Derby database may run in two modes:
For this you need two files from the Oracle web site. There are a set for each major version of Java. Look on Oracle website for "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files"
You should copy the US_export_policy.jar and local_policy.jar files into the Java jre\lib\security folder. Look for currently used Java in DbSchema Help / About dialog.
You can find the files on this page for JDK/JRE 8. It's a ways down the page and you have to click the Download link to get the files. http://www.oracle.com/technetwork/java/javase/downloads/index.html