Added missing import

git-svn-id: https://svn.apache.org/repos/asf/chemistry/dotcmis/trunk@1297193 13f79535-47bb-0310-9956-ffa450edef68
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;