Thursday, June 11, 2015

Apache CXF Fediz 1.2.0 tutorial - part II

This is the second in a series of blog posts on the new features and changes in Apache CXF Fediz 1.2.0. The previous blog entry gave instructions about how to deploy the Fediz IdP and a sample service application in Apache Tomcat. This article describes how different client authentication methods are supported in the IdP, and how they can be selected by the service via the "wauth" parameter. Then we will extend the previous tutorial by showing how to authenticate to the IdP using a client certificate in the browser, as opposed to entering a username + password.

1) Supporting different client authentication methods in the IdP

The Apache Fediz IdP in 1.2.0 supports different client authentication methods by default using different URL paths, as follows:
  • /federation -> the main entry point
  • /federation/up -> authentication using HTTP B/A
  • /federation/krb -> authentication using Kerberos
  • /federation/clientcert -> authentication using a client cert
The way it works is as follows. The service provider (SP) should use the URL for the main entry point (although the SP has the option of choosing one the more specific URLs as well). The IdP extracts the "wauth" parameter from the request ("default" is the default value), and looks for a matching key in the "authenticationURIs" section of the service configuration. For example:

<property name="authenticationURIs">
        <entry key="default" value="federation/up" />
        <entry key="" value="federation/krb" />
        <entry key="" value="federation/up" />
        <entry key="" value="federation/clientcert" />

If a matching key is found for the wauth value, then the browser gets redirected to the associated URL. Therefore, a service provider can specify a value for "wauth" in the plugin configuration, and select the client authentication mode as a result. The values defined for "wauth" above are taken from the specification, but can be changed if required. The service provider can specify the value for "wauth" by using the "authenticationType" configuration tag, as documented here.

2) Client authentication using a certificate

A new feature of Fediz 1.2.0 is the ability for a client to authenticate to the IdP using a certificate embedded in the browser. To see how this works in practice, please follow the steps given in the previous tutorial to set up the IdP and service web application in Apache Tomcat. To switch to use client certificate authentication, only one change is required in the service provider configuration:
  • Edit ${catalina.home}/conf/fediz_config.xml, and add the following under the "protocol" section: <authenticationType></authenticationType>
The next step is to add a client certificate to the browser that you are using. To avoid changing the IdP TLS configuration, we will just use the same certificate / private key that is used by the IdP on the client side for the purposes of this demo. First, we need to convert the IdP key from JKS to PKCS12. So take the idp-ssl-key.jks configured in the previous tutorial and run:
  • keytool -importkeystore -srckeystore idp-ssl-key.jks -destkeystore idp-ssl-key.p12 -srcstoretype JKS -deststoretype PKCS12 -srcstorepass tompass -deststorepass tompass -srcalias mytomidpkey -destalias mytomidpkey -srckeypass tompass -destkeypass tompass -noprompt
I will use Chrome for the client browser. Under Settings, Advanced Settings, "HTTPS/SSL", click on the Manage Certificates button, and add the idp-ssl-key.p12 keystore above using the password "tompass":
Next, we need to tell the STS to trust the key used by the client (you can skip these steps if using Fediz 1.2.1):
  • First, export the certificate as follows: keytool -keystore idp-ssl-key.jks -storepass tompass -export -alias mytomidpkey -file MyTCIDP.cer
  • Take the ststrust.jks + import the cert: keytool -import -trustcacerts -keystore ststrust.jks -storepass storepass -alias idpcert -file MyTCIDP.cer -noprompt
  • Finally, copy the modified ststrust.jks into the STS: ${catalina.home}/webapps/fediz-idp-sts/WEB-INF/classes
The last configuration step is to tell the STS where to retrieve claims for the cert. We will just copy the claims for Alice:
  • Edit ${catalina.home}/webapps/fediz-idp-sts/WEB-INF/userClaims.xml
  • Add the following under "userClaimsREALMA": <entry key="CN=localhost" value-ref="REALMA_aliceClaims" />
Now restart Tomcat and navigate to the service URL:
  • https://localhost:8443/fedizhelloworld/secure/fedservlet
Select the certificate that we have uploaded, and you should be able to authenticate to the IdP and be redirected back to the service, without having to enter any username/password credentials!

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