CAC

Develop a Personal Identity Verification (PIV) module that could be implemented into the Drupal CMS platform to allow for two-factor authentication using a Smart Card (SC) or US Government Department of Defense Common Access Card (CAC) card for verification and access to secure website environments.

There was once sandbox-related activity found here http://drupal.org/sandbox/larquin/1292622 , but it seems to have been abandoned.