Q: Digital Signatures that can be used with El Capitan on MacPro

Yes, we are using the epass2003 usb tokens for SSH connections with the OpenSC drivers:

https://github.com/OpenSC/OpenSC

However, ssh-agent (and ssh-agent forwarding) does not seem to work out of the box yet. If you (or anyone else) managed to get this working, any tips would be appreciated.