Biometric Authentication: Benefits, Risks, and Tips
About 10 min read
Biometric authentication such as fingerprint, facial, and iris recognition offers a convenient way to access devices and services without typing passwords. However, biometric data has the fundamental characteristic of being irreplaceable - once leaked, it cannot be reset like a password. According to a 2024 Juniper Research study, smartphones equipped with biometric authentication exceed 5 billion worldwide, and over 80% of mobile payments use biometric authentication. As of 2025, the evolution of deepfake technology has increased the risk of bypassing facial recognition, prompting a reassessment of biometric security. This article explains the risks and limitations of biometric authentication and how to combine it with password generation on passtsuku.com for defense in depth.
How Biometric Authentication Works
Biometric authentication is a technology that verifies identity using physical or behavioral characteristics. During enrollment, a template (feature data) of biometric information is created, and during authentication, the input biometric data is compared against the template to determine the degree of match. It uses a probabilistic determination method where authentication succeeds if the similarity exceeds a threshold, rather than requiring an exact match. This probabilistic determination involves two metrics: FRR (False Rejection Rate), which incorrectly rejects the genuine user, and FAR (False Acceptance Rate), which incorrectly accepts an impostor, determining the trade-off between security and convenience.
Fingerprint Authentication
This is the most widely adopted biometric authentication method. A fingerprint sensor built into smartphones and laptops reads fingerprint patterns and compares them against registered templates. Multiple sensor technologies exist, including capacitive, optical, and ultrasonic, each with different accuracy and forgery resistance. The typical FAR for fingerprint authentication is approximately 0.002% (1 in 50,000), meaning the probability of false acceptance with someone else's fingerprint is low but not zero.
Facial Recognition
Facial recognition extracts feature points from a face image captured by a camera to verify identity. Apple's Face ID uses an infrared dot projector to create a 3D map of the face, preventing spoofing with photos or videos. According to Apple's specifications, Face ID has a FAR of 1 in 1,000,000, which is 20 times more accurate than fingerprint authentication's 1 in 50,000. On the other hand, facial recognition using only a 2D camera carries the risk of being bypassed with high-resolution photos, and its security level is significantly inferior.
Iris and Vein Authentication
Authentication using iris patterns or palm vein patterns is difficult to forge and highly accurate, but its adoption in consumer devices is limited because it requires specialized sensors. The FAR for iris authentication is approximately 1 in 1,200,000, boasting the highest accuracy among biometric methods. It is primarily used in scenarios requiring high security, such as access control systems and ATMs at financial institutions.
To systematically learn how biometric authentication works, biometric authentication technology guides (Amazon) are helpful.
Comparison of Biometric Methods
| Item | Fingerprint | Facial (3D) | Iris |
|---|---|---|---|
| Accuracy (FAR) | Approx. 1/50,000 | Approx. 1/1,000,000 | Approx. 1/1,200,000 |
| Forgery risk | Medium (silicone duplication possible) | Low (bypass with 3D masks reported) | Very low |
| Environmental factors | Accuracy drops with wet/dry hands | Accuracy drops with masks/lighting | Relatively stable |
| Adoption | Very high (smartphones, PCs) | High (iPhone, some Android) | Limited (access control, ATMs) |
| Recommended for | Daily device unlocking | Hands-free authentication | High-security scenarios |
No single method is foolproof on its own. The safest approach is to set a strong password generated by passtsuku.com as a fallback and combine it with biometric authentication for defense in depth.
What Should You Actually Do?
Biometric authentication is a convenient method, but it is not infallible. Beginners should change their device fallback PIN to 6 digits or more and set up two-factor authentication for important accounts. Intermediate users should verify that biometric data is stored on-device (Secure Enclave) and set up TOTP or hardware key authentication for financial services. The idea that "biometrics are enough so a simple password is fine" is dangerous. As a last line of defense in case biometric authentication is bypassed, always set a strong password with passtsuku.com. Also review your smartphone lock screen security.
Risks and Limitations of Biometric Authentication
Biometric Data Cannot Be Changed
If a password is leaked, you can change it to a new one, but fingerprints and facial features cannot be changed. If biometric template data is leaked, authentication using that biometric data becomes permanently untrustworthy. This is the most fundamental risk of biometric authentication. In 2019, approximately 1 million fingerprint records were leaked from the biometric database of security company Suprema. With passwords, all users can be asked to reset them, but since fingerprints cannot be reset, the victims could never trust authentication using those fingerprints again.
