Checking if your JRE has the Unlimited-strength Policy Files in place

To use the included 256-bit encryption algorithms within Java, Oracle Java JDK or JRE requires you to download and replace the US_export_policy.jar and local_policy.jar files under your $JAVA_HOME/jre/lib/security/ directory with a variant of these files called JCE Unlimited Strength Jurisdiction Policy Files obtained here.

These jars, commonly referred to as the Unlimited JCE files, limit which security algorithms you can or cannot use in your code.

An installation with the files replaced with the unlimited variants will show the below. Note specifically the permissive name of the granted permission:

$ unzip -c $JAVA_HOME/jre/lib/security/local_policy.jar default_local.policy
// Country-specific policy file for countries
// with no limits on crypto strength.
grant {
    // There is no restriction to any algorithms.
    permission javax.crypto.CryptoAllPermission;

Note: This only applies to Java release versions prior to Java 8 Update 161 (1.8u161). From that version onwards, the default included policy is unlimited and no file replacement is necessary anymore on higher versions.