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#1
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Any better way to wipe data from a HDD?
I was advised that in addition to fdisking and formating a hard disk
drive I should do the following, then fdisk and format again. Are the following instructions a sure-fire way of erasing data? Many thanks. ----- Enter the following lines at the debug prompt (-) followed by the enter key. Note: this completely erases the MBR and your whole drive. F 200 L200 0 a 100 mov ax,301 [note from here on you may see a number like fff:1234 [type all commands next to this number [do _not_ press enter when this number appears. mov bx,200 mov cx,1 mov dx,0080 [note: use 0081 for second fixed disk int 13 int 3 (enter a blank line here) G=100 q |
#2
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Danny Jenkins wrote in message om... I was advised that in addition to fdisking and formating a hard disk drive I should do the following, then fdisk and format again. Are the following instructions a sure-fire way of erasing data? Depends what you mean by sure fire. If you dont have anything illegal on the drive, there isnt any point in going to this much trouble if you just want to ensure that anyone you sell/give the drive to wont be able to get anything useful off it. Its rather simpler to just use something like http://dban.sourceforge.net/ The only real risk with something like that is that there is a microscopic risk that its actually a scam/trap deliberately setup by 'the authoritys' to catch those who store stuff like child porn or drug money laundering details on their hard drives etc. ----- Enter the following lines at the debug prompt (-) followed by the enter key. Note: this completely erases the MBR and your whole drive. F 200 L200 0 a 100 mov ax,301 [note from here on you may see a number like fff:1234 [type all commands next to this number [do _not_ press enter when this number appears. mov bx,200 mov cx,1 mov dx,0080 [note: use 0081 for second fixed disk int 13 int 3 (enter a blank line here) G=100 q |
#4
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Previously Danny Jenkins wrote:
I was advised that in addition to fdisking and formating a hard disk drive I should do the following, then fdisk and format again. Are the following instructions a sure-fire way of erasing data? This is rather unreliable. First, it depends on the BIOS seeing the whole drive. That is not necessarily the case. Int 13 classic sees only the first 504MB. Since modern OSes do their own disk access the BIOS only needs to see the beginning of the drive where the boot code is usually located. On a closer look into the code below, it does not overwrite the drive at all! It rather overwrites sector 1 on disk one single time. You can recover from this. It requires finding the partition boundaries but is feasible. (If sector 1 is the partition table, I am not quite sure, since it has been a long time since I did BIOS calls. If it is the MBR, a rescue floppy/CD is all it takes fro recovery.) Fdisk and format will also not erase any data. They will just remove the administrative information. Whoever told you to use this for disk erasure does not know anything about the subject or lied to you. In addition there is no sure-fire way for disk erasure. Commercial data recovery companies claim they cannot recover a single overwrite, and given todays drives that may or may not be true. There is valid speculation that with enough effort iy may be possible to recover from one or even a few overwrites. However that would be expensive and tedious. My advice: Use one overwrite with zeroes to protect against most attackers. If you have really important data on the disk overwrite several times with random data. If it is even more important destroy the disk physically afterwards. Just burning a disk is often not enough. Recovery from that is something data recovery companies can often do. You need to shred or melt it to be safe. Best tool for overwrite: Linux. I use knoppix (- google) and dd_rescue for this type of task Boot, go into root shell and do dd_rescue -w /dev/zero /dev/hda Overwrites with zeroes and gives you a nice progress indicator and tells you how much data has actually been overwritten. Repeat as needed and with /dev/urandom in the first argument for random data. Regards, Arno ----- Enter the following lines at the debug prompt (-) followed by the enter key. Note: this completely erases the MBR and your whole drive. F 200 L200 0 a 100 mov ax,301 [note from here on you may see a number like fff:1234 [type all commands next to this number [do _not_ press enter when this number appears. mov bx,200 mov cx,1 mov dx,0080 [note: use 0081 for second fixed disk int 13 int 3 (enter a blank line here) G=100 q -- For email address: lastname AT tik DOT ee DOT ethz DOT ch GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F "The more corrupt the state, the more numerous the laws" - Tacitus |
#5
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Have a look at this:
http://staff.washington.edu/jdlarios/autoclave/ NB: if your data is really valuable, a proper physical destruction is the only solution. -- ;-) |
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