Understand fingerprint security
Your fingerprint data is stored securely and never leaves your Pixel or Nexus phone. Your fingerprint data isn't shared with Google or any apps on your device. Apps are notified only whether your fingerprint was verified.
If you're ready to get started using your fingerprint to unlock your phone, learn how to set up your fingerprints.
Cautions about fingerprints
Fingerprints are an easy way to unlock your phone. But a fingerprint may be less secure than a strong PIN, pattern, or password.
A copy of your fingerprint could be used to unlock your phone. You leave fingerprints on many things you touch, including your phone.
Fingerprint data is stored securely
Google has strict guidelines for device makers about how fingerprint data can be stored on a Pixel or Nexus device.
- Capturing and recognizing your fingerprint must happen in a secure part of the hardware known as a Trusted Execution Environment (TEE).
- Hardware access must be limited to the TEE and protected by an SELinux policy.
- Fingerprint data must be secured within sensor hardware or trusted memory so that images of your fingerprint aren't accessible.
Secure storage & removal
- Only the encrypted form of the fingerprint data can be stored on the file system, even if the file system itself is encrypted.
- Fingerprint data must be removed from the device when a user is removed.
- Rooting of a device must not compromise fingerprint data.
Google's guidelines require fingerprint templates — that is, the processed versions of raw fingerprint images — to be cryptographically authenticated.
Fingerprint templates must be signed with a private, device-specific key — like keyed-hash message authentication code (HMAC) — with at least the absolute file-system path, group, and finger ID, such that template files won't work on another device, or for anyone besides the person who set them up on the same device. For example, copying the fingerprint data from a different user on the same device, or from another device, must not work.
A device-specific encryption key — like Advanced Encryption Standard (AES) — must be used for fingerprint data so that a raw image or fingerprint template isn't readable by a separate device.
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