My Ex wants something to overwrite securely all space left by those deleted files; as we all know deleting a file doesn’t delete the actual data off the disk. The reason being she wants to be able to pass on her old laptop to a friend in a working state, so my normal method of hitting the disk with a large hammer isn’t going to work in this case.
I haven’t played with tools like that in a while, the last one I used was an anti-theft one that splattered my name across all the freespace bytes on the disk, that was on a 486 :-). You don’t see programs like that anymore.
But onto programs that will only erase freespace to ensure deleted files are actually (after being removed from windows trash as well) deleted forever.
Searching on google provides links to quite a few secure erase programs, however most of them are applications that just add a trash can to the desktop to allow secure erasing of deleted files, which is not what I wanted.
The only FREE program I found that would do what I wanted was SDelete; which as it one of the sysinternals utilities I automatically assume it’s going to work well anyway. And now microsoft owns sysinternals the SDelete tool is available from the micreosoft site itself, so on the assumption that microsoft regularly checks for viruses in the software they provide for download thats another confidence tick. Confidence always being key when about to run a program that is going to play with your disk :-).
The SDelete program is available at
http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx
As always, take a backup of your system before playing with any tools like this, no matter where they are from.
They only thing that may put people off using SDelete is that it is a command line tool. Having said that users that don’t want to go near the command line should perhaps not be playing with disk erasure tools.
So I downloaded SDelete into a personal directory to have a look at it. The inbuilt help is pretty sparse, but relatively self explainatory.
C:\Marks>sdelete -?
SDelete – Secure Delete v1.51
Copyright (C) 1999-2005 Mark Russinovich
Sysinternals – www.sysinternals.com
usage: sdelete [-p passes] [-s] [-q]
sdelete [-p passes] [-z|-c] [drive letter]
-c Zero free space (good for virtual disk optimization)
-p passes Specifies number of overwrite passes (default is 1)
-q Don’t print errors (Quiet)
-s Recurse subdirectories
-z Clean free space
So I ran it using the disk option. It said it was doing what it was supposed to be doing, a percentage update of how far it had progressed was displayed throughout. And at the end a simple message to say it had done what was requested.
C:\Marks>sdelete -c -z -p 2 C:
SDelete – Secure Delete v1.51
Copyright (C) 1999-2005 Mark Russinovich
Sysinternals – www.sysinternals.com
SDelete is set for 2 passes.
Free space cleaned on C:
C:\Marks>
The only main issue with sdelete is the statement on the download page
SDelete implements the Department of Defense clearing and sanitizing standard DOD 5220.22-M, to give you confidence that once deleted with SDelete, your file data is gone forever. Note that SDelete securely deletes file data, but not file names located in free disk space.
so data only is deleted, the filenames are left, so hopfully you don’t have incrimiating filenames :-). The download page explains why that is the case, and it seems perfectly resonable to me. I’ve never read the DOD 5220.22-M standard and don’t intend to, I’ll assume its a secure delete.
The other toatally expected issue is that this can take a long time to run depending on the size of the disk being cleaned and how much free space you have on it. I ran it on a 110gb disk that had 83Gb free; and quickly decided just to leave it to run overnight. It had completed by the morning (so within 8hrs) but I was only using two passes, the standard for ensuring a disk is securely erased is 5 so expect a much longer time if you are serious.
At this stage I can’t actually say the program works as expected, and am relying on a microsoft website not fibbing to me. I really need to download some file recover tools and make sure that there is actually nothing recoverable that is usable. Thats on the todo list.
