BiometricPrompt

const val AUTHENTICATION_RESULT_TYPE_BIOMETRIC = 2: Int

Authentication type reported by AuthenticationResult when the user authenticated by presenting some form of biometric (e.g. fingerprint or face).

const val AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL = 1: Int

Authentication type reported by AuthenticationResult when the user authenticated by entering their device PIN, pattern, or password.

const val AUTHENTICATION_RESULT_TYPE_UNKNOWN = -1: Int

Authentication type reported by AuthenticationResult when the user authenticated via an unknown method.

This value may be returned on older Android versions due to partial incompatibility with a newer API. It does NOT necessarily imply that the user authenticated with a method other than those represented by AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL and AUTHENTICATION_RESULT_TYPE_BIOMETRIC.

const val ERROR_CANCELED = 5: Int

The operation was canceled because the biometric sensor is unavailable. This may happen when the user is switched, the device is locked, or another pending operation prevents it.

const val ERROR_HW_NOT_PRESENT = 12: Int

The device does not have the required authentication hardware.

const val ERROR_HW_UNAVAILABLE = 1: Int

The hardware is unavailable. Try again later.

const val ERROR_LOCKOUT = 7: Int

The operation was canceled because the API is locked out due to too many attempts. This occurs after 5 failed attempts, and lasts for 30 seconds.

const val ERROR_LOCKOUT_PERMANENT = 9: Int

The operation was canceled because ERROR_LOCKOUT occurred too many times. Biometric authentication is disabled until the user unlocks with their device credential (i.e. PIN, pattern, or password).

const val ERROR_MORE_OPTIONS_BUTTON = 16: Int

The user pressed the more options button on prompt content.

const val ERROR_NEGATIVE_BUTTON = 13: Int

The user pressed the negative button.

const val ERROR_NO_BIOMETRICS = 11: Int

The user does not have any biometrics enrolled.

const val ERROR_NO_DEVICE_CREDENTIAL = 14: Int

The device does not have pin, pattern, or password set up.

const val ERROR_NO_SPACE = 4: Int

The operation can't be completed because there is not enough device storage remaining.

const val ERROR_SECURITY_UPDATE_REQUIRED = 15: Int

A security vulnerability has been discovered with one or more hardware sensors. The affected sensor(s) are unavailable until a security update has addressed the issue.

const val ERROR_TIMEOUT = 3: Int

The current operation has been running too long and has timed out.

This is intended to prevent programs from waiting for the biometric sensor indefinitely. The timeout is platform and sensor-specific, but is generally on the order of ~30 seconds.

const val ERROR_UNABLE_TO_PROCESS = 2: Int

The sensor was unable to process the current image.

const val ERROR_USER_CANCELED = 10: Int

The user canceled the operation.

Upon receiving this, applications should use alternate authentication, such as a password. The application should also provide the user a way of returning to biometric authentication, such as a button.

const val ERROR_VENDOR = 8: Int

The operation failed due to a vendor-specific error.

This error code may be used by hardware vendors to extend this list to cover errors that don't fall under one of the other predefined categories. Vendors are responsible for providing the strings for these errors.

These messages are typically reserved for internal operations such as enrollment but may be used to express any error that is not otherwise covered. In this case, applications are expected to show the error message, but they are advised not to rely on the message ID, since this may vary by vendor and device.

BiometricPrompt(
    activity: FragmentActivity,
    callback: BiometricPrompt.AuthenticationCallback
)

Constructs a BiometricPrompt, which can be used to prompt the user to authenticate with a biometric such as fingerprint or face. The prompt can be shown to the user by calling authenticate() and persists across device configuration changes by default.

If authentication is in progress, calling this constructor to recreate the prompt will also update the AuthenticationCallback for the current session. Thus, this method should be called by the client activity each time the configuration changes (e.g. in onCreate()).

BiometricPrompt(
    fragment: Fragment,
    callback: BiometricPrompt.AuthenticationCallback
)

Constructs a BiometricPrompt, which can be used to prompt the user to authenticate with a biometric such as fingerprint or face. The prompt can be shown to the user by calling authenticate() and persists across device configuration changes by default.

If authentication is in progress, calling this constructor to recreate the prompt will also update the AuthenticationCallback for the current session. Thus, this method should be called by the client fragment each time the configuration changes (e.g. in onCreate()).

BiometricPrompt(
    activity: FragmentActivity,
    executor: Executor,
    callback: BiometricPrompt.AuthenticationCallback
)

Constructs a BiometricPrompt, which can be used to prompt the user to authenticate with a biometric such as fingerprint or face. The prompt can be shown to the user by calling authenticate() and persists across device configuration changes by default.

If authentication is in progress, calling this constructor to recreate the prompt will also update the Executor and AuthenticationCallback for the current session. Thus, this method should be called by the client activity each time the configuration changes (e.g. in onCreate()).

BiometricPrompt(
    fragment: Fragment,
    executor: Executor,
    callback: BiometricPrompt.AuthenticationCallback
)

Constructs a BiometricPrompt, which can be used to prompt the user to authenticate with a biometric such as fingerprint or face. The prompt can be shown to the user by calling authenticate() and persists across device configuration changes by default.

If authentication is in progress, calling this constructor to recreate the prompt will also update the Executor and AuthenticationCallback for the current session. Thus, this method should be called by the client fragment each time the configuration changes (e.g. in onCreate()).

fun authenticate(info: BiometricPrompt.PromptInfo): Unit

Shows the biometric prompt to the user. The prompt survives lifecycle changes by default. To cancel authentication and dismiss the prompt, use cancelAuthentication.

fun authenticate(
    info: BiometricPrompt.PromptInfo,
    crypto: BiometricPrompt.CryptoObject
): Unit

Shows the biometric prompt to the user. The prompt survives lifecycle changes by default. To cancel authentication and dismiss the prompt, use cancelAuthentication.

Calling this method invokes crypto-based authentication, which is incompatible with Class 2 (formerly Weak) biometrics and (prior to Android 11) device credential. Therefore, it is an error for info to explicitly allow any of these authenticator types on an incompatible Android version.

fun cancelAuthentication(): Unit

Cancels the ongoing authentication session and dismisses the prompt.

On versions prior to Android 10 (API 29), calling this method while the user is authenticating with their device credential will NOT work as expected. See setDeviceCredentialAllowed for more details.