rsaBits := 2048

	if len(host) == 0 {
		return nil, nil, fmt.Errorf("Missing host parameter")
	}

	publicKey := func(priv interface{}) interface{} {
		switch k := priv.(type) {
		case *rsa.PrivateKey:
			return &k.PublicKey
		case *ecdsa.PrivateKey:
			return &k.PublicKey
		default:
			return nil
		}
	}

	pemBlockForKey := func(priv interface{}) *pem.Block {