diff --git a/nfq/crypto/sha.h b/nfq/crypto/sha.h
index ddf71c7..8b3a63b 100644
--- a/nfq/crypto/sha.h
+++ b/nfq/crypto/sha.h
@@ -1,3 +1,37 @@
+/**************************** sha.h ****************************/
+/***************** See RFC 6234 for details. *******************/
+/*
+   Copyright (c) 2011 IETF Trust and the persons identified as
+   authors of the code.  All rights reserved.
+   Redistribution and use in source and binary forms, with or
+   without modification, are permitted provided that the following
+   conditions are met:
+   - Redistributions of source code must retain the above
+     copyright notice, this list of conditions and
+     the following disclaimer.
+   - Redistributions in binary form 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.
+   - Neither the name of Internet Society, IETF or IETF Trust, nor
+     the names of specific contributors, may be used to endorse or
+     promote products derived from this software without specific
+     prior written permission.
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+   CONTRIBUTORS "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 THE COPYRIGHT OWNER OR
+   CONTRIBUTORS 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.
+*/
+
 #pragma once
 
 /*