I am new to crypto so hopefully I ask this right. There are existing clients that talk to our server that used OpenSSL to generate the certs. Now we are converting that app to a Java app. From my reading, it looks like OpenSSL and Java's jks stores are different. In order to not break the current clients that are in production, as well as have a way to create new certs in Java for new clients, what are my options?

To generate certs: From what I can tell, I could continue using the existing shell scripts from the Java app that use OpenSSL to create the new certs. Or maybe I could use a library like Bouncy Castle to generate private and public keys. I'm not sure if that's different than how OpenSSL works.

To read the existing certs from clients in prod: How would I be able to do this? Would/Could I import the existing keys into Java's trust store (again sorry if I don't have all the concepts down, just starting to read about crypto).