Re: binary versions of functions

[Brian Blais]

> On Oct 10, 2004, at 7:49 PM, Brian Blais wrote:
>
>> If not, can anyone think of some way I could distribute
>> working code, but not have the source readable?
>
>
>

Paul Kienzle wrote:
> Octave does not have a virtual machine but instead interprets code by 
> walking the parse tree, so enterprising students would always be able to 
> create a modified version to decrypt the binary functions.   Of course, 
> students who take the initiative to work around whatever code 
> obfuscation you put in place probably don't need to cheat in the first 
> place, so maybe simple solutions aren't so bad. 

Yeah, I was thinking that a simple solution would be fine.

A quick solution that I wrote was to convert a .m file into ascii 
numbers, and save the result as a string variable as a .mat file.  I can 
load the variable, and eval the particular string (without actually 
converting back to characters).  It's not perfect, but it will probably 
keep most students out of the source.

> Turning your code into a C++ extension doesn't help.  Even assuming the 
> m-file to C++ translators were far enough along for your purpose, the 
> GPL requires that you distribute the source for any oct-file that you 
> supply. 

I think there must be an exception to code distributed within a class, 
for educational purposes.  I am all in favor of open information, and 
the GPL, but within a class you don't necessarily want to disclose all 
immediately.


> You could use the parallel octave code from octave-forge.  Put a version 
> of octave on a server which has you private functions available.  
> Students could send octave commands to the server and get back the 
> results.  You would have to remove a number of commands from the 
> interpreter for this to be secure, such as type, file_in_loadpath, 
> fopen, system, and maybe some others.  

Interesting solution, but a bit involved for my purposes.  I also don't 
want to count on the net being up, or that the students have access to it.

thanks for the ideas!


                        Brian Blais

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