Make utils module part of the platform
diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
new file mode 100644
index 0000000..bda9710
--- /dev/null
+++ b/include/mbedtls/platform_util.h
@@ -0,0 +1,57 @@
+/**
+ * \file platform_util.h
+ *
+ * \brief Common and shared functions used by multiple modules in the Mbed TLS
+ * library.
+ */
+/*
+ * Copyright (C) 2018, Arm Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * This file is part of Mbed TLS (https://tls.mbed.org)
+ */
+#ifndef MBEDTLS_PLATFORM_UTIL_H
+#define MBEDTLS_PLATFORM_UTIL_H
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief Securely zeroize a buffer
+ *
+ * \param buf Buffer to be zeroized
+ * \param len Length of the buffer in bytes
+ *
+ * \note This implementation should never be optimized out by the
+ * compiler
+ *
+ * \note It is extremely difficult to guarantee that calls to
+ * mbedtls_platform_zeroize() are not removed by aggressive
+ * compiler optimizations in a portable way. For this reason, Mbed
+ * TLS provides the configuration option
+ * MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
+ * mbedtls_platform_zeroize() to use a suitable implementation for
+ * their platform and needs
+ */
+void mbedtls_platform_zeroize( void *buf, size_t len );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MBEDTLS_PLATFORM_UTIL_H */