Sign java jars for security

We have an enterprise system that utilizes many in house jars, java applications, to run on a centos 7 linux system.

How do I go about achieving the following in order of importance:

1. Only signed jars can run. If its not signed, I dont want it to run at all.


2. 
   

   My jars only run on these systems and no other systems.

   
   

   I don't mind modifying the jars so that it checks something regarding its environment before running.

   
   


3. 
   

   Prevent easy decompiling of the java code. (This might be for stackoverflow). But thought Id give it a shot here.