Re: [PATCH 6/12] random pt4: Replace SHA with faster version

From: Denis Vlasenko
Date: Tue Jan 25 2005 - 16:40:00 EST


On Tuesday 25 January 2005 23:14, Matt Mackall wrote:
> On Tue, Jan 25, 2005 at 11:07:21PM +0200, Denis Vlasenko wrote:
> > On Friday 21 January 2005 23:41, Matt Mackall wrote:
> > > - * @W: 80 words of workspace
> > > + * @W: 80 words of workspace, caller should clear
> >
> > Why?
>
> Are you asking why should the caller clear or why should it be cleared at all?
>
> For the first question, having the caller do the clear avoids
> redundant clears on repeated calls.
>
> For the second question, forward security. If an attacker breaks into
> the box shortly after a secret is generated, he may be able to recover
> the secret from such state.

Whoops. I understood a comment as 'caller should clear prior to use'
and this seems to be untrue (code overwrites entire W[80] vector
without using prior contents).

Now I think that you most probably meant 'caller should clear AFTER use'.
If so, comment should be amended.
--
vda

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/