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From: john@frog.UUCP (John Woods, Software)
Newsgroups: sci.crypt
Subject: Re: Erasing magnetic media
Message-ID: <1908@frog.UUCP>
Date: Wed, 4-Nov-87 17:33:00 EST
Article-I.D.: frog.1908
Posted: Wed Nov  4 17:33:00 1987
Date-Received: Sat, 7-Nov-87 11:50:13 EST
References: <7566@reed.UUCP> <1175@cup.portal.com> <6964@pur-ee.UUCP>
Organization: Superfrog Heaven [ CRDS, Framingham MA ]
Lines: 23

In article <6964@pur-ee.UUCP>, 3ksnn64@pur-ee.UUCP (Joe Cychosz) writes:
> In article <1175@cup.portal.com> Kenneth_R_Jongsma@cup.portal.com writes:
> >Others may be interested.... The actual requirement is that the media
> >be written with at least 100 alternating 1/0 bits. i.e 11111 00000 11111,
> >etc...  Some media cannot be declassified. If memory serves, the old (still
> >in use in the Minuteman system) core memory had to be destroyed.
> I believe that once a media has been used for classified data, it can not
> be re-used for unclassified data.  To dispose of, it must be destroyed.
> It is quite easy (given the proper equipment) to recover information that
> has be written over several times.

At the Concourse Computer Center at MIT, most of our tapes were used tapes.
Many of these had little stickers saying "SECRET", which had been blotted out
with a magic marker.  Presumably, there are ways to PREVENT the recovery of
information that has been on the tape.

--
John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101
...!decvax!frog!john, ...!mit-eddie!jfw, jfw@eddie.mit.edu

"Cutting the space budget really restores my faith in humanity.  It
eliminates dreams, goals, and ideals and lets us get straight to the
business of hate, debauchery, and self-annihilation."
		-- Johnny Hart