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OT: Hard Drive wipe

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  • #16
    Originally posted by rjs44032 View Post
    +1 on what macona said. There are utilities that write 0s to all areas of the drive. This essentially wipes out all residual data.

    Then if you're still nervous, destruction fun!

    Best Regards,
    Bob
    There is some suspicion that zero over write may leave residual magnetism that can still be recovered. I read a paper on it when the zero over write became the defacto standard some years ago. Because the zero over write is uniform the data may be reconstructed by reading variances left behind by the prior data. The conclusion was zero over write probably won't keep Langley from recovering some of your data, but when paired with drive shredding it was the best thing you could do at the time. They went on to talk about hardware specific overwrite routines with a good random digit generator, and went off into melting down drives.

    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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    • #17
      I use Enhanced CCleaner and it it can be used to wipe the hard drive with 35 passes.
      Location: Saskatoon, Saskatchewan, Canada

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      • #18
        Eh, trying to magnetically wipe the drive is too much work, plus i wouldnt be surprised if more modern drives actually have some sort of shielding to keep them from being easily wiped by magnets. If you have to open the case to get the magnets to do their thing, easier to just smash the platters with a hammer. If you dont have to open the case, its still easier to smash the platters with a hammer

        Point is hammers are both faster and more fun. Alternately, if you have access to a gun range, a couple 6mm holes do a good job at scattering your data

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        • #19
          Couple of years ago my sister asked about wiping the drive of a laptop we'd given her some years before which had died. Neither she or her husband have any tech knowledge at all.

          I told her "have Dennis take it out in the back yard at midnight with a full moon and drive a stake through its heart". Dunno how much of the ritual they observed, but I know he has some big hammers...

          -js
          There are no stupid questions. But there are lots of stupid answers. This is the internet.

          Location: SF Bay Area

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          • #20




            Random blobs of power expressed as that which we all disregard
            Ordered states of nature on a scale which no one thinks about
            Don't speak to me of anarchy or peace or calm revolt, man
            We're in a play of slow decay orchestrated by Boltzmann

            It's entropy, it's not a human issue
            Entropy, it's matter of course
            Entropy, energy at all levels
            Entropy, from it you can not divorce

            And your pathetic moans of suffrage tend to lose all significance

            Extinction, degradation, the natural outcomes of our ordered lives
            Power, motivation, temporary fixtures for which we strive
            Something in our synapses assures us we're okay
            But in our disequilibrium we simply cannot stay

            It's entropy, it's not a human issue
            Entropy, it's matter of course
            Entropy, energy at all levels
            Entropy, from it you can not divorce

            A stolid proposition from a man unkempt as I
            My affectatious nature I can't rectify
            But we are out of equilibrium unnaturally
            A pang of consciousness of death and then you will agree

            It's entropy
            Entropy, it's matter of course
            Entropy, energy at all levels
            Entropy, from it you can not divorce


            ---Greg Gaffin
            DZER

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            • #21
              I've picked up the odd HDD to hack just for fun or parts, and some were drilled through the platters. Seems an effective way to prevent them from being read.

              I recently read an article on how hard is it to erase magnetic media. Hard to know what to believe, but the consensus was that it wasn't exactly easy. But I don't give a disc much chance against a neodymium magnet passing directly over it in contact- though even a small spacing like perhaps 1/2 inch is likely to leave data still readable. The field from a record head is tiny, but it is in direct contact and focused, so perhaps the local field strength is higher than a typical magnet could provide- unless as I said it's in direct contact.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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              • #22
                Originally posted by darryl View Post
                The field from a record head is tiny, but it is in direct contact and focused
                The head is not in direct contact with the platter - ever (except when they crash).

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                • #23
                  Originally posted by OaklandGB View Post
                  Hey maybe you are on to something!! Sounds like a perfect excuse...er...reason to buy a hydraulic press for the garage shop....hmmmm....
                  Gonna "compress" those old files?

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                  • #24
                    I keep a copy of R.A.s "Never going to give you up" around for this very purpose .
                    --
                    Tom C
                    ... nice weather eh?

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                    • #25
                      I know the head rides on a cushion of air, but it's so close that it's virtually the same- as opposed to any gap that you could see.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                      • #26
                        OK, On the subject of strong magnets, that is NOT a good way to ensure erasure. I worked in TV engineering for many years and we erased tapes all the time. Video tapes, usually of the 2" variety but later 3/4" and 1/2" ones and, of course various types of audio tapes. This is basically the same idea as erasing a hard disk except the magnetic media is on a thin, plastic tape instead of aluminum or other material platters. It was necessary to completely erase the tapes before using them again because with the erase head in the recorder there was always a possibility of the previous recording remaining, if only at a lower level.

                        We did know that it was not a good idea to have a strong magnet around a magnetic tape, but it also would have been difficult to completely erase them with even the strongest of the permanent magnets. They would align most of the magnetic domains in one direction, but still leave some of them in the orientation in which they were for the previous recording. And that could become a low level signal when the tape was re-used. Another reason for not using a permanent magnet to erase is that the recording magnetic fields would then need to overcome that magnetic bias. But that is not an issue here.

