Added in API level 28

BiometricPrompt

open class BiometricPrompt
kotlin.Any
   ↳ android.hardware.biometrics.BiometricPrompt

A class that manages a system-provided biometric dialog.

Summary

Nested classes
abstract

Callback structure provided to BiometricPrompt.authenticate(CancellationSignal, or BiometricPrompt.authenticate(CryptoObject,.
open

Container for callback data from authenticate(android.os.CancellationSignal,java.util.concurrent.Executor,android.hardware.biometrics.BiometricPrompt.AuthenticationCallback) and authenticate(android.hardware.biometrics.BiometricPrompt.CryptoObject,android.os.CancellationSignal,java.util.concurrent.Executor,android.hardware.biometrics.BiometricPrompt.AuthenticationCallback).
open

A builder that collects arguments to be shown on the system-provided biometric dialog.

A wrapper class for the cryptographic operations supported by BiometricPrompt.
Constants
static Int

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

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

The image acquired was good.
static Int

The biometric image was too noisy due to suspected or detected dirt on the sensor.
static Int

The biometric image was too noisy to process due to a detected condition or a possibly dirty sensor (See BIOMETRIC_ACQUIRED_IMAGER_DIRTY).
static Int

Only a partial biometric image was detected.
static Int

The biometric image was incomplete due to quick motion.
static Int

The biometric image was unreadable due to lack of motion.
static Int

The operation was canceled because the biometric sensor is unavailable.
static Int

The device does not have a biometric sensor.
static Int

The hardware is unavailable.
static Int

The operation was canceled because the API is locked out due to too many attempts.
static Int

The operation was canceled because BIOMETRIC_ERROR_LOCKOUT occurred too many times.
static Int

The user does not have any biometrics enrolled.
static Int

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

Error state returned for operations like enrollment; the operation cannot be completed because there's not enough storage remaining to complete the operation.
static Int

A security vulnerability has been discovered and the sensor is unavailable until a security update has addressed this issue.
static Int

Error state returned when the current request has been running too long.
static Int

Error state returned when the sensor was unable to process the current image.
static Int

The user canceled the operation.
static Int

OEMs should use this constant if there are conditions that do not fit under any of the other publicly defined constants, and must provide appropriate strings for these errors to the BiometricPrompt.AuthenticationCallback.onAuthenticationError(int, callback.
static Long

Returned from BiometricManager.getLastAuthenticationTime(int) when there has been no successful authentication for the given authenticator since boot.
Public methods
open Unit

This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric.
open Unit

This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric.
open Int

Gets the type(s) of authenticators that may be invoked by the prompt to authenticate the user, as set by Builder.setAllowedAuthenticators(int).
open PromptContentView?

Gets the content view for the prompt, as set by Builder.setContentView(PromptContentView).
open CharSequence?

Gets the description for the prompt, as set by Builder.setDescription(CharSequence).
open Bitmap?

Gets the logo bitmap for the prompt, as set by Builder.setLogoBitmap(Bitmap).
open String?

Gets the logo description for the prompt, as set by Builder.setLogoDescription(String).
open Int

Gets the drawable resource of the logo for the prompt, as set by Builder.setLogoRes(int).
open CharSequence?

Gets the negative button text for the prompt, as set by Builder.setNegativeButton(CharSequence, Executor, DialogInterface.OnClickListener).
open CharSequence?

Gets the subtitle for the prompt, as set by Builder.setSubtitle(CharSequence).
open CharSequence

Gets the title for the prompt, as set by Builder.setTitle(CharSequence).
open Boolean

Determines if explicit user confirmation is required by the prompt, as set by Builder.setConfirmationRequired(boolean).

Constants

AUTHENTICATION_RESULT_TYPE_BIOMETRIC

Added in API level 30
static val AUTHENTICATION_RESULT_TYPE_BIOMETRIC: Int

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

Value: 2

AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL

Added in API level 30
static val AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL: Int

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

Value: 1

BIOMETRIC_ACQUIRED_GOOD

static val BIOMETRIC_ACQUIRED_GOOD: Int

The image acquired was good.

