Wednesday, July 15, 2015

Apache CXF Fediz 1.2.0 tutorial - part III

This is the third in a series of blog posts on the new features and changes in Apache CXF Fediz 1.2.0. The previous blog entry described how different client authentication mechanisms are supported in the IdP, and how to configure client authentication via an X.509 certificate, a new feature in Fediz 1.2.0. Another new authentication mechanism in Fediz 1.2.0 is the ability to authenticate to the IdP using Kerberos, which we will cover in this article.

1) Kerberos client authentication in the IdP

Recall that the Apache Fediz IdP in 1.2.0 supports different client authentication methods by default using different URL paths. In particular for Kerberos, the URL path is:
  • /federation/krb -> authentication using Kerberos
The default value for the "wauth" parameter added by the service provider to the request to activate this URL path is:
When the IdP receives a request at the URL path configured for Kerberos, it sends back a request for a Negotiate Authorization header if none is present. Otherwise it parses the header and BASE-64 decodes the Kerberos token and dispatches it to the configured authentication provider. Kerberos tokens are authenticated in the IdP via the STSKrbAuthenticationProvider, which is configured in the Spring security-config.xml

2) Authenticating Kerberos tokens in the IdP

The IdP supports two different ways of validating Kerberos tokens:
  • Passthrough Authentication. Here we do not authenticate the Kerberos token at all in the IdP, but pass it through to the STS for authentication. This is similar to what is done for the Username/Password authentication case. The default security binding of the STS for this scenario requires a KerberosToken Supporting Token. This is the default way of authenticating Kerberos tokens in the IdP.
  • Delegation. If delegation is enabled in the IdP, then the received token is validated locally in the IdP. The delegated credential is then used to get a new Kerberos Token to authenticate the STS call "on behalf of" the original user. 
To enable the delegation scenario, simply update the STSKrbAuthenticationProvider bean in the security-config.xml,
set the "requireDelegation" property to "true", and configure the kerberosTokenValidator property to validate the received Kerberos token:

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