[Nottingham] Secure deletion of files

[Paul Sladen]

On Wed, 25 May 2005, David Aldred wrote:

Hello David,

> how secure is deletion of files in Linux?  

No worse than anywhere else...

> Specifically, if I'm working on something for my employer using my own PC, and 
> need it completely deleted and irrecoverable afterwards, can I do that?

  for i in `seq 10`; do cat /dev/urandom > "$file"; sync; done ; rm "$file" 

Unless you're excepting the Police forensics then adjusting the number to
'1' would be enough.

> And is there any way of doing it retrospectively, if I were to forget at the 
> time and simply delete the file in the usual way?

I wrote a Python utility the other day to zero the unused blocks of a
unmounted ext2 partition:

  http://www.paul.sladen.org/ubuntu/e2fszero/e2fs-zero.py

Could equally well overwrite it with something that's not zero...

	-Paul
-- 
It sometimes snows here.  London, GB