Common Access Card

The Common Access Card, also colloquially referred to as the CAC or CAC card, is a smart card about the size of a credit card. It is the standard identification for Active Duty United States Defense personnel, to include the Selected Reserve and National Guard, United States Department of Defense (DoD) civilian employees, United States Coast Guard (USCG) civilian employees and eligible DoD and USCG contractor personnel. It is also the principal card used to enable physical access to buildings and controlled spaces, and it provides access to defense computer networks and systems. It also serves as an identification card under the Geneva Conventions (esp. the Third Geneva Convention). The CAC satisfies two-factor authentication: something that belongs to the user, and something only known to the user. The CAC also satisfies the requirements for digital signature and data encryption technologies: authentication, integrity and non-repudiation.