If your environment is configured properly, you can create your database as an encrypted database (one in which the database is encrypted on disk). To do this, you use the dataEncryption=true attribute to turn on encryption and the bootPassword=key attribute or the encryptionKey attribute to specify a key for the encryption.
You can also specify an encryption provider and encryption algorithm other than the defaults with the encryptionProvider=providerName and encryptionAlgorithm=algorithm attributes.
jdbc:derby:encryptedDB;create=true;dataEncryption=true; bootPassword=DBpassword