On Mon, 17 Sep 2007, Dennis Fisher wrote:
> Colleagues,
>
> I have an unusual problem; I am wondering whether anyone has dealt
> with it and found a solution.
>
> I have a script that needs to be encrypted. R will then be run on
> the script. There are various means to decrypt the file, some of
> which leave the decrypted code on the hard drive for an excessive
> period.
>
> One means that I have considered to deal with this is the following
> (the unix code is not correct, just sufficient to communicate the idea):
> system("decrypt ...")
> system("rm encrypted file")
> source(decrypted file)
> system("rm decrypted file")
>
> Another approach would be to pipe the decrypted version to R in the
> command line (as it is being decrypted). Obviously, this could be
> done with R < decryptedFile but this leaves the decrypted code
> exposed. Is there some other means to accomplish my goals using
> something on the command line?
That's not what I understand by 'to pipe'. You could use a pipe()
connection with source() if you had a pipeline decrypter, either
decrypt filename | Rscript
or
source(pipe("decrypt filename"))
Those would be slightly safer as the decrypted source code is (probably)
never written to the file system.
I am not sure what you are trying to achieve: since the R code is going to
be decrypted it will be possible (and I suspect easy) to get hold of the
decrypted version. (Consider for example running a modified version of
source() that dumped out the parse tree.) Using a package to read the
encrypted file and feed the decrypted source to the parser at C level an
expression at a time would make this harder to circumvent.
(Unlike Marc Schwartz, I am presuming the aim is to protect scripts from
casual inspection on someone else's machine: as Marc says there are better
ways to protect code and data on your own systems.)
> Of note, the scripts are not terribly long - 50-200 lines each.
>
> Thanks
>
> Dennis
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-415-564-2220
> www.PLessThan.com
>
>
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>
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--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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