Forgery and Reproduction Risks
Researchers have demonstrated that fingerprints can be duplicated using silicone or gelatin. Techniques for reproducing fingerprint patterns from high-resolution photos have also been reported, and the possibility of extracting fingerprints from photos posted on social media has been pointed out. Regarding facial recognition, cases of bypassing it using 3D-printed masks or deepfake video technology have been reported. A common misconception is that biometric authentication is more secure than passwords, but biometric data is fundamentally different from passwords, which are secret information, in that it is constantly exposed in public.
Authentication Failures Due to Environmental Factors
Fingerprint authentication accuracy decreases when hands are wet or fingertips are rough. FRR is said to increase 5 to 10 times after winter dryness or water work. Facial recognition can fail when wearing a mask or when lighting conditions change. PIN or password is set as a fallback when authentication fails, but if this fallback is weak, the strength of biometric authentication becomes meaningless.
Defense in Depth with Biometrics and Passwords
Do Not Use Biometrics Alone
Biometric authentication functions as two-factor authentication combining "something you have" (device) and "something you are" (biometric data), but considering the risk of device theft, combining it with a strong password is essential. Set a random password of 16 or more characters generated by passtsuku.com as a fallback.
Strengthen Your Device Lock Screen
The PIN or password required when smartphone biometric authentication fails must be sufficiently strong. A 4-digit PIN has only 10,000 combinations and can potentially be cracked by brute force or shoulder surfing. Set a PIN of 6 or more digits, or an alphanumeric password generated by passtsuku.com. Note that iOS allows setting data erasure after 10 consecutive failed PIN attempts, but some Android devices lack this restriction, making a sufficiently long PIN especially important.
Set Up Additional Authentication for Important Accounts
For particularly important accounts such as financial services and email, set up two-factor authentication using an authenticator app or hardware security key in addition to biometric authentication. Biometric authentication is merely a device-level unlock mechanism, and the safest design secures account-level security with passwords and two-factor authentication.
FIDO2-compatible hardware keys are available from FIDO2 hardware security keys (Amazon).
Precautions for Protecting Biometric Data
When using biometric authentication, verify where your biometric data is stored. Apple's Face ID and Touch ID store biometric data in the device's Secure Enclave and do not transmit it externally. On the other hand, cloud-based biometric authentication services may store template data on servers, posing a risk of leakage if the server is compromised. The FIDO2/WebAuthn standard developed by the FIDO Alliance adopts a design that confines biometric data within the device and sends only the public key to the server, structurally eliminating the risk of biometric data leakage. Passkeys are an authentication method based on this FIDO2 standard, attracting attention as a technology that combines the convenience of biometric authentication with the security of passwordless authentication.
Biometric authentication is a convenient method, but it is not infallible. The safest approach is to use strong passwords generated by passtsuku.com as the foundation and position biometric authentication as a supplementary means for improving convenience. The idea that "biometrics are enough so a simple password is fine" is dangerous. As a last line of defense in case biometric authentication is bypassed, always set a strong password. Keeping up with trends in passkeys and passwordless authentication will also help you choose future authentication methods.
Biometric Authentication Security Checklist
To use biometric authentication safely, regularly check the following items.
- Verify that your device fallback PIN/password is 6 digits or more (or an alphanumeric password)
- Verify that biometric data is stored on-device (Secure Enclave, etc.) and not sent to the cloud
- Set up TOTP or hardware key two-factor authentication in addition to biometrics for financial services and email accounts
- Set a random password of 16 or more characters from passtsuku.com for services that do not support biometric authentication
- Keep your device OS and security patches up to date
- Do not post photos with clearly visible fingerprints on social media
- Do not register biometric data on shared devices
What You Can Do Right Now
- Change your smartphone fallback PIN to 6 digits or more (or generate and set an alphanumeric password with passtsuku.com)
- Set up two-factor authentication with a TOTP app or hardware security key for financial services and email accounts
- Verify that biometric data is stored on-device (Secure Enclave, etc.) and reconsider the use of cloud-based biometric authentication services
- Update your device OS and security patches to the latest version
- Check if you have posted photos with clearly visible fingerprints on social media and delete them if applicable
Frequently Asked Questions
- Is biometric authentication safe? Is it better than passwords?
- Biometric authentication is convenient and eliminates password reuse risks, but it is not foolproof. Since biometric data cannot be changed if leaked, combining it with passwords and two-factor authentication is the safest approach.
- What happens if fingerprint or facial recognition data is stolen?
- Unlike passwords, fingerprints and faces cannot be changed. Stolen data could be used to bypass authentication, and the impact is permanent. Therefore, storing biometric data in a secure area on the device without sending it to servers is recommended.
- What are the key points for using biometric authentication safely?
- Keep your device OS and firmware up to date, and set up backup authentication like PIN or password alongside biometrics. Avoid services that store biometric data in the cloud and choose device-local processing.
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