Re: partially encrypted filesystem

From: Linus Torvalds <torvalds@osdl.org>
To: "Jörn Engel" <joern@wohnheim.fh-wedel.de>
Cc: Kallol Biswas <kbiswas@neoscale.com>,
	linux-kernel@vger.kernel.org,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: partially encrypted filesystem
Date: Thu, 4 Dec 2003 07:20:21 -0800 (PST)	[thread overview]
Message-ID: <Pine.LNX.4.58.0312040712270.2055@home.osdl.org> (raw)
In-Reply-To: <20031204141725.GC7890@wohnheim.fh-wedel.de>

On Thu, 4 Dec 2003, Jörn Engel wrote:
>
> Isn't that a problem already handled by all compressing filesystems?
> Or did I miss something really stupid?

Yes, compression and encryption are really the same thing from a fs
implementation standpoint - they just have different goals. So yes, any
compressed filesystem will largely have all the same issues.

And compression isn't very easy to tack on later either.

Encryption does have a few extra problems, simply because of the intent.
In a compressed filesystem it is ok to say "this information tends to be
small and hard to compress, so let's not" (for example, metadata). While
in an encrypted filesystem you shouldn't skip the "hard" pieces..

(Encrypted filesystems also have the key management issues, further
complicating the thing, but that complication tends to be at a higher
level).

		Linus