Laramie wrote:
I knew a couple guys who would attend DefCon every year. They explained to me that an area on disk, is not like a checkbox, but an area, and that it would be possible to read the last several writes to that area. Consequently, the best way to clear a disk is to overwrite everything at least ten times with random data. Then crush it.
Writing over with random data, like cipher does, should be sufficient.
I set cipher to write all 0s, then all 1s, then random data.
That way you or someone else can use the drive or recycle it without fear.