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SEC-701: Update X.509 Section 

http://jira.springframework.org/browse/SEC-701
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Luke Taylor 2008-03-09 13:24:13 +00:00
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src/docbkx/x509-auth-provider.xml
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@ -1,134 +1,78 @@
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.docbook.org/xml/4.4/docbookx.dtd">
<chapter id="x509">
<title>X509 Authentication</title>
<sect1 id="x509-overview">
<title>Overview</title>
<para>The most common use of X509 certificate authentication is in
verifying the identity of a server when using SSL, most commonly when
using HTTPS from a browser. The browser will automatically check that
the certificate presented by a server has been issued (ie digitally
signed) by one of a list of trusted certificate authorities which it
maintains.</para>
<para>You can also use SSL with <quote>mutual authentication</quote>;
the server will then request a valid certificate from the client as
part of the SSL handshake. The server will authenticate the client by
checking that it's certificate is signed by an acceptable authority.
If a valid certificate has been provided, it can be obtained through
the servlet API in an application. Spring Security X509 module
extracts the certificate using a filter and passes it to the
configured X509 authentication provider to allow any additional
application-specific checks to be applied. It also maps the
certificate to an application user and loads that user's set of
granted authorities for use with the standard Spring Security
infrastructure.</para>
<para>You should be familiar with using certificates and setting up
client authentication for your servlet container before attempting to
use it with Spring Security. Most of the work is in creating and
installing suitable certificates and keys. For example, if you're
using Tomcat then read the instructions here <ulink
url="http://jakarta.apache.org/tomcat/tomcat-5.0-doc/ssl-howto.html"></ulink>.
It's important that you get this working before trying it out with
Spring Security</para>
</sect1>
<sect1 id="x509-with-acegi">
<title>Using X509 with Spring Security</title>
<para>With X509 authentication, there is no explicit login procedure
so the implementation is relatively simple; there is no need to
redirect requests in order to interact with the user. As a result,
some of the classes behave slightly differently from their equivalents
in other packages. For example, the default <quote>entry point</quote>
class, which is normally responsible for starting the authentication
process, is only invoked if the certificate is rejected and it always
returns an error to the user. With a suitable bean configuration, the
normal sequence of events is as follows <orderedlist>
<listitem>
<para>The <classname>X509ProcessingFilter</classname> extracts
the certificate from the request and uses it as the credentials
for an authentication request. The generated authentication
request is an <classname>X509AuthenticationToken</classname>.
The request is passed to the authentication manager.</para>
</listitem>
<listitem>
<para>The <classname>X509AuthenticationProvider</classname>
receives the token. Its main concern is to obtain the user
information (in particular the user's granted authorities) that
matches the certificate. It delegates this responsibility to an
<interfacename>X509AuthoritiesPopulator</interfacename>.</para>
</listitem>
<listitem>
<para>The populator's single method,
<methodname>getUserDetails(X509Certificate
userCertificate)</methodname> is invoked. Implementations should
return a <classname>UserDetails</classname> instance containing
the array of <classname>GrantedAuthority</classname> objects for
the user. This method can also choose to reject the certificate
(for example if it doesn't contain a matching user name). In
such cases it should throw a
<exceptionname>BadCredentialsException</exceptionname>. A
DAO-based implementation,
<classname>DaoX509AuthoritiesPopulator</classname>, is provided
which extracts the user's name from the subject <quote>common
name</quote> (CN) in the certificate. It also allows you to set
your own regular expression to match a different part of the
subject's distinguished name. A UserDetailsService is used to
load the user information.<!-- TODO: Give email matching as an example --></para>
</listitem>
<listitem>
<para>If everything has gone smoothly then there should be a
valid <classname>Authentication</classname> object in the secure
context and the invocation will procede as normal. If no
certificate was found, or the certificate was rejected, then the
<classname>ExceptionTranslationFilter</classname> will invoke
the <classname>X509ProcessingFilterEntryPoint</classname> which
returns a 403 error (forbidden) to the user.</para>
</listitem>
</orderedlist></para>
</sect1>
<sect1 id="x509-config">
<title>Configuration</title>
<para>There is a version of the <link
linkend="contacts-sample">Contacts Sample Application</link> which
uses X509. Copy the beans and filter setup from this as a starting
point for configuring your own application. A set of example
certificates is also included which you can use to configure your
server. These are <itemizedlist>
<listitem>
<para><filename>user.p12</filename>: A PKCS12 format file
containing the client key and certificate. These should be
installed in your browser. It maps to a use in the
application.</para>
</listitem>
<listitem>
<para><filename>server.p12</filename>: The server certificate
and key for HTTPS connections.</para>
</listitem>
<listitem>
<para><filename>ca.jks</filename>: A Java keystore containing
the certificate for the authority which issued the user's
