domain is optional when generate new key

glide.lock

@@ -1,8 +1,8 @@
 hash: 217e5bc8c4d3160eeddd18dda7f8f8785f1b2b7f2ca58779b94ed8fd91ab226d
-updated: 2018-06-04T16:04:51.812734-07:00
+updated: 2018-06-05T11:36:14.582087-07:00
 imports:
 - name: golang.org/x/crypto
-  version: d36f3ee340e0aa6549738d42e0cb9139c902d7fd
+  version: 4dad02e057d03c4f12a519a73d4b4f1837de135d
   repo: https://github.com/ProtonMail/crypto.git
   subpackages:
   - bitcurves

key.go

@@ -151,10 +151,12 @@ func (o *OpenPGP) GenerateKey(userName string, domain string, passphrase string,
 	if len(userName) <= 0 {
 		return "", errors.New("Invalid user name format")
 	}
-	if len(domain) <= 0 {
-		return "", errors.New("Invalid domain")
+	var email = userName
+
+	if len(domain) > 0 {
+		email = email + "@" + domain
 	}
-	email := userName + "@" + domain
+
 	comments := ""
 	timeNow := func() time.Time {
 		return o.getNow()