The persistence of the Chef Identities is currently done using the Scramble class. I'm changing this to use the Secret class instead. Another lesson of RTFM of the Jenkins API docs.
And make the change reserve compatible for those that already script the creation of their io.chef.jenkins.ChefIdentityBuildWrapper.xml files assuming the base64 encoding.
Bonus points, this will get the plugin to a 1.0.0 state.