Chapter 7.2, Problem 7.16ACI

Authorizing computer users with palm prints. Access to computers, email, and Facebook accounts is achieved via a password—a collection of symbols (usually letters and numbers) selected by the user. One problem with passwords is that persistent hackers can create programs that enter millions of combinations of symbols into a target system until the correct password is found. An article in IEEE Pervasive Computing (October-December2007) investigated the effectiveness of using palm prints to Identify authorized users. For example, a system developed by Palmguard, Inc. tests the hypothesis

H₀: The proposed user is authorized

H_a: The proposed user is unauthorized by checking characteristics of the proposed user’s palm print against those stored in the authorized users’ data bank.

1. a. Define a Type I error and Type II error for this test. Which is the more serious error? Why?
2. b. Palmguard reports that the Type I error rate for its system is less than 1%, whereas the Type II error rate is .00025%. Interpret these error rates.
3. c. Another successful security system, the EyeDentifyer, “spots authorized computer users by reading the one-of-a-kind patterns formed by the network of minute blood vessels across the retina at the back of the eye.” The EyeDentifyer reports Type I and II error rates of .01% (1 in 10,000) and ,005% (5 in 100,000), respectively. Interpret these rates.