Path: utzoo!attcan!ontmoh!peter
From: peter@ontmoh.UUCP (Peter Renzland)
Newsgroups: comp.sys.ibm.pc
Subject: Re: "secure" diskette?
Message-ID: <643828809.19406@ontmoh.UUCP>
Date: 27 May 90 17:20:09 GMT
References: <1990May25.165210.25386@cbnewsl.att.com>
Organization: Ontario Ministry of Health -- Decision Support, Toronto, Canada
Lines: 45

vxb@cbnewsl.att.com (vern.bradner) writes:

> I have nearly 300 files on a 1.44 meg floppy disk, many of which
> contain proprietary information. [...]
> I could encrypt each of the files,

Do it!  (You sound as if you have an MS-DOS crypt.)  you can write a script
to do it all automatically.  Or you can transfer all files to your Unix
system, easily encrypt them automatically, then transfer back to MS-DOS
diskette.  You can use the same (secret, unguessable) key for all files.
Each time you need a file you need to
	1. decrypt
	2. use
	3. re-encrypt

(I have two commands, hide and seek, which do 1 and 3 conveniently.)

It's not very much work for each file, it works, and the risk from oversight
is low -- one or two files left in the clear.
You can have a bye command that checks for plaintext files in the secret
directory hierarchy before ending a session, and also on startup, to reduce
such risks.

> Instead, I would like to make the disk unreadable without a password key
> (that sounds a bit like a virus which I don't want!).

(Doesn't sound at all like a virus to me.)  If the (proposed) solution
leaves the actual data blocks un-encrypted, then only the most ignorant
villains will be deterred.  I wouldn't trust it.


Perhaps a *secure* shell might be the answer -- perhaps 4dos or some such
wonder could be taught to decrypt/encrypt any file before/after giving it
to programs to read/write.  It could offer to prompt for a key at each
reference, or use the same key for an entire session.  The second option
could be risky if you walk away from your PC during a session.

There is also the technical problem of left-over, partially encrypted
files when programs fail or are interrupted.

-- 
Peter Renzland @ Ontario Ministry of Health  416/964-9141  peter@ontmoh.UUCP
  o, 
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