Common Access Card

Definition of Common Access Card

A Common Access Card (CAC) is a smart card issued by the United States Department of Defense (DoD) to military personnel, civilian employees, and select contractors. It serves as a multi-functional identification card, providing physical access to secure areas and granting access to DoD computer networks and systems. The card contains personal information, biometrics, and cryptographic features, ensuring secure and authorized usage.


The phonetic pronunciation of “Common Access Card” would be:KOM-uhn AK-ses kard

Key Takeaways

  1. Common Access Card (CAC) is a secure identification card used by the United States Department of Defense for physical and digital access to military resources, networks, and systems.
  2. Each CAC contains an encoded chip that stores personal biometric data and digital certificates for secure communication and authentication purposes.
  3. CACs are not only used for security purposes but also to conveniently access essential services and benefits, such as healthcare and financial resources by military personnel, contractors, and affiliates.

Importance of Common Access Card

The Common Access Card (CAC) is a crucial element in modern technology, particularly for matters of security and authentication.

Serving as a personalized smart card that carries an individual’s credentials such as electronic certificates, biometric data, and other relevant information, it plays a pivotal role in securing sensitive data and physical access to facilities.

For many organizations, including governmental and military sectors, the CAC streamlines identity management and enhances security by minimizing unauthorized access to protected resources, ensuring that only authorized personnel can access critical systems and data.

Furthermore, this advanced identification method boosts overall efficiency and plays a vital role in maintaining organizational security measures in the digital age.


A Common Access Card (CAC) primarily serves as an identification tool that enhances the security of various processes within an organization, particularly for governmental or defense institutions. The main purpose of a CAC is to provide individuals with a highly secure and reliable method for accessing different facilities and information systems.

This multi-functional smart card technology adds an extra layer of protection to sensitive data and physical access points, thereby reducing the risk of unauthorized access, data breaches, and identity theft. As a standard form of identification, a CAC usually contains an individual’s photo, name, affiliation, and an electronic chip that stores personal and biometric data.

The card enables both physical access to secure facilities and logical access to computer networks and systems. To ensure that only authorized personnel gain access to vital information, the card features multiple authentication methods such as Personal Identification Numbers (PINs), fingerprints, or digital certificates.

Consequently, the use of a Common Access Card significantly bolsters the security of an organization’s premises and information systems, thus providing an essential tool for maintaining the integrity of critical data and safeguarding national security interests.

Examples of Common Access Card

A Common Access Card (CAC) is a smart card used by the United States Department of Defense for identification and secure access to information systems and buildings. Here are three real-world examples of how CAC technology is used:

Military Base Access: Military personnel, civilian employees, and contractors are required to use a CAC card to gain entry to secured military installations. The card is inserted into a card reader, verifying the person’s identity, and granting access only to those who possess the appropriate clearance levels and job requirements.

Secure Computer Networks: Within the Department of Defense, a CAC is used as a form of two-factor authentication to access secure computer networks, systems, and sensitive data. Users insert their CAC into a card reader connected to their computer, and input a Personal Identification Number (PIN) to gain access to the network, ensuring that only authorized individuals can access the sensitive information.

Secure Email Communication: Employees and military personnel utilizing secure email communication platforms within the Department of Defense are required to use their CAC for digitally signing, encrypting, and decrypting emails. This process helps protect sensitive information from unauthorized personnel and ensures the integrity of the messages being sent between users. Using a CAC helps verify the sender’s identity and ensures the email has not been tampered with during transmission.

Common Access Card FAQ

What is a Common Access Card?

A Common Access Card (CAC) is a smart card issued by the United States Department of Defense (DoD) to military personnel, civilian employees, and eligible contractors. It serves as a form of identification, as well as providing access to secure facilities, networks, and other resources.

How can I obtain a Common Access Card?

To obtain a CAC, you must be a member of the US military, a civilian employee of the DoD, or an eligible contractor. The process typically involves verifying your eligibility, completing required training, and visiting a CAC issuance facility to have your photograph and fingerprints taken.

What information is stored on a Common Access Card?

A CAC contains a variety of information, including the cardholder’s name, photograph, pay grade, rank, personal identification number (PIN), and digital signatures. It also stores security certificates used for authentication and encryption purposes.

How do I update or renew my Common Access Card?

When your CAC is due for renewal or if your information changes, you must visit a CAC issuance facility to update or renew your card. You may need to provide documentation to verify any changes in information or status. It is essential to update your card promptly, as an expired or inaccurate card may limit your access to resources and facilities.

What should I do if my Common Access Card is lost or stolen?

If your CAC is lost or stolen, you should report it to your supervisor or chain of command immediately. They will assist you in deactivating the card and obtaining a replacement. It is crucial to report a missing card as soon as possible to prevent unauthorized access to secure resources or potential identity theft.

Related Technology Terms

  • Smart Card Technology
  • Public Key Infrastructure (PKI)
  • Card Reader
  • Two-factor Authentication
  • Personal Identification Number (PIN)

Sources for More Information


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