This is annoying.
Using a the included DSM plugin with vnc practically disables the Java viewer
since it doesn't support them.
I'm not sure on how much this is possible perhaps with some JNI calls? (If java will let you to send the dll along with the jar)
EDIT: Or coding a version of the DSM plugin in java.
You can have a different encryption (SSL?) available for the Java viewer as long as you retain the ability to also have a key file.
Although the handling of key files in most OS's will hurt the benefit of the Java viewer (Access to server in unprivileged environments), That is unless you do make the initial download of the Java viewer via unsecured http and have the Java viewer handle the connection and encryption so it doesn't relay on OS ssl implementations.