this is not seam issue, to make authentication with certificate from smart card to seam app you must configure http server to require ssl client certificates and you must have software on your machine to properly read and send certificate to the web site.
This is actually a client thing, the only thing on server site in this case in seam all you need is to read ssl certificate from request(witch is set by web server not seam)
I have a system that works exactly that way...
digital signing? How in what do you mean by that? What will you be signing?
Digital signing of data in browser (web page).
Then you want xml signature if I understand right.
We have exactly the same problem. And we solved it with 3rd party plug in http://www.setcce.si/eng/index42a.php proXSign that works for ie and ff. (i am not in any way affiliated with them...)
and digital signing differs what and how will you be signing, we are doing everything based on XMLSignature standard and for that I haven't found any other cross browser component(activex or plugin) that would support this standard properly...
If you know any let me know...
Thank you for your help Tomaz.
P.S.: Unfortunately I do not know any such component.