[comp.sys.ibm.pc.misc] How to protect an MS/PC-DOS file from being copied or the diskette.

djwi@computing-maths.cardiff.ac.uk (D J Williams) (05/19/91)

I would like to know on behalf of a friend how to protect an MS/PC-DOS file

from being copied, or indeed the whole diskette, either 5.25" or 3.5"

Many thanks,
David J. Williams.

danr@bcsfse.boeing.com (Dan Richardson) (05/22/91)

Protecting a file/diskette on DOS, huh? Well, I would assume that this file is
executable code that your friend wrote, right? If that's the case, the program
could be modified so that it looks for a different sector size on the diskette. This was one of the
first "copy protection" schemes in the early DOS days. Peter Norton talks about
it in his Programmers Guide to the IBM Personal Computer, I believe. If you're not
that worried about the disk being copied and just one file is your concern, you
could try to disguise the file by imbedding a 254 character at the end of the file name. This works for users who aren't particularly savvy about the workings
of the PC, but more seasoned "pros" can catch on to this in short order.
How about changing the file's attributes to system/hidden?
If you really wanted to get militant about it, you could utilize one of those
software key ("dongle") things that some vendors sell in magazines like Computer
Language.
Anybody else in Netland know of a better scheme? This is off the top of my head
*early* in the morning. I need a shot of caffeine...
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Dan Richardson                  | "If there's anything more important than my
Analysts International Corp.    |  ego around here, I want it caught and shot
for Boeing Computer Services    |  now!"    --Zaphod Beeblebrox
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