The WebAuth Java Toolkit provides assorted classes implementing functionality associated with the Raven. Current content of the package includes classes representing authentication requests and responses (WebauthRequest and WebauthResponse respectively), and a class for validating response messages (WebauthValidator).
This toolkit should currently be regarded as of beta quality since details of the various abstractions may still change in the light of experience. Feedback on this would be welcome.
The Toolkit is available as a source and binary tarball. The README file and Javadoc documentation (also included in the distribution) contain additional information.
William Billingsley (whb21 at cam.ac.uk) has written a Raven valve for Tomcat based on the toolkit. It is available as Java source and in a .jar archive packed with a copy of the toolkit.
Philip Shore (pms52 at cam.ac.uk) has adapted William Billingsley's Tomcat valve into a servlet filter which can be used in any servlet container - ie not just Tomcat. It is available as Java source together with a copy of the associated JavaDoc.
The Toolkit, Tomcat valve, and servlet filter are distributed under the terms of the GNU Lesser General Public License.
See also Tomcat support and JAVA Servlet Library in the Wiki.