Date: Tue, 29 Nov 2016 08:32:09 +0100
From: Gert Doering <gert@...1296...>
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Subject: Re: [Openvpn-devel] [PATCH v2] Introduce and use secure_memzero()
 to erase secrets
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Hi,

On Tue, Nov 29, 2016 at 12:36:25AM +0100, David Sommerseth wrote:
> If we "do not care" if a memory region is wiped or not (just that it's
> nice if it happens), then I'd say these are code paths which *do* *not*
> require CLEAR() at all.

"wiping" and "clearing a structure before using, so everything is=20
well-defined" are two very different things.

> If we *know* a certain memory region *must* be cleared, then we do the
> proper call which does what it promises us.

CLEAR() will also do what it promises: that the block in question is
zeroed *for subsequent use*.

What it does not promise is "if we never use it again, it is cleared
nevertheless" - that's what secure_memzero() is for.

One thing is "initialization before use", one is "scrubbing so secret
material doesn't leak *after* use".


Different requirements, different functions.  Reasonable approach.

gert

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Gert Doering - Munich, Germany                             gert@...1296...
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