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<title>mod_session_crypto - Apache HTTP Server Version 2.4</title>
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<div id="preamble"><h1>Apache Module mod_session_crypto</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/mod/mod_session_crypto.html" title="English">&nbsp;en&nbsp;</a> |
<a href="../fr/mod/mod_session_crypto.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Session encryption support</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>session_crypto_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_session_crypto.c</td></tr>
<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3 and later</td></tr></table>
<h3>Summary</h3>

    <div class="warning"><h3>Warning</h3>
      <p>The session modules make use of HTTP cookies, and as such can fall
      victim to Cross Site Scripting attacks, or expose potentially private
      information to clients. Please ensure that the relevant risks have
      been taken into account before enabling the session functionality on
      your server.</p>
    </div>

    <p>This submodule of <code class="module"><a href="../mod/mod_session.html">mod_session</a></code> provides support for the
    encryption of user sessions before being written to a local database, or
    written to a remote browser via an HTTP cookie.</p>

    <p>This can help provide privacy to user sessions where the contents of
    the session should be kept private from the user, or where protection is
    needed against the effects of cross site scripting attacks.</p>

    <p>For more details on the session interface, see the documentation for
    the <code class="module"><a href="../mod/mod_session.html">mod_session</a></code> module.</p>

</div>
<div id="quickview"><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif" /> <a href="#sessioncryptocipher">SessionCryptoCipher</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#sessioncryptodriver">SessionCryptoDriver</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#sessioncryptopassphrase">SessionCryptoPassphrase</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#sessioncryptopassphrasefile">SessionCryptoPassphraseFile</a></li>
</ul>
<h3>Topics</h3>
<ul id="topics">
<li><img alt="" src="../images/down.gif" /> <a href="#basicusage">Basic Usage</a></li>
</ul><h3>See also</h3>
<ul class="seealso">
<li><code class="module"><a href="../mod/mod_session.html">mod_session</a></code></li>
<li><code class="module"><a href="../mod/mod_session_cookie.html">mod_session_cookie</a></code></li>
<li><code class="module"><a href="../mod/mod_session_dbd.html">mod_session_dbd</a></code></li>
</ul><ul class="seealso"><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="basicusage" id="basicusage">Basic Usage</a></h2>

      <p>To create a simple encrypted session and store it in a cookie called
      <var>session</var>, configure the session as follows:</p>

      <div class="example"><h3>Browser based encrypted session</h3><pre class="prettyprint lang-config">Session On
SessionCookieName session path=/
SessionCryptoPassphrase secret</pre>
</div>

      <p>The session will be encrypted with the given key. Different servers can
      be configured to share sessions by ensuring the same encryption key is used
      on each server.</p>

      <p>If the encryption key is changed, sessions will be invalidated
      automatically.</p>

      <p>For documentation on how the session can be used to store username
      and password details, see the <code class="module"><a href="../mod/mod_auth_form.html">mod_auth_form</a></code> module.</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="SessionCryptoCipher" id="SessionCryptoCipher">SessionCryptoCipher</a> <a name="sessioncryptocipher" id="sessioncryptocipher">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The crypto cipher to be used to encrypt the session</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SessionCryptoCipher <var>name</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>aes256</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_session_crypto</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3.0 and later</td></tr>
</table>
    <p>The <code class="directive">SessionCryptoCipher</code> directive allows the cipher to
    be used during encryption. If not specified, the cipher defaults to
    <code>aes256</code>.</p>

    <p>Possible values depend on the crypto driver in use, and could be one of:</p>

    <ul><li>3des192</li><li>aes128</li><li>aes192</li><li>aes256</li></ul>


</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="SessionCryptoDriver" id="SessionCryptoDriver">SessionCryptoDriver</a> <a name="sessioncryptodriver" id="sessioncryptodriver">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The crypto driver to be used to encrypt the session</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SessionCryptoDriver <var>name</var> <var>[param[=value]]</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</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>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_session_crypto</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3.0 and later</td></tr>
</table>
    <p>The <code class="directive">SessionCryptoDriver</code> directive specifies the name of
    the crypto driver to be used for encryption. If not specified, the driver defaults
    to the recommended driver compiled into APR-util.</p>

    <p>The <var>NSS</var> crypto driver requires some parameters for configuration,
    which are specified as parameters with optional values after the driver name.</p>

