Re: CDF Security
- To: mathgroup at smc.vnet.net
- Subject: [mg128521] Re: CDF Security
- From: Joseph Gwinn <joegwinn at comcast.net>
- Date: Sun, 28 Oct 2012 01:54:59 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- Delivered-to: l-mathgroup@wolfram.com
- Delivered-to: mathgroup-newout@smc.vnet.net
- Delivered-to: mathgroup-newsend@smc.vnet.net
- References: <20121025054133.AA444687F@smc.vnet.net> <k6d0ki$282$1@smc.vnet.net>
Gregory, One possible solution jumps to mind, a Hill Cipher: <http://en.wikipedia.org/wiki/Hill_cipher>. The answers could be stored in ciphertext form in the CDF notebook, and the key released a week later. I suppose that the absolute time (~date) could be woven in somehow, as an added limit. Joe Gwinn In article <k6d0ki$282$1 at smc.vnet.net>, Gregory Lypny <gregory.lypny at videotron.ca> wrote: > Hi Juan, > > Thanks for the heads up. Even when opened in a text editor the code is > sufficiently obscure that it wouldn't pose too much of a risk with my > first-year students. But of course that is meaningless if just one savvy > student does what you describe. I am going to tie the answer array to a > variable with the absolute time (somewhat obscure) so that the array contains > null in all its elements before the deadline and proper answers afterwards. > Still far from foolproof, but perhaps enough to buy time to think of > something better. Ultimately, I don't that CDF will work for critical > coursework and large classes. I will probably just set up a workflow to > generate PDFs instead. Disappointing but a good learning experience. > > Thanks again for responding, > > Gregory > > > > On Thu, Oct 25, 2012, at 1:17 PM, "Miranda, Juan" <juan.miranda at hp.com> > wrote: > > > You can open any cdf file in Mathematica and use the ImputForm function to > > get its definition. You can do the same for any Mathematica palette. You > > can even right-click in the file ubication and select open with NotePad and > > all the definition of the CDF will be available, you can just paste the > > code in Mathematica and use it. > > > > Best, > > > > Juan > > > > -----Original Message----- > > From: Gregory Lypny [mailto:gregory.lypny at videotron.ca] > > Sent: Wednesday, October 24, 2012 10:42 PM > > To: mathgroup at smc.vnet.net > > Subject: CDF Security > > > > 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 > > pulldown menu > > - Open old quiz (where answers are not blocked), enable dynamics, select ID > > - 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? > > > > Gregory > >
- References:
- CDF Security
- From: Gregory Lypny <gregory.lypny@videotron.ca>
- CDF Security