Which event results in a legitimate user being denied access?

• A. False acceptance
• B. True rejection
• C. Denied access
• D. False rejection

Answer: (D)

In authentication systems, you distinguish how the system handles matching or rejecting users using two common error types. A legitimate user being denied access is a false rejection: the system fails to recognize a valid user and blocks them even though they should be allowed in. This happens when the recognition threshold is set too high, or the input is noisy or degraded, causing an enrolled, legitimate template not to match enough to pass the check.

This is different from a true rejection, which is when the system correctly blocks an unauthorized user. False acceptance would be granting access to someone who shouldn’t have it, while a generic “denied access” phrase doesn’t specify whether the denial was appropriate or an error.