diff --git a/UpdateStream.hh b/UpdateStream.hh
index 051131a..f79ed8c 100644
--- a/UpdateStream.hh
+++ b/UpdateStream.hh
@@ -19,8 +19,6 @@ namespace pEp {
         using namespace std;
         namespace io = boost::iostreams;
 
-        struct NoUpdateAvailable : runtime_error { };
-    
         struct product {
             string name;
             string url;
diff --git a/downloadclient.cc b/downloadclient.cc
index e0182fc..97a3c31 100644
--- a/downloadclient.cc
+++ b/downloadclient.cc
@@ -2,24 +2,32 @@
 // see LICENSE.txt
 
 #include "downloadclient.hh"
-#include "UpdateStream.hh"
 
 #include <iostream>
 #include <sstream>
 
 namespace pEp {
     namespace UpdateClient {
-        /*
-        istream update(const product& p)
+        string update(product p, PublicKey update_key)
         {
+            UpdateStream us { UpdateDevice(p) };
+
             try {
-                return UpdateStream(p);
-            }
-            catch (NoUpdateAvailable&) {
-                return stringstream(string(""));
+                us->open(update_key);
             }
+            catch (exception&) { }
+
+            if (us->filename() == "")
+                throw DownloadError();
+
+            return us->filename();
+        }
+
+        string update(product p, string keyfile)
+        {
+            PublicKey update_key = load_key(keyfile);
+            return update(p, update_key);
         }
-        */
     }
 }
 
diff --git a/downloadclient.hh b/downloadclient.hh
index c72f427..2440b1c 100644
--- a/downloadclient.hh
+++ b/downloadclient.hh
@@ -10,7 +10,12 @@ namespace pEp {
     namespace UpdateClient {
         using namespace std;
 
-        istream update(const product& p);
+        struct DownloadError : runtime_error {
+            DownloadError() : runtime_error("download not possible") { }
+        };
+
+        string update(product p, PublicKey update_key);
+        string update(product p, string keyfile);
     }
 }
 
diff --git a/test_updater.cc b/test_updater.cc
index c5702fd..6f5f00a 100644
--- a/test_updater.cc
+++ b/test_updater.cc
@@ -3,14 +3,14 @@
 
 #include <iostream>
 #include <assert.h>
-#include <cryptopp/files.h>
-#include "UpdateStream.hh"
+#include "downloadclient.cc"
 
 using namespace std;
 using namespace pEp::UpdateClient;
 
 int main()
 {
+    /*
     product p { "pEp for Something", "https://fdik.org/cgidownload?hash=23232323234242" };
     UpdateStream us { UpdateDevice(p) };
 
@@ -30,6 +30,20 @@ int main()
         str << us.rdbuf();
         cout << str.str() << "\n";
     }
+    */
+
+    cout << "downloading...\n";
+
+    product p { "pEp for Something", "https://fdik.org/cgidownload?hash=23232323234242" };
+
+    try {
+        string filename = update(p, "public.der");
+        cout << "downloaded " << filename << "\n";
+    }
+    catch (DownloadError&)
+    {
+        cout << "cannot download\n";
+    }
 
     return 0;
 }