Rearrange sources (#4997)

include/xrpl/crypto/secure_erase.h

@@ -0,0 +1,46 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2020 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_CRYPTO_SECURE_ERASE_H_INCLUDED
+#define RIPPLE_CRYPTO_SECURE_ERASE_H_INCLUDED
+
+#include <cstddef>
+
+namespace ripple {
+
+/** Attempts to clear the given blob of memory.
+
+    The underlying implementation of this function takes pains to
+    attempt to outsmart the compiler from optimizing the clearing
+    away. Please note that, despite that, remnants of content may
+    remain floating around in memory as well as registers, caches
+    and more.
+
+    For a more in-depth discussion of the subject please see the
+    below posts by Colin Percival:
+
+    http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
+    http://www.daemonology.net/blog/2014-09-06-zeroing-buffers-is-insufficient.html
+*/
+void
+secure_erase(void* dest, std::size_t bytes);
+
+}  // namespace ripple
+
+#endif