lkml.org 
[lkml]   [2004]   [Apr]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Using compression before encryption in device-mapper
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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:02    [W:0.076 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site