diff --git a/license.txt b/license.txt
new file mode 100644
index 0000000..7e165eb
--- /dev/null
+++ b/license.txt
@@ -0,0 +1,29 @@
+==========================================================================
+Copyright License
+==========================================================================
+
+Copyright (c) 2008, Zhiyuan Shao (邵志远)
+All rights reserved.
+
+Redistribution and use in source and documentation forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+* Redistributions of documentation must retain the above copyright
+  notice, this list of conditions, and the following disclaimer.
+
+* Redistributions must reproduce the above copyright
+  notice, this list of conditions, and the following disclaimer in the
+  documentation and/or other materials provided with the distribution.
+
+THIS DOCUMENTATION IS PROVIDED BY Zhiyuan Shao ''AS IS'' AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL Zhiyuan Shao BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+THE POSSIBILITY OF SUCH DAMAGE.