Will it work? BiFeO3

Send them to Hillary. She knows how to take care of them.

If they can be mounted in an external drive case, there's secure-erase commands that will (in a while) rewrite and verify all the available blocks. There's also low-level commands in many drives, that can be entered from the auxiiliaary serial interface, that do something similar.

Some top-of-the-line drives have an onboard encryption key, and once you erase THAT (which takes seconds) all recorded data is forever lost. Big data centers like this feature, for its speed.

If the drive doesn't accept commands, though, all you can do is unscrew the top plate (takes tiny torx screwdriver) and pull off the platters.

Few magnets will erase a hard drive, the airgaps and medium coercivity make remagnetization unlikely. Erasing a platter from a millimeter away, though, is something any supermagnet can handle.

Nowadays, unless there's thousands of adjacent intact bits, you can't grab even one block of data off a drive, let alone find a file system.

I've heard stories of ATA secure erase bricking drives when attempted over USB. (but that may not actually be a problem) ESATA should be fine though. after a successful secure erase the drive behaves like a new one (except for wear and tear)

yeah, that feature where available is triggerd by ATA secure erase if the drive reports that secure erase will take "2 minutes" that's what it's going to do, (typically in well under 2 minutes)

or just slag the whole thing in a furnace.

On a sunny day (Wed, 5 Dec 2018 18:22:54 -0800 (PST)) it happened whit3rd wrote in :

And advanced enemy is able to read what is left after a track is erased, or even overwritten. So it depends who you want to hide your from.

No, they can't. There is a myth that writing over the track does not fully erase it, and data could be recovered by a sophisticated process. But it is merely a myth, dating back to misunderstandings about a theoretical paper on reading overwritten data on old floppy disk technology. The myth has been continued by people selling expensive multi-pass disk wiper software.

Data recovery firms can do a surprisingly good job of recovering some data from damaged disks, after head crashes, fires, etc. But hard disk data that is overwritten, even with simple zeros, is gone.

(Re-mapped sectors and a few metadata blocks are not overwritten, and therefore recoverable, after a "dd if=/dev/zero of=/dev/sda bs=1M" wipe. But it's highly unlikely they contain anything useful.)

I have that knowledge from a paper in sci.crypt many years ago. Something to do with erasure track width IIRC. Never underestimate your adversary. IMO there is also info in using 'write depth' in modern disks.

On other leak, referring to your 'dd' is when burning CDs, DVDs or Blurays what is in the not used parts of the buffers. I verified that (burned a lot of discs) and indeed it may contain things you do expect to be visible.

Sometimes in espionage just a few simple clues, words, will do. These days with trumpet he gives most away himself, makes it so much easier.

But I found a solution for all this, .

Anyways, maybe you are right, and it was just an attemp to sell more expensive stuff alias snake oil, like human made glowball worming fear is used to sell new 'trickety cars.

Now that is a big one.

But ..

On floppies, that was an issue. In particular, if you used a 40-track

overwrite it (as either 40 or 80 track), the original data was still readily accessible with specialist equipment, due to differences in track widths.

For hard drives, this was never a serious problem. On earlier drives there was enough wiggle on the disk head that there might be a little residue left from previous writes - but not enough to be of any concern.

Never underestimate their ability to use FUD to make you waste time, money and effort. And never underestimate their understanding of economics and the concept of value for money. If they want to steal your secrets, it is much more efficient to kidnap your dog and force you to reveal the information, than to try to recover it from wiped disks.

Look, it is /really/ simple. If it were practical to get read even a small percentage of the overwritten bits, then that would be wasted information space. Modern disks don't waste such space - they already store at a level where there is significant possibility of not being able to read the bit they have just written, never mind previous writes. They rely on ECC to patch the gaps.

I read a paper by a group that actually tried to read erased data from a disk. With top-class equipment (specialised electron microscopes), they spent weeks studying a tiny bit of a disk. I can't remember the exact numbers, but I think it was a section of several hundred disk bits - of which they managed to recover about half a dozen. They demonstrated convincingly that it is impossible to recover anything useful from a single erase with zeros, regardless of the time and money spent on it.

That won't stop people speculating on new ways to get information leakage, but it does show the reality.

That sentence is to garbled to interpret, sorry.

Again, the sentence makes no sense. You burned disks and they might contain things that you expected? Usually when I burn a disk, it will be filled with the things I expect to be visible.

A CD or DVD does not have data on it from before. And even if there /were/ recoverable erased data left on your disk, your OS will not see it (at least not with normal tools). So if you have copied data from your hard disk onto a CD and see that the CD has extra leaked information, it came from the /files/ on the hard disk.

Certainly there are many sources of information leakage. MS Office documents are classic cases - they are usually full of information about past histories that you thought you had erased or changed. There have been many examples of pdf documents published with sensitive parts overwritten with black squares - while the actual words were still there in the file.

But a hard disk will faithfully duplicate this data when you write to it, and faithfully delete it when you overwrite.

