From: maccorin@cfl.rr.com
To: linux-kernel@vger.kernel.org
Subject: Re: Using compression before encryption in device-mapper
Date: Wed, 14 Apr 2004 09:58:33 -0400 [thread overview]
Message-ID: <20040414135833.GA30062@lappy> (raw)
In-Reply-To: <407D3231.2080605@grupopie.com>
On Wed, Apr 14, 2004 at 01:44:33PM +0100, Paulo Marques wrote:
> Guillaume Lac?te wrote:
>
> >>>Oops ! I thought it was possible to guarantee with the Huffman encoding
> >>>(which is more basic than Lempev-Zif) that the compressed data use no
> >>>more than 1 bit for every byte (i.e. 12,5% more space).
>
> WTF??
>
> Zlib gives a maximum increase of 0.1% + 12 bytes (from the zlib manual),
> which for a 512 block will be a 2.4% guaranteed increase.
>
> I think that zlib already does the "if this is bigger than original, just
> mark the block type as uncompressed" algorithm internally, so the increase
> is minimal in the worst case.
It is my impression that meta-data is exactly what he wants to avoid as it would
provide known data for crackers
next prev parent reply other threads:[~2004-04-14 13:58 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-13 15:44 Guillaume Lacôte
2004-04-13 16:57 ` Timothy Miller
2004-04-14 6:48 ` Guillaume Lacôte
2004-04-13 17:45 ` Jörn Engel
2004-04-13 19:42 ` Ville Herva
2004-04-14 6:54 ` Guillaume Lacôte
2004-04-14 9:43 ` Jörn Engel
2004-04-14 10:02 ` Guillaume Lacôte
2004-04-14 11:25 ` Jörn Engel
2004-04-14 12:44 ` Paulo Marques
2004-04-14 13:34 ` Jörn Engel
2004-04-14 13:58 ` maccorin [this message]
2004-04-14 14:02 ` Guillaume Lacôte
2004-04-14 14:39 ` Grzegorz Kulewski
2004-04-14 15:07 ` Guillaume Lacôte
2004-04-14 16:14 ` Grzegorz Kulewski
2004-04-14 15:23 ` Paulo Marques
2004-04-14 15:32 ` Guillaume Lacôte
2004-04-14 17:25 ` Bill Davidsen
2004-04-15 9:28 ` Jörn Engel
2004-04-22 7:59 ` Guillaume Lacôte
2004-04-22 9:18 ` Jörn Engel
2004-04-22 10:20 ` Guillaume Lacôte
2004-04-22 12:15 ` Jörn Engel
2004-04-22 13:06 ` Guillaume Lacôte
2004-04-22 16:00 ` Jörn Engel
2004-04-23 15:16 ` Guillaume Lacôte
2004-04-23 16:57 ` Jörn Engel
[not found] <1KykU-4VD-17@gated-at.bofh.it>
[not found] ` <1KPvh-26S-7@gated-at.bofh.it>
[not found] ` <1KSMw-4P1-13@gated-at.bofh.it>
[not found] ` <1KTfJ-5gK-25@gated-at.bofh.it>
2004-04-14 15:02 ` Pascal Schmidt
2004-04-14 15:25 ` Guillaume Lacôte
2004-04-14 19:29 ` Pascal Schmidt
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