                        What we did use was a degaussing coil that was powered by an AC power source, usually the 115VAC household current we all use. The AC or alternating current provides a magnetic field that also alternates it's poles. But even that had to be used with a special technique. The coil was energized and the magnetic tape was brought into the coil's field. Often the tape had to be rotated because it was a lot larger than the area where the field was the strongest and very wide tapes had to have the reel turned over to reach both sides. But, and this is the important point, the tape was then withdrawn from the coil (or the coil from the tape) BEFORE the AC current was turned off. This withdrawal was usually for about two to four feet. This produced a period of time in which the alternating N-S field of the coil was diminished by the increasing distance for each half cycle. The tape was magnetized first in one direction and then in the other and each time the amount of magnetization was less than the last one. After this what remained on the tape was only a very small magnetic field that could have only very little effect on the new recording.

                        The lesson here is that a permanent magnet, no matter how strong it is, may destroy the ordinary usability of the magnetic recording, while not completely erasing the information on the magnetic recording media. That is why we used the alternating field and also used the technique of somewhat slowly withdrawing it from the area where that field exists.

                        And this is much of why a good lab, as you may find at the FBI or NSA, can retrieve data from a disk that has been either written over or erased with a permanent magnet. They have equipment that can detect the weak magnetic differences left after "erasure" with such a permanent magnet. The AC powered, degaussing devices, when PROPERLY USED can achieve a much better degree of erasure.



                        Originally posted by darryl View Post
                        I've picked up the odd HDD to hack just for fun or parts, and some were drilled through the platters. Seems an effective way to prevent them from being read.

                        I recently read an article on how hard is it to erase magnetic media. Hard to know what to believe, but the consensus was that it wasn't exactly easy. But I don't give a disc much chance against a neodymium magnet passing directly over it in contact- though even a small spacing like perhaps 1/2 inch is likely to leave data still readable. The field from a record head is tiny, but it is in direct contact and focused, so perhaps the local field strength is higher than a typical magnet could provide- unless as I said it's in direct contact.
                        Paul A.
                        SE Texas

                        And if you look REAL close at an analog signal,
                        You will find that it has discrete steps.

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                        • #27
                          Back when I did data security, there were several different standards that you could work towards. I vaguely recall that any "wipe" via an overwrite with repetition of the same data can be recovered by experts. Overwriting with random data is the best way to do it. And I recall the gold standard was 7 wipes using random data for each pass. It took all day for big disks.

                          Degaussing is quick and worked well in most cases, since any MS Windows or DOS machine would barf as soon as it hit the right corrupted directory structure. But that does not stop experts. Degauss plus a few holes from a drill press slowed down most expert tools to where it was not worthwhile.

                          For disks with data that you never wanted to see referenced on a grand jury subpoena we'd send the disks to a company that certified that they destroyed the disks by shredding followed by heat. That was in addition to the multi pass wipe.

                          Does all this work? Only if you do it. I still have a disk from a Solaris workstation that was used at NASA's Ames Research Center. I know that because they did not do even a cursory wipe before throwing the whole workstation in the dumpster. It booted right up. Idiots.

                          At the end of the project, there is a profound difference between spare parts and left over parts.

                          Location: SF East Bay.

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                          • #28
                            Yeah, random data overwrites are the way to ensure the data cannot be recovered from the disk using forensic tools - a magnet is insufficient (as pointed out, coverage is not 100%), and writing with zeros doesn't work because the hard drive head writes at a slightly different position every time (if you need a reason why, take your pick - thermal expansion is the most likely).

                            But it's important to keep some perspective as to what the threat model is. Somebody dumpster-diving your laptop in order to steal your identity and resell it for fifty bucks isn't going to pay fifty thousand dollars to perform a data recovery. Likewise, a competitor isn't going to fork out that kind of money unless they are absolutely certain that the information on the drive will enable them to put you out of business, generating profits in excess of any data recovery costs.

                            This is why physical destruction of the disk platters is often the best choice, as it is fast, cheap, and effective for most data (for the rest, chuck the drive in a heat-treat oven for a few hours). This assumes disposal rather than resale is the goal. My personal opinion is that resale results in data theft: I never resell computer equipment (and I never hear the end of it, either).


                            Now for the really bad news: Flash memory (SD cards, SSD) cannot be erased. Every write occurs at a new location, with the old location marked as invalid.

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                            • #29
                              There have been organized operations that buy computer recycling and mine it for data. Do not under estimate "dumpster diving." To be fair your drive is probably less likely to be recovered in a land fill than it is if sent to a recycler.
                              *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

                              Comment


                              • #30
                                Every now and then we get some storage data media from several government departments to destroy by our shredders. They bring a container and wait to see it being destroyed.
                                Helder Ferreira
                                Setubal, Portugal

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