Value: 0

BIOMETRIC_ACQUIRED_IMAGER_DIRTY

static val BIOMETRIC_ACQUIRED_IMAGER_DIRTY: Int

The biometric image was too noisy due to suspected or detected dirt on the sensor. For example, it's reasonable return this after multiple BIOMETRIC_ACQUIRED_INSUFFICIENT or actual detection of dirt on the sensor (stuck pixels, swaths, etc.). The user is expected to take action to clean the sensor when this is returned.

Value: 3

BIOMETRIC_ACQUIRED_INSUFFICIENT

static val BIOMETRIC_ACQUIRED_INSUFFICIENT: Int

The biometric image was too noisy to process due to a detected condition or a possibly dirty sensor (See BIOMETRIC_ACQUIRED_IMAGER_DIRTY).

Value: 2

BIOMETRIC_ACQUIRED_PARTIAL

static val BIOMETRIC_ACQUIRED_PARTIAL: Int

Only a partial biometric image was detected. During enrollment, the user should be informed on what needs to happen to resolve this problem, e.g. "press firmly on sensor." (for fingerprint)

Value: 1

BIOMETRIC_ACQUIRED_TOO_FAST

static val BIOMETRIC_ACQUIRED_TOO_FAST: Int

The biometric image was incomplete due to quick motion. For example, this could also happen if the user moved during acquisition. The user should be asked to repeat the operation more slowly.

Value: 5

BIOMETRIC_ACQUIRED_TOO_SLOW

static val BIOMETRIC_ACQUIRED_TOO_SLOW: Int

The biometric image was unreadable due to lack of motion.

Value: 4

BIOMETRIC_ERROR_CANCELED

static val BIOMETRIC_ERROR_CANCELED: Int

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

Value: 5

BIOMETRIC_ERROR_HW_NOT_PRESENT

static val BIOMETRIC_ERROR_HW_NOT_PRESENT: Int

The device does not have a biometric sensor.

Value: 12

BIOMETRIC_ERROR_HW_UNAVAILABLE

static val BIOMETRIC_ERROR_HW_UNAVAILABLE: Int

The hardware is unavailable. Try again later.

Value: 1

BIOMETRIC_ERROR_LOCKOUT

static val BIOMETRIC_ERROR_LOCKOUT: 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.

Value: 7

BIOMETRIC_ERROR_LOCKOUT_PERMANENT

static val BIOMETRIC_ERROR_LOCKOUT_PERMANENT: Int

The operation was canceled because BIOMETRIC_ERROR_LOCKOUT occurred too many times. Biometric authentication is disabled until the user unlocks with strong authentication (PIN/Pattern/Password)

Value: 9

BIOMETRIC_ERROR_NO_BIOMETRICS

static val BIOMETRIC_ERROR_NO_BIOMETRICS: Int

The user does not have any biometrics enrolled.

Value: 11

BIOMETRIC_ERROR_NO_DEVICE_CREDENTIAL

static val BIOMETRIC_ERROR_NO_DEVICE_CREDENTIAL: Int

The device does not have pin, pattern, or password set up. See BiometricPrompt.Builder.setAllowedAuthenticators(int), Authenticators.DEVICE_CREDENTIAL, and BiometricManager.canAuthenticate(int).

Value: 14

BIOMETRIC_ERROR_NO_SPACE

static val BIOMETRIC_ERROR_NO_SPACE: Int

Error state returned for operations like enrollment; the operation cannot be completed because there's not enough storage remaining to complete the operation.

Value: 4

BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED

static val BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED: Int

A security vulnerability has been discovered and the sensor is unavailable until a security update has addressed this issue. This error can be received if for example, authentication was requested with Authenticators.BIOMETRIC_STRONG, but the sensor's strength can currently only meet Authenticators.BIOMETRIC_WEAK.

Value: 15

BIOMETRIC_ERROR_TIMEOUT

static val BIOMETRIC_ERROR_TIMEOUT: Int

Error state returned when the current request has been running too long. 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.

Value: 3

BIOMETRIC_ERROR_UNABLE_TO_PROCESS

static val BIOMETRIC_ERROR_UNABLE_TO_PROCESS: Int

Error state returned when the sensor was unable to process the current image.

Value: 2

BIOMETRIC_ERROR_USER_CANCELED

static val BIOMETRIC_ERROR_USER_CANCELED: Int

The user canceled the operation. Upon receiving this, applications should use alternate authentication (e.g. a password). The application should also provide the means to return to biometric authentication, such as a "use " button.

