Encryption of data stored on the server

First of all excuse my English, I am translating this message.

I am currently developing a project with openfire. I have a sql server database installed where I have all the user information encrypted, but I do not save the attached files in this database for space, I save them in the xmpp server itself, these files are unencrypted, there is some way of encrypt content at rest and have it encrypted on the server?

Is there any openfire fortification guide? I want to make a secure installation, where all the information is on the server and not on the phones, and I want all that information to be encrypted so that if my server is hacked I won’t be able to recover any data.

Thank you