The card may also communicate with the card reader using radio frequency. Users worried about their PINs being compromised through electronic eavesdropping can buy smart cards with small keypads. The PIN code is entered directly into the card, which then creates a scrambled PIN with the one-time code. An alternative authentication technique called biometrics relies on such methods as retina or fingerprint scans, but these are currently too expensive to be widely practical. Companies that sell software-based authentication include Security Dynamics and Bellcore.
Access control is primarily software-based.
In many cases, sufficient security can be achieved by simply implementing the built-in access controls of operating systems and applications. These can ask users for passwords before allowing them to boot up the computer system or before allowing them to open a document.