Contact or Contactless CAC Reader

Two Types of CAC Readers

CAC readers come in two main varieties: contact readers that require physical card insertion and contactless readers that communicate via radio frequency. Each type has specific advantages depending on your needs.

How Contact Readers Work

Contact readers use a physical connection to your CAC card. You insert the card into the reader slot where metal contacts touch the chip. This direct connection provides reliable data transfer and works with all CAC cards.

Common contact readers include the SCR3310, Identiv SCR3500, and ACS ACR39U. These readers range from $15 to $40 and connect via USB.

How Contactless Readers Work

Contactless readers use Near Field Communication (NFC) technology. You tap or hold your CAC card near the reader instead of inserting it. The reader communicates with the contactless chip embedded in newer CAC cards.

Popular contactless options include the HID Omnikey 5427 and ACR122U. These typically cost $40 to $80.

Compatibility Considerations

Not all CAC cards support contactless reading. Cards issued before 2018 generally lack the contactless chip. Check your card for the contactless symbol (four curved lines) to confirm compatibility.

Contact readers work with every CAC card regardless of issue date. If you’re unsure about your card’s capabilities, a contact reader guarantees compatibility.

Speed Comparison

Contact readers provide marginally faster data transfer for certificate operations. The difference is typically less than one second and rarely noticeable during normal use.

Contactless readers eliminate insertion time but may require holding the card steady for a moment. Some users find the tap-and-go approach faster for frequent authentications.

Durability Factors

Contact readers experience mechanical wear from repeated card insertions. The card slot and contacts may degrade after thousands of uses. Higher-quality readers use spring-loaded contacts that last longer.

Contactless readers have no moving parts contacting your card. This eliminates mechanical wear, though the reader’s internal electronics can still fail over time.

Security Differences

Both reader types provide equivalent security for CAC authentication. The cryptographic operations happen on your CAC card’s chip, not the reader. The reader simply facilitates communication between your card and computer.

Some security-conscious environments prefer contact readers because the physical connection prevents potential wireless interception, though this risk is largely theoretical with properly implemented contactless systems.

Which Should You Choose

Choose a contact reader if you need guaranteed compatibility with any CAC card, prefer lower cost, or work in an environment requiring physical card insertion.

Choose a contactless reader if you have a newer CAC card, want faster tap-and-go authentication, or prefer the convenience of not inserting your card repeatedly.

Many users keep both types: a contact reader at their desk and a portable contactless reader for travel.