diff --git a/cas_server/cas.py b/cas_server/cas.py
index bea0638..b12359d 100644
--- a/cas_server/cas.py
+++ b/cas_server/cas.py
@@ -1,3 +1,26 @@
+# Copyright (C) 2014, Ming Chen
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is furnished
+# to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+
+# This file is originated from https://github.com/python-cas/python-cas
+# at commit ec1f2d4779625229398547b9234d0e9e874a2c9a
+
 from six.moves.urllib import parse as urllib_parse
 from six.moves.urllib import request as urllib_request
 from six.moves.urllib.request import Request