[openssl-dev] [openssl.org #4362] chacha-x86.pl has stricter aliasing requirements than other files

Viktor Dukhovni openssl-users at dukhovni.org
Fri Mar 4 14:13:34 UTC 2016

> On Mar 4, 2016, at 7:24 AM, Andy Polyakov via RT <rt at openssl.org> wrote:
> Fear is irrational and destructive feeling. Having faith that world is
> better than that it nothing but healthy :-) What I'm saying is that
> let's put a little bit more substance into discourse. Would anybody
> consider it *sane* programming practice to rely on partially overlapping
> buffers in *general* case? I.e. without actually *knowing* (as opposite
> to *assuming*) what's gong on? [Control question: does compiler
> guarantee order of references to memory?] As said in last message I
> don't consider it sane and even consider it natural [which means that
> I'd expect majority to not consider it sane too].

One the cool features of the OCB code some folks I know to be using
and relying on is that it supports in-place encryption.  You give
it a buffer, and it is encrypted in place.  This is specifically
promised by the API and is noticeably fast.

No idea whether this is a useful datapoint...


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