Computer security has been a consideration of computer designers, software developers, and users for virtually as long as the computer has existed. As any Internet user knows, computer security is a critical factor in the web-connected e-world. It is also important in business, industry, and government, where internally networked computers create an environment in which confidential or proprietary data must be protected from unauthorized access.

Computer security measures can be broken into three basic components and functions:

• Identification: "Who are you?"
• Authentication: "OK, I know who you are, but prove it."
• Authorization: "Now that I know you are you, here's what you can do in my system."

Computer security attempts to ensure that "the good guys" (authorized users) are able to access the systems and data they desire, and that "the bad guys" (unauthorized users) do not gain access. Although this is a simple idea, the implementation and...