Delete --- all flavours ...
The action Delete results in various responses ranging from move to destroy.
In Win98, highlight a file and press delete. The file gets moved to the Recycle folder on the same drive. Explorer will display the file in the Recycle Bin. You can click the Recycle Bin and re-visit the file. In this case, Delete means copy file to Recycle before deleting from the current location.
If you Right Click your Recycle Bin, you can choose to have Explorer not save the file for possible future use, but to delete it permanently.
Windows 98, and earlier versions are graphical user interfaces running on top of DOS. Windows executes many file functions through this underlying DOS. So to predict what happens with files, one must examine how DOS works.
DOS stores files on disk. Along with the data, DOS stores the location where the data may be found. When DOS reads data, it first must determine where to look. When DOS writes data, it first must determine where unused disk space is available.
When DOS deletes a file, it doesn't remove any data, it simply marks the data as unused. The next time a file gets written to the disk, and DOS searches for suitable locations for it, DOS will find this space that was used previously, but is now marked as available, and use it.
So, until DOS writes data to the space previously occupied by a file, that file will remain exactly as it was written, except for one small detail: The first letter of the file name will be replaced by a character indicating the file was deleted. Un-delete programs can change this file from deleted to current by restoring the original first character of the file name. (Actually, any letter will do: A deleted file ROB.TXT can become BOB.TXT OK.) Norton's popular UnErase presents file names as ?ileName.Ext and expect you to supply the first letter.
It now becomes clear that to be sure a deleted file doesn’t return and bite you, you not only need to delete the file, you need to replace the data previously occupied by that file too, including the directory entries DOS uses to locate this data. Several programs are available which will repeatedly overwrite unused disk space, including unused directory entries, insuring deleted data remains unrecoverable. Some even meet Dept of Defence standards.
But there’s more…
Many programs store temporary working files. Some automatically make periodic back-ups while you work. Often these files are stored with the hidden attribute set. As I type this post in Word, I’m working on a document called Delete, I can open Explorer and see a hidden file $~elete, a file most people wouldn’t be aware of. (In Word, click Tools, Options…,Save Tab, and make your choices.)
Windows itself maintains copies of your work. Virtual memory, or swap file, (WIN386.SWP) holds Windows’ work in progress, which may include work you’re doing. Couple this with caches of Web pages, Cookies, History, Favourites, Links, Quick Launch choices, and Shortcuts, and your system contains sufficient information to re-construct much of your recent work. Check the files in C:\Windows\Applog and find the history of the programs you run. Click Start, Find, Files, *.*, Date tab, and enter 1 day, and you’ll see a list of files you accessed today. Imagine your boss learning that you developed Solitare expertise on company time. Typical systems contain many additional Log files.
While in Find, enter some text you used recently and see how many places it’s stored. An eye opener!
And let’s not forget E-mail folders, caches, outboxes, and deleted E-mails too. Outlook Express has an option allowing folders to be compacted. Un-compacted folders contain data MARKED as deleted. You want this stuff gone.
Securing secrets from prying eyes is a challenge on Windows machines. I’d suggest installing Tweak-UI, click Paranoia tab, and indicate you want everything to disappear. Delete unwanted E-mail, compact mail folders. Take a close look at address book too. In IE, delete Temporary Internet Files, and History. Choose to view hidden files in Explore. Check through My Documents. Save files with passwords if the option is available (In word, File, Save As…(Options button)), but be aware that these can be cracked in seconds. I’d search the Registry for stuff I want to keep private too. Then boot to DOS. In DOS, erase swap file, DelTree cookies folder, erase logs in Applog. Then use one of those packages that wipe empty disk space to a secure standard. This may take a few hours on a large disk.
I haven’t covered many other items such as phone numbers in dial-up ISPs, file access dates, or data stored in images or back-ups. I’m sure the list can go on and on and on, but I’ve already overstepped the scope of your original question by quite some distance. I’m responding to some privacy issues in the same post.
In short, you can un-delete in DOS, sometimes.
Cheers, PW. |
