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I have to securely wipe all data from a hard drive as I'm going to give it away. I plan on using the dd under linux utility to do so, after a little bit of research, I found two ways of doing so:

  • dd if=/dev/zero of=/dev/sde Will overwrite the WHOLE hard drive with 0 characters, this technique apparently makes data easier to recover, althought still hard to pull of.
  • dd if=/dev/urandom of=/dev/sde Will overwrite the WHOLE hard drive with random data.

Which one of these two technique is the best? Would overwriting the whole hard drive with random data put to much strain on it?

Informancien
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1 Answers1

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In practice using either will work similay only a modern drive (with caveats below) however using /dev/urandom is slower and safer. Slower because it needs to build entropy, safer because it prevents the (practical on very old drives) attack of amplifying the read signal to recover and differentiate a 1 from a 0. The reality is data is spaced so close together on modern drives the zero amplification attack can not work because drive tolerances are to tight and close to theoretical limits.

A more realistic issue with both solutions is that DD may not write parts of the drive marked bad and thus fragments of data might be recoverable.

davidgo
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