Re: [pdf-devel] Contribute to the project

[jemarch]

Hello David.

   I tell you: the standard defines only two algorithms in order to
   decrypt pdf streams and strings.

In the GNU PDF Library we will want to provide the possibility of
using more advanced encryption algorithms from libgcrypt.

   On the one hand we must implement the AES algorithm, just like it
   already is in the pdf knowledge database [1]. 

Do libgcrypt implment the AES algorithm? If not we may need to write
it ourselves.

   On the other hand, the second algorithm is known as RC4, which
   unfortunately is, according to the reference, a proprietary
   algorithm copyrighted by RSA Security, Inf.  I hope it doesn't
   arise any legal impediment.

We discussed the legal issue of RC4 some time ago and the conclusion
was that it is not a problem to implement the 4arcs algorithm.

   Finally we will need md5 message-digest functions too.

   I am not sure but I think libcrypt doesn't provide this. Have we
   work to do here?

Could you please check?