Re: Default number of overwrites in shred

[Paul Eggert]

Peter Eckersley <address@hidden> writes:

> We might choose 2, because of the 1% chance of recovery cited by one of
> the recovery firms in that paper.  
>
> Or 3, because we're paranoid.

DoD 5220 specifies 3, in a certain way, so perhaps that should be the
default.  But that's a pretty old standard; time has marched on.

CMRR claims that the ATA SECURITY ERASE UNIT command is just as
secure, and is a lot, lot faster.  And NIST 800-88
<http://csrc.nist.gov/publications/nistpubs/800-88/NISTSP800-88_rev1.pdf>
page 8 says "Studies have shown that most of today's media can be
effectively cleared by one overwrite."  I view that as a more reliable
than an offhand unsourced claim by one recovery firm out of many,
which is why I suggested defaulting to one overwrite.