Patterns - Fingerprint

Authentication

Your app’s users can set up the option to log in or authenticate purchases using Fingerprint.

When a user action needs to be authenticated, display the Fingerprint authentication dialog in place of your login screen.

Title

Use the title to describe the action being performed, such as “Sign in.” The title should not be used to introduce Fingerprint.

Secondary text

Use the phase “Confirm fingerprint.” This wording maintains consistency with Android Settings.

You may combine the above text with the associated user action, such as “Confirm fingerprint to complete purchase.”

Specifications for confirm fingerprint dialog:
Dialog left and right padding: 24dp
Dialog top padding: 24dp
Title bottom margin: 20dp
Subtitle bottom margin: 28dp
Fingerprint icon right margin: 16dp
Touch sensor height: 40dp
Touch sensor call to action top and bottom padding: 12dp
Button container height: 52dp
Button container bottom padding: 8dp
Button height: 36p
Button right padding: 8dp

Behavior

Default state

Ask the user to put their finger on the sensor.

Success state

Once the fingerprint is recognized, change the dialog to a success message and the image to the fingerprint icon with the check mark.

Specification:

Use your app’s primary color for the success text and icon, or Teal 500 (#009688)

Success states should avoid:

Displaying two success states simultaneously
Extensive transitions between default and success states

Success message that the fingerprint has been recognized.

Failure state

Upon failure, provide a clear indication that the user’s fingerprint was not recognized and that they should try again, using the error icon either with or without a status message.

Specification:

Use your app’s color assigned to failure states, or Deep Orange 600 (#F4511E)

Failure states should avoid:

Extensive transitions between default and failure states

Error message stating the fingerprint was not recognized.

Exiting

Provide alternative ways to exit the dialog. At minimum, provide an affordance to close the Fingerprint dialog, such as a “Cancel” button.

Authentication alternatives

Fingerprint should not be the only way to authenticate. Provide alternative authentication methods, such as:

User’s account password
App PIN
Device credentials

Fingerprint icon

Usage and size

The Fingerprint icon should be displayed at the standard system icon size, 24dp, within a 40dp circle.

Default icon

Users will be asked to look for this icon for places where they can use Fingerprint.

Specifications:

Circular background color: #607D8B
Works on white backgrounds

Tinted icon

The circle surrounding the icon can be customized with a color that provides appropriate contrast against the lines of the Fingerprint icon.

UIs with light backgrounds

Use the Fingerprint icon with a dark circle background.

Specifications:

Color: #FFFFFF
Opacity: 100%

Dark circle background with the Fingerprint icon for a light background.

UIs with dark backgrounds

Use the Fingerprint icon with a light circle background.

Specifications:

Color: #000000
Opacity: 54%

Icon with no circular background

Apps requiring a more versatile Fingerprint icon may eliminate the circular background.

Dialog box with icon with no circular background.

Reauthentication

Reauthentication applies when users need to confirm their identity before continuing.

Reauthentication uses:

To prevent unauthorized viewing of sensitive information
To guard against unauthorized purchases
When cryptographic keys expire and users are asked to reconfirm their identity

Alternatively, if a user forgets about Fingerprint authentication, you can ask users to use their backup password and remind them of the Fingerprint option next time.

Dialog asking user for their backup password