BiometricPrompt
class BiometricPrompt
A class that manages a system-provided biometric prompt. On devices running Android 9.0 (API 28) and above, this will show a system-provided authentication prompt, using one of the device's supported biometric modalities (fingerprint, iris, face, etc) with Class 2 or Class 3 strength. Prior to Android 9.0, this will instead show a custom fingerprint authentication dialog. The prompt will persist across configuration changes unless explicitly canceled. For security reasons, the prompt will be dismissed when the client application is no longer in the foreground.
To persist authentication across configuration changes, developers should (re)create the prompt every time the activity/fragment is created. Instantiating the prompt with a new callback early in the fragment/activity lifecycle (e.g. in onCreate()) will allow the ongoing authentication session's callbacks to be received by the new fragment/activity instance. Note that cancelAuthentication() should not be called, and authenticate() does not need to be invoked during activity/fragment creation.
Note that if multiple instances of BiometricPrompt are created within a single Fragment or Activity, only the callback registered with the last created instance will be saved and receive authentication results. This behavior can lead to unexpected results if multiple independent biometric authentication flows are attempted within the same Fragment or Activity. It is highly recommended to avoid creating multiple BiometricPrompt instances in this scenario.
Summary
Nested types |
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abstract class BiometricPrompt.AuthenticationCallbackA collection of methods that may be invoked by |
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A container for data passed to |
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A wrapper class for the crypto objects supported by |
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A set of configurable options for how the |
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A builder used to set individual options for the |
Constants |
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const Int |
Authentication type reported by |
const Int |
Authentication type reported by |
const Int |
Authentication type reported by |
const Int |
ERROR_CANCELED = 5The operation was canceled because the biometric sensor is unavailable. |
const Int |
The user pressed the more options button on |
const Int |
ERROR_HW_NOT_PRESENT = 12The device does not have the required authentication hardware. |
const Int |
The hardware is unavailable. |
const Int |
Identity Check is currently not active. |
const Int |
ERROR_LOCKOUT = 7The operation was canceled because the API is locked out due to too many attempts. |
const Int |
The operation was canceled because |
const Int |
The user pressed the negative button. |
const Int |
ERROR_NO_BIOMETRICS = 11The user does not have any biometrics enrolled. |
const Int |
The device does not have pin, pattern, or password set up. |
const Int |
ERROR_NO_SPACE = 4The operation can't be completed because there is not enough device storage remaining. |
const Int |
A security vulnerability has been discovered with one or more hardware sensors. |
const Int |
ERROR_TIMEOUT = 3The current operation has been running too long and has timed out. |
const Int |
The sensor was unable to process the current image. |
const Int |
ERROR_USER_CANCELED = 10The user canceled the operation. |
const Int |
ERROR_VENDOR = 8The operation failed due to a vendor-specific error. |
Public constructors |
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BiometricPrompt(Constructs a |
BiometricPrompt(Constructs a |
BiometricPrompt(Constructs a |
BiometricPrompt(Constructs a |
Public functions |
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Unit |
Shows the biometric prompt to the user. |
Unit |
authenticate(Shows the biometric prompt to the user. |
Unit |
Cancels the ongoing authentication session and dismisses the prompt. |
Constants
AUTHENTICATION_RESULT_TYPE_BIOMETRIC
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).
AUTHENTICATION_RESULT_TYPE_DEVICE_CREDENTIAL
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.
AUTHENTICATION_RESULT_TYPE_UNKNOWN
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.
ERROR_CANCELED
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.
ERROR_CONTENT_VIEW_MORE_OPTIONS_BUTTON
const val ERROR_CONTENT_VIEW_MORE_OPTIONS_BUTTON = 22: Int
The user pressed the more options button on PromptContentViewWithMoreOptionsButton set by setContentView
ERROR_HW_NOT_PRESENT
const val ERROR_HW_NOT_PRESENT = 12: Int
The device does not have the required authentication hardware.
ERROR_HW_UNAVAILABLE
const val ERROR_HW_UNAVAILABLE = 1: Int
The hardware is unavailable. Try again later.
ERROR_IDENTITY_CHECK_NOT_ACTIVE
const val ERROR_IDENTITY_CHECK_NOT_ACTIVE = 20: Int
Identity Check is currently not active. This device either doesn't have this feature enabled, or it's not considered in a high-risk environment that requires extra security measures for accessing sensitive data.
ERROR_LOCKOUT
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.
ERROR_LOCKOUT_PERMANENT
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).
ERROR_NEGATIVE_BUTTON
const val ERROR_NEGATIVE_BUTTON = 13: Int
The user pressed the negative button.
ERROR_NO_BIOMETRICS
const val ERROR_NO_BIOMETRICS = 11: Int
The user does not have any biometrics enrolled.
ERROR_NO_DEVICE_CREDENTIAL
const val ERROR_NO_DEVICE_CREDENTIAL = 14: Int
The device does not have pin, pattern, or password set up.
ERROR_NO_SPACE
const val ERROR_NO_SPACE = 4: Int
The operation can't be completed because there is not enough device storage remaining.
ERROR_SECURITY_UPDATE_REQUIRED
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.
ERROR_TIMEOUT
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.
ERROR_UNABLE_TO_PROCESS
const val ERROR_UNABLE_TO_PROCESS = 2: Int
The sensor was unable to process the current image.
ERROR_USER_CANCELED
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.
ERROR_VENDOR
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.
Public constructors
BiometricPrompt
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()).
| Parameters | |
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activity: FragmentActivity |
The activity of the client application that will host the prompt. |
callback: BiometricPrompt.AuthenticationCallback |
The object that will receive and process authentication events. |
BiometricPrompt
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()).
| Parameters | |
|---|---|
fragment: Fragment |
The fragment of the client application that will host the prompt. |
callback: BiometricPrompt.AuthenticationCallback |
The object that will receive and process authentication events. |
BiometricPrompt
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()).
| Parameters | |
|---|---|
activity: FragmentActivity |
The activity of the client application that will host the prompt. |
executor: Executor |
The executor that will be used to run |
callback: BiometricPrompt.AuthenticationCallback |
The object that will receive and process authentication events. |
BiometricPrompt
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()).
| Parameters | |
|---|---|
fragment: Fragment |
The fragment of the client application that will host the prompt. |
executor: Executor |
The executor that will be used to run |
callback: BiometricPrompt.AuthenticationCallback |
The object that will receive and process authentication events. |
Public functions
authenticate
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.
| Parameters | |
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info: BiometricPrompt.PromptInfo |
An object describing the appearance and behavior of the prompt. |
| See also | |
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authenticate |
authenticate
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.
| Parameters | |
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info: BiometricPrompt.PromptInfo |
An object describing the appearance and behavior of the prompt. |
crypto: BiometricPrompt.CryptoObject |
A crypto object to be associated with this authentication. |
| Throws | |
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java.lang.IllegalArgumentException |
If any of the allowed authenticator types specified by |
| See also | |
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authenticate |
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setAllowedAuthenticators |
cancelAuthentication
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.