This diff updates cleanse.cpp with a change from [[https://github.com/bitcoin/bitcoin/pull/11558 | PR11558]] ("Minimal code changes to allow msvc compilation") and a complete backport of [[https://github.com/bitcoin/bitcoin/pull/16158 | PR16158]] ("Fix logic of memory_cleanse() on MSVC and clean up docs")
First commit:
https://github.com/bitcoin/bitcoin/pull/11558/commits/fbf327b13868861c2877c5754caf5a9816f2603c
> Minimal code changes to allow msvc compilation.
This change uses `SecureZeroMemory` to ensure the memory is cleansed on Windows systems, but it introduced a code smell because it did this in addition to std::memset, and did not update the documentation properly.
Second commit:
https://github.com/bitcoin/bitcoin/pull/16158/commits/cac30a436cab3641bba3b774d3d3ddbc426e7908
> Commit fbf327b13868861c2877c5754caf5a9816f2603c ("Minimal code
> changes to allow msvc compilation.") was indeed minimal in terms
> of lines touched. But as a result of that minimalism it changed the
> logic in memory_cleanse() to first call std::memset() and then
> additionally the MSVC-specific SecureZeroMemory() function, and it
> also moved a comment to the wrong location.
> This commit removes the superfluous call to std::memset() on MSVC
> and ensures that the comment is in the right position again.
Third commit:
https://github.com/bitcoin/bitcoin/pull/16158/commits/f53a70ce95231d34bb14cd6c58503927e8d7ff59
> So far, the documentation of memory_cleanse() is a verbatim copy of
> the commit message in BoringSSL, where this code was originally
> written. However, our code evolved since then, and the commit message
> is not particularly helpful in the code but is rather of historical
> interested in BoringSSL only.
>
> This commit improves improves the comments around memory_cleanse()
> and gives a better rationale for the method that we use. This commit
> touches only comments.
This is a backport of Core [[https://github.com/bitcoin/bitcoin/pull/16158 | PR16158]]