diff --git a/DotCMIS/binding/http.cs b/DotCMIS/binding/http.cs
index 7200a50..4b3ce28 100644
--- a/DotCMIS/binding/http.cs
+++ b/DotCMIS/binding/http.cs
@@ -21,6 +21,7 @@
 using System.Diagnostics;
 using System.IO;
 using System.Net;
+using System.Security.Cryptography;
 using System.Text;
 using System.Web;
 using DotCMIS.Enums;