Ezt olvasd el szerintem:
https://www.java.com/en/download/help/jcp_security.xml
High
This is the minimum recommended (and default) security level setting. Applications that are signed with a valid or expired certificate and include the Permissions attribute in the manifest for the main JAR file are allowed to run with security prompts. Applications are also allowed to run with security prompts when the revocation status of the certificate cannot be checked. All other applications are blocked.