How retrieve or recreate a delete file from the /etc/ssh directory

In Mac El Capitan in the /etc/ssh directory exists the following content:

moduli          ssh_host_dsa_key      ssh_host_key  
ssh_config    ssh_host_ed25519_key        sshd_config
ssh_config~orig ssh_host_ecdsa_key    ssh_host_rsa_key        sshd_config~previous

I can see practically two categories:

  1. public/private keys
  2. configuration files

If any of those files for any of these categories is deleted by mistake.

How that file can be re-generated? Is possible?, How? it according of each category (1 or 2)