If I try to get an instance of a javax.crypto.Mac, usingjavax.crypto.Mac mac = javax.crypto.Mac.getInstance("HmacSHA1");, I get a NoClassDefFoundError. I've looked at the JRE (Sun 1.5.0.10), and see jce.jar in the lib directory and sure enough javax.crypto.Mac.class is in that jar, so I wonder why it isn't loading in JBoss and how to make it do so. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4170705#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...