IPA IP 2021 Question 69
A question IPA Japan published in 令和3年度 ITパスポート試験 公開問題 問69, translated into English. ITPEC is based on the same exams.
Same question on ITPEC: Oct 2022 Q44
Which of the following is the appropriate combination of terms or phrases to be inserted into blanks A and B in the description below concerning authentication accuracy in biometric authentication?
In biometric authentication, the probability of incorrectly rejecting the relevant person is called the false rejection rate, and the probability of incorrectly accepting another person is called the false acceptance rate. The rate that an authentication device or algorithm cannot recognize biometric information is called the unsupported rate.
In the settings for authentication accuracy, setting the A lower increases convenience, and setting B lower increases security.
Explanation
A: false rejection rate, B: false acceptance rate — fewer false rejections spare genuine users, fewer false acceptances keep impostors out.
- •False rejection rate (FRR): the genuine person is rejected and has to try again. A lower FRR means fewer retries, so it raises convenience.
- •False acceptance rate (FAR): another person is accepted as the genuine one. A lower FAR lets fewer impostors in, so it raises security.
The two trade off through the matching threshold: a strict threshold lowers FAR but raises FRR, a loose one does the reverse. The unsupported rate depends on whether the device or algorithm can read a person's biometric features at all, not on this setting.
Answer (c)
Why not others:
- •(a) — swaps the two: lowering FAR is the security setting and lowering FRR the convenience one
- •(b) — lowering FAR raises security, not convenience, and the unsupported rate is not the rate that governs impostors being accepted
- •(d) — the unsupported rate is not the convenience setting, and lowering FRR makes acceptance easier, which weakens security rather than strengthening it
Key rule: FAR measures security and FRR measures convenience; one threshold cannot lower both at once, so it is set by which failure costs more.
Security · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.