Add support for ECDSA P-256 with SHA256

This adds a small EC library that is capable of verifying a signature of
SHA256 with ECDSA on the NIST P-256 curve.

Change-Id: I2a16639c92a77e8e4783c47ffbc56676de56eb59
diff --git a/include/mincrypt/sha.h b/include/mincrypt/sha.h
index 120ddcb..ef60aab 100644
--- a/include/mincrypt/sha.h
+++ b/include/mincrypt/sha.h
@@ -1,8 +1,30 @@
-// Copyright 2005 Google Inc. All Rights Reserved.
-// Author: mschilder@google.com (Marius Schilder)
-
-#ifndef SECURITY_UTIL_LITE_SHA1_H__
-#define SECURITY_UTIL_LITE_SHA1_H__
+/*
+ * Copyright 2005 The Android Open Source Project
+ *
+ * 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 Google Inc. nor the names of its contributors may
+ *       be used to endorse or promote products derived from this software
+ *       without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY Google Inc. ``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 Google Inc. 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.
+ */
+#ifndef SYSTEM_CORE_INCLUDE_MINCRYPT_SHA1_H_
+#define SYSTEM_CORE_INCLUDE_MINCRYPT_SHA1_H_
 
 #include <stdint.h>
 #include "hash-internal.h"
@@ -27,4 +49,4 @@
 }
 #endif // __cplusplus
 
-#endif  // SECURITY_UTIL_LITE_SHA1_H__
+#endif  // SYSTEM_CORE_INCLUDE_MINCRYPT_SHA1_H_