Mac® Security Bible

6.8. Using Smart Cards, Tokens, and Biometric Authentication Devices

Earlier in this chapter, I described multi-factor authentication, in which you identify yourself based on not only something you know (for example, a password) but also something you have (a physical object with unique characteristics), something you are (a physical feature, such as a fingerprint), or all three. You can implement some types of multi-factor authentication by adding third-party hardware to your Mac, thus adding an extra layer of security to your account password (or other passwords).

Before I describe some of these devices, however, I should mention that hardware-based authentication isn't necessarily multi-factor. For example, the front door of the apartment building in which I live has an electronic lock that can be opened either by typing a code (something I know) or by using an RFID key fob (something I have). Because the lock requires just one method, not both, it's only single-factor security. Similarly, you can install a fingerprint reader on your Mac that lets you authenticate by swiping your finger instead of typing your password, which is a convenience feature but is still single-factor authentication. However, if you configure the reader's software to work only if you type a password and also swipe your finger, it becomes multi-factor authentication.

6.8.1. Smart cards and tokens

A smart card is a small device (typically the size and shape of a credit card) that contains its own microprocessor ...