diff --git a/firefox_addon/lib/hmac.js b/firefox_addon/lib/hmac.js
new file mode 100644
index 0000000..a70525d
--- /dev/null
+++ b/firefox_addon/lib/hmac.js
@@ -0,0 +1,40 @@
+/*
+  Copyright (C) 2013 Grégory Soutadé
+  
+  This file is part of gPass.
+  
+  gPass is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+  
+  gPass is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  
+  You should have received a copy of the GNU General Public License
+  along with gPass.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+var {Cc, Ci} = require("chrome");
+
+var hmac = Cc["@mozilla.org/security/hmac;1"]
+    .createInstance(Ci.nsICryptoHMAC);
+
+function hmac_init(key) {
+    var keyObject = Cc["@mozilla.org/security/keyobjectfactory;1"]
+                .getService(Ci.nsIKeyObjectFactory)
+                .keyFromString(Ci.nsIKeyObject.HMAC, key);
+    hmac.init(hmac.SHA256, keyObject);
+}
+
+function hmac_digest(message) {
+    var data = new Uint8Array(message.length);
+    for(i=0; i<message.length; i++)
+	data[i] = message.charCodeAt(i);
+    hmac.update(data, data.length);
+    res = hmac.finish(false);
+    hmac.reset();
+    return res;
+}
diff --git a/firefox_addon/lib/pkdbf2.js b/firefox_addon/lib/pkdbf2.js
index 33639d5..b45d011 100644
--- a/firefox_addon/lib/pkdbf2.js
+++ b/firefox_addon/lib/pkdbf2.js
@@ -17,27 +17,7 @@
   along with gPass.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-var {Cc, Ci} = require("chrome");
-
-var hmac = Cc["@mozilla.org/security/hmac;1"]
-    .createInstance(Ci.nsICryptoHMAC);
-
-function hmac_init(key) {
-    var keyObject = Cc["@mozilla.org/security/keyobjectfactory;1"]
-                .getService(Ci.nsIKeyObjectFactory)
-                .keyFromString(Ci.nsIKeyObject.HMAC, key);
-    hmac.init(hmac.SHA256, keyObject);
-}
-
-function hmac_digest(message) {
-    var data = new Uint8Array(message.length);
-    for(i=0; i<message.length; i++)
-	data[i] = message.charCodeAt(i);
-    hmac.update(data, data.length);
-    res = hmac.finish(false);
-    hmac.reset();
-    return res;
-}
+require("hmac.js");
 
 exports.pkdbf2 = {
     
@@ -74,4 +54,4 @@ exports.pkdbf2 = {
 
 	return result.substr(0, outlen);
     }
-};
\ No newline at end of file
+};