From: tcmay@sensemedia.net (Timothy C. May)
Date: Thu, 27 Jul 95 22:48:37 PDT
To: cypherpunks@toad.com
Subject: Re: mac share/freeware app for overwriting unused hd space?
Message-ID: <ac3dc7f7060210042380@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 2:27 PM 7/27/95, j. ercole wrote:
>Can anyone point me towards a program that's freeware or shareware that
>will overwrite all the unused i.e., "trashed" space on my hard drive(s)?  I
>sincerely apologise if this is a faq.  I know norton's will do it but I
>don't presently have that installed on my machine.  Thanks oodles,

Well, getting the commercial products (fairly cheap, for Norton) is the
first line of defense if you're paranoid.

Erasing a file and then filling the disk with other files (even copies of
existing files) will do the same thing, albeit only once.

At the most serious level of attack (the "threat model"), such as the FBI
labs in Quantico or the NSA, there are reports that specialized disk drive
heads are used to recover earlier signals that are not erased even with N
active overwrite steps (apparently the head jitter in most drives means
that each write cycle is slightly different, even on the same disk region,
and a slight "shadow" or "ghost" of previous writes can sometimes be
extracted).

--Tim May, who hopes this will not reignite the thread about how to use
thermite to permanently erase disk drives

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