</directive> directive
152 controls how long the server nonce is valid. When the client
153 contacts the server using an expired nonce the server will send
154 back a 401 with <code>stale=true</code>. If <var>seconds</var> is
155 greater than 0 then it specifies the amount of time for which the
156 nonce is valid; this should probably never be set to less than 10
157 seconds. If <var>seconds</var> is less than 0 then the nonce never
158 expires. <!-- Not implemented yet If <var>seconds</var> is 0 then
159 the nonce may be used exactly once by the client. Note that while
160 one-time-nonces provide higher security against replay attacks,
161 they also have significant performance implications, as the
162 browser cannot pipeline or multiple connections for the
163 requests. Because browsers cannot easily detect that
164 one-time-nonces are being used, this may lead to browsers trying
165 to pipeline requests and receiving 401 responses for all but the
166 first request, requiring the browser to resend the requests. Note
167 also that the protection against reply attacks only makes sense
168 for dynamically generated content and things like POST requests;
169 for static content the attacker may already have the complete
170 response, so one-time-nonces do not make sense here. -->
176 <name>AuthDigestNonceFormat</name>
177 <description>Determines how the nonce is generated</description>
178 <syntax>AuthDigestNonceFormat <var>format</var></syntax>
179 <contextlist><context>directory</context><context>.htaccess</context>
181 <override>AuthConfig</override>
184 <p><strong>Not implemented yet.</strong> <!--
185 <P>The AuthDigestNonceFormat directive determines how the nonce is
193 <name>AuthDigestNcCheck</name>
194 <description>Enables or disables checking of the nonce-count sent by the
196 <syntax>AuthDigestNcCheck On|Off</syntax>
197 <default>AuthDigestNcCheck Off</default>
198 <contextlist><context>server config</context></contextlist>
205 <P>The AuthDigestNcCheck directive enables or disables the checking of the
206 nonce-count sent by the server.
208 <P>While recommended from a security standpoint, turning this directive
209 On has one important performance implication. To check the nonce-count
210 *all* requests (which have an Authorization header, irrespective of
211 whether they require digest authentication) must be serialized through
212 a critical section. If the server is handling a large number of
213 requests which contain the Authorization header then this may noticeably
220 <name>AuthDigestAlgorithm</name>
221 <description>Selects the algorithm used to calculate the challenge and
222 response hases in digest authentication</description>
223 <syntax>AuthDigestAlgorithm MD5|MD5-sess</syntax>
224 <default>AuthDigestAlgorithm MD5</default>
225 <contextlist><context>directory</context><context>.htaccess</context>
227 <override>AuthConfig</override>
230 <p>The <directive>AuthDigestAlgorithm</directive> directive
231 selects the algorithm used to calculate the challenge and response
235 <code>MD5-sess</code> is not correctly implemented yet.
238 <P>To use <EM>MD5-sess</EM> you must first code up the
239 <VAR>get_userpw_hash()</VAR> function in <VAR>mod_auth_digest.c</VAR> .
245 <name>AuthDigestDomain</name>
246 <description>URIs that are in the same protection space for digest
247 authentication</description>
248 <syntax>AuthDigestDomain <var>URI</var> [<var>URI</var>] ...</syntax>
249 <contextlist><context>directory</context><context>.htaccess</context>
251 <override>AuthConfig</override>
254 <p>The <directive>AuthDigestDomain</directive> directive allows
255 you to specify one or more URIs which are in the same protection
256 space (i.e. use the same realm and username/password info). The
257 specified URIs are prefixes, i.e. the client will assume that all
258 URIs "below" these are also protected by the same
259 username/password. The URIs may be either absolute URIs
260 (i.e. inluding a scheme, host, port, etc) or relative URIs.</p>
262 <p>This directive <em>should</em> always be specified and
263 contain at least the (set of) root URI(s) for this space.
264 Omitting to do so will cause the client to send the
265 Authorization header for <em>every request</em> sent to this
266 server. Apart from increasing the size of the request, it may
267 also have a detrimental effect on performance if
268 "AuthDigestNcCheck" is on.</p>
270 <p>The URIs specified can also point to different servers, in
271 which case clients (which understand this) will then share
272 username/password info across multiple servers without
273 prompting the user each time. </p>