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_ecdsa_key.pub      ssh_host_key            ssh_host_rsa_key.pub
ssh_config      ssh_host_dsa_key.pub    ssh_host_ed25519_key        ssh_host_key.pub        sshd_config
ssh_config~orig ssh_host_ecdsa_key      ssh_host_ed25519_key.pub    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)