What is a CAC?

A Common Access Card (CAC) serves a critical role in the security and operational functionality of the U.S. Department of Defense (DoD). This card is a credit card-sized smart card that contains a chip which stores personal information and public key infrastructure (PKI) certificates. It is used for authentication, granting access to DoD networks and facilities, and facilitating secure communications.

One of the key elements of the CAC is its ability to provide a secured means of identity verification, allowing military and authorized civilian personnel to access government resources safely. Additionally, the CAC is pivotal in enabling digital signatures and encrypting data transmissions, ensuring secure communication within DoD operations.

The other options do not accurately describe the function of a CAC. A digital signature for financial transactions could refer to a variety of identifiers, but it does not encompass the broader security access provided by a CAC. Similarly, a type of encryption key and a software program for secure communications do not relate directly to the physical access and identity verification function that the CAC performs.