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# Biometric unlock

WalletChan can use a platform passkey/biometric assertion to unlock encrypted
wallet capabilities on the current device.

## Set up

Open **Settings → Security → Biometric Unlock** while in a master session.
Follow the operating system's platform-authenticator prompt.

The implementation uses WebAuthn PRF and purpose-separated encryption wrappers.
The biometric itself is verified by your device; WalletChan does not receive a
fingerprint or face scan.

## Use

Choose **Use biometric unlock** or accept the supported automatic prompt on the
lock screen. Successful assertion creates a passwordless master session for the
capabilities stored in the passkey record.

It does not bypass Ledger hardware confirmation or turn a view-only account
into a signer.

## Device scope

The factor is local to the configured browser/device and intentionally not a
sync-based recovery mechanism. Keep the master password and all account
recovery material.

## Legacy upgrade

An older biometric record may support only signing access. WalletChan shows an
upgrade notice before allowing newer local-secret/seed flows so it can create a
full purpose-separated record.

## Actions that still require the master password

Secret reveal, master-password change, passkey removal, some factor changes,
and explicit recovery proofs can still ask for the actual master password even
after biometric unlock.

Agent-password sessions cannot configure or remove biometric unlock.

## Related guides

* [Understand password and lock behavior](/security/passwords)
* [Back up every account recovery method](/security/backups)
* [Configure constrained agent-password access](/security/agent-password)