SSD Drives Much Harder To Wipe

[Renk]

The difficulty of reliably wiping SSDs stems from their radically different internal design. Traditional ATA and SCSI hard drives employ magnetizing materials to write contents to a physical location that’s known as the LBA, or logical block address. SSDs, by contrast, use computer chips to store data digitally and employ an FTL, or flash translation later, to manage the contents. When data is modified, the FTL frequently writes new files to a different location and updates its map to reflect the change.


According to scientists at the University of California at San Diego, different wiping techniques left varying levels of information behind. Up to 67% of data remained when using Mac’s OSX secure wipe. Up to 58% of data was recoverable when using British HMG IS5. Pseudorandom wipes were the worse, up to 75% of wiped data was recoverable.

So, what can we do ?

Maybe wiping the entire free space would be a solution, but it is a large waste of ressources in order to get rid of only one file.



Flash drives dangerously hard to purge of sensitive data ? The Register (http://www.theregister.co.uk/2011/02/21/flash_drive_erasing_peril/)
FAST '11 Technical Sessions (http://static.usenix.org/events/fast11/tech/tech.html#Wei)

[v6ph1]

So, what can we do ?
Don't sell any drives, disks,... with personal data.
And just destroy them physically:
Harddisks can be a good toy for kids within a sand box.
And SSDs can be destroyed with by burning them. - So you may ask someone with a big oven.
Or you just use them with net voltage directly.


Maybe wiping the entire free space would be a solution, but it is a large waste of ressources in order to get rid of only one file.
No this doesn't work well - SSDs use some of the memory for wear-leveling so even a SSD filled with random data contains some of the old data.
Therefore the AHCI specification and SSDs have a command called "Secure Erease" - but I doubt the vendors implemented it correctly.

Writing random data multiple times enhances the amount of cleaned memory cells - but you can't be sure that the whole data is destroyed.

best regards
v6ph1

[Renk]

Don't sell any drives, disks,... with personal data.
And just destroy them physically:
Harddisks can be a good toy for kids within a sand box.
And SSDs can be destroyed with by burning them. - So you may ask someone with a big oven.
Or you just use them with net voltage directly.

v6ph1


Thanks for these advices, but what if I want to wipe my SSD because I plan to sell it ?

I was'nt aware of these SSD's drives particularities. So, the wear leveling make the correspondence between logical and physical locations as clear as mud. And the over-provisioning, specific to SSD Drive (I think that USB Drive don't have this feature) make things even more complex.

Next time, I will realize a full SSD Drive encryption before any use.


But I have a suggestion for the "only one file wiping problem".

What if I:

1) Copy all files (except the one I wan to wipe) from my SSD Drive to some directory on an old good magnetic HD Drive
2) Format my SSD Drive
3) Wipe entire free space of the SSD Drive (->maybe useless ?)
4) Full encrypt the SSD
5) Copy all files from the used directory of my magnetic HD to the SSD

[Sazzy]

Harddisks can be a good toy for kids within a sand box.

I wouldn't exactly give a child a hard disk to play with. Not only is it kind of a weird thing to do, it's pretty dangerous with its sharp corners and it's kind of a blunt object just waiting to crack open a skull... I'd just stick with giving toys to kids.


Might have misunderstood sandbox, hoping you're talking about a real sandbox, where children belong, rather than a sandbox on some computer, being in front of it all day. Make children go outside, tbh.


As far as selling an SSD goes, they don't exactly have a huge lifespan. In SSD Life, it says that mine is still good for about 7 more years, being 1 year old. If you buy a new one for your desktop, stick the old one in your laptop. By the time you buy another one, the lifespan of the one in your laptop will, more or less, be over and you can move the one in your desktop to your laptop again. After that, you can just destroy the oldest one, or something.

So if you don't sell it, you'd be wiping just for privacy sake in case someone stole or confiscate your computer (though then it will always still have data). If that would be the case, you'd have to wipe on an almost daily basis to keep it clean enough, completely destroying its lifespan.

Anyway, if tl;dr; -> Don't sell your SSD, don't really bother with whiping it either. And if you have data that is really so important that you HAVE to wipe afterwards, don't put in on your SSD. Chances are that you won't be needing its superb speed for that kind of data anyway.

Just my two cents.