DC add-on: Use security tokens and smart cards in Java applet
The Java applet is able to use security tokens and smart cards which provide PKCS#11 library. To use such device, it must be registered in JRE on the client computer (see the link for the registration instructions).
When the applet starts, it looks for all the providers which names begin with SunPKCS11- prefix. If no such providers found, the option will be disabled. You're able to force the user to use certain device by specifying its name in the Token parameter of the applet: