clean install

[Baz]

my son has a computer to sell maybe as he has his laptop now.If he sells it we need to delete all info etc that is on it, best way been a format and clean install, Yes?

If we do this could we re install Office which was on it originally or can you only install it so many times.

[kinmel]

If I am disposing of a computer I always run Kill Disc first and then do a re-install of the O.S.

If you want to include any other software give them the disks and COA and let them install those themselves.

[Technical Ben]

If you can put the disk in a second pc, you could also use eraser. Format the drive, then select "erase blank space" or entire disk. But I think Kinmel's method is simpler and easier.
You probably only need a single pass of random data to permanently delete any details. This needs to be done, as if the data is not written over, it can be retrieved. Check my post out on how I recovered my entire HDD for an example of doing the opposite! 

[D-Dan]

I hate to say it, but the only secure way to completely wipe a hard drive is with a hammer. Professional recovery software is so good these days, even a military wipe may not be enough.

Having said that, unless the buyer has access to a sterile lab and highly sophisticated equipment, you are probably OK.

Steve

[Gary]

I always used Darik's Boot And Nuke, but as has been said if someone wants to....tbh though being wiped 35 times should be enough for most people 

[Technical Ben]

I hate to say it, but the only secure way to completely wipe a hard drive is with a hammer. Professional recovery software is so good these days, even a military wipe may not be enough.

Having said that, unless the buyer has access to a sterile lab and highly sophisticated equipment, you are probably OK.

Steve

AFAIK even a single write only, with random data is irrecoverable with software alone. Unless you can prove otherwise? You can try and read the left over magnetic charge, but you need special equipment for that, plus a sterile lab.

[Glenn]

Forensic software and time is all you need, it did cost $50,000 to install though. Scanning a 20gb drive, we recovered approximately all of the data ever held on the drive, even after several re-images.

[Rik]

Luckily, the average person isn't going to go to such extremes.

[Glenn]

It does show though that just an erase won't render the drive unreadable, the only safe way is a hammer or crush it.

[Rik]

Which is what I always do.

[Technical Ben]

I'd love to have data that was worth £50 grand.
Only software? Wow. It must have scanned for information between the information. I did not think you could get the drive heads to do that through software only.
I'd like to use a disk grinder to turn my old hdd into dust.

[Rik]

I often use bolt cutters on the smaller disks.

[Glenn]

Ben it was $50k just to get the company to install the software, not to buy it in the first place.

The security manager that had it installed, showed Ericsson how secure Pointsec wasn't. He asked to borrow one of their laptops, around 30 minutes later he gave it back, at the windows login screen, you get there after putting in the Pointsec password. Needless to say, PointSec updated their system fast.

[Technical Ben]

I'm sorry Glenn. But can you confirm your HDD was "erased" with a random data entire disk write? As everything, including "data recovery" firms shows that this cannot be recovered.
HDD crashes can be, I did one for free last week. But erased data is a lot more of a problem (it's overwritten with new data. How do you recover that?).

Source http://www.actionfront.com/ts_dataremoval.aspx and wiki.

(Oh, you said encryption in one post, and erasure in another? I'm confused as to which your talking about. I agree encryption is breakable. But erasure removes the data from the disk. Same as "burning" a paper record. Just in a magnetic version instead.)

[Glenn]

As far as I know it was, but I don't know with what method.

I'll ask my colleague at work to contact the chap, he is on his Facebook friends, I'll see if he can remember the software name involved.

[Technical Ben]

Here is why I am skeptical (that he just brute forced the password, like "opensesame" etc). Wiki notes it's impossible, at the bottom, even in a lab... http://en.wikipedia.org/wiki/Data_erasure
Encrypted disks are another kettle of fish. I'd never trust it beyond a home user security really. But there is no other option.

[kinmel]

If you need true security against the Government, you can house your drives in one of THESE and have a panic button by the front door to start it up.

[Rik]

I'll take two.

[Glenn]

The software used was Encase examiner, but the drives were not erased, just overwritten.

[Technical Ben]

Thanks Glenn. The part of the suite that does the work in question is EnCase Forensic. It looks to be a fully features enterprise scale and quality file recovery and data collection (for law cases or legal requirements) tool.
I'm not saying you should have erased the HDD, just that the technician would have had a less impressive result if you had.
The tool does look like it does exactly what you would need though. Even if the disk was erased in software, there is a likely hood that windows stored file data else where (names of files, file sizes etc). So the tool could be used to prove what type of data was on a disk, even if you cannot recover it.
I think Gary's link to Boot and Nuke should take those last bits of data out though. Leaving you with a HDD as clean as when it left the factory.


(Interestingly, in my quest to find info on the systems, I found out that HDDs can support total erasure of data. However, no motherboard companies support this, as they do not want to be accused of deleting a customers data. This would cause massive lawsuits if ever misused for them. However, the Defence agencies etc who do need this option, do get it on their HDDs.)