Starting with Java 1.8.0_151 and 1.8.0_152 there is a new somewhat easier way to enable the unlimited strength jurisdiction policy for the JVM. Without enabling this you cannot use AES-256 for example.
First download the JRE, I like to use the server-jre for servers. When you extract the server-jre look for the file java.security in the jre/lib/security folder. For example for Java 1.8.0_152 the file structure looks like this:
/jdk1.8.0_152
|- /jre
|- /lib
|- /security
|- java.security
Now open java.security with a text editor and look for the line that defines the java security property crypto.policy it can have two values limited or unlimited - the default is limited.
By default you should find a commented out line:
#crypto.policy=unlimited
You can enable unlimited by uncommenting that line, remove the #:
crypto.policy=unlimited
Now restart your java applications that point to the JVM and you should be all set.