Re: CDF Security
- To: mathgroup at smc.vnet.net
- Subject: [mg128503] Re: CDF Security
- From: John Fultz <jfultz at wolfram.com>
- Date: Thu, 25 Oct 2012 23:32:46 -0400 (EDT)
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In general, it's difficult to lock down CDF to totally prevent this sort
of thing. CDF is, after all, an open, plain text format which any
sufficiently knowledgeable user could crack open with only modest
effort. So no solution you're going to come up with is foolproof.
That being said, I strongly suspect that your current method is using
global variables and is thus much less foolproof than it could be.
Probably the quickest and easiest way to deal with this particular issue
is to, when creating your notebooks, make sure to choose the menu:
Evaluation->Notebook's Default Context->Unique to this Notebook
This will, at least, make sure that notebooks aren't colliding with each
other and using the same variables.
jfultz at wolfram.com
User Interface Group
Wolfram Research, Inc.
On Oct 25, 2012, at 12:41 AM, Gregory Lypny <gregory.lypny at videotron.ca>
> Hello everyone,
> I create CDF assignments for my students. They are pretty basic. A
student selects their ID using a pull-down menu in a Manipulate, and the
notebook is populated with randomized questions. The answers are buried
in the document and are inaccessible until the deadline passes a week
later, at which time I upload the same CDF but with a checkbox in the
Manipulate that displays the answer under each question. So, at any
given time, students have old CDF assignments for which the answers are
accessible and new assignments in which they are not. I received a
disturbing email today from a student who claims that he was able to see
the answers for the new assignment by doing the following on his PC.
> - Open new quiz (where answers are blocked) in Mathematica (not the
CDF player), enable dynamics when prompted, select ID in the Manipulate
> - Open old quiz (where answers are not blocked), enable dynamics,
> - Minimize both documents and Mathematica
> - Reopen old quiz and then close it
> - Reopen new quiz, and sadly, the answers are revealed
> He sent me a screenshot showing the answers, but I was not able to
reproduce this on my Mac. I'm trying to convince him to demonstrate this
to me on my laptop. The only thing I can think of is that because the
assignments use variables with the same name, Mathematica is loading
answer variables from the old as globals and these are "unlocking" the
same variables in the new. Any thoughts?
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