True. But analysing an overwritten hard disk will not give you these. (Though the fact that it has been overwritten might be a clue.)

Trump does not try to hide things - he is happy to say and do whatever crazy ideas pop into his head, and then re-define history by labelling it "fake news".

blocks.

away, though,

grab even one block

d,

wipe.

nsive stuff alias snake oil, like human made glowball worming fear is used to sell new 'trickety cars.

Jan is just being provocative. Anthropogenic global warming isn't a particu larly good way of selling electric cars - the fact that they work better th an gasoline powered cars, so you can travel further for less money - is a m uch stronger selling point.

Nobody would have bothered to invent anthropogenic global warming to sell e lectric cars, or solar cells.

It happens that anthropogenic global warming is real, which makes it a good idea to burn as little fossil carbon for fuel as possible, and electric ca rs do make this easier, but only a lunatic enthusiast for conspiracy theori es of the sillier sort would put forward the idea that a bunch of climate s cientists would spend years faking results just so that Tesla could sell mo re of his electric cars.

Arrhenius first put forward the idea in 1896, rather earlier than Elon Musk was born (in 1971, as it happens) so it would have been an implausibly lon g-running conspiracy, on top of all it's other implausibilities.

David Brown

OK, so you fall for that ;-)

No, not how it works. When burning an optical disk, say in the simplest way a CD image, it may contain, apart from the files and filesystems, old data, just as old data will be on your harddisk or FLASH memory when it is erased (by you, using the filesystem). Making an image of such a system copies all that data. Example from yesterday, I made some SDcards with a raspberry OS that have special capabilities (no not ionic flight..), but in this case among other things DVB and DVB-T recording and streaming capabilities. All on ext4 filesystem. Then made a coppy to harddisk with dd if=/dev/sdb of=card.img. This card.img is then as file also copied to a bluray disk along with other files. As card.img holds an exact image of whatever I ever have done on that ext4 filesystem including erased parts, all data is now on the CD, DVD, or whatever. All you need is a hex editor and dd to read the sectors. Typing 'strings /dev/dvd | grep -i confidential' may work too, Long time ago in a hacker group I surprised somebody by telling him about secret options in his program found it with 'strings' in a minute,, 'HOW did you do that', strings your binary. disk 969 BD-R-25 Platinum 4x inkjet printable burner LG BH10LS38 ext2 filesystem mount -o loop=/dev/loop0 bluray.iso /mnt/loop cp ... /mnt/loop/ du /mnt/loop umount /mnt/loop growisofs -speed=4 -dvd-compat -Z /dev/dvd=bluray.iso dvdimagecmp -a bluray.iso -b /dev/dvd # l /mnt/loop total 20506404

-rw-r--r-- 1 root root 3774873600 Apr 5 06:34 raspi-pskmail.img

-rw-r--r-- 1 root root 15811477504 May 5 20:59 green_raspi_server.img ....

etc etc

Just a simple example, there is so much more, 'secret' is a hard target.

Some year or so ago I bought a second hand camera on line as replacement for my old canon, wanted the same model, came with card, 'no pictures'. Got all pictures and an AVI from it with just a text editor. Report in sci.crypt with details at that time.

Are you talking about doing a direct copy of your harddisk to the CD - reading from the raw disk partition rather than the filesystem? If that's the case, then yes, you'll get whatever is visible on the raw disk partition. That will typically include files that are deleted but whose data has not been actively wiped or where the data sectors have not been reused for other files.

But that is nothing special about optical disks - it's just standard "del/rm does not actually wipe the data".

Yes, here you will get all the erased but not wiped data. This is standard stuff that has been established for decades, not the voodoo "read residual magnetic data from the disk surface" stuff from TV and films.

Yes, "strings" is very handy for this sort of thing!

So why reply to it? Why let yourself get provoked all the time, and bring this into every single thread in this group? Just ignore it, and stick to the topic in the thread.

Paying him back in his own coin? At least some of the threads here are themes and variations of nonsense, and churning out a paragraph of complementary nonsense is a mildly entertaining exercise - as here.

David Brown

Maybe the guys with the electron microscope peaking at disk surfaces need to read up on what others did.

'Secret' and 'impossible' are often just day-dreams.

We use ours as rifle targets on company shooting trips. We are in Idaho where such things are seen as 'normal'. I must admit, it is fun though.

I once seeded southern Mississippi with infrasonic sound monitors, Hoffmann boxes up on telephone poles. Guess what was the major failure mode?

Obviously they just needed a little more shielding. :^) George H.

Or active armor. There's this neat mix of Tannerite, red dye, and butyl mercaptan, I understand. Doesn't do anything to protect the _first_ target that some yahoo decides to shoot at, but it can significantly discourage said yahoo from shooting at another. At least, not from up close :-)

NASA thought my amps were oscillating intermittently. It turned out to be the previously unknown subsonic mating call of bull alligators.

Or drive a 10 inch nail through the platters.