CAC

Common access card (CAC), a "smart" card about the size of a credit card, is a United States Department of Defense (DoD) Smart Card issued as standard identification for active-duty military personnel.

It is also the principal card used to enable physical access to buildings and controlled spaces, and it provides access to DoD computer network, secure KVM switches and computer systems.

CAC is used as a general identification card as well as for authentication to enable access to DoD computers, networks, and certain DoD facilities. It also serves as an identification card under the Geneva Conventions.

CAC enables encrypting and cryptographically signing email, facilitating the use of PKI authentication tools, and establishes an authoritative process for the use of identity credentials.