I've developed a JAAS Login Module for my application, extending the class AbstractServerLoginModule, as suggested in JBoss documentation. The basics of my Login Module is working as expected. I can authenticate and authorize my users without problems. However, if a username contains a non ASCII-US character like ü, ä or ö, for example, after the authentication, the method getCallerPrincipal() of the class SessionContext returns null. I have seen that my customized authentication is returning true when the passwords match, but something outside my code is failing to complete the authentication process. Probably the problem is that JBoss is not configured to use UTF-8 as charset. The rest of my web application is already supporting UTF-8 characters, but as far as I know, this configuration has no influence on JAAS. Does anyone know how to make this configuration for JAAS?