Value: 10

BIOMETRIC_ERROR_VENDOR

static val BIOMETRIC_ERROR_VENDOR: Int

OEMs should use this constant if there are conditions that do not fit under any of the other publicly defined constants, and must provide appropriate strings for these errors to the BiometricPrompt.AuthenticationCallback.onAuthenticationError(int, callback. OEMs should expect that the error message will be shown to users.

Value: 8

BIOMETRIC_NO_AUTHENTICATION

static val BIOMETRIC_NO_AUTHENTICATION: Long

Returned from BiometricManager.getLastAuthenticationTime(int) when there has been no successful authentication for the given authenticator since boot.

Value: -1L

Public methods

authenticate

Added in API level 28
open fun authenticate(
    crypto: BiometricPrompt.CryptoObject, 
    cancel: CancellationSignal, 
    executor: Executor, 
    callback: BiometricPrompt.AuthenticationCallback
): Unit

This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric. It terminates when android.hardware.biometrics.BiometricPrompt.AuthenticationCallback#onAuthenticationError(int,java.lang.CharSequence) is called, when android.hardware.biometrics.BiometricPrompt.AuthenticationCallback#onAuthenticationSucceeded(android.hardware.biometrics.BiometricPrompt.AuthenticationResult), or when the user dismisses the system-provided dialog, at which point the crypto object becomes invalid. This operation can be canceled by using the provided cancel object. The application will receive authentication errors through AuthenticationCallback, and button events through the corresponding callback set in Builder.setNegativeButton(CharSequence, Executor,. It is safe to reuse the BiometricPrompt object, and calling BiometricPrompt.authenticate(CancellationSignal, Executor, while an existing authentication attempt is occurring will stop the previous client and start a new authentication. The interrupted client will receive a cancelled notification through AuthenticationCallback.onAuthenticationError(int,.

Note: Applications generally should not cancel and start authentication in quick succession. For example, to properly handle authentication across configuration changes, it's recommended to use BiometricPrompt in a fragment with setRetainInstance(true). By doing so, the application will not need to cancel/restart authentication during the configuration change.

Per the Android CDD, only biometric authenticators that meet or exceed the requirements for Strong are permitted to integrate with Keystore to perform related cryptographic operations. Therefore, it is an error to call this method after explicitly calling Builder.setAllowedAuthenticators(int) with any biometric strength other than Authenticators.BIOMETRIC_STRONG.
Requires android.Manifest.permission#USE_BIOMETRIC

Parameters
crypto BiometricPrompt.CryptoObject: A cryptographic operation to be unlocked after successful authentication. This value cannot be null.
cancel CancellationSignal: An object that can be used to cancel authentication. This value cannot be null.
executor Executor: An executor to handle callback events. This value cannot be null. Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
callback BiometricPrompt.AuthenticationCallback: An object to receive authentication events. This value cannot be null.
Exceptions
java.lang.IllegalArgumentException If any argument is null, or if the allowed biometric authenticator strength is explicitly set to Authenticators.BIOMETRIC_WEAK. Prior to android.os.Build.VERSION_CODES#R, this exception is also thrown if Builder.setDeviceCredentialAllowed(boolean) was explicitly set to true.

authenticate

Added in API level 28
open fun authenticate(
    cancel: CancellationSignal, 
    executor: Executor, 
    callback: BiometricPrompt.AuthenticationCallback
): Unit

This call warms up the biometric hardware, displays a system-provided dialog, and starts scanning for a biometric. It terminates when android.hardware.biometrics.BiometricPrompt.AuthenticationCallback#onAuthenticationError(int,java.lang.CharSequence) is called, when android.hardware.biometrics.BiometricPrompt.AuthenticationCallback#onAuthenticationSucceeded(android.hardware.biometrics.BiometricPrompt.AuthenticationResult) is called, or when the user dismisses the system-provided dialog. This operation can be canceled by using the provided cancel object. The application will receive authentication errors through AuthenticationCallback, and button events through the corresponding callback set in android.hardware.biometrics.BiometricPrompt.Builder#setNegativeButton(java.lang.CharSequence,java.util.concurrent.Executor,android.content.DialogInterface.OnClickListener). It is safe to reuse the BiometricPrompt object, and calling android.hardware.biometrics.BiometricPrompt#authenticate(android.os.CancellationSignal,java.util.concurrent.Executor,android.hardware.biometrics.BiometricPrompt.AuthenticationCallback) while an existing authentication attempt is occurring will stop the previous client and start a new authentication. The interrupted client will receive a cancelled notification through android.hardware.biometrics.BiometricPrompt.AuthenticationCallback#onAuthenticationError(int,java.lang.CharSequence).

