Utilities use temporary files in %temp%, all the time.
When Windows "deletes" a file, all it has done, is
flipped a single byte in the %MFT table. It does not
remove the cluster contents. Utilities like Recuva,
can flip the byte back.
If you were to engineer a file system to "tromp" all
over every last bit of an deleted file, that would be
non-scalable and slow.
The closest equivalent to doing that, is Heidi Eraser.
It must be installed in advance of any "secret" "crypto"
When a %temp% file shows up, and Windows "deletes" it,
Heidi can listen to the journal and take details.
It knows what clusters to stomp on.
If you "deleted" a 10GB file, then you'd have to wait
while Heidi does 10GB of writes to clean the disk areas.
This is like Sdelete cleaning white space, the difference
is, it's happening while you are working.
Having higher speed storage devices, may help hide
the performance issues Heidi might cause.
But word of warning, computers leak. Despite your best
efforts, you might still find stuff. My favorite
peeve, is if I use Windows to search for password "12345678",
then the registry record of "what I searched for"
now has "12345678" in it :-) I think you can see
the unintended comedy, of "searching for a secret",
by having the "secret" now recorded in the Registry.
Try and erase that now (bulk erase the registry).
The way to search for something, is to boot a second
OS and do the searching from there. For example, Linux
LiveDVD OSes, store working files in RAM (TMPFS) rather
than on rotating media. If I use my Linux Mint stick
without persistence, then when the stick is unplugged
after a session, nothing of what I was doing is recorded
So there are ways to improve your technique, when
I did a test on sdelete, and I *did* find all sorts
of bits of my test string on the drive later. This is
all part of the "fun", is learning where the leaks
come from, and trying to figure out a way to stop
them from happening.
My guess is, a policeman is only too glad when you're
using Windows. Your dirty fingerprints will be all over
the place, and he'll be wallowing in evidence. It's not
easy to make a drive "squeaky clean", short of bulk
erasing it and removing the OS in the process.