diff --git a/src/authm_mad/one_auth_mad.rb b/src/authm_mad/one_auth_mad.rb
index 7f6a0b9f82..b1d40bcaf9 100755
--- a/src/authm_mad/one_auth_mad.rb
+++ b/src/authm_mad/one_auth_mad.rb
@@ -117,7 +117,7 @@ class AuthDriver < OpenNebulaDriver
         authN_path = File.join(@local_scripts_path, protocol)
         
         command = File.join(authN_path,ACTION[:authN].downcase) 
-        command << ' ' << user << ' ' << password << ' ' << secret_attr.join(':')
+        command << ' ' << user << ' ' << password << ' ' << secret_attr.join(' ')
 
         local_action(command, request_id, ACTION[:authN])
     end
diff --git a/src/um/User.cc b/src/um/User.cc
index c649eace68..71b2d4cd28 100644
--- a/src/um/User.cc
+++ b/src/um/User.cc
@@ -27,7 +27,7 @@
 #include "Group.h"
 
 
-const string User::INVALID_CHARS = " \t\n\v\f\r";
+const string User::INVALID_CHARS = " :\t\n\v\f\r";
 
 /* ************************************************************************** */
 /* User :: Database Access Functions                                          */