[lug] drive free space "wiper" recommendation

[Nate Duehr]

> * Patterns are used because sufficiently-motivated labs (think 100k$
>    attack cost) can find traces of previous written values on the
>    media.  That is, if you write "10101010", and then later write
>    "11110000" to the same location, a trace of the original pattern
>    remains.  That trace can be detected with sufficiently advanced
>    gear.
>
>    + This is the origin of the old "37 passes" approach; the idea is
>      that sufficient passes of 1s and 0s would put down so many
>      residual traces, the original would no longer be recoverable.

The vast majority of places I've talked to that have *really* sensitive 
data... you know, the kind of data that $100K to look at the platters, 
and various other hideously expensive techniques, would be cheap 
compared to what the person looking would gain -- no longer wipe 
drives.  They just shred them in machines designed to turn them into a 
very fine powder...

Nate