func ExamplePublicKeys() {
	var hostKey ssh.PublicKey
	// A public key may be used to authenticate against the remote
	// server by using an unencrypted PEM-encoded private key file.
	//
	// If you have an encrypted private key, the crypto/x509 package
	// can be used to decrypt it.
	key, err := ioutil.ReadFile("/home/user/.ssh/id_rsa")
	if err != nil {
		log.Fatalf("unable to read private key: %v", err)
	}

	// Create the Signer for this private key.
	signer, err := ssh.ParsePrivateKey(key)
	if err != nil {
		log.Fatalf("unable to parse private key: %v", err)
	}

	config := &ssh.ClientConfig{
		User: "user",
		Auth: []ssh.AuthMethod{
			// Use the PublicKeys method for remote authentication.
			ssh.PublicKeys(signer),
		},
		HostKeyCallback: ssh.FixedHostKey(hostKey),
	}

	// Connect to the remote server and perform the SSH handshake.
	client, err := ssh.Dial("tcp", "host.com:22", config)
	if err != nil {
		log.Fatalf("unable to connect: %v", err)
	}
	defer client.Close()
}