certificate. This will be used by the container to validate
client certificates.</para>
</listitem>
</itemizedlist> For JBoss 3.2.7 (with Tomcat 5.0), the SSL
configuration in the <filename>server.xml</filename> file looks like
this <programlisting>
&lt;!-- SSL/TLS Connector configuration --&gt;
&lt;Connector port="8443" address="${jboss.bind.address}"
<title>X.509 Authentication</title>
<sect1 id="x509-overview">
<title>Overview</title>
<para>The most common use of X.509 certificate authentication is in verifying the identity
of a server when using SSL, most commonly when using HTTPS from a browser. The browser
will automatically check that the certificate presented by a server has been issued (ie
digitally signed) by one of a list of trusted certificate authorities which it
maintains.</para>
<para>You can also use SSL with <quote>mutual authentication</quote>; the server will then
request a valid certificate from the client as part of the SSL handshake. The server
will authenticate the client by checking that it's certificate is signed by an
acceptable authority. If a valid certificate has been provided, it can be obtained
through the servlet API in an application. Spring Security X.509 module extracts the
certificate using a filter and passes it to the configured X.509 authentication provider
to allow any additional application-specific checks to be applied. It also maps the
certificate to an application user and loads that user's set of granted authorities for
use with the standard Spring Security infrastructure.</para>
<para>You should be familiar with using certificates and setting up client authentication
for your servlet container before attempting to use it with Spring Security. Most of the
work is in creating and installing suitable certificates and keys. For example, if
you're using Tomcat then read the instructions here <ulink
url="http://tomcat.apache.org/tomcat-6.0-doc/ssl-howto.html"/>. It's important that
you get this working before trying it out with Spring Security</para>
</sect1>
<sect1>
<title>Adding X.509 Authentication to Your Web Application</title>
<para> Enabling X.509 client authentication is very straightforward. Just add the <literal
>&lt;x509/&gt;</literal> element to your http security namespace configuration. <programlisting><![CDATA[
<http>
...
<x509 subject-principal-regex="CN=(.*?)," user-service-ref="userService"/>
...
</http>]]>
</programlisting> The element has two optional attributes: <itemizedlist>
<listitem>
<para><literal>subject-principal-regex</literal>. The regular expression used to
extract a username from the certificate's subject name. The default value is
shown above. This is the username which will be passed to the <literal
>UserDetailsService</literal> to load the authorities for the
user.</para>
</listitem>
<listitem>
<para><literal>user-service-ref</literal>. This is the bean Id of the
<interfacename>UserDetailsService</interfacename> to be used with X.509.
It isn't needed if there is only one defined in your application
context.</para>
</listitem>
</itemizedlist> The <literal>subject-principal-regex</literal> should contain a single
group. For example the default expression "CN=(.*?)," matches the common name field. So
if the subject name in the certificate is "CN=Jimi Hendrix, OU=...", this will give a
user name of "Jimi Hendrix". The matches are case insensitive. So "emailAddress=(.?),"
will match "EMAILADDRESS=jimi@hendrix.org,CN=..." giving a user name "jimi@hendrix.org".
If the client presents a certificate and a valid username is successfully extracted,
then there should be a valid <classname>Authentication</classname> object in the
security context. If no certificate is found, or no corresponding user could be found
then the security context will remain empty. This means that you can easily use X.509
authentication with other options such as a form-based login. </para>
</sect1>
<sect1 id="x509-config">
<title>Configuring Tomcat</title>
<para>There are some pre-generated certificates in the Spring Security
<filename>samples/certificate</filename> directory which you can use to enable SSL. The file
<filename>server.jks</filename> contains the server certificate, private key and the
issuing certificate authority. There are also some client certificate files for the users from the
sample applications. You can install these in your browser to enable SSL client authentication.
</para>
<para>
To enable SSL in tomcat <filename>server.xml</filename> file looks like this
<programlisting><![CDATA[
<!-- SSL/TLS Connector configuration -->
<Connector port="8443" address="${jboss.bind.address}"
maxThreads="100" minSpareThreads="5" maxSpareThreads="15"
scheme="https" secure="true"
sslProtocol = "TLS"
@ -136,13 +80,12 @@
keystoreType="PKCS12" keystorePass="password"
truststoreFile="${jboss.server.home.dir}/conf/ca.jks"
truststoreType="JKS" truststorePass="password"
/&gt;
</programlisting><parameter>clientAuth</parameter> can also be set to
<parameter>want</parameter> if you still want SSL connections to
succeed even if the client doesn't provide a certificate. Obviously
these clients won't be able to access any objects secured by Spring
Security (unless you use a non-X509 authentication mechanism, such as
BASIC authentication, to authenticate the user)</para>
</sect1>
</chapter>
/> ]]>
</programlisting>
<parameter>clientAuth</parameter> can also be set to <parameter>want</parameter> if you still
want SSL connections to succeed even if the client doesn't provide a certificate.
Obviously these clients won't be able to access any objects secured by Spring Security
(unless you use a non-X509 authentication mechanism, such as BASIC authentication, to
authenticate the user)</para>
</sect1>
</chapter>