Fix ssh key permissions in windows

This sets correct access control for the ssh key
and makes openssh on windows able to use the key
without any "permission are too open error"

Author: anjannath

Gopkg.lock

@@ -37,3 +37,7 @@
 [prune]
   go-tests = true
   unused-packages = true
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/hectane/go-acl"

Gopkg.toml

@@ -14,6 +14,7 @@ import (
 	"runtime"
 
 	gossh "golang.org/x/crypto/ssh"
+	"github.com/hectane/go-acl"
 )
 
 var (
@@ -86,6 +87,10 @@ func (kp *KeyPair) WriteToFile(privateKeyPath string, publicKeyPath string) erro
 			if err := f.Chmod(0600); err != nil {
 				return err
 			}
+		case "windows":
+			if err = windowsChmod(v.File, 0600); err != nil {
+				return err
+			}
 		}
 	}
 
@@ -122,3 +127,12 @@ func GenerateSSHKey(path string) error {
 
 	return nil
 }
+
+// change windows acl based permissions on file
+func windowsChmod(filePath string, fileMode os.FileMode) error {
+	if err := acl.Chmod(filePath, fileMode); err != nil {
+		return err
+	}
+	return nil
+}
+