A question about hard drives

I just recently sold a laptop to a friend of mine, but I didn't completely wipe out the hard drive because I didn't see there being anything that was too important on there. I just deleted things that I thought needed to be deleted (software, documents, pictures, etc.) and emptied the recycling bin. I realize that doing that doesn't completely delete everything. I've heard of imprints and things of that nature. He is not exactly IT type of guy, but my only concern is him selling it to someone who actually knows what they are doing. So my question is how hard would it be for someone to find my info on the hard drive in a year or two?

 

it really depends on your individual case........did you use the computer for many years.....how often did you defragment/reformat your harddrive.....how thorough you deleted....and what was on that computer

if you didn't have sensitive information on that laptop like creditcard info....identification stuff like birthdate/phonenumbers etc......banking info you should be fine.....otherwise it would be moderately hard to recover this information but someone who knows what they are doing might get lucky and be able to recover and use the information you forgot to delete.

 

I have had the laptop for about two and a half years. It's been about 6 months ago since I deleted something siginificant. I probably haven't done a defrag in 3 months.

 

Ok, I was told that if I do a system restore 3 or 4 times it would get rid of the information on the hard drive. After restoring the system I did a clean up on the drive and the old files have been compressed to 222 kb. I also defragged the drive twice. All of the fragmented files are gone. Do you think that took care of everything?

 

I don't think so. It's fairly easy to recover data from a drive like that.

To really make sure all data is 100% erased you need a shredder. I recommend File Shredder. Free and effective.

 

Many people done understand how data is "deleted" from their computers hard drives and how data recovery works so I'll give you a high level view from what I know. I'll explain in my understanding but I am by no means an expert and I highly suggest those that spot mistakes to correct me.

1. How a hard drive works (VERY SIMPLISTIC VIEW)
As a VERY simple likeness I'm going to say imagine your hard drive consists of two parts: an index and area. Data (video, phone number, picture, etc.) get put onto area's of your hard disk and then get pointed to by the index. The index basically says this is the area of the hard disk that this data is on. If you like, imagine it somewhat similar to a library. The index is the card catalog, area is shelf space and data would be like a book taking up shelf space. (However it is much more technical, here's wikipedia on windows index: http://en.wikipedia.org/wiki/File_system)

2. "Empty the recycle bin"
When you "empty" your recycling bin what you are actually doing is not deleting any data but deleting the index or pointer to the data. What this does is tell the computer that this area is now "free" to be used by other data and to not pay attention to it anymore... But the data is not destroyed.

3. How data gets overwritten (damaged/destroyed).
After you have designated an area as "free" by deleting the index record (empty the recycle bin) the computer must write over or change the data itself before it is deleted. Kind of like an etch a sketch that you are done with and set down... the picture is still there... until you draw over it or shake it up.

The computer will actually do this naturally given enough time and enough activity. A computer is constantly writing files to the hard drive and deleting files off it and when it finds a need or convenience to use that space you designated as free at a later date it will begin to write over it and damage it until it is no longer usable.

To answer your question... it depends on alot but... If you deleted the file and it was small (text, picture, small video) 6 months ago... and you have downloaded, installed or put new pictures/video onto your computer regularly since then... then the file is likely damaged beyond repair.

If you deleted that important thing as a chunk of a BUNCH of stuff... and have NOT downloaded or used up that much space since then, then there may be parts of it remaining (or the whole thing).

As a personal example:

I have a digital camera. I once filled the memory card all the way up with pictures and then had to delete them all at once. As I continued to use the camera I never filled it up more than 75% of the way when I accidentally deleted a picture I didn't mean to. I used a program to recover the pictures off the card and what I would have been able to recover was the picture I wanted... as well as 4-5 pictures I had deleted a long while ago. The reason was, was because I never filled the memory card all the way back up, the camera never wrote over those "free" spaces that had those last few pictures on them. Your hard drive is the same way. Things aren't gone until the data on them gets wrote over by new data.

SO... Back to your question again though... Will someone find your stuff?
1. They have to look first and even know what they are looking for. So they have to TRY first. That eliminates 99.9% of people.
2. If you data has been overwritten then that means that only experts can find it (99.999% of people eliminated).
3. IF (BIG IF) someone REALLY wants to and KNOWS how with the right equipment... You data can be recovered in part or in total... even if it has been written over. BUT the only people that would do that are people that are already investigating you and know you have data that is worth tens if not hundreds of thousands of dollars. SO... unless you are selling secrets to the Chinese or have invented cold fusion... you are most likely OK.

SO after reading this are you wondering how to keep the layman (computer geek who tries to recover data from your computer) from getting that data? Here's some tips/options:

1. Encrypt sensitive data: There are many programs that do this and certain web traffic is already encrypted (common for bank websites, etc.).
2. Use removable storage such as CD's, DVD's or thumb drives and keep them locked up. Store these files like you would your social security card or birth certificate. BUT... CD's and DVD's are much easier to destroy than thumb drives (melt, burn use duct tape ), thumb drives work similarly to what I described above.
3. Do both! Encrypt what you want to keep secure onto portable media then store it in a safe location. Security is about layers, having both means that a thief has to defeat two layers instead of one.
4. ALWAYS reformat your hard drive before handing it over to someone you don't trust. This ensures that they would have to spend SIGNIFICANT effort to get at your data. It does this by destroying the WHOLE index which is much harder to recover from than simply removing a few entries (deleting files).
5. if you are REALLY worried, before selling a hard drive use a drive wiper or similar tool that advertises hard drive cleaning. These work by REPEATEDLY writing over data on the whole drive to ensure that the disk is unreadable. Note though that on today's drives (60+ Gb's) that this may take a long while to do though.

I realize I have begun to rant or go WAY too far in my explanation... but hopefully this helps! Love the forums, have found TONS of good info on here, just thought I would give back where I could!

 

Ok, well I used the file shredder and wiped the drive as recommended by Philflow so I am assuming that everything is good now.