Using keytool for a chat room

I am developing a chatroom with all the security features- like public key encryption (public and private key pairs fo开发者_如何学JAVAr every chat client) and also a certificate authority that signs their public keys. Can anybody tell me how I can use the keytool facility to generate public private key pairs in java? I know the basic keytool commands, but how do I use them in java?

Here is about Java Keytool commands