[Cryptography] Rubber-hose resistance?

[Patrick Chkoreff]

Jerry Leichter wrote on 12/20/2017 10:29 PM:

> Then you don't understand how SSD's work.
> 
> The number of pages actually available inside the SSD may be - likely is - quite a bit larger than the size visible outside the device.  When you write a block, it goes on some page.  You don't know - there's no interface to find out - what page that block lies on.  If you write the same block again, it almost certainly ends up on some other page.  The old page goes into a "to be erased and reused later" list.

Thanks, that's good to know.


> Just because you filled up every block does not mean the list of free pages is empty.  Nor does it mean those pages have been erased.
> 
> There is simply no way to know you've erased all the pages in an SSD using only the interface the device presents to you that makes it look like a disk.

Got it.


> If you don't know enough about how the device you are trying to erase is organized internally to rule out or rule in such possibilities, you have no business claiming you have an effective erasure tool.

Now I claim the opposite:  No such tool exists, and it is impossible to
create one in software only.

The border crossing scenario just got more difficult.  If you copy
anything to the laptop, and then try to erase it using software
techniques only, there is no way to be sure that it's gone.

I suppose now it's safest just to shred the SSD physically before you
return from the trip.  Either return with no hard drive or install a spare.


-- Patrick