    <div class="example"><h3>NSS without a certificate database</h3><pre class="prettyprint lang-config">SessionCryptoDriver nss</pre>
</div>

    <div class="example"><h3>NSS with certificate database</h3><pre class="prettyprint lang-config">SessionCryptoDriver nss dir=certs</pre>
</div>

    <div class="example"><h3>NSS with certificate database and parameters</h3><pre class="prettyprint lang-config">SessionCryptoDriver nss dir=certs key3=key3.db cert7=cert7.db secmod=secmod</pre>
</div>

    <div class="example"><h3>NSS with paths containing spaces</h3><pre class="prettyprint lang-config">SessionCryptoDriver nss "dir=My Certs" key3=key3.db cert7=cert7.db secmod=secmod</pre>
</div>

    <p>The <var>NSS</var> crypto driver might have already been
    configured by another part of the server, for example from
    <code>mod_nss</code> or <code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code>. If found to
    have already been configured, a warning will be logged, and the
    existing configuration will have taken affect.  To avoid this
    warning, use the noinit parameter as follows.</p>

    <div class="example"><h3>NSS with certificate database</h3><pre class="prettyprint lang-config">SessionCryptoDriver nss noinit</pre>
</div>

    <p>To prevent confusion, ensure that all modules requiring NSS are configured with
    identical parameters.</p>

    <p>The <var>openssl</var> crypto driver supports an optional parameter to specify
    the engine to be used for encryption.</p>

    <div class="example"><h3>OpenSSL with engine support</h3><pre class="prettyprint lang-config">SessionCryptoDriver openssl engine=name</pre>
</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="SessionCryptoPassphrase" id="SessionCryptoPassphrase">SessionCryptoPassphrase</a> <a name="sessioncryptopassphrase" id="sessioncryptopassphrase">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The key used to encrypt the session</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SessionCryptoPassphrase <var>secret</var> [ <var>secret</var> ... ] </code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_session_crypto</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3.0 and later</td></tr>
</table>
    <p>The <code class="directive">SessionCryptoPassphrase</code> directive specifies the keys
    to be used to enable symmetrical encryption on the contents of the session before
    writing the session, or decrypting the contents of the session after reading the
    session.</p>

    <p>Keys are more secure when they are long, and consist of truly random characters.
    Changing the key on a server has the effect of invalidating all existing sessions.</p>

    <p>Multiple keys can be specified in order to support key rotation. The first key
    listed will be used for encryption, while all keys listed will be attempted for
    decryption. To rotate keys across multiple servers over a period of time, add a new
    secret to the end of the list, and once rolled out completely to all servers, remove
    the first key from the start of the list.</p>

    <p>As of version 2.4.7 if the value begins with <var>exec:</var> the resulting command
    will be executed and the first line returned to standard output by the program will be
    used as the key.</p>
<div class="example"><pre>#key used as-is
SessionCryptoPassphrase secret

#Run /path/to/program to get key
SessionCryptoPassphrase exec:/path/to/program

#Run /path/to/otherProgram and provide arguments
SessionCryptoPassphrase "exec:/path/to/otherProgram argument1"</pre></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="SessionCryptoPassphraseFile" id="SessionCryptoPassphraseFile">SessionCryptoPassphraseFile</a> <a name="sessioncryptopassphrasefile" id="sessioncryptopassphrasefile">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File containing keys used to encrypt the session</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SessionCryptoPassphraseFile <var>filename</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>none</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_session_crypto</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3.0 and later</td></tr>
</table>
    <p>The <code class="directive">SessionCryptoPassphraseFile</code> directive specifies the
    name of a configuration file containing the keys to use for encrypting or decrypting
    the session, specified one per line. The file is read on server start, and a graceful
    restart will be necessary for httpd to pick up changes to the keys.</p>

    <p>Unlike the <code class="directive">SessionCryptoPassphrase</code> directive, the keys are
    not exposed within the httpd configuration and can be hidden by protecting the file
    appropriately.</p>

    <p>Multiple keys can be specified in order to support key rotation. The first key
    listed will be used for encryption, while all keys listed will be attempted for
    decryption. To rotate keys across multiple servers over a period of time, add a new
    secret to the end of the list, and once rolled out completely to all servers, remove
    the first key from the start of the list.</p>


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