OS X Mavericks: About smart cards
Smart cards, such as U.S. Department of Defense Common Access Cards and the U.S. Personal Identity Verification (PIV) Cards, are access-control devices. You use a smart card to physically authenticate yourself in situations like these:
Client-side authentication to PK-enabled websites (HTTPS)
Remote access (VPN: L2TP/PPTP)
Port-based Network Access Control (802.1X)
Unlocking keychains (/usr/sbin/systemkeychain)
You must obtain the driver (Tokend) installer necessary to support the type of smart card in use from one of several open source or commercial third-party providers. For more information on tokend installers, smart cards, smart card software updates, or for discussion and support, see the SmartCard Services project on the MacOSForge.org website.