From: Joe Thornber <thornber@redhat.com>
To: device-mapper development <dm-devel@redhat.com>
Cc: dm-crypt@saout.de
Subject: Re: [dm-crypt] [dm-devel] [RFC] dm-thin: Random block placement strategy?
Date: Fri, 20 Jul 2012 09:50:59 +0000 [thread overview]
Message-ID: <20120720095058.GA1990@raspberrypi> (raw)
In-Reply-To: <ju9vdv$vpa$1@dough.gmane.org>
On Thu, Jul 19, 2012 at 02:49:51PM -0700, Alex Elsayed wrote:
> This may be insufficiently useful to justify implementing, but I thought it
> was an interesting concept.
>
> One of the current issues with dm-crypt and discard is that enabling it can
> leak information about the filesystem and usage patterns of the disk[1].
>
> If a dm-thin device with a random block placement strategy is layered on top
> of dm-crypt however, this could solve some of the issues involved and
> partially mitigate others.
>
> Such a random block placement strategy would heavily disguise any layout
> patterns that could be used to identify the filesystem, most likely to the
> point of being completely unrecognizable.
A couple of things spring to mind.
- If you're using a spindle device this will destroy performance,
unless you use large block size (which I suspect you don't want
to do because you're trying to disguise access patterns).
- How expensive will acquiring a cryptographically secure random
destination be?
WARNING: multiple messages have this Message-ID (diff)
From: Joe Thornber <thornber@redhat.com>
To: device-mapper development <dm-devel@redhat.com>
Cc: dm-crypt@saout.de
Subject: Re: [RFC] dm-thin: Random block placement strategy?
Date: Fri, 20 Jul 2012 09:50:59 +0000 [thread overview]
Message-ID: <20120720095058.GA1990@raspberrypi> (raw)
In-Reply-To: <ju9vdv$vpa$1@dough.gmane.org>
On Thu, Jul 19, 2012 at 02:49:51PM -0700, Alex Elsayed wrote:
> This may be insufficiently useful to justify implementing, but I thought it
> was an interesting concept.
>
> One of the current issues with dm-crypt and discard is that enabling it can
> leak information about the filesystem and usage patterns of the disk[1].
>
> If a dm-thin device with a random block placement strategy is layered on top
> of dm-crypt however, this could solve some of the issues involved and
> partially mitigate others.
>
> Such a random block placement strategy would heavily disguise any layout
> patterns that could be used to identify the filesystem, most likely to the
> point of being completely unrecognizable.
A couple of things spring to mind.
- If you're using a spindle device this will destroy performance,
unless you use large block size (which I suspect you don't want
to do because you're trying to disguise access patterns).
- How expensive will acquiring a cryptographically secure random
destination be?
next prev parent reply other threads:[~2012-07-20 9:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-19 21:49 [dm-crypt] [RFC] dm-thin: Random block placement strategy? Alex Elsayed
2012-07-19 21:49 ` Alex Elsayed
2012-07-20 9:50 ` Joe Thornber [this message]
2012-07-20 9:50 ` Joe Thornber
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