[afnog] Untar large files

[Veronique Umutesi]

Dear Stephane

Actually the 100GB is the expected size of the tar.gz file. It is a backup
of mails.

Veronique Umutesi
System Administrator
Broadband Systems Corporation (BSC Ltd) Office : 2nd  Floor, 
Telecom House, Blv de L'Umuganda | P. O.Box  7229 Kigali, Rwanda | 
Call 4141 | Email: veronique.umutesi @bsc.rw Website: www.bsc.rw





-----Original Message-----
From: Stephane Bortzmeyer [mailto:bortzmeyer at nic.fr] 
Sent: Wednesday, October 24, 2012 3:31 PM
To: Veronique Umutesi
Cc: 'Youness Hamidi'; afnog at afnog.org
Subject: Re: Untar large files

On Wed, Oct 24, 2012 at 03:20:01PM +0200,  Veronique Umutesi
<veronique.umutesi at bsc.rw> wrote  a message of 247 lines which said:

> When I do gunzip the tar.gz file which was 100GB becomes 10k!!!

Actually, it is possible. Mathematical reasoning based on the amount of
information in a file: if each possible uncompressed file has one and one
only (otherwise, uncompression would not work) compressed equivalent, then
some files will be larger when compressed.

Could it be a crafted attack? Because usual files do not exhibit this
behaviour. 100 GB was the expected size? (It is a *lot* of data, you work in
bio-informatics or particle physics?)