Create key file if not exist

PrivateData.cs

@@ -6,12 +6,18 @@ using System;
 class PrivateData
 {
     private RSACryptoServiceProvider RSA;
-
+    private string keyFile = "KeyInfo.xml";
 
     public PrivateData()
     {
+        if (File.Exists(keyFile)) {
             RSA = new RSACryptoServiceProvider();
-        RSA.FromXmlString(File.ReadAllText("KeyInfo.xml"));
+            RSA.FromXmlString(File.ReadAllText(keyFile));
+        } else {
+            RSA = new RSACryptoServiceProvider(4096);
+            string KeyInfo = RSA.ToXmlString(true);
+            File.WriteAllText(keyFile, KeyInfo);
+        }
     }
 
     public string EncryptString(string input)