Authentication: Something One Is

Still, Biometric methods have challenges:

• Intrusive: Some biometric methods require awkward, privacy-challenging scans, e.g., DNA matching.
• Expensive: Accurate readers/scanners require costy hardware.
• Overly sensitive: Even a minor change (e.g., a wound in one's fingertip) will fail authentication.
• Collected incorrectly: The biometrics machine might have stored an incorrect reading of your biometric data in the database (so you will not be able to authenticate.)
• Slow: because biometrics methods need to process a great deal of data, the authentication process might be slow.
• Prone to forgery: e.g., a hacker breaking into a biometrics database might replace your fingerprint with theirs, or forges your fingerprint with a fake play doh finger from an existing print you left somewhere (e.g., door handle.)

Systems should store biometric data in an encrypted form to prevent hackers from re-using biometric data in case they break into the database.