GPGME and multiple subkeys

[David Anderson]

Hi all,

I am currently trying to use GPGME in a project ( 
http://gobelins.nekeme.net ), and I have run into some trouble.

In our project, we had envisionned using OpenPGP keys for signing and 
encrypting data, using subkeys created especially for Gobelins: someone 
using his everyday GPG key to play would have a Gobelins signature 
subkey and a Gobelins encryption subkey added to his key.

However, after looking through the programmer's reference of GPGME, I 
didn't find any way of signing data with a specific subkey. There is a 
function to sign data, but it takes the key as a whole.

Is this something which is part of OpenPGP (not being able to sign using 
a specific signature subkey), or is it just that GPGME cannot do this 
yet? If this is the case, when would it be implemented, and what other 
library could I use instead of GPGME to be able to sign using a specific 
subkey?

Thanks in advance
David Anderson