Note: Applications generally should not cancel and start authentication in quick succession. For example, to properly handle authentication across configuration changes, it's recommended to use BiometricPrompt in a fragment with setRetainInstance(true). By doing so, the application will not need to cancel/restart authentication during the configuration change.
Requires android.Manifest.permission#USE_BIOMETRIC

Parameters
cancel CancellationSignal: An object that can be used to cancel authentication. This value cannot be null.
executor Executor: An executor to handle callback events. This value cannot be null. Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
callback BiometricPrompt.AuthenticationCallback: An object to receive authentication events. This value cannot be null.
Exceptions
java.lang.IllegalArgumentException If any of the arguments are null.

getAllowedAuthenticators

Added in API level 30
open fun getAllowedAuthenticators(): Int

Gets the type(s) of authenticators that may be invoked by the prompt to authenticate the user, as set by Builder.setAllowedAuthenticators(int).

Return
Int A bit field representing the type(s) of authenticators that may be invoked by the prompt (as defined by Authenticators), or 0 if this field was not set. This value may be null.

getContentView

Added in API level 35
open fun getContentView(): PromptContentView?

Gets the content view for the prompt, as set by Builder.setContentView(PromptContentView).

Return
PromptContentView? The content view for the prompt, or null if the prompt has no content view.

getDescription

Added in API level 30
open fun getDescription(): CharSequence?

Gets the description for the prompt, as set by Builder.setDescription(CharSequence).

Return
CharSequence? The description for the prompt, or null if the prompt has no description.

getLogoBitmap

Added in API level 35
open fun getLogoBitmap(): Bitmap?

Gets the logo bitmap for the prompt, as set by Builder.setLogoBitmap(Bitmap). Currently for system applications use only.
Requires android.Manifest.permission#SET_BIOMETRIC_DIALOG_ADVANCED

Return
Bitmap? The logo bitmap of the prompt, or null if the prompt has no logo bitmap set.

getLogoDescription

Added in API level 35
open fun getLogoDescription(): String?

Gets the logo description for the prompt, as set by Builder.setLogoDescription(String). Currently for system applications use only.
Requires android.Manifest.permission#SET_BIOMETRIC_DIALOG_ADVANCED

Return
String? The logo description of the prompt, or null if the prompt has no logo description set.

getLogoRes

Added in API level 35
open fun getLogoRes(): Int

Gets the drawable resource of the logo for the prompt, as set by Builder.setLogoRes(int). Currently for system applications use only.
Requires android.Manifest.permission#SET_BIOMETRIC_DIALOG_ADVANCED

Return
Int The drawable resource of the logo, or 0 if the prompt has no logo resource set.

getNegativeButtonText

Added in API level 30
open fun getNegativeButtonText(): CharSequence?

Gets the negative button text for the prompt, as set by Builder.setNegativeButton(CharSequence, Executor, DialogInterface.OnClickListener).

Return
CharSequence? The negative button text for the prompt, or null if no negative button text was set.

getSubtitle

Added in API level 30
open fun getSubtitle(): CharSequence?

Gets the subtitle for the prompt, as set by Builder.setSubtitle(CharSequence).

Return
CharSequence? The subtitle for the prompt, or null if the prompt has no subtitle.

getTitle

Added in API level 30
open fun getTitle(): CharSequence

Gets the title for the prompt, as set by Builder.setTitle(CharSequence).

Return
CharSequence The title of the prompt, which is guaranteed to be non-null.

isConfirmationRequired

Added in API level 30
open fun isConfirmationRequired(): Boolean

Determines if explicit user confirmation is required by the prompt, as set by Builder.setConfirmationRequired(boolean).

Return
Boolean true if explicit user confirmation is required, or false otherwise.