Note that it's a better idea to encrypt the stuff you put on the drives than the drives themselves.
Are you sure?
As hard as it is to securely delete data from HDDs
(Peter Guttman's 1996 "Secure Deletion of Data from Magnetic and Solid-State Memory,") to me, at least, the
Wear Leveling technology used by many thumb drive manufacturers would seem to mean that any PLAINTEXT created on a USB flash drive would probably be
much harder to remove by 'erasing' or 'wiping' software AND those crypto aps that claim
specifically to decrypt and then re-encrypt a file the to same disk location (to cover the plaintext.)
Wear Leveling would
probably mean that an 'eraser' would wipe an area that
does not contain the plaintext. For the same reason any encryption ap
wouldn't even know that it was not overwriting the plaintext.
Wear Leveling would seem to make an already iffy situation potentially much worse.
Transparent, On-The-Fly volumes on a flash drive would, at least, seem to overcome
those difficulties since no plaintext is ever written to the thumb drive.
I often use UNIX encryption utes that have also been ported to Win32, which is a handy and portable approach -- but a very long way from perfect. Ya can't win. :sigh: